NMR imaging of density distributions in tablets.

PubMed

Djemai, A; Sinka, I C

2006-08-17

This paper describes the use of (1)H nuclear magnetic resonance (NMR) for 3D mapping of the relative density distribution in pharmaceutical tablets manufactured under controlled conditions. The tablets are impregnated with a compatible liquid. The technique involves imaging of the presence of liquid which occupies the open pore space. The method does not require special calibration as the signal is directly proportional to the porosity for the imaging conditions used. The NMR imaging method is validated using uniform density flat faced tablets and also by direct comparison with X-ray computed tomography. The results illustrate (1) the effect of die wall friction on density distribution by compressing round, curved faced tablets using clean and pre-lubricated tooling, (2) the evolution of density distribution during compaction for both clean and pre-lubricated die wall conditions, by imaging tablets compressed to different compaction forces, and (3) the effect of tablet image on density distribution by compressing two complex shape tablets in identical dies to the same average density using punches with different geometries.

NMR-based diffusion pore imaging.

PubMed

Laun, Frederik Bernd; Kuder, Tristan Anselm; Wetscherek, Andreas; Stieltjes, Bram; Semmler, Wolfhard

2012-08-01

Nuclear magnetic resonance (NMR) diffusion experiments offer a unique opportunity to study boundaries restricting the diffusion process. In a recent Letter [Phys. Rev. Lett. 107, 048102 (2011)], we introduced the idea and concept that such diffusion experiments can be interpreted as NMR imaging experiments. Consequently, images of closed pores, in which the spins diffuse, can be acquired. In the work presented here, an in-depth description of the diffusion pore imaging technique is provided. Image artifacts due to gradient profiles of finite duration, field inhomogeneities, and surface relaxation are considered. Gradients of finite duration lead to image blurring and edge enhancement artifacts. Field inhomogeneities have benign effects on diffusion pore images, and surface relaxation can lead to a shrinkage and shift of the pore image. The relation between boundary structure and the imaginary part of the diffusion weighted signal is analyzed, and it is shown that information on pore coherence can be obtained without the need to measure the phase of the diffusion weighted signal. Moreover, it is shown that quite arbitrary gradient profiles can be used for diffusion pore imaging. The matrices required for numerical calculations are stated and provided as supplemental material.

Novel detection schemes of nuclear magnetic resonance and magnetic resonance imaging: applications from analytical chemistry to molecular sensors.

PubMed

Harel, Elad; Schröder, Leif; Xu, Shoujun

2008-01-01

Nuclear magnetic resonance (NMR) is a well-established analytical technique in chemistry. The ability to precisely control the nuclear spin interactions that give rise to the NMR phenomenon has led to revolutionary advances in fields as diverse as protein structure determination and medical diagnosis. Here, we discuss methods for increasing the sensitivity of magnetic resonance experiments, moving away from the paradigm of traditional NMR by separating the encoding and detection steps of the experiment. This added flexibility allows for diverse applications ranging from lab-on-a-chip flow imaging and biological sensors to optical detection of magnetic resonance imaging at low magnetic fields. We aim to compare and discuss various approaches for a host of problems in material science, biology, and physics that differ from the high-field methods routinely used in analytical chemistry and medical imaging.

Mathematical Development and Computational Analysis of Harmonic Phase-Magnetic Resonance Imaging (HARP-MRI) Based on Bloch Nuclear Magnetic Resonance (NMR) Diffusion Model for Myocardial Motion.

PubMed

Dada, Michael O; Jayeoba, Babatunde; Awojoyogbe, Bamidele O; Uno, Uno E; Awe, Oluseyi E

2017-09-13

Harmonic Phase-Magnetic Resonance Imaging (HARP-MRI) is a tagged image analysis method that can measure myocardial motion and strain in near real-time and is considered a potential candidate to make magnetic resonance tagging clinically viable. However, analytical expressions of radially tagged transverse magnetization in polar coordinates (which is required to appropriately describe the shape of the heart) have not been explored because the physics required to directly connect myocardial deformation of tagged Nuclear Magnetic Resonance (NMR) transverse magnetization in polar geometry and the appropriate harmonic phase parameters are not yet available. The analytical solution of Bloch NMR diffusion equation in spherical geometry with appropriate spherical wave tagging function is important for proper analysis and monitoring of heart systolic and diastolic deformation with relevant boundary conditions. In this study, we applied Harmonic Phase MRI method to compute the difference between tagged and untagged NMR transverse magnetization based on the Bloch NMR diffusion equation and obtained radial wave tagging function for analysis of myocardial motion. The analytical solution of the Bloch NMR equations and the computational simulation of myocardial motion as developed in this study are intended to significantly improve healthcare for accurate diagnosis, prognosis and treatment of cardiovascular related deceases at the lowest cost because MRI scan is still one of the most expensive anywhere. The analysis is fundamental and significant because all Magnetic Resonance Imaging techniques are based on the Bloch NMR flow equations.

Remotely detected high-field MRI of porous samples

NASA Astrophysics Data System (ADS)

Seeley, Juliette A.; Han, Song-I.; Pines, Alexander

2004-04-01

Remote detection of NMR is a novel technique in which an NMR-active sensor surveys an environment of interest and retains memory of that environment to be recovered at a later time in a different location. The NMR or MRI information about the sensor nucleus is encoded and stored as spin polarization at the first location and subsequently moved to a different physical location for optimized detection. A dedicated probe incorporating two separate radio frequency (RF)—circuits was built for this purpose. The encoding solenoid coil was large enough to fit around the bulky sample matrix, while the smaller detection solenoid coil had not only a higher quality factor, but also an enhanced filling factor since the coil volume comprised purely the sensor nuclei. We obtained two-dimensional (2D) void space images of two model porous samples with resolution less than 1.4 mm 2. The remotely reconstructed images demonstrate the ability to determine fine structure with image quality superior to their directly detected counterparts and show the great potential of NMR remote detection for imaging applications that suffer from low sensitivity due to low concentrations and filling factor.

Spatially resolved D-T(2) correlation NMR of porous media.

PubMed

Zhang, Yan; Blümich, Bernhard

2014-05-01

Within the past decade, 2D Laplace nuclear magnetic resonance (NMR) has been developed to analyze pore geometry and diffusion of fluids in porous media on the micrometer scale. Many objects like rocks and concrete are heterogeneous on the macroscopic scale, and an integral analysis of microscopic properties provides volume-averaged information. Magnetic resonance imaging (MRI) resolves this spatial average on the contrast scale set by the particular MRI technique. Desirable contrast parameters for studies of fluid transport in porous media derive from the pore-size distribution and the pore connectivity. These microscopic parameters are accessed by 1D and 2D Laplace NMR techniques. It is therefore desirable to combine MRI and 2D Laplace NMR to image functional information on fluid transport in porous media. Because 2D Laplace resolved MRI demands excessive measuring time, this study investigates the possibility to restrict the 2D Laplace analysis to the sum signals from low-resolution pixels, which correspond to pixels of similar amplitude in high-resolution images. In this exploratory study spatially resolved D-T2 correlation maps from glass beads and mortar are analyzed. Regions of similar contrast are first identified in high-resolution images to locate corresponding pixels in low-resolution images generated with D-T2 resolved MRI for subsequent pixel summation to improve the signal-to-noise ratio of contrast-specific D-T2 maps. This method is expected to contribute valuable information on correlated sample heterogeneity from the macroscopic and the microscopic scales in various types of porous materials including building materials and rock. Copyright © 2014 Elsevier Inc. All rights reserved.

Magnetic resonance imaging of granular materials

NASA Astrophysics Data System (ADS)

Stannarius, Ralf

2017-05-01

Magnetic Resonance Imaging (MRI) has become one of the most important tools to screen humans in medicine; virtually every modern hospital is equipped with a Nuclear Magnetic Resonance (NMR) tomograph. The potential of NMR in 3D imaging tasks is by far greater, but there is only "a handful" of MRI studies of particulate matter. The method is expensive, time-consuming, and requires a deep understanding of pulse sequences, signal acquisition, and processing. We give a short introduction into the physical principles of this imaging technique, describe its advantages and limitations for the screening of granular matter, and present a number of examples of different application purposes, from the exploration of granular packing, via the detection of flow and particle diffusion, to real dynamic measurements. Probably, X-ray computed tomography is preferable in most applications, but fast imaging of single slices with modern MRI techniques is unmatched, and the additional opportunity to retrieve spatially resolved flow and diffusion profiles without particle tracking is a unique feature.

Flow Quantification by Nuclear Magnetic Resonance Imaging

NASA Astrophysics Data System (ADS)

Vu, Anthony Tienhuan

1994-01-01

In this dissertation, a robust method for the measurement and visualization of flow field in laminar, complex and turbulent flows by Nuclear Magnetic Resonance Imaging utilizing flow induced Adiabatic Fast Passage (AFP) principle will be presented. This dissertation focuses on the application of AFP in spatially resolvable size vessels. We first review two main flow effects in NMR: time-of-flight and phase dispersion. The discussion of NMR flow imaging application - flow measurements and NMR angiography will be given. The theoretical framework of adiabatic passage will be discussed in order to explain the principle of flow-induced adiabatic passage tagging for flow imaging applications. From a knowledge of the basic flow-induced adiabatic passage principle, we propose a multi-zone AFP excitation scheme to deal with flow in a curved tube, branches and constrictions, i.e. complex and turbulent flow regimes. The technique provides a quick and simple way to acquire flow profiles simultaneously at several locations and arbitrary orientations inside the field-of-view. The flow profile is the time-averaged evolution of the labeled flowing material. Results obtained using a carotid bifurcation and circular jet phantoms are similar to the previous experimental studies employing laser Doppler Anemometry, and other flow visualization techniques. In addition, the preliminary results obtained with a human volunteer support the feasibility of the technique for in vivo flow quantification. Finally, a quantitative comparison of flow measurement of the new proposed techniques with the more established Phase Contrast MRA was performed. The results show excellent correlation between the two methods and with the standard volumetric flow rate measurement indicating that the flow measurements obtained using this technique are reliable and accurate under various flow regimes.

Predicting permeability with NMR imaging in the Edwards Limestone/Stuart City Trend

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dewitt, H.; Globe, M.; Sorenson, R.

1996-09-01

Determining pore size and pore geometry relationships in carbonate rocks and relating both to permeability is difficult using traditional logging methods. This problem is further complicated by the presence of abundant microporosity (pore size less than 62 microns) in the Edwards Limestone. The use of Nuclear Magnetic Resonance Imaging (NMR) allows for an alternative approach to evaluating the pore types present by examining the response of hydrogen nuclei contained within the free fluid pore space. By testing the hypothesis that larger pore types exhibit an NMR signal decay much slower than smaller pore types, an estimate of the pore typemore » present, (i.e.) vuggy, interparticle, or micropores, can be inferred. Calibration of the NMR decay curve to known samples with measured petrophysical properties allows for improved predictability of pore types and permeability. The next stage of the analysis involves the application of the calibration technique to the borehole environment using an NMR logging tool to more accurately predict production performance.« less

Surface NMR imaging with simultaneously energized transmission loops

NASA Astrophysics Data System (ADS)

Irons, T. P.; Kass, A.; Parsekian, A.

2016-12-01

Surface nuclear magnetic resonance (sNMR) is a unique geophysical technique which allows for the direct detection of liquid-phase water. In saturated media the sNMR response also provides estimates of hydrologic properties including porosity and permeability. The most common survey deployment consists of a single coincident loop performing both transmission and receiving. Because the sNMR method is relatively slow, tomography using coincident loops is time-intensive. Surveys using multiple receiver loops (but a single transmitter) provide additional sensitivity; however, they still require iterating transmission over the loops, and do not decrease survey acquisition time. In medical rotating frame imaging, arrays of transmitters are employed in order to decrease acquisition time, whilst optimizing image resolving power-a concept which we extend to earth's field imaging. Using simultaneously energized transmission loops decreases survey time linearly with the number of channels. To demonstrate the efficacy and benefits of multiple transmission loops, we deployed simultaneous sNMR transmission arrays using minimally coupled loops and a specially modified instrument at the Red Buttes Hydrogeophysics Experiment Site-a well-characterized location near Laramie, Wyoming. The proposed survey proved capable of acquiring multiple-channel imaging data with comparable noise levels to figure-eight configurations. Finally, the channels can be combined after acquisition or inverted simultaneously to provide composite datasets and images. This capability leverages the improved near surface resolving power of small loops but retains sensitivity to deep media through the use of synthetic aperature receivers. As such, simultaneously acquired loop arrays provide a great deal of flexibility.

SQUIDs vs. Induction Coils for Ultra-Low Field Nuclear Magnetic Resonance: Experimental and Simulation Comparison

PubMed Central

Matlashov, Andrei N.; Schultz, Larry J.; Espy, Michelle A.; Kraus, Robert H.; Savukov, Igor M.; Volegov, Petr L.; Wurden, Caroline J.

2011-01-01

Nuclear magnetic resonance (NMR) is widely used in medicine, chemistry and industry. One application area is magnetic resonance imaging (MRI). Recently it has become possible to perform NMR and MRI in the ultra-low field (ULF) regime requiring measurement field strengths of the order of only 1 Gauss. This technique exploits the advantages offered by superconducting quantum interference devices or SQUIDs. Our group has built SQUID based MRI systems for brain imaging and for liquid explosives detection at airport security checkpoints. The requirement for liquid helium cooling limits potential applications of ULF MRI for liquid identification and security purposes. Our experimental comparative investigation shows that room temperature inductive magnetometers may provide enough sensitivity in the 3–10 kHz range and can be used for fast liquid explosives detection based on ULF NMR technique. We describe experimental and computer-simulation results comparing multichannel SQUID based and induction coils based instruments that are capable of performing ULF MRI for liquid identification. PMID:21747638

NMR of thin layers using a meanderline surface coil

DOEpatents

Cowgill, Donald F.

2001-01-01

A miniature meanderline sensor coil which extends the capabilities of nuclear magnetic resonance (NMR) to provide analysis of thin planar samples and surface layer geometries. The sensor coil allows standard NMR techniques to be used to examine thin planar (or curved) layers, extending NMRs utility to many problems of modern interest. This technique can be used to examine contact layers, non-destructively depth profile into films, or image multiple layers in a 3-dimensional sense. It lends itself to high resolution NMR techniques of magic angle spinning and thus can be used to examine the bonding and electronic structure in layered materials or to observe the chemistry associated with aging coatings. Coupling this sensor coil technology with an arrangement of small magnets will produce a penetrator probe for remote in-situ chemical analysis of groundwater or contaminant sediments. Alternatively, the sensor coil can be further miniaturized to provide sub-micron depth resolution within thin films or to orthoscopically examine living tissue. This thin-layer NMR technique using a stationary meanderline coil in a series-resonant circuit has been demonstrated and it has been determined that the flat meanderline geometry has about he same detection sensitivity as a solenoidal coil, but is specifically tailored to examine planar material layers, while avoiding signals from the bulk.

Environmental optimization and shielding for NMR experiments and imaging in the earth's magnetic field.

PubMed

Favre, B; Bonche, J P; Meheir, H; Peyrin, J O

1990-02-01

For many years, a number of laboratories have been working on the applications of very low field NMR. In 1985, our laboratory presented the first NMR images using the earth's magnetic field. However, the use of this technique was limited by the weakness of the signal and the disturbing effects of the environment on the signal-to-noise ratio and on the homogeneity of the static magnetic field. Therefore experiments has to be performed in places with low environmental disturbances, such as open country or large parks. In 1986, we installed a new station in Lyon, in the town's hostile environment. Good NMR signals can now be obtained (with a signal-to-noise ratio better than 200 and a time constant T2 better than 3s for 200-mnl water samples and at a temperature of about 40 degrees C). We report the terrace roof of our faculty building. Gradient coils were used to correct the local inhomogeneities of the earth's magnetic field. We show FIDs and MR images of water-filled tubes made with or without these improvements.

Prospects for sub-micron solid state nuclear magnetic resonance imaging with low-temperature dynamic nuclear polarization.

PubMed

Thurber, Kent R; Tycko, Robert

2010-06-14

We evaluate the feasibility of (1)H nuclear magnetic resonance (NMR) imaging with sub-micron voxel dimensions using a combination of low temperatures and dynamic nuclear polarization (DNP). Experiments are performed on nitroxide-doped glycerol-water at 9.4 T and temperatures below 40 K, using a 30 mW tunable microwave source for DNP. With DNP at 7 K, a 0.5 microL sample yields a (1)H NMR signal-to-noise ratio of 770 in two scans with pulsed spin-lock detection and after 80 db signal attenuation. With reasonable extrapolations, we infer that (1)H NMR signals from 1 microm(3) voxel volumes should be readily detectable, and voxels as small as 0.03 microm(3) may eventually be detectable. Through homonuclear decoupling with a frequency-switched Lee-Goldburg spin echo technique, we obtain 830 Hz (1)H NMR linewidths at low temperatures, implying that pulsed field gradients equal to 0.4 G/d or less would be required during spatial encoding dimensions of an imaging sequence, where d is the resolution in each dimension.

Prospects for Sub-Micron Solid State Nuclear Magnetic Resonance Imaging with Low-Temperature Dynamic Nuclear Polarization

PubMed Central

Thurber, Kent R.; Tycko, Robert

2010-01-01

Summary We evaluate the feasibility of 1H nuclear magnetic resonance (NMR) imaging with sub-micron voxel dimensions using a combination of low temperatures and dynamic nuclear polarization (DNP). Experiments are performed on nitroxide-doped glycerol/water at 9.4 T and temperatures below 40 K, using a 30 mW tunable microwave source for DNP. With DNP at 7 K, a 0.5 µl sample yields a 1H NMR signal-to-noise ratio of 770 in two scans with pulsed spin-lock detection and after 80 db signal attenuation. With reasonable extrapolations, we infer that 1H NMR signals from 1 µm3 voxel volumes should be readily detectable, and voxels as small as 0.03 µm3 may eventually be detectable. Through homonuclear decoupling with a frequency-switched Lee-Goldburg spin echo technique, we obtain 830 Hz 1H NMR linewidths at low temperatures, implying that pulsed field gradients equal to 0.4 G/d or less would be required during spatial encoding dimensions of an imaging sequence, where d is the resolution in each dimension. PMID:20458431

Computational Diffusion Magnetic Resonance Imaging Based on Time-Dependent Bloch NMR Flow Equation and Bessel Functions.

PubMed

Awojoyogbe, Bamidele O; Dada, Michael O; Onwu, Samuel O; Ige, Taofeeq A; Akinwande, Ninuola I

2016-04-01

Magnetic resonance imaging (MRI) uses a powerful magnetic field along with radio waves and a computer to produce highly detailed "slice-by-slice" pictures of virtually all internal structures of matter. The results enable physicians to examine parts of the body in minute detail and identify diseases in ways that are not possible with other techniques. For example, MRI is one of the few imaging tools that can see through bones, making it an excellent tool for examining the brain and other soft tissues. Pulsed-field gradient experiments provide a straightforward means of obtaining information on the translational motion of nuclear spins. However, the interpretation of the data is complicated by the effects of restricting geometries as in the case of most cancerous tissues and the mathematical concept required to account for this becomes very difficult. Most diffusion magnetic resonance techniques are based on the Stejskal-Tanner formulation usually derived from the Bloch-Torrey partial differential equation by including additional terms to accommodate the diffusion effect. Despite the early success of this technique, it has been shown that it has important limitations, the most of which occurs when there is orientation heterogeneity of the fibers in the voxel of interest (VOI). Overcoming this difficulty requires the specification of diffusion coefficients as function of spatial coordinate(s) and such a phenomenon is an indication of non-uniform compartmental conditions which can be analyzed accurately by solving the time-dependent Bloch NMR flow equation analytically. In this study, a mathematical formulation of magnetic resonance flow sequence in restricted geometry is developed based on a general second order partial differential equation derived directly from the fundamental Bloch NMR flow equations. The NMR signal is obtained completely in terms of NMR experimental parameters. The process is described based on Bessel functions and properties that can make it possible to distinguish cancerous cells from normal cells. A typical example of liver distinguished from gray matter, white matter and kidney is demonstrated. Bessel functions and properties are specifically needed to show the direct effect of the instantaneous velocity on the NMR signal originating from normal and abnormal tissues.

Improvements in Technique of NMR Imaging and NMR Diffusion Measurements in the Presence of Background Gradients.

NASA Astrophysics Data System (ADS)

Lian, Jianyu

In this work, modification of the cosine current distribution rf coil, PCOS, has been introduced and tested. The coil produces a very homogeneous rf magnetic field, and it is inexpensive to build and easy to tune for multiple resonance frequency. The geometrical parameters of the coil are optimized to produce the most homogeneous rf field over a large volume. To avoid rf field distortion when the coil length is comparable to a quarter wavelength, a parallel PCOS coil is proposed and discussed. For testing rf coils and correcting B _1 in NMR experiments, a simple, rugged and accurate NMR rf field mapping technique has been developed. The method has been tested and used in 1D, 2D, 3D and in vivo rf mapping experiments. The method has been proven to be very useful in the design of rf coils. To preserve the linear relation between rf output applied on an rf coil and modulating input for an rf modulating -amplifying system of NMR imaging spectrometer, a quadrature feedback loop is employed in an rf modulator with two orthogonal rf channels to correct the amplitude and phase non-linearities caused by the rf components in the rf system. The modulator is very linear over a large range and it can generate an arbitrary rf shape. A diffusion imaging sequence has been developed for measuring and imaging diffusion in the presence of background gradients. Cross terms between the diffusion sensitizing gradients and background gradients or imaging gradients can complicate diffusion measurement and make the interpretation of NMR diffusion data ambiguous, but these have been eliminated in this method. Further, the background gradients has been measured and imaged. A dipole random distribution model has been established to study background magnetic fields Delta B and background magnetic gradients G_0 produced by small particles in a sample when it is in a B_0 field. From this model, the minimum distance that a spin can approach a particle can be determined by measuring and <{bf G}_sp{0 }{2}>. From this model, the particle concentration in a sample can be determined by measuring the lineshape of a free induction decay (fid).

In situ nuclear magnetic resonance microimaging of live biofilms in a microchannel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renslow, R. S.; Marshall, M. J.; Tucker, A. E.

Nuclear magnetic resonance (NMR) microimaging and spectroscopy was used to interrogate fluids of biological importance (e.g., water, buffer, medium solution) and live biofilms in a microchannel compatible for analyses at ambient pressure and under vacuum. Studies using buffer, growth medium, and actively growing Shewanella oneidensis biofilms were used to demonstrate in situ NMR microimaging measurement capabilities including velocity mapping, diffusion coefficient mapping, relaxometry, localized spectroscopy, and 2D and 3D imaging within a microchannel suitable for different analytical platforms. This technique is promising for diverse applications of correlative imaging using a portable microfluidic platform.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koeller, E.; Dobmann, G.; Kuhn, W.

Initial results are presented on the application of NMR techniques to prepregs in order to characterize the crosslink state under exposure to room and elevated (50 C) temperature. The experiments were conducted with a MSL-400 Bruker NMR spectrometer and microimaging system which works at 400 MHz. Aside from the sensitive measurement of the cross-link density there is also the potential to separate the influence of moisture content as a further parameter contributing to the aging process. It is shown that these experimental results correlate with results of destructive tests and document the potential of NMR as a NDT tool. Anmore » NMR-image of the moisture distribution in a glassfiber reinforced expoxy resin sample is shown. 17 refs.« less

SQUIDs vs. Faraday coils for ultlra-low field nuclear magnetic resonance: experimental and simulation comparison

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matlashov, Andrei N; Espy, Michelle A; Kraus, Robert H

2010-01-01

Nuclear magnetic resonance (NMR) methods are widely used in medicine, chemistry and industry. One application area is magnetic resonance imaging or MRI. Recently it has become possible to perform NMR and MRI in ultra-low field (ULF) regime that requires measurement field strengths only of the order of 1 Gauss. These techniques exploit the advantages offered by superconducting quantum interference devices or SQUIDs. Our group at LANL has built SQUID based MRI systems for brain imaging and for liquid explosives detection at airports security checkpoints. The requirement for liquid helium cooling limits potential applications of ULF MRI for liquid identification andmore » security purposes. Our experimental comparative investigation shows that room temperature inductive magnetometers provide enough sensitivity in the 3-10 kHz range and can be used for fast liquid explosives detection based on ULF NMR/MRI technique. We describe an experimental and computer simulation comparison of the world's first multichannel SQUID based and Faraday coils based instruments that are capable of performing ULF MRI for liquids identification.« less

Investigating the Dissolution Performance of Amorphous Solid Dispersions Using Magnetic Resonance Imaging and Proton NMR.

PubMed

Tres, Francesco; Coombes, Steven R; Phillips, Andrew R; Hughes, Leslie P; Wren, Stephen A C; Aylott, Jonathan W; Burley, Jonathan C

2015-09-10

We have investigated the dissolution performance of amorphous solid dispersions of poorly water-soluble bicalutamide in a Kollidon VA64 polymeric matrix as a function of the drug loading (5% vs. 30% bicalutamide). A combined suite of state-of-the-art analytical techniques were employed to obtain a clear picture of the drug release, including an integrated magnetic resonance imaging UV-Vis flow cell system and 1H-NMR. Off-line 1H-NMR was used for the first time to simultaneously measure the dissolution profiles and rates of both the drug and the polymer from a solid dispersion. MRI and 1H-NMR data showed that the 5% drug loading compact erodes linearly, and that bicalutamide and Kollidon VA64 are released at approximately the same rate from the molecular dispersion. For the 30% extrudate, data indicated a slower water ingress into the compact which corresponds to a slower dissolution rate of both bicalutamide and Kollidon VA64.

Hyperpolarized xenon NMR and MRI signal amplification by gas extraction

PubMed Central

Zhou, Xin; Graziani, Dominic; Pines, Alexander

2009-01-01

A method is reported for enhancing the sensitivity of NMR of dissolved xenon by detecting the signal after extraction to the gas phase. We demonstrate hyperpolarized xenon signal amplification by gas extraction (Hyper-SAGE) in both NMR spectra and magnetic resonance images with time-of-flight information. Hyper-SAGE takes advantage of a change in physical phase to increase the density of polarized gas in the detection coil. At equilibrium, the concentration of gas-phase xenon is ≈10 times higher than that of the dissolved-phase gas. After extraction the xenon density can be further increased by several orders of magnitude by compression and/or liquefaction. Additionally, being a remote detection technique, the Hyper-SAGE effect is further enhanced in situations where the sample of interest would occupy only a small proportion of the traditional NMR receiver. Coupled with targeted xenon biosensors, Hyper-SAGE offers another path to highly sensitive molecular imaging of specific cell markers by detection of exhaled xenon gas. PMID:19805177

NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richards, T.

NMR imaging, NMR spectroscopic, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the central nervous system after helium beam in vivo irradiation of the rodent brain. The spectroscopic observations reported in this dissertation were made possible by development of methods for measuring the NMR parameters of the rodent brain in vivo and in vitro. The methods include (1) depth selective spectroscopy using an optimization of rf pulse energy based on a priori knowledge of N-acetyl aspartate and lipid spectra of the normal brain, (2) phase-encoded proton spectroscopy of the living rodent usingmore » a surface coil, and (3) dual aqueous and organic tissue extraction technique for spectroscopy. Radiation induced increases were observed in lipid and p-choline peaks of the proton spectrum, in vivo. Proton NMR spectroscopy measurements on brain extracts (aqueous and organic solvents) were made to observe chemical changes that could not be seen in vivo. Radiation-induced changes were observed in lactate, GABA, glutamate, and p-choline peak areas of the aqueous fraction spectra. In the organic fraction, decreases were observed in peak area ratios of the terminal-methyl peaks, the N-methyl groups of choline, and at a peak at 2.84 ppM (phosphatidyl ethanolamine and phosphatidyl serine resonances) relative to TMS. With histology and Evans blue injections, blood-brain barrier alternations were seen as early as 4 days after irradiation. 83 references, 53 figures.« less

Magnetic Resonance Imaging Studies of Process Rheology

DTIC Science & Technology

1990-08-14

a Twin - screw Extruder ................ 7 2.1.2 NMR Flow Imaging Studies ................................... 7U 2.2 Theoretical Modeling ...run at high production rates, mixed in a 50.8 mm fully intermeshing, co - rotating twin - screw off-line techniques of quality control may lead to very...Imaging Studies of............... A -1 Mixing in a Twin - Screw Extruder " B. "Stokesian Dynamics Simulation of Polyether-coated

Apparatus for preparing a solution of a hyperpolarized noble gas for NMR and MRI analysis

DOEpatents

Pines, Alexander [Berkeley, CA; Budinger, Thomas [Berkeley, CA; Navon, Gil [Ramat Gan, IL; Song, Yi-Qiao [Berkeley, CA; Appelt, Stephan [Waiblingen, DE; Bifone, Angelo [Rome, IT; Taylor, Rebecca [Berkeley, CA; Goodson, Boyd [Berkeley, CA; Seydoux, Roberto [Berkeley, CA; Room, Toomas [Albany, CA; Pietrass, Tanja [Socorro, NM

2008-06-10

The present invention relates generally to nuclear magnetic resonance (NMR) techniques for both spectroscopy and imaging. More particularly, the present invention relates to methods in which hyperpolarized noble gases (e.g., Xe and He) are used to enhance and improve NMR and MRI. Additionally, the hyperpolarized gas solutions of the invention are useful both in vitro and in vivo to study the dynamics or structure of a system. When used with biological systems, either in vivo or in vitro, it is within the scope of the invention to target the hyperpolarized gas and deliver it to specific regions within the system.

Enhancement of NMR and MRI in the presence of hyperpolarized noble gases

DOEpatents

Pines, Alexander; Budinger, Thomas; Navon, Gil; Song, Yi-Qiao; Appelt, Stephan; Bifone, Angelo; Taylor, Rebecca; Goodson, Boyd; Seydoux, Roberto; Room, Toomas; Pietrass, Tanja

2004-11-16

The present invention relates generally to nuclear magnetic resonance (NMR) techniques for both spectroscopy and imaging. More particularly, the present invention relates to methods in which hyperpolarized noble gases (e.g., Xe and He) are used to enhance and improve NMR and MRI. Additionally, the hyperpolarized gas solutions of the invention are useful both in vitro and in vivo to study the dynamics or structure of a system. When used with biological systems, either in vivo or in vitro, it is within the scope of the invention to target the hyperpolarized gas and deliver it to specific regions within the system.

Neuronal current detection with low-field magnetic resonance: simulations and methods.

PubMed

Cassará, Antonino Mario; Maraviglia, Bruno; Hartwig, Stefan; Trahms, Lutz; Burghoff, Martin

2009-10-01

The noninvasive detection of neuronal currents in active brain networks [or direct neuronal imaging (DNI)] by means of nuclear magnetic resonance (NMR) remains a scientific challenge. Many different attempts using NMR scanners with magnetic fields >1 T (high-field NMR) have been made in the past years to detect phase shifts or magnitude changes in the NMR signals. However, the many physiological (i.e., the contemporarily BOLD effect, the weakness of the neuronal-induced magnetic field, etc.) and technical limitations (e.g., the spatial resolution) in observing the weak signals have led to some contradicting results. In contrast, only a few attempts have been made using low-field NMR techniques. As such, this paper was aimed at reviewing two recent developments in this front. The detection schemes discussed in this manuscript, the resonant mechanism (RM) and the DC method, are specific to NMR instrumentations with main fields below the earth magnetic field (50 microT), while some even below a few microteslas (ULF-NMR). However, the experimental validation for both techniques, with differentiating sensitivity to the various neuronal activities at specific temporal and spatial resolutions, is still in progress and requires carefully designed magnetic field sensor technology. Additional care should be taken to ensure a stringent magnetic shield from the ambient magnetic field fluctuations. In this review, we discuss the characteristics and prospect of these two methods in detecting neuronal currents, along with the technical requirements on the instrumentation.

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

PubMed

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

2007-11-01

Nuclear Magnetic Resonance (NMR) is unsurpassed in its ability to non-destructively probe chemical identity. Portable, low-cost NMR sensors would enable on-site identification of potentially hazardous substances, as well as the study of samples in a variety of industrial applications. Recent developments in RF microcoil construction (i.e. coils much smaller than the standard 5mm NMR RF coils), have dramatically increased NMR sensitivity and decreased the limits-of-detection (LOD). We are using advances in laser pantographic microfabrication techniques, unique to LLNL, to produce RF microcoils for field deployable, high sensitivity NMR-based detectors. This same fabrication technique can be used to produce imaging coils for MRI as well as for standard hardware shimming or "ex-situ" shimming of field inhomogeneities typically associated with inexpensive magnets. This paper describes a portable NMR system based on the use of a 2 kg hand-held permanent magnet, laser-fabricated microcoils, and a compact spectrometer. The main limitations for such a system are the low resolution and sensitivity associated with the low field values and quality of small permanent magnets, as well as the lack of large amounts of sample of interest in most cases. The focus of the paper is on the setting up of this system, initial results, sensitivity measurements, discussion of the limitations and future plans. The results, even though preliminary, are promising and provide the foundation for developing a portable, inexpensive NMR system for chemical analysis. Such a system will be ideal for chemical identification of trace substances on site.

The use of 1H NMR microscopy to study proton-exchange membrane fuel cells.

PubMed

Feindel, Kirk W; Bergens, Steven H; Wasylishen, Roderick E

2006-01-16

To understand proton-exchange membrane fuel cells (PEMFCs) better, researchers have used several techniques to visualize their internal operation. This Concept outlines the advantages of using 1H NMR microscopy, that is, magnetic resonance imaging, to monitor the distribution of water in a working PEMFC. We describe what a PEMFC is, how it operates, and why monitoring water distribution in a fuel cell is important. We will focus on our experience in constructing PEMFCs, and demonstrate how 1H NMR microscopy is used to observe the water distribution throughout an operating hydrogen PEMFC. Research in this area is briefly reviewed, followed by some comments regarding challenges and anticipated future developments.

Validation of a low field Rheo-NMR instrument and application to shear-induced migration of suspended non-colloidal particles in Couette flow

NASA Astrophysics Data System (ADS)

Colbourne, A. A.; Blythe, T. W.; Barua, R.; Lovett, S.; Mitchell, J.; Sederman, A. J.; Gladden, L. F.

2018-01-01

Nuclear magnetic resonance rheology (Rheo-NMR) is a valuable tool for studying the transport of suspended non-colloidal particles, important in many commercial processes. The Rheo-NMR imaging technique directly and quantitatively measures fluid displacement as a function of radial position. However, the high field magnets typically used in these experiments are unsuitable for the industrial environment and significantly hinder the measurement of shear stress. We introduce a low field Rheo-NMR instrument (1 H resonance frequency of 10.7MHz), which is portable and suitable as a process monitoring tool. This system is applied to the measurement of steady-state velocity profiles of a Newtonian carrier fluid suspending neutrally-buoyant non-colloidal particles at a range of concentrations. The large particle size (diameter > 200 μm) in the system studied requires a wide-gap Couette geometry and the local rheology was expected to be controlled by shear-induced particle migration. The low-field results are validated against high field Rheo-NMR measurements of consistent samples at matched shear rates. Additionally, it is demonstrated that existing models for particle migration fail to adequately describe the solid volume fractions measured in these systems, highlighting the need for improvement. The low field implementation of Rheo-NMR is complementary to shear stress rheology, such that the two techniques could be combined in a single instrument.

MR imaging of ore for heap bioleaching studies using pure phase encode acquisition methods

NASA Astrophysics Data System (ADS)

Fagan, Marijke A.; Sederman, Andrew J.; Johns, Michael L.

2012-03-01

Various MRI techniques were considered with respect to imaging of aqueous flow fields in low grade copper ore. Spin echo frequency encoded techniques were shown to produce unacceptable image distortions which led to pure phase encoded techniques being considered. Single point imaging multiple point acquisition (SPI-MPA) and spin echo single point imaging (SESPI) techniques were applied. By direct comparison with X-ray tomographic images, both techniques were found to be able to produce distortion-free images of the ore packings at 2 T. The signal to noise ratios (SNRs) of the SESPI images were found to be superior to SPI-MPA for equal total acquisition times; this was explained based on NMR relaxation measurements. SESPI was also found to produce suitable images for a range of particles sizes, whereas SPI-MPA SNR deteriorated markedly as particles size was reduced. Comparisons on a 4.7 T magnet showed significant signal loss from the SPI-MPA images, the effect of which was accentuated in the case of unsaturated flowing systems. Hence it was concluded that SESPI was the most robust imaging method for the study of copper ore heap leaching hydrology.

Damage and repair of irradiated mammalian brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frankel, K.; Lo, E.; Phillips, M.

1989-07-01

We have demonstrated that focal charged particle irradiation of the rabbit brain can create well-defined lesions which are observable by nuclear magnetic resonance imaging (NMR) and positron emission tomography (PET) imaging techniques. These are similar, in terms of location and characteristic NMR and PET features, to those that occur in the brain of about 10% of clinical research human subjects, who have been treated for intracranial vascular malformations with stereotactic radiosurgery. These lesions have been described radiologically as vasogenic edema of the deep white matter,'' and the injury is of variable intensity and temporal duration, can recede or progress tomore » serious neurologic sequelae, and persist for a considerable period of time, frequently 18 mon to 3 yr. 8 refs., 6 figs.« less

Calibration standard of body tissue with magnetic nanocomposites for MRI and X-ray imaging

NASA Astrophysics Data System (ADS)

Rahn, Helene; Woodward, Robert; House, Michael; Engineer, Diana; Feindel, Kirk; Dutz, Silvio; Odenbach, Stefan; StPierre, Tim

2016-05-01

We present a first study of a long-term phantom for Magnetic Resonance Imaging (MRI) and X-ray imaging of biological tissues with magnetic nanocomposites (MNC) suitable for 3-dimensional and quantitative imaging of tissues after, e.g. magnetically assisted cancer treatments. We performed a cross-calibration of X-ray microcomputed tomography (XμCT) and MRI with a joint calibration standard for both imaging techniques. For this, we have designed a phantom for MRI and X-ray computed tomography which represents biological tissue enriched with MNC. The developed phantoms consist of an elastomer with different concentrations of multi-core MNC. The matrix material is a synthetic thermoplastic gel, PermaGel (PG). The developed phantoms have been analyzed with Nuclear Magnetic Resonance (NMR) Relaxometry (Bruker minispec mq 60) at 1.4 T to obtain R2 transverse relaxation rates, with SQUID (Superconducting QUantum Interference Device) magnetometry and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to verify the magnetite concentration, and with XμCT and 9.4 T MRI to visualize the phantoms 3-dimensionally and also to obtain T2 relaxation times. A specification of a sensitivity range is determined for standard imaging techniques X-ray computed tomography (XCT) and MRI as well as with NMR. These novel phantoms show a long-term stability over several months up to years. It was possible to suspend a particular MNC within the PG reaching a concentration range from 0 mg/ml to 6.914 mg/ml. The R2 relaxation rates from 1.4 T NMR-relaxometry show a clear connection (R2=0.994) with MNC concentrations between 0 mg/ml and 4.5 mg/ml. The MRI experiments have shown a linear correlation of R2 relaxation and MNC concentrations as well but in a range between MNC concentrations of 0 mg/ml and 1.435 mg/ml. It could be shown that XμCT displays best moderate and high MNC concentrations. The sensitivity range for this particular XμCT apparatus yields from 0.569 mg/ml to 6.914 mg/ml. The cross-calibration has defined a shared sensitivity range of XμCT, 1.4 T NMR relaxometer minispec, and 9.4 T MRI. The shared sensitivity range for the measuring method (NMR relaxometry) and the imaging modalities (XμCT and MRI) is from 0.569 mg/ml, limited by XμCT, and 1.435 mg/ml, limited by MRI. The presented phantoms have been found to be suitable to act as a body tissue substitute for XCT imaging as well as an acceptable T2 phantom of biological tissue enriched with magnetic nanoparticles for MRI.

Unilateral NMR applied to the conservation of works of art.

PubMed

Del Federico, Eleonora; Centeno, Silvia A; Kehlet, Cindie; Currier, Penelope; Stockman, Denise; Jerschow, Alexej

2010-01-01

In conventional NMR, samples from works of art in sizes above those considered acceptable in the field of art conservation would have to be removed to place them into the bore of large superconducting magnets. The portable permanent-magnet-based systems, by contrast, can be used in situ to study works of art, in a noninvasive manner. One of these portable NMR systems, NMR-MOUSE(R), measures the information contained in one pixel in an NMR image from a region of about 1 cm(2), which can be as thin as 2-3 microm. With such a high depth resolution, profiles through the structures of art objects can be measured to characterize the materials, the artists' techniques, and the deterioration processes. A novel application of the technique to study a deterioration process and to follow up a conservation treatment is presented in which micrometer-thick oil stains on paper are differentiated and characterized. In this example, the spin-spin relaxation T (2) of the stain is correlated to the iodine number and to the degree of cross-linking of the oil, parameters that are crucial in choosing an appropriate conservation treatment to remove them. It is also shown that the variation of T (2) over the course of treatments with organic solvents can be used to monitor the progress of the conservation interventions. It is expected that unilateral NMR in combination with multivariate data analysis will fill a gap within the set of high-spatial-resolution techniques currently available for the noninvasive analysis of materials in works of art, where procedures to study the inorganic components are currently far more developed than those suitable for the study of the organic components.

Interactive NMR: A Simulation Based Teaching Tool for Fundamentals to Applications with Tangible Analogies

NASA Astrophysics Data System (ADS)

Griesse-Nascimento, Sarah; Bridger, Joshua; Brown, Keith; Westervelt, Robert

2011-03-01

Interactive computer simulations increase students' understanding of difficult concepts and their ability to explain complex ideas. We created a module of eight interactive programs and accompanying lesson plans for teaching the fundamental concepts of Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) that we call interactive NMR (iNMR). We begin with an analogy between nuclear spins and metronomes to start to build intuition about the dynamics of spins in a magnetic field. We continue to explain T1, T2, and pulse sequences with the metronome analogy. The final three programs are used to introduce and explain the Magnetic Resonance Switch, a recent diagnostic technique based on NMR. A modern relevant application is useful to generate interest in the topic and confidence in the students' ability to apply their knowledge. The iNMR module was incorporated into a high school AP physics class. In a preliminary evaluation of implementation, students expressed enthusiasm and demonstrated enhanced understanding of the material relative to the previous year. Funded by NSF PHY-0646094 grant.

Investigation of fluorocarbon blowing agents in insulating polymer foams by 19F NMR imaging.

PubMed

Fyfe, C A; Mei, Z; Grondey, H

1996-01-01

Currently, there is no reliable and readily accessible technique with which the distribution and diffusion of blowing agents in rigid insulating foams can be detected and monitored. In this paper, we demonstrate that 19F NMR microscopic imaging together with 19F solid-state MAS NMR spectroscopy is ideally suited for such measurements and yield quantitatively reliable information that will be critical to the development and fabrication of optimized insulating materials with alternative blowing agents. Polystyrene (PS) and polyurethane (PU) foam samples were investigated with the objective of determining quantitatively the amount of blowing agents in the gaseous phase and dissolved in the polymer phase, and to determine and monitor the distribution of the blowing agents in aged foams as a function of time and temperature. The concentrations of the gaseous blowing agents in the cells and dissolved in the solid were simultaneously and quantitatively measured by 19F MAS NMR spectroscopy. An unfaced 1-yr-old PS foam filled with CH3CF2Cl has about 13% of total HCFCs dissolved in the solid; while there is about 24% of HCFCs in the solid of a faced 3-mos-old PU foam filled with CH3CCl2F. The data from 19F NMR imaging demonstrate that the distributions of the blowing agents in an aged foam are quite uniform around the center part (2 cm away from any edge) of a foam board; however, a gradient in blowing agent concentration was found as a function of distance from the initial factory cut edge. The effective diffusion coefficients of the blowing agents can be directly calculated from the imaging data. Quantitative diffusion constants and activation barriers were determined. Additionally, a foam treated with a second blowing agent was monitored with chemical shift selective imaging and the diffusion of the second gas into the foam and the out-diffusion of the original gas were determined.

Nuclear magnetic resonance imaging of water content in the subsurface

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. Hendricks; T. Yao; A. Kearns

1999-01-21

Previous theoretical and experimental studies indicated that surface nuclear magnetic resonance (NMR) has the potential to provide cost-effective water content measurements in the subsurface and is a technology ripe for exploitation in practice. The objectives of this investigation are (a) to test the technique under a wide range of hydrogeological conditions and (b) to generalize existing NMR theories in order to correctly model NMR response from conductive ground and to assess properties of the inverse problem. Twenty-four sites with different hydrogeologic settings were selected in New Mexico and Colorado for testing. The greatest limitation of surface NMR technology appears tomore » be the lack of understanding in which manner the NMR signal is influenced by soil-water factors such as pore size distribution, surface-to-volume ratio, paramagnetic ions dissolved in the ground water, and the presence of ferromagnetic minerals. Although the theoretical basis is found to be sound, several advances need to be made to make surface NMR a viable technology for hydrological investigations. There is a research need to investigate, under controlled laboratory conditions, how the complex factors of soil-water systems affect NMR relaxation times.« less

Single-sided magnetic resonance profiling in biological and materials science.

PubMed

Danieli, Ernesto; Blümich, Bernhard

2013-04-01

Single-sided NMR was inspired by the oil industry that strived to improve the performance of well-logging tools to measure the properties of fluids confined downhole. This unconventional way of implementing NMR, in which stray magnetic and radio frequency fields are used to recover information of arbitrarily large objects placed outside the magnet, motivated the development of handheld NMR sensors. These devices have moved the technique to different scientific disciplines. The current work gives a review of the most relevant magnets and methodologies developed to generate NMR information from spatially localized regions of samples placed in close proximity to the sensors. When carried out systematically, such measurements lead to 'single-sided depth profiles' or one-dimensional images. This paper presents recent and most relevant applications as well as future perspectives of this growing branch of MRI. Copyright © 2012 Elsevier Inc. All rights reserved.

Spider Silk: From Protein-Rich Gland Fluids to Diverse Biopolymer Fibers

DTIC Science & Technology

2016-01-06

characterize the protein-rich fluid in the various spider silk producing glands. We have been using a battery of magnetic resonance methods including...solution and solid-state nuclear magnetic resonance (NMR) and micro imaging (MRI) in combination with wide angle and small angle X-ray diffraction...range of magnetic resonance methods. We successfully developed magnetic resonance imaging (MRI) techniques with localized spectroscopy to probe the silk

A Training Program in Breast Cancer Research Using NMR Techniques

DTIC Science & Technology

2002-07-01

Howard University Cancer Center. The trainees have continued to learn the theory and instrumentation of nuclear magnetic resonance imaging and spectroscopy. The trainees have rotated through the mammography service in the Department of Radiology in the hospital to learn the mammography procedures. Besides attending the weekly seminars in the Cancer Center, the trainees also have attended a special seminar series on the breast imaging sponsored by this grant and

Using NMR chemical shift imaging to monitor swelling and molecular transport in drug-loaded tablets of hydrophobically modified poly(acrylic acid): methodology and effects of polymer (in)solubility.

PubMed

Knöös, Patrik; Topgaard, Daniel; Wahlgren, Marie; Ulvenlund, Stefan; Piculell, Lennart

2013-11-12

A new technique has been developed using NMR chemical shift imaging (CSI) to monitor water penetration and molecular transport in initially dry polymer tablets that also contain small low-molecular weight compounds to be released from the tablets. Concentration profiles of components contained in the swelling tablets could be extracted via the intensities and chemical shift changes of peaks corresponding to protons of the components. The studied tablets contained hydrophobically modified poly(acrylic acid) (HMPAA) as the polymer component and griseofulvin and ethanol as hydrophobic and hydrophilic, respectively, low-molecular weight model compounds. The water solubility of HMPAA could be altered by titration with NaOH. In the pure acid form, HMPAA tablets only underwent a finite swelling until the maximum water content of the polymer-rich phase, as confirmed by independent phase studies, had been reached. By contrast, after partial neutralization with NaOH, the polyacid became fully miscible with water. The solubility of the polymer affected the water penetration, the polymer release, and the releases of both ethanol and griseofulvin. The detailed NMR CSI concentration profiles obtained highlighted the clear differences in the disintegration/dissolution/release behavior for the two types of tablet and provided insights into their molecular origin. The study illustrates the potential of the NMR CSI technique to give information of importance for the development of pharmaceutical tablets and, more broadly, for the general understanding of any operation that involves the immersion and ultimate disintegration of a dry polymer matrix in a solvent.

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

ERIC Educational Resources Information Center

Chesick, John P.

1989-01-01

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

Hammersmith cardiology workshop series. Volume 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maseri, A.

1985-01-01

This book contains over 30 selections. Some of the titles are: Digital Subtraction Angiography: The Optimal Radiologic Technique for Cardiac Diagnosis; NMR Imaging of the Heart; Radioisotopes in the Evaluation of Right and Left Ventricular Function; Role of Membrane Abnormalities in the Pathogenesis of Heart Disease; and Influence of Arrhythmias on Cardiac Function.

A Training Program in Breast Cancer Research Using NMR Techniques

DTIC Science & Technology

2006-07-01

subtlety, and location. Both the cranio-caudal (CC) and medio -lateral oblique (MLO) projec- tion views were used. The films were digitized with a com...thermal optical monitoring system used to monitor animals’ skin temperature, ambient temper- ature, and wall temperature of the device. For imaging

MR Fingerprinting Using The Quick Echo Splitting NMR Imaging Technique

PubMed Central

Jiang, Yun; Ma, Dan; Jerecic, Renate; Duerk, Jeffrey; Seiberlich, Nicole; Gulani, Vikas; Griswold, Mark A.

2016-01-01

Purpose The purpose of the study is to develop a quantitative method for the relaxation properties with a reduced radio frequency (RF) power deposition by combining Magnetic Resonance Fingerprinting (MRF) technique with Quick Echo Splitting NMR Imaging Technique (QUEST). Methods A QUEST-based MRF sequence was implemented to acquire high order echoes by increasing the gaps between RF pulses. Bloch simulations were used to calculate a dictionary containing the range of physically plausible signal evolutions using a range of T1 and T2 values based on the pulse sequence. MRF-QUEST was evaluated by comparing to the results of spin-echo methods. The SAR of QUEST-MRF was compared to the clinically available methods. Results MRF-QUEST quantifies the relaxation properties with good accuracy at the estimated head Specific Absorption Rate (SAR) of 0.03 W/kg. T1 and T2 values estimated by MRF-QUEST are in good agreement with the traditional methods. Conclusion The combination of the MRF and the QUEST provides an accurate quantification of T1 and T2 simultaneously with reduced RF power deposition. The resulting lower SAR may provide a new acquisition strategy for MRF when RF energy deposition is problematic. PMID:26924639

Review of progress in quantitative NDE

NASA Astrophysics Data System (ADS)

s of 386 papers and plenary presentations are included. The plenary sessions are related to the national technology initiative. The other sessions covered the following NDE topics: corrosion, electromagnetic arrays, elastic wave scattering and backscattering/noise, civil structures, material properties, holography, shearography, UT wave propagation, eddy currents, coatings, signal processing, radiography, computed tomography, EM imaging, adhesive bonds, NMR, laser ultrasonics, composites, thermal techniques, magnetic measurements, nonlinear acoustics, interface modeling and characterization, UT transducers, new techniques, joined materials, probes and systems, fatigue cracks and fracture, imaging and sizing, NDE in engineering and process control, acoustics of cracks, and sensors. An author index is included.

Nuclear Magnetic Resonance Technology for Medical Studies.

ERIC Educational Resources Information Center

Budinger, Thomas F.; Lauterbur, Paul C.

1984-01-01

Reports on the status of nuclear magnetic resonance (NMR) from theoretical and clinical perspectives, reviewing NMR theory and relaxation parameters relevant to NMR imaging. Also reviews literature related to modern imaging strategies, signal-to-noise ratio, contrast agents, in vivo spectroscopy, spectroscopic imaging, clinical applications, and…

Monitoring of fluid motion in a micromixer by dynamic NMR microscopy.

PubMed

Ahola, Susanna; Casanova, Federico; Perlo, Juan; Münnemann, Kerstin; Blümich, Bernhard; Stapf, Siegfried

2006-01-01

The velocity distribution of liquid flowing in a commercial micromixer has been determined directly by using pulsed-field gradient NMR. Velocity maps with a spatial resolution of 29 microm x 43 microm were obtained by combining standard imaging gradient units with a homebuilt rectangular surface coil matching the mixer geometry. The technique provides access to mixers and reactors of arbitrary shape regardless of optical transparency. Local heterogeneities in the signal intensity and the velocity pattern were found and serve to investigate the quality and functionality of a micromixer, revealing clogging and inhomogeneous flow distributions.

Skeletal Muscle Quantitative Nuclear Magnetic Resonance Imaging and Spectroscopy as an Outcome Measure for Clinical Trials

PubMed Central

Carlier, Pierre G.; Marty, Benjamin; Scheidegger, Olivier; Loureiro de Sousa, Paulo; Baudin, Pierre-Yves; Snezhko, Eduard; Vlodavets, Dmitry

2016-01-01

Recent years have seen tremendous progress towards therapy of many previously incurable neuromuscular diseases. This new context has acted as a driving force for the development of novel non-invasive outcome measures. These can be organized in three main categories: functional tools, fluid biomarkers and imagery. In the latest category, nuclear magnetic resonance imaging (NMRI) offers a considerable range of possibilities for the characterization of skeletal muscle composition, function and metabolism. Nowadays, three NMR outcome measures are frequently integrated in clinical research protocols. They are: 1/ the muscle cross sectional area or volume, 2/ the percentage of intramuscular fat and 3/ the muscle water T2, which quantity muscle trophicity, chronic fatty degenerative changes and oedema (or more broadly, “disease activity”), respectively. A fourth biomarker, the contractile tissue volume is easily derived from the first two ones. The fat fraction maps most often acquired with Dixon sequences have proven their capability to detect small changes in muscle composition and have repeatedly shown superior sensitivity over standard functional evaluation. This outcome measure will more than likely be the first of the series to be validated as an endpoint by regulatory agencies. The versatility of contrast generated by NMR has opened many additional possibilities for characterization of the skeletal muscle and will result in the proposal of more NMR biomarkers. Ultra-short TE (UTE) sequences, late gadolinium enhancement and NMR elastography are being investigated as candidates to evaluate skeletal muscle interstitial fibrosis. Many options exist to measure muscle perfusion and oxygenation by NMR. Diffusion NMR as well as texture analysis algorithms could generate complementary information on muscle organization at microscopic and mesoscopic scales, respectively. 31P NMR spectroscopy is the reference technique to assess muscle energetics non-invasively during and after exercise. In dystrophic muscle, 31P NMR spectrum at rest is profoundly perturbed, and several resonances inform on cell membrane integrity. Considerable efforts are being directed towards acceleration of image acquisitions using a variety of approaches, from the extraction of fat content and water T2 maps from one single acquisition to partial matrices acquisition schemes. Spectacular decreases in examination time are expected in the near future. They will reinforce the attractiveness of NMR outcome measures and will further facilitate their integration in clinical research trials. PMID:27854210

High-Resolution Magic-Angle-Spinning NMR and Magnetic Resonance Imaging Spectroscopies Distinguish Metabolome and Structural Properties of Maize Seeds from Plants Treated with Different Fertilizers and Arbuscular mycorrhizal fungi.

PubMed

Mazzei, Pierluigi; Cozzolino, Vincenza; Piccolo, Alessandro

2018-03-21

Both high-resolution magic-angle-spinning (HRMAS) and magnetic resonance imaging (MRI) NMR spectroscopies were applied here to identify the changes of metabolome, morphology, and structural properties induced in seeds (caryopses) of maize plants grown at field level under either mineral or compost fertilization in combination with the inoculation by arbuscular mycorrhizal fungi (AMF). The metabolome of intact caryopses was examined by HRMAS-NMR, while the morphological aspects, endosperm properties and seed water distribution were investigated by MRI. Principal component analysis (PCA) was applied to evaluate 1 H CPMG (Carr-Purcel-Meiboom-Gill) HRMAS spectra as well as several MRI-derived parameters ( T 1 , T 2 , and self-diffusion coefficients) of intact maize caryopses. PCA score-plots from spectral results indicated that both seeds metabolome and structural properties depended on the specific field treatment undergone by maize plants. Our findings show that a combination of multivariate statistical analyses with advanced and nondestructive NMR techniques, such as HRMAS and MRI, enables the evaluation of the effects induced on maize caryopses by different fertilization and management practices at field level. The spectroscopic approach adopted here may become useful for the objective appraisal of the quality of seeds produced under a sustainable agriculture.

Direct imaging of neural currents using ultra-low field magnetic resonance techniques

DOEpatents

Volegov, Petr L [Los Alamos, NM; Matlashov, Andrei N [Los Alamos, NM; Mosher, John C [Los Alamos, NM; Espy, Michelle A [Los Alamos, NM; Kraus, Jr., Robert H.

2009-08-11

Using resonant interactions to directly and tomographically image neural activity in the human brain using magnetic resonance imaging (MRI) techniques at ultra-low field (ULF), the present inventors have established an approach that is sensitive to magnetic field distributions local to the spin population in cortex at the Larmor frequency of the measurement field. Because the Larmor frequency can be readily manipulated (through varying B.sub.m), one can also envision using ULF-DNI to image the frequency distribution of the local fields in cortex. Such information, taken together with simultaneous acquisition of MEG and ULF-NMR signals, enables non-invasive exploration of the correlation between local fields induced by neural activity in cortex and more `distant` measures of brain activity such as MEG and EEG.

Two Phase Flow Measurements by Nuclear Magnetic Resonance (NMR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altobelli, Stephen A; Fukushima, Eiichi

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

Monitoring bacterially induced calcite precipitation in porous media using magnetic resonance imaging and flow measurements

NASA Astrophysics Data System (ADS)

Sham, E.; Mantle, M. D.; Mitchell, J.; Tobler, D. J.; Phoenix, V. R.; Johns, M. L.

2013-09-01

A range of nuclear magnetic resonance (NMR) techniques are employed to provide novel, non-invasive measurements of both the structure and transport properties of porous media following a biologically mediated calcite precipitation reaction. Both a model glass bead pack and a sandstone rock core were considered. Structure was probed using magnetic resonance imaging (MRI) via a combination of quantitative one-dimensional profiles and three-dimensional images, applied before and after the formation of calcite in order to characterise the spatial distribution of the precipitate. It was shown through modification and variations of the calcite precipitation treatment that differences in the calcite fill would occur but all methods were successful in partially blocking the different porous media. Precipitation was seen to occur predominantly at the inlet of the bead pack, whereas precipitation occurred almost uniformly along the sandstone core. Transport properties are quantified using pulse field gradient (PFG) NMR measurements which provide probability distributions of molecular displacement over a set observation time (propagators), supplementing conventional permeability measurements. Propagators quantify the local effect of calcite formation on system hydrodynamics and the extent of stagnant region formation. Collectively, the combination of NMR measurements utilised here provides a toolkit for determining the efficacy of a biological-precipitation reaction for partially blocking porous materials.

A Robust Magnetic Resonance Imager For Ground and Flight Based Measurements of Fluid Physics Phenomena

NASA Technical Reports Server (NTRS)

2002-01-01

Nuclear magnetic resonance (NMR) is a powerful and versatile, noninvasive method for studying fluid transport problems, However, its applications to these types of investigations have been limited. A primary factor that limits the application of NMR has been the lack of a user-friendly, versatile, and inexpensive NMR imaging apparatus that can be used by scientists who are not familiar with sophisticated NMR. To rectify this situation, we developed a user-friendly, NMR imager for projects of relevance to the MRD science community. To that end, we performed preliminary collaborative experiments between NASA, NCMR, and New Mexico Resonance in the high field NMR set up at New Mexico Resonance to track wetting front dynamics in foams under gravity. The experiments were done in a 30 cm, 1.9T Oxford magnet with a TECMAG Libra spectrometer (Tecmag, Inc., Houston, TX). We used two different imaging strategies depending on whether the water in the foam sample was static or moving. Stationary water distributions were imaged with the standard Fourier imaging method, as used in medical MRI, in which data are acquired from all parts of the region of interest at all times and Fourier transformed into a static spatial image.

Polymer mobilization and drug release during tablet swelling. A 1H NMR and NMR microimaging study.

PubMed

Dahlberg, Carina; Fureby, Anna; Schuleit, Michael; Dvinskikh, Sergey V; Furó, István

2007-09-26

The objective of this study was to investigate the swelling characteristics of a hydroxypropyl methylcellulose (HPMC) matrix incorporating the hydrophilic drug antipyrine. We have used this matrix to introduce a novel analytical method, which allows us to obtain within one experimental setup information about the molecular processes of the polymer carrier and its impact on drug release. Nuclear magnetic resonance (NMR) imaging revealed in situ the swelling behavior of tablets when exposed to water. By using deuterated water, the spatial distribution and molecular dynamics of HPMC and their kinetics during swelling could be observed selectively. In parallel, NMR spectroscopy provided the concentration of the drug released into the aqueous phase. We find that both swelling and release are diffusion controlled. The ability of monitoring those two processes using the same experimental setup enables mapping their interconnection, which points on the importance and potential of this analytical technique for further application in other drug delivery forms.

Using an NMR Spectrometer to Do Magnetic Resonance Imaging: An Undergraduate Physical Chemistry Laboratory Experiment

ERIC Educational Resources Information Center

Steinmetz, Wayne E.; Maher, M. Cyrus

2007-01-01

A conventional Fourier-transform NMR spectrometer with a triple-axis gradient probe can function as a MRI imager. In this experiment students gain hands-on experience with MRI while they learn about important principles underlying the practice of NMR, such as gradients, multi-dimensional spectroscopy, and relaxation. Students image a biological…

High resolution NMR imaging using a high field yokeless permanent magnet.

PubMed

Kose, Katsumi; Haishi, Tomoyuki

2011-01-01

We measured the homogeneity and stability of the magnetic field of a high field (about 1.04 tesla) yokeless permanent magnet with 40-mm gap for high resolution nuclear magnetic resonance (NMR) imaging. Homogeneity was evaluated using a 3-dimensional (3D) lattice phantom and 3D spin-echo imaging sequences. In the central sphere (20-mm diameter), peak-to-peak magnetic field inhomogeneity was about 60 ppm, and the root-mean-square was 8 ppm. We measured room temperature, magnet temperature, and NMR frequency of the magnet simultaneously every minute for about 68 hours with and without the thermal insulator of the magnet. A simple mathematical model described the magnet's thermal property. Based on magnet performance, we performed high resolution (up to [20 µm](2)) imaging with internal NMR lock sequences of several biological samples. Our results demonstrated the usefulness of the high field small yokeless permanent magnet for high resolution NMR imaging.

Utility of magnetic resonance imaging and nuclear magnetic resonance-based metabolomics for quantification of inflammatory lung injury

PubMed Central

Serkova, Natalie J.; Van Rheen, Zachary; Tobias, Meghan; Pitzer, Joshua E.; Wilkinson, J. Erby; Stringer, Kathleen A.

2008-01-01

Magnetic resonance imaging (MRI) and metabolic nuclear magnetic resonance (NMR) spectroscopy are clinically available but have had little application in the quantification of experimental lung injury. There is a growing and unfulfilled need for predictive animal models that can improve our understanding of disease pathogenesis and therapeutic intervention. Integration of MRI and NMR could extend the application of experimental data into the clinical setting. This study investigated the ability of MRI and metabolic NMR to detect and quantify inflammation-mediated lung injury. Pulmonary inflammation was induced in male B6C3F1 mice by intratracheal administration of IL-1β and TNF-α under isoflurane anesthesia. Mice underwent MRI at 2, 4, 6, and 24 h after dosing. At 6 and 24 h lungs were harvested for metabolic NMR analysis. Data acquired from IL-1β+TNF-α-treated animals were compared with saline-treated control mice. The hyperintense-to-total lung volume (HTLV) ratio derived from MRI was higher in IL-1β+TNF-α-treated mice compared with control at 2, 4, and 6 h but returned to control levels by 24 h. The ability of MRI to detect pulmonary inflammation was confirmed by the association between HTLV ratio and histological and pathological end points. Principal component analysis of NMR-detectable metabolites also showed a temporal pattern for which energy metabolism-based biomarkers were identified. These data demonstrate that both MRI and metabolic NMR have utility in the detection and quantification of inflammation-mediated lung injury. Integration of these clinically available techniques into experimental models of lung injury could improve the translation of basic science knowledge and information to the clinic. PMID:18441091

MR fingerprinting using the quick echo splitting NMR imaging technique.

PubMed

Jiang, Yun; Ma, Dan; Jerecic, Renate; Duerk, Jeffrey; Seiberlich, Nicole; Gulani, Vikas; Griswold, Mark A

2017-03-01

The purpose of the study is to develop a quantitative method for the relaxation properties with a reduced radio frequency (RF) power deposition by combining magnetic resonance fingerprinting (MRF) technique with quick echo splitting NMR imaging technique (QUEST). A QUEST-based MRF sequence was implemented to acquire high-order echoes by increasing the gaps between RF pulses. Bloch simulations were used to calculate a dictionary containing the range of physically plausible signal evolutions using a range of T 1 and T 2 values based on the pulse sequence. MRF-QUEST was evaluated by comparing to the results of spin-echo methods. The specific absorption rate (SAR) of MRF-QUEST was compared with the clinically available methods. MRF-QUEST quantifies the relaxation properties with good accuracy at the estimated head SAR of 0.03 W/kg. T 1 and T 2 values estimated by MRF-QUEST are in good agreement with the traditional methods. The combination of the MRF and the QUEST provides an accurate quantification of T 1 and T 2 simultaneously with reduced RF power deposition. The resulting lower SAR may provide a new acquisition strategy for MRF when RF energy deposition is problematic. Magn Reson Med 77:979-988, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Advanced solid-state NMR spectroscopy of natural organic matter.

PubMed

Mao, Jingdong; Cao, Xiaoyan; Olk, Dan C; Chu, Wenying; Schmidt-Rohr, Klaus

2017-05-01

Solid-state NMR is essential for the characterization of natural organic matter (NOM) and is gaining importance in geosciences and environmental sciences. This review is intended to highlight advanced solid-state NMR techniques, especially a systematic approach to NOM characterization, and their applications to the study of NOM. We discuss some basics of how to acquire high-quality and quantitative solid-state 13 C NMR spectra, and address some common technical mistakes that lead to unreliable spectra of NOM. The identification of specific functional groups in NOM, primarily based on 13 C spectral-editing techniques, is described and the theoretical background of some recently-developed spectral-editing techniques is provided. Applications of solid-state NMR to investigating nitrogen (N) in NOM are described, focusing on limitations of the widely used 15 N CP/MAS experiment and the potential of improved advanced NMR techniques for characterizing N forms in NOM. Then techniques used for identifying proximities, heterogeneities and domains are reviewed, and some examples provided. In addition, NMR techniques for studying segmental dynamics in NOM are reviewed. We also briefly discuss applications of solid-state NMR to NOM from various sources, including soil organic matter, aquatic organic matter, organic matter in atmospheric particulate matter, carbonaceous meteoritic organic matter, and fossil fuels. Finally, examples of NMR-based structural models and an outlook are provided. Copyright © 2016 Elsevier B.V. All rights reserved.

Use of multi-coil parallel-gap resonators for co-registration EPR/NMR imaging

NASA Astrophysics Data System (ADS)

Kawada, Yuuki; Hirata, Hiroshi; Fujii, Hirodata

2007-01-01

This article reports experimental investigations on the use of RF resonators for continuous-wave electron paramagnetic resonance (cw-EPR) and proton nuclear magnetic resonance (NMR) imaging. We developed a composite resonator system with multi-coil parallel-gap resonators for co-registration EPR/NMR imaging. The resonance frequencies of each resonator were 21.8 MHz for NMR and 670 MHz for EPR. A smaller resonator (22 mm in diameter) for use in EPR was placed coaxially in a larger resonator (40 mm in diameter) for use in NMR. RF magnetic fields in the composite resonator system were visualized by measuring a homogeneous 4-hydroxy-2,2,6,6-tetramethyl-piperidinooxy (4-hydroxy-TEMPO) solution in a test tube. A phantom of five tubes containing distilled water and 4-hydroxy-TEMPO solution was also measured to demonstrate the potential usefulness of this composite resonator system in biomedical science. An image of unpaired electrons was obtained for 4-hydroxy-TEMPO in three tubes, and was successfully mapped on the proton image for five tubes. Technical problems in the implementation of a composite resonator system are discussed with regard to co-registration EPR/NMR imaging for animal experiments.

The application of absolute quantitative (1)H NMR spectroscopy in drug discovery and development.

PubMed

Singh, Suruchi; Roy, Raja

2016-07-01

The identification of a drug candidate and its structural determination is the most important step in the process of the drug discovery and for this, nuclear magnetic resonance (NMR) is one of the most selective analytical techniques. The present review illustrates the various perspectives of absolute quantitative (1)H NMR spectroscopy in drug discovery and development. It deals with the fundamentals of quantitative NMR (qNMR), the physiochemical properties affecting qNMR, and the latest referencing techniques used for quantification. The precise application of qNMR during various stages of drug discovery and development, namely natural product research, drug quantitation in dosage forms, drug metabolism studies, impurity profiling and solubility measurements is elaborated. To achieve this, the authors explore the literature of NMR in drug discovery and development between 1963 and 2015. It also takes into account several other reviews on the subject. qNMR experiments are used for drug discovery and development processes as it is a non-destructive, versatile and robust technique with high intra and interpersonal variability. However, there are several limitations also. qNMR of complex biological samples is incorporated with peak overlap and a low limit of quantification and this can be overcome by using hyphenated chromatographic techniques in addition to NMR.

High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance of Intact Zebrafish Embryos Detects Metabolic Changes Following Exposure to Teratogenic Polymethoxyalkenes from Algae

PubMed Central

Roy, Upasana; Jaja-Chimedza, Asha; Sanchez, Kristel; Matysik, Joerg

2016-01-01

Abstract Techniques based on nuclear magnetic resonance (NMR) for imaging and chemical analyses of in vivo, or otherwise intact, biological systems are rapidly emerging and finding diverse applications within a wide range of fields. Very recently, several NMR-based techniques have been developed for the zebrafish as a model animal system. In the current study, the novel application of high-resolution magic angle spinning (HR-MAS) NMR is presented as a means of metabolic profiling of intact zebrafish embryos. Toward investigating the utility of HR-MAS NMR as a toxicological tool, these studies specifically examined metabolic changes of embryos exposed to polymethoxy-1-alkenes (PMAs)—a recently identified family of teratogenic compounds from freshwater algae—as emerging environmental contaminants. One-dimensional and two-dimensional HR-MAS NMR analyses were able to effectively identify and quantify diverse metabolites in early-stage (≤36 h postfertilization) embryos. Subsequent comparison of the metabolic profiles between PMA-exposed and control embryos identified several statistically significant metabolic changes associated with subacute exposure to the teratogen, including (1) elevated inositol as a recognized component of signaling pathways involved in embryo development; (2) increases in several metabolites, including inositol, phosphoryl choline, fatty acids, and cholesterol, which are associated with lipid composition of cell membranes; (3) concomitant increase in glucose and decrease in lactate; and (4) decreases in several biochemically related metabolites associated with central nervous system development and function, including γ-aminobutyric acid, glycine, glutamate, and glutamine. A potentially unifying model/hypothesis of PMA teratogenicity based on the data is presented. These findings, taken together, demonstrate that HR-MAS NMR is a promising tool for metabolic profiling in the zebrafish embryo, including toxicological applications. PMID:27348393

Quantification of left to right atrial shunts with velocity-encoded cine nuclear magnetic resonance imaging.

PubMed

Brenner, L D; Caputo, G R; Mostbeck, G; Steiman, D; Dulce, M; Cheitlin, M D; O'Sullivan, M; Higgins, C B

1992-11-01

The purpose of this study was to evaluate the ability of velocity-encoded nuclear magnetic resonance (NMR) imaging to quantify left to right intracardiac shunts in patients with an atrial septal defect. Quantification of intracardiac shunts is clinically important in planning therapy. Velocity-encoded NMR imaging was used to quantify stroke flow in the aorta and in the main pulmonary artery in a group of patients who were known to have an increased pulmonary to systemic flow ratio (Qp/Qs). The velocity-encoded NMR flow data were used to calculate Qp/Qs, and these values were compared with measurements of Qp/Qs obtained with oximetric data derived from cardiac catheterization and from stroke volume measurements of the two ventricles by using volumetric data from biphasic spin echo and cine NMR images obtained at end-diastole and end-systole. Two independent observers measured Qp/Qs by using velocity-encoded NMR imaging in 11 patients and found Qp/Qs ranging from 1.4:1 to 3.9:1. These measurements correlated well with both oximetric data (r = 0.91, SEE = 0.35) and ventricular volumetric data (r = 0.94, SEE = 0.30). Interobserver reproducibility for Qp/Qs by velocity-encoded NMR imaging was good (r = 0.97, SEE = 0.20). Velocity-encoded NMR imaging is an accurate and reproducible method for measuring Qp/Qs in left to right shunts. Because it is completely noninvasive, it can be used to monitor shunt volume over time.

Parameters and symbols for use in nuclear magnetic resonance (IUPAC recommendations 1997).

PubMed

Harris, R K; Kowalewski, J; Cabral de Menezes, S

1998-01-01

NMR is now frequently the technique of choice for the determination of chemical structure in solution. Its uses also span structure in solids and mobility at the molecular level in all phases. The research literature in the subject is vast and ever-increasing. Unfortunately, many articles do not contain sufficient information for experiments to be repeated elsewhere, and there are many variations in the usage of symbols for the same physical quantity. It is the aim of the present recommendations to provide simple check-lists that will enable such problems to be minimised in a way that is consistent with general IUPAC formulation. The area of medical NMR and imaging is not specifically addressed in these recommendations, which are principally aimed at the mainstream use of NMR by chemists (of all sub-disciplines) and by many physicists, biologists, materials scientists and geologists etc. working with NMR. The document presents recommended notation for use in journal publications involving a significant contribution of nuclear magnetic resonance (NMR) spectroscopy. The recommendations are in two parts: (1) Experimental parameters which should be listed so that the work in question can be repeated elsewhere. (2) A list of symbols (using Roman or Greek characters) to be used for quantities relevant to NMR.

A biofilm microreactor system for simultaneous electrochemical and nuclear magnetic resonance techniques.

PubMed

Renslow, R S; Babauta, J T; Majors, P D; Mehta, H S; Ewing, R J; Ewing, T W; Mueller, K T; Beyenal, H

2014-01-01

Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for noninvasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live biofilms respiring on electrodes. Here, we describe a biofilm microreactor system, including a reusable and a disposable reactor, that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactors were designed with custom radio frequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system we grew Geobacter sulfurreducens biofilms on electrodes. EC-NMR was used to investigate growth medium flow velocities and depth-resolved acetate concentration inside the biofilm. As a novel contribution we used Monte Carlo error analysis to estimate the standard deviations of the acetate concentration measurements. Overall, we found that the disposable EC-NMR microreactor provided a 9.7 times better signal-to-noise ratio over the reusable reactor. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms.

MR CAT scan: a modular approach for hybrid imaging.

PubMed

Hillenbrand, C; Hahn, D; Haase, A; Jakob, P M

2000-07-01

In this study, a modular concept for NMR hybrid imaging is presented. This concept essentially integrates different imaging modules in a sequential fashion and is therefore called CAT (combined acquisition technique). CAT is not a single specific measurement sequence, but rather a sequence design concept whereby distinct acquisition techniques with varying imaging parameters are employed in rapid succession in order to cover k-space. The power of the CAT approach is that it provides a high flexibility toward the acquisition optimization with respect to the available imaging time and the desired image quality. Important CAT sequence optimization steps include the appropriate choice of the k-space coverage ratio and the application of mixed bandwidth technology. Details of both the CAT methodology and possible CAT acquisition strategies, such as FLASH/EPI-, RARE/EPI- and FLASH/BURST-CAT are provided. Examples from imaging experiments in phantoms and healthy volunteers including mixed bandwidth acquisitions are provided to demonstrate the feasibility of the proposed CAT concept.

In vivo NMR imaging of sodium-23 in the human head.

PubMed

Hilal, S K; Maudsley, A A; Ra, J B; Simon, H E; Roschmann, P; Wittekoek, S; Cho, Z H; Mun, S K

1985-01-01

We report the first clinical nuclear magnetic resonance (NMR) images of cerebral sodium distribution in normal volunteers and in patients with a variety of pathological lesions. We have used a 1.5 T NMR magnet system. When compared with proton distribution, sodium shows a greater variation in its concentration from tissue to tissue and from normal to pathological conditions. Image contrast calculated on the basis of sodium concentration is 7 to 18 times greater than that of proton spin density. Normal images emphasize the extracellular compartments. In the clinical studies, areas of recent or old cerebral infarction and tumors show a pronounced increase of sodium content (300-400%). Actual measurements of image density values indicate that there is probably a further accentuation of the contrast by the increased "NMR visibility" of sodium in infarcted tissue. Sodium imaging may prove to be a more sensitive means for early detection of some brain disorders than other imaging methods.

High-pressure autoclave for multipurpose nuclear magnetic resonance measurements up to 10 MPa

NASA Astrophysics Data System (ADS)

Behr, W.; Haase, A.; Reichenauer, G.; Fricke, J.

1999-05-01

High-pressure nuclear magnetic resonance (NMR) is an established method in NMR spectroscopy: on-line coupling of high-performance liquid chromatography with NMR, for example, reveals structural information which cannot be obtained with any other method. However, applications has been focused solely on high-pressure NMR spectroscopy, even though high-pressure NMR imaging allows in situ studies of processes such as the fluid exchange in porous media. A versatile high-pressure autoclave for NMR imaging is described in this article. The autoclave allows measurements in any horizontal NMR imager using magnetic field coil systems with an inside diameter of more than 70 mm. Any sample with a diameter up to 28 mm and a length of about 200 mm can be investigated. The autoclave is constructed for operating pressures up to 10 MPa and is temperature controlled between 10 and 60 °C. The materials of the high-pressure cell which are the thermoplastic polyetheretherketon (PEEK) for the pressure tube and brass (63% Cu, 37% Zn) for the caps also permit investigations with aggressive fluids such as supercritical carbon dioxide. Inlet and outlet valves allow replacement of fluids and pressure variations in the autoclave during the NMR measurement. FLASH NMR images of the fluid exchange of methanol for liquid carbon dioxide in silica alcogels at 6.5 MPa are presented in order to demonstrate possible applications.

Construction and 13C NMR signal-amplification efficiency of a dynamic nuclear polarizer at 6.4 T and 1.4 K

NASA Astrophysics Data System (ADS)

Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Ferguson, Sarah; Taylor, David; McDonald, George; Lumata, Lloyd

Dissolution dynamic nuclear polarization (DNP) is a rapidly emerging technique in biomedical and metabolic imaging since it amplifies the liquid-state nuclear magnetic resonance (NMR) and imaging (MRI) signals by >10,000-fold. Originally used in nuclear scattering experiments, DNP works by creating a non-Boltzmann nuclear spin distribution by transferring the high electron (γ = 28,000 MHz/T) thermal polarization to the nuclear spins via microwave irradiation of the sample at high magnetic field and low temperature. A dissolution device is used to rapidly dissolve the frozen sample and consequently produces an injectable ``hyperpolarized'' liquid at physiologically-tolerable temperature. Here we report the construction and performance evaluation of a dissolution DNP hyperpolarizer at 6.4 T and 1.4 K using a continuous-flow cryostat. The solid and liquid-state 13C NMR signal enhancement levels of 13C acetate samples doped with trityl OX063 and 4-oxo-TEMPO free radicals will be discussed and compared with the results from the 3.35 T commercial hyperpolarizer. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

Push-through Direction Injectin NMR Automation

EPA Science Inventory

Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the two major spectroscopic techniques successfully used in metabolomics studies. The non-invasive, quantitative and reproducible characteristics make NMR spectroscopy an excellent technique for detection of endogeno...

BOOK REVIEW: NMR Imaging of Materials

NASA Astrophysics Data System (ADS)

Blümich, Bernhard

2003-09-01

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

A hyperboliod representation of the bone-marrow interface within 3D NMR images of trabecular bone: applications to skeletal dosimetry

NASA Astrophysics Data System (ADS)

Rajon, D. A.; Shah, A. P.; Watchman, C. J.; Brindle, J. M.; Bolch, W. E.

2003-06-01

Recent advances in physical models of skeletal dosimetry utilize high-resolution NMR microscopy images of trabecular bone. These images are coupled to radiation transport codes to assess energy deposition within active bone marrow irradiated by bone- or marrow-incorporated radionuclides. Recent studies have demonstrated that the rectangular shape of image voxels is responsible for cross-region (bone-to-marrow) absorbed fraction errors of up to 50% for very low-energy electrons (<50 keV). In this study, a new hyperboloid adaptation of the marching cube (MC) image-visualization algorithm is implemented within 3D digital images of trabecular bone to better define the bone-marrow interface, and thus reduce voxel effects in the assessment of cross-region absorbed fractions. To test the method, a mathematical sample of trabecular bone was constructed, composed of a random distribution of spherical marrow cavities, and subsequently coupled to the EGSnrc radiation code to generate reference values for the energy deposition in marrow or bone. Next, digital images of the bone model were constructed over a range of simulated image resolutions, and coupled to EGSnrc using the hyperboloid MC (HMC) algorithm. For the radionuclides 33P, 117mSn, 131I and 153Sm, values of S(marrow←bone) estimated using voxel models of trabecular bone were shown to have relative errors of 10%, 9%, <1% and <1% at a voxel size of 150 µm. At a voxel size of 60 µm, these errors were 6%, 5%, <1% and <1%, respectively. When the HMC model was applied during particle transport, the relative errors on S(marrow←bone) for these same radionuclides were reduced to 7%, 6%, <1% and <1% at a voxel size of 150 µm, and to 2%, 2%, <1% and <1% at a voxel size of 60 µm. The technique was also applied to a real NMR image of human trabecular bone with a similar demonstration of reductions in dosimetry errors.

Novel Techniques for Pulsed Field Gradient NMR Measurements

NASA Astrophysics Data System (ADS)

Brey, William Wallace

Pulsed field gradient (PFG) techniques now find application in multiple quantum filtering and diffusion experiments as well as in magnetic resonance imaging and spatially selective spectroscopy. Conventionally, the gradient fields are produced by azimuthal and longitudinal currents on the surfaces of one or two cylinders. Using a series of planar units consisting of azimuthal and radial current elements spaced along the longitudinal axis, we have designed gradient coils having linear regions that extend axially nearly to the ends of the coil and to more than 80% of the inner radius. These designs locate the current return paths on a concentric cylinder, so the coils are called Concentric Return Path (CRP) coils. Coils having extended linear regions can be made smaller for a given sample size. Among the advantages that can accrue from using smaller coils are improved gradient strength and switching time, reduced eddy currents in the absence of shielding, and improved use of bore space. We used an approximation technique to predict the remaining eddy currents and a time-domain model of coil performance to simulate the electrical performance of the CRP coil and several reduced volume coils of more conventional design. One of the conventional coils was designed based on the time-domain performance model. A single-point acquisition technique was developed to measure the remaining eddy currents of the reduced volume coils. Adaptive sampling increases the dynamic range of the measurement. Measuring only the center of the stimulated echo removes chemical shift and B_0 inhomogeneity effects. The technique was also used to design an inverse filter to remove the eddy current effects in a larger coil set. We added pulsed field gradient and imaging capability to a 7 T commercial spectrometer to perform neuroscience and embryology research and used it in preliminary studies of binary liquid mixtures separating near a critical point. These techniques and coil designs will find application in research areas ranging from functional imaging to NMR microscopy.

{sup 19}F NMR measurements of NO production in hypertensive ISIAH and OXYS rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bobko, Andrey A.; Sergeeva, Svetlana V.; Bagryanskaya, Elena 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 weremore » 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.« less

Evaluation of three different decontamination techniques on biofilm formation, and on physical and chemical properties of resin composites.

PubMed

André, Carolina Bosso; Dos Santos, Andressa; Pfeifer, Carmem Silvia; Giannini, Marcelo; Girotto, Emerson Marcelo; Ferracane, Jack Liborio

2018-04-01

This study evaluated three different sterilization/disinfection techniques for resin composites on bacterial growth and surface modification after decontamination. Two resin composites were sterilized/disinfected with three different techniques: UV light, 1% chloramine T, and 70% ethanol. Four different times were used for each technique to determine the shortest time that the solution or UV light was effective. The influence of sterilization/disinfection technique on bacterial growth was evaluated by analyzing the metabolic activity, using the AlamarBlue™ assay, bacterial viability, and SEM images from biofilms of Streptococcus mutans. The surface change, after the process, was analyzed with ATR/FTIR and SEM images. The solutions used for decontamination (1% chloramine-T and 70% ethanol) were analyzed with 1 H-NMR to identify any resin compounds leached during the process. One minute of decontamination was efficient for all three methods tested. Chloramine-T increased the surface porosity on resin composites, no changes were observed for UV light and 70% ethanol, however, 1 H-NMR identified leached monomers only when 70% ethanol was used. No chemical change of the materials was found under ATR/FTIR analyses after the decontamination process. Chloramine-T, with no previous wash, increased the bacterial viability for both resin composites and increased the bacterial metabolism for the resin composite without fluoride. UV light had no interference on the resin composites properties tested using 1 min of exposure compared to the other decontamination methods. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 945-953, 2018. © 2017 Wiley Periodicals, Inc.

Targeted Molecular Imaging of Cancer Cells Using MS2-Based 129 Xe NMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeong, Keunhong; Netirojjanakul, Chawita; Munch, Henrik K.

Targeted, selective, and highly sensitive 129Xe NMR nanoscale biosensors have been synthesized using a spherical MS2 viral capsid, Cryptophane A molecules, and DNA aptamers. The biosensors showed strong binding specificity toward targeted lymphoma cells (Ramos line). Hyperpolarized 129Xe NMR signal contrast and hyper-CEST 129Xe MRI image contrast indicated its promise as highly sensitive hyperpolarized 129Xe NMR nanoscale biosensor for future applications in cancer detection in vivo.

Proton NMR studies of functionalized nanoparticles in aqueous environments

NASA Astrophysics Data System (ADS)

Tataurova, Yulia Nikolaevna

Nanoscience is an emerging field that can provide potential routes towards addressing critical issues such as clean and sustainable energy, environmental remediation and human health. Specifically, porous nanomaterials, such as zeolites and mesoporous silica, are found in a wide range of applications including catalysis, drug delivery, imaging, environmental protection, and sensing. The characterization of the physical and chemical properties of nanocrystalline materials is essential to the realization of these innovative applications. The great advantage of porous nanocrystals is their increased external surface area that can control their biological, chemical and catalytic activities. Specific functional groups synthesized on the surface of nanoparticles are able to absorb heavy metals from the solution or target disease cells, such as cancer cells. In these studies, three main issues related to functionalized nanomaterials will be addressed through the application of nuclear magnetic resonance (NMR) techniques including: 1) surface composition and structure of functionalized nanocrystalline particles; 2) chemical properties of the guest molecules on the surface of nanomaterials, and 3) adsorption and reactivity of surface bound functional groups. Nuclear magnetic resonance (NMR) is one of the major spectroscopic techniques available for the characterization of molecular structure and conformational dynamics with atomic level detail. This thesis deals with the application of 1H solution state NMR to porous nanomaterial in an aqueous environment. Understanding the aqueous phase behavior of functionalized nanomaterials is a key factor in the design and development of safe nanomaterials because their interactions with living systems are always mediated through the aqueous phase. This is often due to a lack of fundamental knowledge in interfacial chemical and physical phenomena that occur on the surface of nanoparticles. The use of solution NMR spectroscopy results in high-resolution NMR spectra. This technique is selective for protons on the surface organic functional groups due to their motional averaging in solution. In this study, 1H solution NMR spectroscopy was used to investigate the interface of the organic functional groups in D2O. The pKa for these functional groups covalently bound to the surface of nanoparticles was determined using an NMR-pH titration method based on the variation in the proton chemical shift for the alkyl group protons closest to the amine group with pH. The adsorption of toxic contaminants (chromate and arsenate anions) on the surface of functionalized silicalite-1 and mesoporous silica nanoparticles has been studied by 1H solution NMR spectroscopy. With this method, the surface bound contaminants are detected. The analysis of the intensity and position of these peaks allows quantitative assessment of the relative amounts of functional groups with adsorbed metal ions. These results demonstrate the sensitivity of solution NMR spectroscopy to the electronic environment and structure of the surface functional groups on porous nanomaterials.

In vitro quantitative ((1))H and ((19))F nuclear magnetic resonance spectroscopy and imaging studies of fluvastatin™ in Lescol® XL tablets in a USP-IV dissolution cell.

PubMed

Zhang, Qilei; Gladden, Lynn; Avalle, Paolo; Mantle, Michael

2011-12-20

Swellable polymeric matrices are key systems in the controlled drug release area. Currently, the vast majority of research is still focused on polymer swelling dynamics. This study represents the first quantitative multi-nuclear (((1))H and ((19))F) fast magnetic resonance imaging study of the complete dissolution process of a commercial (Lescol® XL) tablet, whose formulation is based on the hydroxypropyl methylcellulose (HPMC) polymer under in vitro conditions in a standard USP-IV (United States Pharmacopeia apparatus IV) flow-through cell that is incorporated into high field superconducting magnetic resonance spectrometer. Quantitative RARE ((1))H magnetic resonance imaging (MRI) and ((19))F nuclear magnetic resonance (NMR) spectroscopy and imaging methods have been used to give information on: (i) dissolution media uptake and hydrodynamics; (ii) active pharmaceutical ingredient (API) mobilisation and dissolution; (iii) matrix swelling and dissolution and (iv) media activity within the swelling matrix. In order to better reflect the in vivo conditions, the bio-relevant media Simulated Gastric Fluid (SGF) and Fasted State Simulated Intestinal Fluid (FaSSIF) were used. A newly developed quantitative ultra-fast MRI technique was applied and the results clearly show the transport dynamics of media penetration and hydrodynamics along with the polymer swelling processes. The drug dissolution and mobility inside the gel matrix was characterised, in parallel to the ((1))H measurements, by ((19))F NMR spectroscopy and MRI, and the drug release profile in the bulk solution was recorded offline by UV spectrometer. We found that NMR spectroscopy and 1D-MRI can be uniquely used to monitor the drug dissolution/mobilisation process within the gel layer, and the results from ((19))F NMR spectra indicate that in the gel layer, the physical mobility of the drug changes from "dissolved immobilised drug" to "dissolved mobilised drug". Copyright © 2011 Elsevier B.V. All rights reserved.

Organ specific mapping of in vivo redox state in control and cigarette smoke-exposed mice using EPR/NMR co-imaging

PubMed Central

Caia, George L.; Efimova, Olga V.; Velayutham, Murugesan; El-Mahdy, Mohamed A.; Abdelghany, Tamer M.; Kesselring, Eric; Petryakov, Sergey; Sun, Ziqi; Samouilov, Alexandre; Zweier, Jay L.

2014-01-01

In vivo mapping of alterations in redox status is important for understanding organ specific pathology and disease. While electron paramagnetic resonance imaging (EPRI) enables spatial mapping of free radicals, it does not provide anatomic visualization of the body. Proton MRI is well suited to provide anatomical visualization. We applied EPR/NMR co-imaging instrumentation to map and monitor the redox state of living mice under normal or oxidative stress conditions induced by secondhand cigarette smoke (SHS) exposure. A hybrid co-imaging instrument, EPRI (1.2 GHz) / proton MRI (16.18 MHz), suitable for whole-body co-imaging of mice was utilized with common magnet and gradients along with dual EPR/NMR resonators that enable co-imaging without sample movement. The metabolism of the nitroxide probe, 3–carbamoyl–proxyl (3-CP), was used to map the redox state of control and SHS-exposed mice. Co-imaging allowed precise 3D mapping of radical distribution and reduction in major organs such as the heart, lungs, liver, bladder and kidneys. Reductive metabolism was markedly decreased in SHS-exposed mice and EPR/NMR co-imaging allowed quantitative assessment of this throughout the body. Thus, in vivo EPR/NMR co-imaging enables in vivo organ specific mapping of free radical metabolism and redox stress and the alterations that occur in the pathogenesis of disease. PMID:22296801

Organ specific mapping of in vivo redox state in control and cigarette smoke-exposed mice using EPR/NMR co-imaging

NASA Astrophysics Data System (ADS)

Caia, George L.; Efimova, Olga V.; Velayutham, Murugesan; El-Mahdy, Mohamed A.; Abdelghany, Tamer M.; Kesselring, Eric; Petryakov, Sergey; Sun, Ziqi; Samouilov, Alexandre; Zweier, Jay L.

2012-03-01

In vivo mapping of alterations in redox status is important for understanding organ specific pathology and disease. While electron paramagnetic resonance imaging (EPRI) enables spatial mapping of free radicals, it does not provide anatomic visualization of the body. Proton MRI is well suited to provide anatomical visualization. We applied EPR/NMR co-imaging instrumentation to map and monitor the redox state of living mice under normal or oxidative stress conditions induced by secondhand cigarette smoke (SHS) exposure. A hybrid co-imaging instrument, EPRI (1.2 GHz)/proton MRI (16.18 MHz), suitable for whole-body co-imaging of mice was utilized with common magnet and gradients along with dual EPR/NMR resonators that enable co-imaging without sample movement. The metabolism of the nitroxide probe, 3-carbamoyl-proxyl (3-CP), was used to map the redox state of control and SHS-exposed mice. Co-imaging allowed precise 3D mapping of radical distribution and reduction in major organs such as the heart, lungs, liver, bladder and kidneys. Reductive metabolism was markedly decreased in SHS-exposed mice and EPR/NMR co-imaging allowed quantitative assessment of this throughout the body. Thus, in vivo EPR/NMR co-imaging enables in vivo organ specific mapping of free radical metabolism and redox stress and the alterations that occur in the pathogenesis of disease.

Benchtop-NMR and MRI--a new analytical tool in drug delivery research.

PubMed

Metz, Hendrik; Mäder, Karsten

2008-12-08

During the last years, NMR spectroscopy and NMR imaging (magnetic resonance imaging, MRI) have been increasingly used to monitor drug delivery systems in vitro and in vivo. However, high installation and running costs of the commonly used superconducting magnet technology limits the application range and prevents the further spread of this non-invasive technology. Benchtop-NMR (BT-NMR) relaxometry uses permanent magnets and is much less cost intensive. BT-NMR relaxometry is commonly used in the food and chemical industry, but so far scarcely used in the pharmaceutical field. The paper shows on several examples that the application field of BT-NMR relaxometry can be extended into the field of drug delivery, including the characterisation of emulsions and lipid ingredients (e.g. the amount and physicochemical state of the lipid) and the monitoring of adsorption characteristics (e.g. oil binding of porous ingredients). The most exciting possibilities of BT-NMR technology are linked with the new development of BT-instruments with imaging capability. BT-MRI examples on the monitoring of hydration and swelling of HPMC-based monolayer and double-layer tablets are shown. BT-MRI opens new MRI opportunities for the non-invasive monitoring of drug delivery processes.

A biofilm microreactor system for simultaneous electrochemical and nuclear magnetic resonance techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renslow, Ryan S.; Babauta, Jerome T.; Majors, Paul D.

2014-03-01

In order to fully understand electrochemically active biofilms and the limitations to their scale-up in industrial biofilm reactors, a complete picture of the microenvironments inside the biofilm is needed. Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for non-invasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live electrochemically active biofilms. Here, we introduce a novel biofilm microreactor system that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactorsmore » were designed with custom radiofrequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system, we grew Geobacter sulfurreducens biofilms. NMR was used to investigate growth media flow velocities, which were compared to simulated laminar flow, and electron donor concentrations inside the biofilms. We use Monte Carlo error analysis to estimate standard deviations of the electron donor concentration measurements within the biofilm. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms.« less

Analytical Applications of NMR: Summer Symposium on Analytical Chemistry.

ERIC Educational Resources Information Center

Borman, Stuart A.

1982-01-01

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

Saturation-Transfer Difference (STD) NMR: A Simple and Fast Method for Ligand Screening and Characterization of Protein Binding

ERIC Educational Resources Information Center

Viegas, Aldino; Manso, Joao; Nobrega, Franklin L.; Cabrita, Eurico J.

2011-01-01

Saturation transfer difference (STD) NMR has emerged as one of the most popular ligand-based NMR techniques for the study of protein-ligand interactions. The success of this technique is a consequence of its robustness and the fact that it is focused on the signals of the ligand, without any need of processing NMR information about the receptor…

Compressed NMR: Combining compressive sampling and pure shift NMR techniques.

PubMed

Aguilar, Juan A; Kenwright, Alan M

2017-12-26

Historically, the resolution of multidimensional nuclear magnetic resonance (NMR) has been orders of magnitude lower than the intrinsic resolution that NMR spectrometers are capable of producing. The slowness of Nyquist sampling as well as the existence of signals as multiplets instead of singlets have been two of the main reasons for this underperformance. Fortunately, two compressive techniques have appeared that can overcome these limitations. Compressive sensing, also known as compressed sampling (CS), avoids the first limitation by exploiting the compressibility of typical NMR spectra, thus allowing sampling at sub-Nyquist rates, and pure shift techniques eliminate the second issue "compressing" multiplets into singlets. This paper explores the possibilities and challenges presented by this combination (compressed NMR). First, a description of the CS framework is given, followed by a description of the importance of combining it with the right pure shift experiment. Second, examples of compressed NMR spectra and how they can be combined with covariance methods will be shown. Copyright © 2017 John Wiley & Sons, Ltd.

Strongly hyperpolarized gas from parahydrogen by rational design of ligand-capped nanoparticles

PubMed Central

Sharma, Ramesh; Bouchard, Louis-S

2012-01-01

The production of hyperpolarized fluids in continuous mode would broaden substantially the range of applications in chemistry, materials science, and biomedicine. Here we show that the rational design of a heterogeneous catalyst based on a judicious choice of metal type, nanoparticle size and surface decoration with appropriate ligands leads to highly efficient pairwise addition of dihydrogen across an unsaturated bond. This is demonstrated in a parahydrogen-induced polarization (PHIP) experiment by a 508-fold enhancement (±78) of a CH3 proton signal and a corresponding 1219-fold enhancement (±187) of a CH2 proton signal using nuclear magnetic resonance (1H-NMR). In contrast, bulk metal catalyst does not show this effect due to randomization of reacting dihydrogen. Our approach results in the largest gas-phase NMR signal enhancement by PHIP known to date. Sensitivity-enhanced NMR with this technique could be used to image microfluidic reactions in-situ, to probe nonequilibrium thermodynamics or for the study of metabolic reactions. PMID:22355789

Postdoctoral Fellow | Center for Cancer Research

Cancer.gov

The Neuro-Oncology Branch (NOB), Center for Cancer Research (CCR), National Cancer Institute (NCI) of the National Institutes of Health (NIH) is seeking outstanding postdoctoral candidates interested in studying the metabolic changes in brain tumors such as glioblastoma multiforme (GBMs).  NOB’s Metabolomics program is interested in revealing the metabolic alterations of isocitrate dehydrogenase (IDH1)-mutated GBMs and in exploiting these deregulations for therapeutic applications.  A combination of methods such as molecular biology, animal models, as well as in vitro and in vivo metabolomics using Raman Imaging Microscopy, Nuclear Magnetic Resonance spectroscopy (NMR), Mass Spectrometry (MS) and Magnetic Resonance Imaging (MRI) techniques are employed.  The position will specifically focus on molecular biology and Raman Imaging Microscopy, which includes work in Western Blotting, mammalian cell culture and other common biomedical techniques used in cancer bio  logy labs such as handling tissue samples, preparing tissue slides, staining, and extracting proteins from brain tissue.

Nanoscale NMR spectroscopy and imaging of multiple nuclear species.

PubMed

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

2015-02-01

Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) provide non-invasive information about multiple nuclear species in bulk matter, with wide-ranging applications from basic physics and chemistry to biomedical imaging. However, the spatial resolution of conventional NMR and MRI is limited to several micrometres even at large magnetic fields (>1 T), which is inadequate for many frontier scientific applications such as single-molecule NMR spectroscopy and in vivo MRI of individual biological cells. A promising approach for nanoscale NMR and MRI exploits optical measurements of nitrogen-vacancy (NV) colour centres in diamond, which provide a combination of magnetic field sensitivity and nanoscale spatial resolution unmatched by any existing technology, while operating under ambient conditions in a robust, solid-state system. Recently, single, shallow NV centres were used to demonstrate NMR of nanoscale ensembles of proton spins, consisting of a statistical polarization equivalent to ∼100-1,000 spins in uniform samples covering the surface of a bulk diamond chip. Here, we realize nanoscale NMR spectroscopy and MRI of multiple nuclear species ((1)H, (19)F, (31)P) in non-uniform (spatially structured) samples under ambient conditions and at moderate magnetic fields (∼20 mT) using two complementary sensor modalities.

Investigation of Lung Structure-Function Relationships Using Hyperpolarized Noble Gases

NASA Astrophysics Data System (ADS)

Thomen, Robert P.

Magnetic Resonance Imaging (MRI) is an application of the nuclear magnetic resonance (NMR) phenomenon to non-invasively generate 3D tomographic images. MRI is an emerging modality for the lung, but it suffers from low sensitivity due to inherent low tissue density and short T(*/2) . Hyperpolarization is a process by which the nuclear contribution to NMR signal is greatly enhanced to more than 100,000 times that of samples in thermal equilibrium. The noble gases 3He and 129Xe are most often hyperpolarized by transfer of light angular momentum through the electron of a vaporized alkali metal to the noble gas nucleus (called Spin Exchange Optical Pumping). The enhancement in NMR signal is so great that the gas itself can be imaged via MRI, and because noble gases are chemically inert, they can be safely inhaled by a subject, and the gas distribution within the interior of the lung can be imaged. The mechanics of respiration is an elegant physical process by which air is is brought into the distal airspaces of the lungs for oxygen/carbon dioxide gas exchange with blood. Therefore proper description of lung function is intricately related to its physical structure , and the basic mechanical operation of healthy lungs -- from pressure driven airflow, to alveolar airspace gas kinetics, to gas exchange by blood/gas concentration gradients, to elastic contraction of parenchymal tissue -- is a process decidedly governed by the laws of physics. This dissertation will describe experiments investigating the relationship of lung structure and function using hyperpolarized (HP) noble gas MRI. In particular HP gases will be applied to the study of several pulmonary diseases each of which demonstrates unique structure-function abnormalities: asthma, cystic fibrosis, and chronic obstructive pulmonary disease. Successful implementation of an HP gas acquisition protocol for pulmonary studies is an involved and stratified undertaking which requires a solid theoretical foundation in NMR and hyperpolarization theory, construction of dedicated hardware, development of dedicated software, and appropriate image analysis techniques for all acquired data. The author has been actively involved in each of these and has dedicated specific chapters of this dissertation to their description. First, a brief description of lung structure-function investigations and pulmonary imaging will be given (chapter 1). Brief discussions of basic NMR, MRI, and hyperpolarization theory will be given (chapters 2 and 3) followed by their particular methods of implementation in this work (chapters 4 and 5). Analysis of acquired HP gas images will be discussed (chapter 6), and the investigational procedures and results for each lung disease examined will be detailed (chapter 7). Finally, a quick digression on the strengths and limitations of HP gas MRI will be provided (chapter 8).

Physicochemical properties of liposomes as potential anticancer drugs carriers. Interaction of etoposide and cytarabine with the membrane: Spectroscopic studies

NASA Astrophysics Data System (ADS)

Pentak, Danuta

2014-03-01

The interactions between etoposide, cytarabine and 1,2-dihexadecanoyl-sn-glycerol-3-phosphocholine bilayers were studied using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR). These techniques have proven to be a very powerful tool in studying the structure and dynamics of phospholipid bilayers. In particular, DSC can provide information on the phase transition temperature and cooperativity of the lipid molecules in the absence and presence of the drug. Vibrational spectroscopy is well suited to the study of drug-lipid interactions, since it allows for an investigation of the conformation of phospholipid molecules at different levels in lipid bilayers and follows structural changes that occur during the gel to liquid-crystalline phase transition. NMR supported the determination of the main phase transition temperatures (TC) of 1,2-dihexadecanoyl-sn-glycerol-3-phosphocholine (DPPC). The main phase transition temperature (TC) determined by 1H NMR is comparable with values obtained by DSC for all studied liposomes. The location of cytarabine and etoposide in liposomes was also determined by NMR. Atomic force microscopy (AFM) images, acquired immediately after sample deposition on a mica surface, revealed the spherical shape of lipid vesicles.

Laser-polarized xenon-129 magnetic resonance spectroscopy and imaging. The development of a method for in vivo perfusion measurement

NASA Astrophysics Data System (ADS)

Rosen, Matthew Scot

2001-07-01

This thesis presents in vivo nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) studies with laser-polarized 129Xe delivered to living rats by inhalation and transported to tissue via blood flow. The results presented herein include the observation, assignment, and dynamic measurement of 129Xe resonances in the brain and body, the first one- and two-dimensional chemical-shift-resolved images of 129Xe in blood, tissue, and gas in the thorax, and the first images of 129Xe in brain tissue. These results establish that laser-polarized 129Xe can be used as a magnetic resonance tracer in vivo. NMR resonances at 0, 191, 198, and 209 ppm relative to the 129 Xe gas resonance are observed in the rat thorax and assigned to 129Xe in gas, fat, tissue, and blood respectively. Resonances at 189, 192, 195, 198, and 209 ppm are observed in the brain, and the 195 and 209 ppm resonances are assigned to 129Xe in grey matter, and blood, respectively. The design and construction of a laser-polarized 129Xe production and delivery system is described. This system produces liter-volumes of laser- polarized 129Xe by spin-exchange optical- pumping. It represented an order of magnitude increase over previously reported production volumes of polarized 129Xe. At approximately 3-7% polarization, 157 cc-atm of xenon is produced and stored as ice every 5 minutes. This reliable, effective, and simple production method for large volumes of 129Xe can be applied to other areas of research involving the use of laser-polarized noble gases. A model of the in vivo transport of laser polarized 129Xe to tissue under realistic experimental NMR conditions is described. Appropriate control of the NMR parameters is shown to allow tissue perfasion and 129Xe tissue T1 to be extracted from measurement of the steady-state 129Xe tissue signal. In vivo rodent 129Xe NMR results are used to estimate the signal-to-noise ratio of this technique, and an inhaled 30% xenon/70% O2 mixture polarized to 5% is estimated to provide sufficient SNR in rodent grey matter. Application to the measurement of regional cerebral blood flow and neuronal activation is discussed.

Solid-state NMR imaging system

DOEpatents

Gopalsami, Nachappa; Dieckman, Stephen L.; Ellingson, William A.

1992-01-01

An apparatus for use with a solid-state NMR spectrometer includes a special imaging probe with linear, high-field strength gradient fields and high-power broadband RF coils using a back projection method for data acquisition and image reconstruction, and a real-time pulse programmer adaptable for use by a conventional computer for complex high speed pulse sequences.

NMR imaging of high-amylose starch tablets. 1. Swelling and water uptake.

PubMed

Baille, Wilms E; Malveau, Cédric; Zhu, Xiao Xia; Marchessault, Robert H

2002-01-01

Pharmaceutical tablets made of modified high-amylose starch have a hydrophilic polymer matrix into which water can penetrate with time to form a hydrogel. Nuclear magnetic resonance imaging was used to study the water penetration and the swelling of the matrix of these tablets. The tablets immersed in water were imaged at different time intervals on a 300 MHz NMR spectrometer. Radial images show clearly the swelling of the tablets and the water concentration profile. The rate constants for water diffusion and the tablet swelling were extracted from the experimental data. The water diffusion process was found to follow case II kinetics at 25 degrees C. NMR imaging also provided spin density profiles of the water penetrating inside the tablets.

Computer Code for Interpreting 13C NMR Relaxation Measurements with Specific Models of Molecular Motion: The Rigid Isotropic and Symmetric Top Rotor Models and the Flexible Symmetric Top Rotor Model

DTIC Science & Technology

2017-01-01

unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT: Carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy is a powerful technique for...FLEXIBLE SYMMETRIC TOP ROTOR MODEL 1. INTRODUCTION Nuclear magnetic resonance (NMR) spectroscopy is a tremendously powerful technique for...application of NMR spectroscopy concerns the property of molecular motion, which is related to many physical, and even biological, functions of molecules in

Sensitivity quantification of remote detection NMR and MRI

NASA Astrophysics Data System (ADS)

Granwehr, J.; Seeley, J. A.

2006-04-01

A sensitivity analysis is presented of the remote detection NMR technique, which facilitates the spatial separation of encoding and detection of spin magnetization. Three different cases are considered: remote detection of a transient signal that must be encoded point-by-point like a free induction decay, remote detection of an experiment where the transient dimension is reduced to one data point like phase encoding in an imaging experiment, and time-of-flight (TOF) flow visualization. For all cases, the sensitivity enhancement is proportional to the relative sensitivity between the remote detector and the circuit that is used for encoding. It is shown for the case of an encoded transient signal that the sensitivity does not scale unfavorably with the number of encoded points compared to direct detection. Remote enhancement scales as the square root of the ratio of corresponding relaxation times in the two detection environments. Thus, remote detection especially increases the sensitivity of imaging experiments of porous materials with large susceptibility gradients, which cause a rapid dephasing of transverse spin magnetization. Finally, TOF remote detection, in which the detection volume is smaller than the encoded fluid volume, allows partial images corresponding to different time intervals between encoding and detection to be recorded. These partial images, which contain information about the fluid displacement, can be recorded, in an ideal case, with the same sensitivity as the full image detected in a single step with a larger coil.

Compact orthogonal NMR field sensor

DOEpatents

Gerald, II, Rex E.; Rathke, Jerome W [Homer Glen, IL

2009-02-03

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

Video Toroid Cavity Imager

DOEpatents

Gerald, II, Rex E.; Sanchez, Jairo; Rathke, Jerome W.

2004-08-10

A video toroid cavity imager for in situ measurement of electrochemical properties of an electrolytic material sample includes a cylindrical toroid cavity resonator containing the sample and employs NMR and video imaging for providing high-resolution spectral and visual information of molecular characteristics of the sample on a real-time basis. A large magnetic field is applied to the sample under controlled temperature and pressure conditions to simultaneously provide NMR spectroscopy and video imaging capabilities for investigating electrochemical transformations of materials or the evolution of long-range molecular aggregation during cooling of hydrocarbon melts. The video toroid cavity imager includes a miniature commercial video camera with an adjustable lens, a modified compression coin cell imager with a fiat circular principal detector element, and a sample mounted on a transparent circular glass disk, and provides NMR information as well as a video image of a sample, such as a polymer film, with micrometer resolution.

Skin age testing criteria: characterization of human skin structures by 500 MHz MRI multiple contrast and image processing.

PubMed

Sharma, Rakesh

2010-07-21

Ex vivo magnetic resonance microimaging (MRM) image characteristics are reported in human skin samples in different age groups. Human excised skin samples were imaged using a custom coil placed inside a 500 MHz NMR imager for high-resolution microimaging. Skin MRI images were processed for characterization of different skin structures. Contiguous cross-sectional T1-weighted 3D spin echo MRI, T2-weighted 3D spin echo MRI and proton density images were compared with skin histopathology and NMR peaks. In all skin specimens, epidermis and dermis thickening and hair follicle size were measured using MRM. Optimized parameters TE and TR and multicontrast enhancement generated better MRI visibility of different skin components. Within high MR signal regions near to the custom coil, MRI images with short echo time were comparable with digitized histological sections for skin structures of the epidermis, dermis and hair follicles in 6 (67%) of the nine specimens. Skin % tissue composition, measurement of the epidermis, dermis, sebaceous gland and hair follicle size, and skin NMR peaks were signatures of skin type. The image processing determined the dimensionality of skin tissue components and skin typing. The ex vivo MRI images and histopathology of the skin may be used to measure the skin structure and skin NMR peaks with image processing may be a tool for determining skin typing and skin composition.

Skin age testing criteria: characterization of human skin structures by 500 MHz MRI multiple contrast and image processing

NASA Astrophysics Data System (ADS)

Sharma, Rakesh

2010-07-01

Ex vivo magnetic resonance microimaging (MRM) image characteristics are reported in human skin samples in different age groups. Human excised skin samples were imaged using a custom coil placed inside a 500 MHz NMR imager for high-resolution microimaging. Skin MRI images were processed for characterization of different skin structures. Contiguous cross-sectional T1-weighted 3D spin echo MRI, T2-weighted 3D spin echo MRI and proton density images were compared with skin histopathology and NMR peaks. In all skin specimens, epidermis and dermis thickening and hair follicle size were measured using MRM. Optimized parameters TE and TR and multicontrast enhancement generated better MRI visibility of different skin components. Within high MR signal regions near to the custom coil, MRI images with short echo time were comparable with digitized histological sections for skin structures of the epidermis, dermis and hair follicles in 6 (67%) of the nine specimens. Skin % tissue composition, measurement of the epidermis, dermis, sebaceous gland and hair follicle size, and skin NMR peaks were signatures of skin type. The image processing determined the dimensionality of skin tissue components and skin typing. The ex vivo MRI images and histopathology of the skin may be used to measure the skin structure and skin NMR peaks with image processing may be a tool for determining skin typing and skin composition.

15N Hyperpolarization by Reversible Exchange Using SABRE-SHEATH

PubMed Central

2016-01-01

NMR signal amplification by reversible exchange (SABRE) is a NMR hyperpolarization technique that enables nuclear spin polarization enhancement of molecules via concurrent chemical exchange of a target substrate and parahydrogen (the source of spin order) on an iridium catalyst. Recently, we demonstrated that conducting SABRE in microtesla fields provided by a magnetic shield enables up to 10% 15N-polarization (Theis, T.; et al. J. Am. Chem. Soc.2015, 137, 1404). Hyperpolarization on 15N (and heteronuclei in general) may be advantageous because of the long-lived nature of the hyperpolarization on 15N relative to the short-lived hyperpolarization of protons conventionally hyperpolarized by SABRE, in addition to wider chemical shift dispersion and absence of background signal. Here we show that these unprecedented polarization levels enable 15N magnetic resonance imaging. We also present a theoretical model for the hyperpolarization transfer to heteronuclei, and detail key parameters that should be optimized for efficient 15N-hyperpolarization. The effects of parahydrogen pressure, flow rate, sample temperature, catalyst-to-substrate ratio, relaxation time (T1), and reversible oxygen quenching are studied on a test system of 15N-pyridine in methanol-d4. Moreover, we demonstrate the first proof-of-principle 13C-hyperpolarization using this method. This simple hyperpolarization scheme only requires access to parahydrogen and a magnetic shield, and it provides large enough signal gains to enable one of the first 15N images (2 × 2 mm2 resolution). Importantly, this method enables hyperpolarization of molecular sites with NMR T1 relaxation times suitable for biomedical imaging and spectroscopy. PMID:25960823

15N Hyperpolarization by Reversible Exchange Using SABRE-SHEATH.

PubMed

Truong, Milton L; Theis, Thomas; Coffey, Aaron M; Shchepin, Roman V; Waddell, Kevin W; Shi, Fan; Goodson, Boyd M; Warren, Warren S; Chekmenev, Eduard Y

2015-04-23

NMR signal amplification by reversible exchange (SABRE) is a NMR hyperpolarization technique that enables nuclear spin polarization enhancement of molecules via concurrent chemical exchange of a target substrate and parahydrogen (the source of spin order) on an iridium catalyst. Recently, we demonstrated that conducting SABRE in microtesla fields provided by a magnetic shield enables up to 10% 15 N-polarization (Theis, T.; et al. J. Am. Chem. Soc. 2015 , 137 , 1404). Hyperpolarization on 15 N (and heteronuclei in general) may be advantageous because of the long-lived nature of the hyperpolarization on 15 N relative to the short-lived hyperpolarization of protons conventionally hyperpolarized by SABRE, in addition to wider chemical shift dispersion and absence of background signal. Here we show that these unprecedented polarization levels enable 15 N magnetic resonance imaging. We also present a theoretical model for the hyperpolarization transfer to heteronuclei, and detail key parameters that should be optimized for efficient 15 N-hyperpolarization. The effects of parahydrogen pressure, flow rate, sample temperature, catalyst-to-substrate ratio, relaxation time ( T 1 ), and reversible oxygen quenching are studied on a test system of 15 N-pyridine in methanol- d 4 . Moreover, we demonstrate the first proof-of-principle 13 C-hyperpolarization using this method. This simple hyperpolarization scheme only requires access to parahydrogen and a magnetic shield, and it provides large enough signal gains to enable one of the first 15 N images (2 × 2 mm 2 resolution). Importantly, this method enables hyperpolarization of molecular sites with NMR T 1 relaxation times suitable for biomedical imaging and spectroscopy.

Superoxygenated Water as an Experimental Sample for NMR Relaxometry

ERIC Educational Resources Information Center

Nestle, Nikolaus; Dakkouri, Marwan; Rauscher, Hubert

2004-01-01

The increase in NMR relaxation rates as a result of dissolved paramagnetic species on the sample of superoxygenated drinking water is demonstrated. It is concluded that oxygen content in NMR samples is an important issue and can give rise to various problems in the interpretation of both spectroscopic and NMR imaging or relaxation experiments.

Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials and organisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodson, Boyd McLean

1999-12-01

Conventional nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are fundamentally challenged by the insensitivity that stems from the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This dissertation is primarily concerned with the principles and practice of optically pumped nuclear magnetic resonance (OPNMR). The enormous sensitivity enhancement afforded by optical pumping noble gases can be exploited to permitmore » a variety of novel NMR experiments across many disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, and zero-field NMR and MRI.« less

Quantification of oil and water in preserved reservoir rock by NMR spectroscopy and imaging.

PubMed

Davies, S; Hardwick, A; Roberts, D; Spowage, K; Packer, K J

1994-01-01

Reservoir rock analysis by proton NMR requires separation of the response into brine and crude oil components. Tests on preserved core from a North Sea chalk reservoir show that spin-lattice relaxation time distributions can be used to distinguish the two fluids. NMR estimates of oil and water saturations for 1.5" diameter core examined in a 10 MHz Bruker Minispec spectrometer closely match fluid contents determined by distillation. The spin-lattice relaxation contrast mechanism developed for core samples can be applied in the quantitative analysis of NMR images. The relaxation data are compared with data from chemical shift imaging on the same core sample. The results indicate that it will be possible to monitor changes in fluid distributions, in this and similar systems, under dynamic conditions such as in a waterflood.

Boosting production yield of biomedical peptides

NASA Technical Reports Server (NTRS)

Manatt, S. L.

1978-01-01

Nuclear magnetic resonance (NMR) technique is employed to monitor synthesis of biomedical peptides. Application of NMR technique may improve production yields of insulin, ACTH, and growth hormones, as well as other synthesized biomedical peptides.

A new multimodality system for quantitative in vivo studies in small animals: combination of nuclear magnetic resonance and the radiosensitive /spl beta/-MicroProbe

NASA Astrophysics Data System (ADS)

Desbree, A.; Pain, F.; Gurden, H.; Pinot, L.; Grenier, D.; Zimmer, L.; Mastrippolito, R.; Laniece, P.

2005-10-01

Elucidating complex physiological mechanisms in small animal in vivo requires the development of new investigatory techniques including imaging with multiple modalities. Combining exploratory techniques has the tremendous advantage to record simultaneously complementary parameters on the same animal. In this field, an exciting challenge remains in the combination of nuclear magnetic resonance (NMR) and positron emission tomography (PET) since small animals studies are limited by strict technical constraints in vivo. Coupling NMR with a radiosensitive /spl beta/-MicroProbe offers therefore an interesting technical alternative. To assess the feasibility of this new dual-modality system, we designed theoretical and experimental approaches to test the ability of the /spl beta/-Microprobe to quantify radioactivity concentration in an intense magnetic field. In an initial step, simulations were carried out using Geant4. First, we evaluated the influence of a magnetic field on the probe detection volume. Then, the detection sensitivity and energy response of the probe were quantified. In a second step, experiments were run within a 7-T magnet to confirm our simulations results. We showed that using the probe in magnetic fields leads to a slight attenuation in sensitivity and an increase of the scintillation light yield. These data demonstrate the feasibility of combining NMR to the /spl beta/-MicroProbe.

Solution NMR Spectroscopy in Target-Based Drug Discovery.

PubMed

Li, Yan; Kang, Congbao

2017-08-23

Solution NMR spectroscopy is a powerful tool to study protein structures and dynamics under physiological conditions. This technique is particularly useful in target-based drug discovery projects as it provides protein-ligand binding information in solution. Accumulated studies have shown that NMR will play more and more important roles in multiple steps of the drug discovery process. In a fragment-based drug discovery process, ligand-observed and protein-observed NMR spectroscopy can be applied to screen fragments with low binding affinities. The screened fragments can be further optimized into drug-like molecules. In combination with other biophysical techniques, NMR will guide structure-based drug discovery. In this review, we describe the possible roles of NMR spectroscopy in drug discovery. We also illustrate the challenges encountered in the drug discovery process. We include several examples demonstrating the roles of NMR in target-based drug discoveries such as hit identification, ranking ligand binding affinities, and mapping the ligand binding site. We also speculate the possible roles of NMR in target engagement based on recent processes in in-cell NMR spectroscopy.

Nuclear Magnetic Resonance Nondestructive Evaluation of Composite Materials

DTIC Science & Technology

1990-04-09

Pat. Appl. EP 26265, 8 Apr 1981, 13 pp. (1981). 9. A. N. Garroway , J. Baum, M. G. Munowitz, and A. Pines, NMR Imaging in Solids by Multiple-Quantum...Resonance, J. Magn. Reson. 60(2), 337-41 (1984). 10. J. Baum, A. N. Garroway , M. Munowitz, and A. Pines, Multiple-Quantum NMR in Solids: Application to... Garroway , NMR Images of Solids, J. Magn. Reson. 66(3), 530-5 (1986). 28. J. B. Miller and A. N. Garroway , Removal of Static Field Inhomogeneity and

Hyperpolarized NMR: d-DNP, PHIP, and SABRE.

PubMed

Kovtunov, Kirill Viktorovich; Pokochueva, Ekaterina; Salnikov, Oleg; Cousin, Samuel; Kurzbach, Dennis; Vuichoud, Basile; Jannin, Sami; Chekmenev, Eduard; Goodson, Boyd; Barskiy, Danila; Koptyug, Igor

2018-05-23

NMR signals intensities can be enhanced by several orders of magnitude via utilization of techniques for hyperpolarization of different molecules, and it allows one to overcome the main sensitivity challenge of modern NMR/MRI techniques. Hyperpolarized fluids can be successfully used in different applications of material science and biomedicine. This focus review covers the fundamentals of the preparation of hyperpolarized liquids and gases via dissolution dynamic nuclear polarization (d-DNP) and parahydrogen-based techniques such as signal amplification by reversible exchange (SABRE) and parahydrogen-induced polarization (PHIP) in both heterogeneous and homogeneous processes. The different novel aspects of hyperpolarized fluids formation and utilization along with the possibility of NMR signal enhancement observation are described. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of high resolution NMR spectroscopy as a structural tool

NASA Astrophysics Data System (ADS)

Feeney, James

1992-06-01

The discovery of the nuclear magnetic resonance (NMR) phenomenon and its development and exploitation as a scientific tool provide an excellent basis for a case-study for examining the factors which control the evolution of scientific techniques. Since the detection of the NMR phenomenon and the subsequent rapid discovery of all the important NMR spectral parameters in the late 1940s, the method has emerged as one of the most powerful techniques for determining structures of molecules in solution and for analysis of complex mixtures. The method has made a dramatic impact on the development of structural chemistry over the last 30 years and is now one of the key techniques in this area. Support for NMR instrumentation attracts a dominant slice of public funding in most scientifically developed countries. The technique is an excellent example of how instrumentation and technology have revolutionised structural chemistry and it is worth exploring how it has been developed so successfully. Clearly its wide range of application and the relatively direct connection between the NMR data and molecular structure has created a major market for the instrumentation. This has provided several competing manufacturers with the incentive to develop better and better instruments. Understanding the complexity of the basics of NMR spectroscopy has been an ongoing challenge attracting the attention of physicists. The well-organised specialist NMR literature and regular scientific meetings have ensured rapid exploitation of any theoretical advances that have a practical relevance. In parallel, the commercial development of the technology has allowed the fruits of such theoretical advances to be enjoyed by the wider scientific community.

Combining Two-Dimensional Diffusion-Ordered Nuclear Magnetic Resonance Spectroscopy, Imaging Desorption Electrospray Ionization Mass Spectrometry, and Direct Analysis in Real-Time Mass Spectrometry for the Integral Investigation of Counterfeit Pharmaceuticals

PubMed Central

Nyadong, Leonard; Harris, Glenn A.; Balayssac, Stéphane; Galhena, Asiri S.; Malet-Martino, Myriam; Martino, Robert; Parry, R. Mitchell; Wang, May Dongmei; Fernández, Facundo M.; Gilard, Véronique

2016-01-01

During the past decade, there has been a marked increase in the number of reported cases involving counterfeit medicines in developing and developed countries. Particularly, artesunate-based antimalarial drugs have been targeted, because of their high demand and cost. Counterfeit antimalarials can cause death and can contribute to the growing problem of drug resistance, particularly in southeast Asia. In this study, the complementarity of two-dimensional diffusion-ordered 1H nuclear magnetic resonance spectroscopy (2D DOSY 1H NMR) with direct analysis in real-time mass spectrometry (DART MS) and desorption electrospray ionization mass spectrometry (DESI MS) was assessed for pharmaceutical forensic purposes. Fourteen different artesunate tablets, representative of what can be purchased from informal sources in southeast Asia, were investigated with these techniques. The expected active pharmaceutical ingredient was detected in only five formulations via both nuclear magnetic resonance (NMR) and mass spectrometry (MS) methods. Common organic excipients such as sucrose, lactose, stearate, dextrin, and starch were also detected. The graphical representation of DOSY 1H NMR results proved very useful for establishing similarities among groups of samples, enabling counterfeit drug “chemotyping”. In addition to bulk- and surface-average analyses, spatially resolved information on the surface composition of counterfeit and genuine antimalarial formulations was obtained using DESI MS that was performed in the imaging mode, which enabled one to visualize the homogeneity of both genuine and counterfeit drug samples. Overall, this study suggests that 2D DOSY 1H NMR, combined with ambient MS, comprises a powerful suite of instrumental analysis methodologies for the integral characterization of counterfeit antimalarials. PMID:19453162

Combining two-dimensional diffusion-ordered nuclear magnetic resonance spectroscopy, imaging desorption electrospray ionization mass spectrometry, and direct analysis in real-time mass spectrometry for the integral investigation of counterfeit pharmaceuticals.

PubMed

Nyadong, Leonard; Harris, Glenn A; Balayssac, Stéphane; Galhena, Asiri S; Malet-Martino, Myriam; Martino, Robert; Parry, R Mitchell; Wang, May Dongmei; Fernández, Facundo M; Gilard, Véronique

2009-06-15

During the past decade, there has been a marked increase in the number of reported cases involving counterfeit medicines in developing and developed countries. Particularly, artesunate-based antimalarial drugs have been targeted, because of their high demand and cost. Counterfeit antimalarials can cause death and can contribute to the growing problem of drug resistance, particularly in southeast Asia. In this study, the complementarity of two-dimensional diffusion-ordered (1)H nuclear magnetic resonance spectroscopy (2D DOSY (1)H NMR) with direct analysis in real-time mass spectrometry (DART MS) and desorption electrospray ionization mass spectrometry (DESI MS) was assessed for pharmaceutical forensic purposes. Fourteen different artesunate tablets, representative of what can be purchased from informal sources in southeast Asia, were investigated with these techniques. The expected active pharmaceutical ingredient was detected in only five formulations via both nuclear magnetic resonance (NMR) and mass spectrometry (MS) methods. Common organic excipients such as sucrose, lactose, stearate, dextrin, and starch were also detected. The graphical representation of DOSY (1)H NMR results proved very useful for establishing similarities among groups of samples, enabling counterfeit drug "chemotyping". In addition to bulk- and surface-average analyses, spatially resolved information on the surface composition of counterfeit and genuine antimalarial formulations was obtained using DESI MS that was performed in the imaging mode, which enabled one to visualize the homogeneity of both genuine and counterfeit drug samples. Overall, this study suggests that 2D DOSY (1)H NMR, combined with ambient MS, comprises a powerful suite of instrumental analysis methodologies for the integral characterization of counterfeit antimalarials.

A "special perspectives" issue: Recent achievements and new directions in biomolecular solid state NMR

NASA Astrophysics Data System (ADS)

Tycko, Robert

2015-04-01

Twenty years ago, applications of solid state nuclear magnetic resonance (NMR) methods to real problems involving biological systems or biological materials were few and far between. Starting in the 1980s, a small number of research groups had begun to explore the possibility of obtaining structural and dynamical information about peptides, proteins, and other biopolymers from solid state NMR spectra. Progress was initially slow due to the relatively primitive state of solid state NMR probes, spectrometers, sample preparation methods, and pulse sequence techniques, coupled with the small number of people contributing to this research area. By the early 1990s, with the advent of new ideas about pulse sequence techniques such as dipolar recoupling, improvements in techniques for orienting membrane proteins and in technology for magic-angle spinning (MAS), improvements in the capabilities of commercial NMR spectrometers, and general developments in multidimensional spectroscopy, it began to appear that biomolecular solid state NMR might have a viable future. It was not until 1993 that the annual number of publications in this area crept above twenty.

High-resolution magnetic resonance spectroscopy using a solid-state spin sensor

NASA Astrophysics Data System (ADS)

Glenn, David R.; Bucher, Dominik B.; Lee, Junghyun; Lukin, Mikhail D.; Park, Hongkun; Walsworth, Ronald L.

2018-03-01

Quantum systems that consist of solid-state electronic spins can be sensitive detectors of nuclear magnetic resonance (NMR) signals, particularly from very small samples. For example, nitrogen–vacancy centres in diamond have been used to record NMR signals from nanometre-scale samples, with sensitivity sufficient to detect the magnetic field produced by a single protein. However, the best reported spectral resolution for NMR of molecules using nitrogen–vacancy centres is about 100 hertz. This is insufficient to resolve the key spectral identifiers of molecular structure that are critical to NMR applications in chemistry, structural biology and materials research, such as scalar couplings (which require a resolution of less than ten hertz) and small chemical shifts (which require a resolution of around one part per million of the nuclear Larmor frequency). Conventional, inductively detected NMR can provide the necessary high spectral resolution, but its limited sensitivity typically requires millimetre-scale samples, precluding applications that involve smaller samples, such as picolitre-volume chemical analysis or correlated optical and NMR microscopy. Here we demonstrate a measurement technique that uses a solid-state spin sensor (a magnetometer) consisting of an ensemble of nitrogen–vacancy centres in combination with a narrowband synchronized readout protocol to obtain NMR spectral resolution of about one hertz. We use this technique to observe NMR scalar couplings in a micrometre-scale sample volume of approximately ten picolitres. We also use the ensemble of nitrogen–vacancy centres to apply NMR to thermally polarized nuclear spins and resolve chemical-shift spectra from small molecules. Our technique enables analytical NMR spectroscopy at the scale of single cells.

Magnetic Resonance Relaxometry at Low and Ultra low Fields.

PubMed

Volegov, P; Flynn, M; Kraus, R; Magnelind, P; Matlashov, A; Nath, P; Owens, T; Sandin, H; Savukov, I; Schultz, L; Urbaitis, A; Zotev, V; Espy, M

2010-01-01

Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are ubiquitous tools in science and medicine. NMR provides powerful probes of local and macromolecular chemical structure and dynamics. Recently it has become possible and practical to perform MR at very low fields (from 1 μT to 1 mT), the so-called ultra-low field (ULF) regime. Pulsed pre-polarizing fields greatly enhance the signal strength and allow flexibility in signal acquisition sequences. Improvements in SQUID sensor technology allow ultra-sensitive detection in a pulsed field environment.In this regime the proton Larmor frequencies (1 Hz - 100 kHz) of ULF MR overlap (on a time scale of 10 μs to 100 ms) with "slow" molecular dynamic processes such as diffusion, intra-molecular motion, chemical reactions, and biological processes such as protein folding, catalysis and ligand binding. The frequency dependence of relaxation at ultra-low fields may provide a probe for biomolecular dynamics on the millisecond timescale (protein folding and aggregation, conformational motions of enzymes, binding and structural fluctuations of coupled domains in allosteric mechanisms) relevant to host-pathogen interactions, biofuels, and biomediation. Also this resonance-enhanced coupling at ULF can greatly enhance contrast in medical applications of ULF-MRI resulting in better diagnostic techniques.We have developed a number of instruments and techniques to study relaxation vs. frequency at the ULF regime. Details of the techniques and results are presented.Ultra-low field methods are already being applied at LANL in brain imaging, and detection of liquid explosives at airports. However, the potential power of ultra-low field MR remains to be fully exploited.

In vivo nuclear magnetic resonance imaging

NASA Technical Reports Server (NTRS)

Leblanc, A.; Evans, H.; Bryan, R. N.; Johnson, P.; Schonfeld, E.; Jhingran, S. G.

1984-01-01

A number of physiological changes have been demonstrated in bone, muscle and blood after exposure of humans and animals to microgravity. Determining mechanisms and the development of effective countermeasures for long duration space missions is an important NASA goal. The advent of tomographic nuclear magnetic resonance imaging (NMR or MRI) gives NASA a way to greatly extend early studies of this phenomena in ways not previously possible; NMR is also noninvasive and safe. NMR provides both superb anatomical images for volume assessments of individual organs and quantification of chemical/physical changes induced in the examined tissues. The feasibility of NMR as a tool for human physiological research as it is affected by microgravity is demonstrated. The animal studies employed the rear limb suspended rat as a model of mucle atrophy that results from microgravity. And bedrest of normal male subjects was used to simulate the effects of microgravity on bone and muscle.

An investigation into the effects of pore connectivity on T2 NMR relaxation

NASA Astrophysics Data System (ADS)

Ghomeshi, Shahin; Kryuchkov, Sergey; Kantzas, Apostolos

2018-04-01

Nuclear Magnetic Resonance (NMR) is a powerful technique used to characterize fluids and flow in porous media. The NMR relaxation curves are closely related to pore geometry, and the inversion of the NMR relaxometry data is known to give useful information with regards to pore size distribution (PSD) through the relative amplitudes of the fluids stored in the small and large pores. While this information is crucial, the main challenge for the successful use of the NMR measurements is the proper interpretation of the measured signals. Natural porous media patterns consist of complex pore structures with many interconnected or "coupled" regions, as well as isolated pores. This connectivity along the throats changes the relaxation distribution and in order to properly interpret this data, a thorough understanding of the effects of pore connectivity on the NMR relaxation distribution is warranted. In this paper we address two main points. The first pertains to the fact that there is a discrepancy between the relaxation distribution obtained from experiments, and the ones obtained from solving the mathematical models of diffusion process in the digitized images of the pore space. There are several reasons that may attribute to this such as the lack of a proper incorporation of surface roughness into the model. However, here we are more interested in the effects of pore connectivity and to understand why the typical NMR relaxation distribution obtained from experiments are wider, while the numerical simulations predict that a wider NMR relaxation distribution may indicate poor connectivity. Secondly, by not taking into account the pore coupling effects, from our experience in interpreting the data, we tend to underestimate the pore volume of small pores and overestimate the amplitudes in the large pores. The role of pore coupling becomes even more prominent in rocks with small pore sizes such as for example in shales, clay in sandstones, and in the microstructures of carbonates.

Phosphorus Imaging as a Tool for Studying the pH Metabolism in Living Insects

NASA Astrophysics Data System (ADS)

Skibbe, U.; Christeller, J. T.; Eccles, C. D.; Laing, W. A.; Callaghan, P. T.

1995-09-01

Comparative 31P NMR and 1H NMR imaging experiments at submillimeter pixel resolution were carried out, using a specially constructed solenoidal RF coil. Chemical-shift imaging is used to provide pH maps from the midgut of a Lepidopteran larvae and to demonstrate physiological dependence in the resulting images, The titration curve of pH versus chemical shift for inorganic phosphate is extended beyond the "normal" biological range to the strong alkaline limit.

Pharmaceutical applications of magnetic resonance imaging (MRI).

PubMed

Richardson, J Craig; Bowtell, Richard W; Mäder, Karsten; Melia, Colin D

2005-06-15

Magnetic resonance imaging (MRI) is a powerful imaging modality that provides internal images of materials and living organisms on a microscopic and macroscopic scale. It is non-invasive and non-destructive, and one of very few techniques that can observe internal events inside undisturbed specimens in situ. It is versatile, as a wide range of NMR modalities can be accessed, and 2D and 3D imaging can be undertaken. Despite widespread use and major advances in clinical MRI, it has seen limited application in the pharmaceutical sciences. In vitro studies have focussed on drug release mechanisms in polymeric delivery systems, but isolated studies of bioadhesion, tablet properties, and extrusion and mixing processes illustrate the wider potential. Perhaps the greatest potential however, lies in investigations of pharmaceuticals in vivo, where pilot human and animal studies have demonstrated we can obtain unique insights into the behaviour of gastrointestinal, topical, colloidal, and targeted drug delivery systems.

PSYCHE Pure Shift NMR Spectroscopy.

PubMed

Foroozandeh, Mohammadali; Morris, Gareth; Nilsson, Mathias

2018-03-13

Broadband homodecoupling techniques in NMR, also known as "pure shift" methods, aim to enhance spectral resolution by suppressing the effects of homonuclear coupling interactions to turn multiplet signals into singlets. Such techniques typically work by selecting a subset of "active" nuclear spins to observe, and selectively inverting the remaining, "passive", spins to reverse the effects of coupling. Pure Shift Yielded by Chirp Excitation (PSYCHE) is one such method; it is relatively recent, but has already been successfully implemented in a range of different NMR experiments. Paradoxically, PSYCHE is one of the trickiest of pure shift NMR techniques to understand but one of the easiest to use. Here we offer some insights into theoretical and practical aspects of the method, and into the effects and importance of the experimental parameters. Some recent improvements that enhance the spectral purity of PSYCHE spectra will be presented, and some experimental frameworks including examples in 1D and 2D NMR spectroscopy, for the implementation of PSYCHE will be introduced. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

NMR imaging and hydrodynamic analysis of neutrally buoyant non-Newtonian slurry flows

NASA Astrophysics Data System (ADS)

Bouillard, J. X.; Sinton, S. W.

The flow of solids loaded suspension in cylindrical pipes has been the object of intense experimental and theoretical investigations in recent years. These types of flows are of great interest in chemical engineering because of their important use in many industrial manufacturing processes. Such flows are for example encountered in the manufacture of solid-rocket propellants, advanced ceramics, reinforced polymer composites, in heterogeneous catalytic reactors, and in the pipeline transport of liquid-solids suspensions. In most cases, the suspension microstructure and the degree of solids dispersion greatly affect the final performance of the manufactured product. For example, solid propellant pellets need to be extremely-well dispersed in gel matrices for use as rocket engine solid fuels. The homogeneity of pellet dispersion is critical to allow good uniformity of the burn rate, which in turn affects the final mechanical performance of the engine. Today's manufacturing of such fuels uses continuous flow processes rather than batch processes. Unfortunately, the hydrodynamics of such flow processes is poorly understood and is difficult to assess because it requires the simultaneous measurements of liquid/solids phase velocities and volume fractions. Due to the recent development in pulsed Fourier Transform NMR imaging, NMR imaging is now becoming a powerful technique for the non intrusive investigation of multi-phase flows. This paper reports and exposes a state-of-the-art experimental and theoretical methodology that can be used to study such flows. The hydrodynamic model developed for this study is a two-phase flow shear thinning model with standard constitutive fluid/solids interphase drag and solids compaction stresses. this model shows good agreement with experimental data and the limitations of this model are discussed.

Fine refinement of solid state structure of racemic form of phospho-tyrosine employing NMR Crystallography approach.

PubMed

Paluch, Piotr; Pawlak, Tomasz; Oszajca, Marcin; Lasocha, Wieslaw; Potrzebowski, Marek J

2015-02-01

We present step by step facets important in NMR Crystallography strategy employing O-phospho-dl-tyrosine as model sample. The significance of three major techniques being components of this approach: solid state NMR (SS NMR), X-ray diffraction of powdered sample (PXRD) and theoretical calculations (Gauge Invariant Projector Augmented Wave; GIPAW) is discussed. Each experimental technique provides different set of structural constraints. From the PXRD measurement the size of the unit cell, space group and roughly refined molecular structure are established. SS NMR provides information about content of crystallographic asymmetric unit, local geometry, molecular motion in the crystal lattice and hydrogen bonding pattern. GIPAW calculations are employed for validation of quality of elucidation and fine refinement of structure. Crystal and molecular structure of O-phospho-dl-tyrosine solved by NMR Crystallography is deposited at Cambridge Crystallographic Data Center under number CCDC 1005924. Copyright © 2014 Elsevier Inc. All rights reserved.

Assessment of higher order structure comparability in therapeutic proteins using nuclear magnetic resonance spectroscopy.

PubMed

Amezcua, Carlos A; Szabo, Christina M

2013-06-01

In this work, we applied nuclear magnetic resonance (NMR) spectroscopy to rapidly assess higher order structure (HOS) comparability in protein samples. Using a variation of the NMR fingerprinting approach described by Panjwani et al. [2010. J Pharm Sci 99(8):3334-3342], three nonglycosylated proteins spanning a molecular weight range of 6.5-67 kDa were analyzed. A simple statistical method termed easy comparability of HOS by NMR (ECHOS-NMR) was developed. In this method, HOS similarity between two samples is measured via the correlation coefficient derived from linear regression analysis of binned NMR spectra. Applications of this method include HOS comparability assessment during new product development, manufacturing process changes, supplier changes, next-generation products, and the development of biosimilars to name just a few. We foresee ECHOS-NMR becoming a routine technique applied to comparability exercises used to complement data from other analytical techniques. Copyright © 2013 Wiley Periodicals, Inc.

Skeletal dosimetry: A hyperboloid representation of the bone-marrow interface to reduce voxel effects in three-dimensional images of trabecular bone

NASA Astrophysics Data System (ADS)

Rajon, Didier Alain

Radiation damage to the hematopoietic bone marrow is clearly defined as the limiting factor to the development of internal emitter therapies. Current dosimetry models rely on chord-length distributions measured through the complex microstructure of the trabecular bone regions of the skeleton in which most of the active marrow is located. Recently, Nuclear Magnetic Resonance (NMR) has been used to obtain high-resolution three-dimensional (3D) images of small trabecular bone samples. These images have been coupled with computer programs to estimate dosimetric parameters such as chord-length distributions, and energy depositions by monoenergetic electrons. This new technique is based on the assumption that each voxel of the image is assigned either to bone tissue or to marrow tissue after application of a threshold value. Previous studies showed that this assumption had important consequences on the outcome of the computer calculations. Both the chord-length distribution measurements and the energy deposition calculations are subject to voxel effects that are responsible for large discrepancies when applied to mathematical models of trabecular bone. The work presented in this dissertation proposes first a quantitative study of the voxel effects. Consensus is that the voxelized representation of surfaces should not be used as direct input to dosimetry computer programs. Instead we need a new technique to transform the interfaces into smooth surfaces. The Marching Cube (MC) algorithm was used and adapted to do this transformation. The initial image was used to generate a continuous gray-level field throughout the image. The interface between bone and marrow was then simulated by the iso-gray-level surface that corresponds to a predetermined threshold value. Calculations were then performed using this new representation. Excellent results were obtained for both the chord-length distribution and the energy deposition measurements. Voxel effects were reduced to an acceptable level and the discrepancies found when using the voxelized representation of the interface were reduced to a few percent. We conclude that this new model should be used every time one performs dosimetry estimates using NMR images of trabecular bone samples.

In vivo observation of tree drought response with low-field NMR and neutron imaging

DOE PAGES

Malone, Michael W.; Yoder, Jacob; Hunter, James F.; ...

2016-05-06

Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accounting for the role of temperature inmore » the observed NMR signal, we demonstrate a change in the diurnal signal behavior due to simulated drought conditions for the tree. Lastly, these results illustrate the utility of our system to perform noninvasive measurements of tree water content outside of a temperature controlled environment.« less

In vivo observation of tree drought response with low-field NMR and neutron imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malone, Michael W.; Yoder, Jacob; Hunter, James F.

Using a simple low-field NMR system, we monitored water content in a living tree in a greenhouse over 2 months. By continuously running the system, we observed changes in tree water content on a scale of half an hour. The data showed a diurnal change in water content consistent both with previous NMR and biological observations. Neutron imaging experiments show that our NMR signal is primarily due to water being rapidly transported through the plant, and not to other sources of hydrogen, such as water in cytoplasm, or water in cell walls. After accounting for the role of temperature inmore » the observed NMR signal, we demonstrate a change in the diurnal signal behavior due to simulated drought conditions for the tree. Lastly, these results illustrate the utility of our system to perform noninvasive measurements of tree water content outside of a temperature controlled environment.« less

A Primer of Fourier Transform NMR.

ERIC Educational Resources Information Center

Macomber, Roger S.

1985-01-01

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

Customizing model membranes and samples for NMR spectroscopic studies of complex membrane proteins.

PubMed

Sanders, C R; Oxenoid, K

2000-11-23

Both solution and solid state nuclear magnetic resonance (NMR) techniques for structural determination are advancing rapidly such that it is possible to contemplate bringing these techniques to bear upon integral membrane proteins having multiple transmembrane segments. This review outlines existing and emerging options for model membrane media for use in such studies and surveys the special considerations which must be taken into account when preparing larger membrane proteins for NMR spectroscopic studies.

NMR studies of multiphase flows II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altobelli, S.A.; Caprihan, A.; Fukushima, E.

NMR techniques for measurements of spatial distribution of material phase, velocity and velocity fluctuation are being developed and refined. Versions of these techniques which provide time average liquid fraction and fluid phase velocity have been applied to several concentrated suspension systems which will not be discussed extensively here. Technical developments required to further extend the use of NMR to the multi-phase flow arena and to provide measurements of previously unobtainable parameters are the focus of this report.

Noise canceling in-situ detection

DOEpatents

Walsh, David O.

2014-08-26

Technologies applicable to noise canceling in-situ NMR detection and imaging are disclosed. An example noise canceling in-situ NMR detection apparatus may comprise one or more of a static magnetic field generator, an alternating magnetic field generator, an in-situ NMR detection device, an auxiliary noise detection device, and a computer.

Multiphase imaging of gas flow in a nanoporous material using remote-detection NMR

NASA Astrophysics Data System (ADS)

Harel, Elad; Granwehr, Josef; Seeley, Juliette A.; Pines, Alex

2006-04-01

Pore structure and connectivity determine how microstructured materials perform in applications such as catalysis, fluid storage and transport, filtering or as reactors. We report a model study on silica aerogel using a time-of-flight magnetic resonance imaging technique to characterize the flow field and explain the effects of heterogeneities in the pore structure on gas flow and dispersion with 129Xe as the gas-phase sensor. The observed chemical shift allows the separate visualization of unrestricted xenon and xenon confined in the pores of the aerogel. The asymmetrical nature of the dispersion pattern alludes to the existence of a stationary and a flow regime in the aerogel. An exchange time constant is determined to characterize the gas transfer between them. As a general methodology, this technique provides insights into the dynamics of flow in porous media where several phases or chemical species may be present.

Quantification of coronary microvascular resistance using angiographic images for volumetric blood flow measurement: in vivo validation

PubMed Central

Zhang, Zhang; Takarada, Shigeho

2011-01-01

Structural coronary microcirculation abnormalities are important prognostic determinants in clinical settings. However, an assessment of microvascular resistance (MR) requires a velocity wire. A first-pass distribution analysis technique to measure volumetric blood flow has been previously validated. The aim of this study was the in vivo validation of the MR measurement technique using first-pass distribution analysis. Twelve anesthetized swine were instrumented with a transit-time ultrasound flow probe on the proximal segment of the left anterior descending coronary artery (LAD). Microspheres were injected into the LAD to create a model of microvascular dysfunction. Adenosine (400 μg·kg−1·min−1) was used to produce maximum hyperemia. A region of interest in the LAD arterial bed was drawn to generate time-density curves using angiographic images. Volumetric blood flow measurements (Qa) were made using a time-density curve and the assumption that blood was momentarily replaced with contrast agent during the injection. Blood flow from the flow probe (Qp), coronary pressure (Pa), and right atrium pressure (Pv) were continuously recorded. Flow probe-based normalized MR (NMRp) and angiography-based normalized MR (NMRa) were calculated using Qp and Qa, respectively. In 258 measurements, Qa showed a strong correlation with the gold standard Qp (Qa = 0.90 Qp + 6.6 ml/min, r2 = 0.91, P < 0.0001). NMRa correlated linearly with NMRp (NMRa = 0.90 NMRp + 0.02 mmHg·ml−1·min−1, r2 = 0.91, P < 0.0001). Additionally, the Bland-Altman analysis showed a close agreement between NMRa and NMRp. In conclusion, a technique based on angiographic image data for quantifying NMR was validated using a swine model. This study provides a method to measure NMR without using a velocity wire, which can potentially be used to evaluate microvascular conditions during coronary arteriography. PMID:21398596

Polymeric proanthocyanidins 13C NMR studies of procyanidins

Treesearch

Lawrence J. Porter; Roger H. Newman; Lai Yeap Foo; Herbert Wong; Richard W. Hemingway

1982-01-01

Proanthocyanidin polymers have been shown to consist entirely of flavan-3-ol units by a combination of techniques including 13C n.m.r. spectroscopy. The 13C n.m.r. spectra of the polymers and related molecules are now considered in more detail. Prior to this study UC n.m.r. data has been published of procyanidins and...

Squid detected NMR and MRI at ultralow fields

DOEpatents

Clarke, John [Berkeley, CA; McDermott, Robert [Louisville, CO; Pines, Alexander [Berkeley, CA; Trabesinger, Andreas Heinz [CH-8006 Zurich, CH

2007-05-15

Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

Squid detected NMR and MRI at ultralow fields

DOEpatents

Clarke, John; McDermott, Robert; Pines, Alexander; Trabesinger, Andreas Heinz

2006-05-30

Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

Squid detected NMR and MRI at ultralow fields

DOEpatents

Clarke, John [Berkeley, CA; Pines, Alexander [Berkeley, CA; McDermott, Robert F [Monona, WI; Trabesinger, Andreas H [London, GB

2008-12-16

Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

SQUID detected NMR and MRI at ultralow fields

DOEpatents

Clarke, John; McDermott, Robert; Pines, Alexander; Trabesinger, Andreas Heinz

2006-10-03

Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

Using quantitative magnetic resonance methods to understand better the gel-layer formation on polymer-matrix tablets.

PubMed

Mikac, Urša; Kristl, Julijana; Baumgartner, Saša

2011-05-01

Magnetic resonance imaging is a powerful, non-invasive technique that can help improve our understanding of the hydrogel layer formed on swellable, polymer-matrix tablets, as well as the layer's properties and its influence on drug release. In this paper, the authors review the NMR and MRI investigations of hydrophilic, swellable polymers published since 1994. The review covers NMR studies on the properties of water and drugs within hydrated polymers. In addition, MRI studies using techniques for determining the different moving-front positions within the swollen tablets, the polymer concentration profiles across them, the influence of the incorporated drug, and so on, are presented. Some complementary methods are also briefly presented and discussed. Using MRI, the formation of a hydrogel along with simultaneous determination of the drug's position within it can be observed non-invasively. However, the MRI parameters can influence the signal's intensity and therefore they need to be considered carefully in order to prevent any misinterpretation of the results. MRI makes possible an in situ investigation of swollen-matrix tablets and provides valuable information that can lead, when combined with other techniques, to a better understanding of polymeric systems and a more effective development of optimal dosage forms.

Deuterium and lithium-6 MAS NMR studies of manganese oxide electrode materials

NASA Astrophysics Data System (ADS)

Paik, Younkee

Electrolytic manganese dioxide (EMD) is used world wide as the cathode materials in both lithium and alkaline primary (non-rechargeable) batteries. We have developed deuterium and lithium MAS NMR techniques to study EMD and related manganese oxides and hydroxides, where diffraction techniques are of limited value due to a highly defective nature of the structures. Deuterons in EMD, manganite, groutite, and deuterium-intercalated pyrolusite and ramsdellite were detected by NMR, for the first time, and their locations and motions in the structures were analyzed by applying variable temperature NMR techniques. Discharge mechanisms of EMD in alkaline (aqueous) electrolytes were studied, in conjunction with step potential electrochemical spectroscopic (SPECS) method, and five distinctive discharge processes were proposed. EMD is usually heat-treated at about 300--400°C to remove water to be used in lithium batteries. Details of the effects of heat-treatment, such as structural and compositional changes as a function of heat-treatment temperature, were studied by a combination of MAS NMR, XRD, and thermogravimetric analysis. Lithium local environments in heat-treated EMD (HEMD) that were discharged in lithium cells, were described in terms of related environments found in model compounds pyrolusite and ramsdellite where specific Li + sites were detected by MAS NMR and the hyperfine shift scale method of Grey et al. Acid-leaching of Li2MnO3 represents an approach for synthesizing new or modified manganese oxide electrode materials for lithium rechargeable batteries. Progressive removal of lithium from specific crystallographic sites, followed by a gradual change of the crystal structure, was monitored by a combination of NMR and XRD techniques.

Raman spectroscopy and Raman imaging for early detection of cancer

NASA Astrophysics Data System (ADS)

Joshi, Narahari V.; Ortega, Angel; Estrela, Jose Maria

2004-06-01

Raman spectroscopy is a powerful technique as it provides fundamental information about vibrational modes of a system. Eigenvalues of these modes are very sensitive to the strength of the chemical bonds and perturbations caused by the environment, particularly charge distribution and alterations in the dipole strength of the system. All these parameters are profoundly modified during the tumor formation process nad hence Raman technique could be a unique and also a direct approach for evaluating tumor genesis at early stages. for this pupose the present investigation was carried out. We used cultured wild type and c-ras transformed NIH 3T3 fibroblast. The samples were treated with methyl alcohol solution ina conventional manner and then Raman spectra nad images were obtained by a specially developed confocal Raman microscope. The present results reveal differences between both cell types in the spectral details as well as in the morphology. Raman images are able to detect the exact site where cancer-related changes have taken place. These results clearly indicate the superiority of the present technique over conventional methods such as images obtained by X-rays or Nuclear Magnetic Resonance (NMR). Moreover, unlike other approaches, Raman images detect alterations at the submicron level rather than in the centimeter or millimeter range. Being an optical method it can be applied in vivo as a non-invasive technique potentially useful to early detection of cancer (particularly easy accessible cancers such as those of the skin and the digestive tract). The obtained resulsts suggest the great potential of Raman imaging in premature clinical diagnostic approaches.

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

PubMed Central

Horník, Štěpán; Sajfrtová, Marie; Sýkora, Jan; Březinová, Anna; Wimmer, Zdeněk

2013-01-01

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

Integrated NMR Core and Log Investigations With Respect to ODP LEG 204

NASA Astrophysics Data System (ADS)

Arnold, J.; Pechnig, R.; Clauser, C.; Anferova, S.; Blümich, B.

2005-12-01

NMR techniques are widely used in the oil industry and are one of the most suitable methods to evaluate in-situ formation porosity and permeability. Recently, efforts are directed towards adapting NMR methods also to the Ocean Drilling Program (ODP) and the upcoming Integrated Ocean Drilling Program (IODP). We apply a newly developed light-weight, mobile NMR core scanner as a non-destructive instrument to determine routinely rock porosity and to estimate the pore size distribution. The NMR core scanner is used for transverse relaxation measurements on water-saturated core sections using a CPMG sequence with a short echo time. A regularized Laplace-transform analysis yields the distribution of transverse relaxation times T2. In homogeneous magnetic fields, T2 is proportional to the pore diameter of rocks. Hence, the T2 signal maps the pore-size distribution of the studied rock samples. For fully saturated samples the integral of the distribution curve and the CPMG echo amplitude extrapolated to zero echo time are proportional to porosity. Preliminary results show that the NMR core scanner is a suitable tool to determine rock porosity and to estimate pore size distribution of limestones and sandstones. Presently our investigations focus on Leg 204, where NMR Logging-While-Drilling (LWD) was performed for the first time in ODP. Leg 204 was drilled into Hydrate Ridge on the Cascadia accretionary margin, offshore Oregon. All drilling and logging operations were highly successful, providing excellent core, wireline, and LWD data from adjacent boreholes. Cores recovered during Leg 204 consist mainly of clay and claystone. As the NMR core scanner operates at frequencies higher than that of the well-logging sensor it has a shorter dead time. This advantage makes the NMR core scanner sensitive to signals with T2 values down to 0.1 ms as compared to 3 ms in NMR logging. Hence, we can study even rocks with small pores, such as the mudcores recovered during Leg 204. We present a comparison of data from core scanning and NMR logging. Future integration of conventional wireline data and electrical borehole wall images (RAB/FMS) will provide a detailed characterization of the sediments in terms of lithology, petrophysics and, fluid flow properties.

Assigning the NMR Spectrum of Glycidol: An Advanced Organic Chemistry Exercise

ERIC Educational Resources Information Center

Helms, Eric; Arpaia, Nicholas; Widener, Melissa

2007-01-01

Various one- and two-dimensional NMR experiments have been found to be extremely useful for assigning the proton and carbon NMR spectra of glycidol. The technique provides extremely valuable information aiding in the complete assignment of the peaks.

Pulsed-field-gradient measurements of time-dependent gas diffusion

NASA Technical Reports Server (NTRS)

Mair, R. W.; Cory, D. G.; Peled, S.; Tseng, C. H.; Patz, S.; Walsworth, R. L.

1998-01-01

Pulsed-field-gradient NMR techniques are demonstrated for measurements of time-dependent gas diffusion. The standard PGSE technique and variants, applied to a free gas mixture of thermally polarized xenon and O2, are found to provide a reproducible measure of the xenon diffusion coefficient (5.71 x 10(-6) m2 s-1 for 1 atm of pure xenon), in excellent agreement with previous, non-NMR measurements. The utility of pulsed-field-gradient NMR techniques is demonstrated by the first measurement of time-dependent (i.e., restricted) gas diffusion inside a porous medium (a random pack of glass beads), with results that agree well with theory. Two modified NMR pulse sequences derived from the PGSE technique (named the Pulsed Gradient Echo, or PGE, and the Pulsed Gradient Multiple Spin Echo, or PGMSE) are also applied to measurements of time dependent diffusion of laser polarized xenon gas, with results in good agreement with previous measurements on thermally polarized gas. The PGMSE technique is found to be superior to the PGE method, and to standard PGSE techniques and variants, for efficiently measuring laser polarized noble gas diffusion over a wide range of diffusion times. Copyright 1998 Academic Press.

Development of a micro nuclear magnetic resonance system

NASA Astrophysics Data System (ADS)

Goloshevsky, Artem

Application of Nuclear Magnetic Resonance (NMR) to on-line/in-line control of industrial processes is currently limited by equipment costs and requirements for installation. A superconducting magnet generating strong fields is the most expensive part of a typical NMR instrument. In industrial environments, fringe magnetic fields make accommodation of NMR instruments difficult. However, a portable, low-cost and low-field magnetic resonance system can be used in virtually any environment. Development of a number of hardware components for a portable, low-cost NMR instrument is reported in this dissertation. Chapter one provides a discussion on a miniaturized Helmholtz spiral radio-frequency (RF) coil (average diameter equal to 3.5 mm) and an NMR probe built around a capillary (outer diameter = 1.59 mm and inner diameter = 1.02 mm) for flow imaging. Experiments of NMR spectroscopy, static and dynamic (flow) imaging, conducted with the use of the miniaturized coil, are described. Chapter two presents a microfabricated package of two biaxial gradient coils and a Helmholtz RF coil. Planar configuration of discrete wires was used to create magnetic field gradients. Performance of the microfabricated gradient coils while imaging water flow compared well with a commercial gradient set of much larger size. Chapter three reports on flow imaging experiments with power law fluids (aqueous solutions of sodium salt of carboxymethyl cellulose (CMC)) of different viscosities, carried out in the NMR probe with the miniaturized RF coil and capillary. Viscosities of the CMC solutions were determined based on the curve fits of the velocity profiles and simultaneous measurements of the flow rates. The curve fits were carried out according to the power law model equations. The NMR viscosity measurements compared well with measurements of the same CMC samples, performed on a conventional rotational rheometer. A portable, home-built transceiver, designed for NMR applications utilizing a miniaturized RF coil, is described in chapter four. The maximum RF power, occurring in the transceiver, was 21.5 dBm. Two transistor-transistor logic (TTL) switches functioned as an active duplexer. A quadrature detection scheme was used. The transceiver, combined with a filter/amplifier module, data acquisition (DAQ and RF generating PC boards, was successfully tested in NMR spectroscopy experiments at low magnetic field. It was demonstrated that, starting with the RF probe, a typical, large size NMR instrument can be miniaturized without impairment to the quality of the data. Such an instrument will be readily used in many industrial process control applications (e.g. for analysis of material properties and identification of chemicals).

Implementation of picoSpin Benchtop NMR Instruments into Organic Chemistry Teaching Laboratories through Spectral Analysis of Fischer Esterification Products

ERIC Educational Resources Information Center

Yearty, Kasey L.; Sharp, Joseph T.; Meehan, Emma K.; Wallace, Doyle R.; Jackson, Douglas M.; Morrison, Richard W.

2017-01-01

[Superscript 1]H NMR analysis is an important analytical technique presented in introductory organic chemistry courses. NMR instrument access is limited for undergraduate organic chemistry students due to the size of the instrument, price of NMR solvents, and the maintenance level required for instrument upkeep. The University of Georgia Chemistry…

Experiments in NMR Force Microscopy

NASA Astrophysics Data System (ADS)

Manzanera, Isaac; Cardenas, Rosa; Paster, Jeremy; Turbyfill, Amanda; Markert, John

2012-02-01

We report details of the construction and use of three nuclear magnetic resonance force microscopy (NMRFM) probes, as well as the development of control systems for three-dimensional nanoscale imaging and spectroscopy. Our variable temperature probe performed position-dependent ^1H NMR force measurements on a 25x15x7 μm^3 single crystal of ammonium sulfate (NH4)2SO4 at room temperature in a sample-on-oscillator geometry. Force signals were detected with a signal-to-noise ratio of 6, and 12 μm resolution, in a one-dimensional scan. Measurements of NMR relaxation times T2^*=1.5±0.2 μs, T2= 44±2 μs, and T1=5.6±0.7 s were obtained. We describe the upgrade of our ^3He NMRFM probe for measurements towards the base temperature of 0.3K for investigation of nanoscale structures and metal oxide interfaces using the iOSCAR technique and perpendicular-cantilever geometry. Force-detected ^11B NMR signals in a 30 μm crystal of superconductor MgB2 have also been achieved using this probe. Efforts in the development of our NMRFM probe for the study of biological samples in liquid media are reported. Magnetic field effects on micromagnet films on cantilevers are being studied for the characterization of the mechanical sensors to be used in these liquid experiments.

Advanced solid-state NMR spectroscopy of natural organic matter

USDA-ARS?s Scientific Manuscript database

Solid-state NMR is essential for the characterization of natural organic matter (NOM) and is gaining importance in geosciences and environmental sciences. This review is intended to highlight advanced solid-state NMR techniques, especially the systematic approach to NOM characterization, and their ...

Recent developments and applications of saturation transfer difference nuclear magnetic resonance (STD NMR) spectroscopy.

PubMed

Wagstaff, Jane L; Taylor, Samantha L; Howard, Mark J

2013-04-05

This review aims to illustrate that STD NMR is not simply a method for drug screening and discovery, but has qualitative and quantitative applications that can answer fundamental and applied biological and biomedical questions involving molecular interactions between ligands and proteins. We begin with a basic introduction to the technique of STD NMR and report on recent advances and biological applications of STD including studies to follow the interactions of non-steroidal anti-inflammatories, minimum binding requirements for virus infection and understating inhibition of amyloid fibre formation. We expand on this introduction by reporting recent STD NMR studies of live-cell receptor systems, new methodologies using scanning STD, magic-angle spinning STD and approaches to use STD NMR in a quantitative fashion for dissociation constants and group epitope mapping (GEM) determination. We finish by outlining new approaches that have potential to influence future applications of the technique; NMR isotope-editing, heteronuclear multidimensional STD and (19)F STD methods that are becoming more amenable due to the latest NMR equipment technologies.

Nuclear magnetic resonance proton imaging of bone pathology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atlan, H.; Sigal, R.; Hadar, H.

Thirty-two patients with diversified pathology were examined with a supraconductive NMR imager using spin echo with different TR and TE to obtain T1 and T2 weighted images. They included 20 tumors (12 primary, eight metastasis), six osteomyelitis, three fractures, two osteonecrosis, and one diffuse metabolic (Gaucher) disease. In all cases except for the stress fractures, the bone pathology was clearly visualized in spite of the normal lack of signal from the compact cortical bone. Nuclear magnetic resonance (NMR) imaging proved to be at least as sensitive as radionuclide scintigraphy but much more accurate than all other imaging procedures including computedmore » tomography (CT) and angiography to assess the extension of the lesions, especially in tumors extended to soft tissue. This is due both to easy acquisition of sagittal and coronal sections and to different patterns of pathologic modifications of T1 and T2 which are beginning to be defined. It is hoped that more experience in clinical use of these patterns will help to discriminate between tumor extension and soft-tissue edema. We conclude that while radionuclide scintigraphy will probably remain the most sensitive and easy to perform screening test for bone pathology, NMR imaging, among noninvasive diagnostic procedures, appears to be at least as specific as CT. In addition, where the extension of the lesions is concerned, NMR imaging is much more informative than CT. In pathology of the spine, the easy visualization of the spinal cord should decrease the need for myelography.« less

Optimization of cell disruption methods for efficient recovery of bioactive metabolites via NMR of three freshwater microalgae (chlorophyta).

PubMed

Ma, Nyuk Ling; Teh, Kit Yinn; Lam, Su Shiung; Kaben, Anne Marie; Cha, Thye San

2015-08-01

This study demonstrates the use of NMR techniques coupled with chemometric analysis as a high throughput data mining method to identify and examine the efficiency of different disruption techniques tested on microalgae (Chlorella variabilis, Scenedesmus regularis and Ankistrodesmus gracilis). The yield and chemical diversity from the disruptions together with the effects of pre-oven and pre-freeze drying prior to disruption techniques were discussed. HCl extraction showed the highest recovery of oil compounds from the disrupted microalgae (up to 90%). In contrast, NMR analysis showed the highest intensity of bioactive metabolites obtained for homogenized extracts pre-treated with freeze-drying, indicating that homogenizing is a more favorable approach to recover bioactive substances from the disrupted microalgae. The results show the potential of NMR as a useful metabolic fingerprinting tool for assessing compound diversity in complex microalgae extracts. Copyright © 2015 Elsevier Ltd. All rights reserved.

Changes in porosity and organic matter phase distribution monitored by NMR relaxometry following hydrous pyrolysis under uniaxial confinement

USGS Publications Warehouse

Washburn, Kathryn E.; Birdwell, Justin E.; Lewan, Michael D.; Miller, Michael; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

2013-01-01

Artificial maturation methods are used to induce changes in source rock thermal maturity without the uncertainties that arise when comparing natural samples from a particular basin that often represent different levels of maturation and different lithofacies. A novel uniaxial confinement clamp was used on Woodford Shale cores in hydrous pyrolysis experiments to limit sample expansion by simulating the effect of overburden present during thermal maturation in natural systems. These samples were then subjected to X-ray computed tomography (X-CT) imaging and low-field nuclear magnetic resonance (LF-NMR) relaxometry measurements. LF-NMR relaxometry is a noninvasive technique commonly used to measure porosity and pore-size distributions in fluid-filled porous media, but may also measure hydrogen present in hydrogen-bearing organic solids. Standard T1 and T2 relaxation distributions were determined and two dimensional T1-T2 correlation measurements were performed on the Woodford Shale cores. The T1-T2 correlations facilitate resolution of organic phases in the system. The changes observed in NMR-relaxation times correspond to bitumen and lighter hydrocarbon production that occur as source rock organic matter matures. The LF-NMR porosities of the core samples at maximum oil generation are significantly higher than porosities measured by other methods. This discrepancy likely arises from the measurement of highly viscous organic constituents in addition to fluid-filled porosity. An unconfined sample showed shorter relaxation times and lower porosity. This difference is attributed to the lack of fractures observed in the unconfined sample by X-CT.

Ultra-low field nuclear magnetic resonance and magnetic resonance imaging to discriminate and identify materials

DOEpatents

Matlashov, Andrei Nikolaevich; Urbaitis, Algis V.; Savukov, Igor Mykhaylovich; Espy, Michelle A.; Volegov, Petr Lvovich; Kraus, Jr., Robert Henry

2013-03-05

Method comprising obtaining an NMR measurement from a sample wherein an ultra-low field NMR system probes the sample and produces the NMR measurement and wherein a sampling temperature, prepolarizing field, and measurement field are known; detecting the NMR measurement by means of inductive coils; analyzing the NMR measurement to obtain at least one measurement feature wherein the measurement feature comprises T1, T2, T1.rho., or the frequency dependence thereof; and, searching for the at least one measurement feature within a database comprising NMR reference data for at least one material to determine if the sample comprises a material of interest.

Measurement of Solution Viscosity via Diffusion-Ordered NMR Spectroscopy (DOSY)

ERIC Educational Resources Information Center

Li, Weibin; Kagan, Gerald; Hopson, Russell; Williard, Paul G.

2011-01-01

Increasingly, the undergraduate chemistry curriculum includes nuclear magnetic resonance (NMR) spectroscopy. Advanced NMR techniques are often taught including two-dimensional gradient-based experiments. An investigation of intermolecular forces including viscosity, by a variety of methods, is often integrated in the undergraduate physical and…

Use of Magnetic Nanoparticles to Monitor Alginate-Encapsulated βTC-tet Cells

PubMed Central

Constantinidis, Ioannis; Grant, Samuel C.; Simpson, Nicholas E.; Oca-Cossio, Jose A.; Sweeney, Carol A.; Mao, Hui; Blackband, Stephen J.; Sambanis, Athanassios

2008-01-01

Non-invasive monitoring of tissue-engineered constructs is an important component in optimizing construct design and assessing therapeutic efficacy. In recent years, cellular and molecular imaging initiatives have spurred the use of iron oxide based contrast agents in the field of NMR imaging. Although their use in medical research has been widespread, their application in tissue engineering has been limited. In this study, the utility of Monocrystalline Iron Oxide Nanoparticles (MION) as an NMR contrast agent was evaluated for βTC-tet cells encapsulated within alginate/poly-L-lysine/alginate (APA) microbeads. The constructs were labeled with MION in two different ways: (a) MION-labeled βTC-tet cells were encapsulated in APA beads (i.e., intracellular compartment); and (b) MION particles were suspended in the alginate solution prior to encapsulation so that the alginate matrix was labeled with MION instead of the cells (i.e., extracellular compartment). The data show that although the location of cells can be identified within APA beads, cell growth or rearrangement within these constructs cannot be effectively monitored, regardless of the location of MION compartmentalization. The advantages and disadvantages of these techniques and their potential use in tissue engineering are discussed. PMID:19165877

Intra- versus Intermolecular Hydrogen Bonding: Solvent-Dependent Conformational Preferences of a Common Supramolecular Binding Motif from 1 H NMR and Vibrational Circular Dichroism Spectra.

PubMed

Demarque, Daniel P; Merten, Christian

2017-12-19

When predicting binding properties of small molecules or larger supramolecular aggregates, intra- and intermolecular hydrogen bonds are often considered the most important factor. Spectroscopic techniques such as 1 H NMR spectroscopy are typically utilized to characterize such binding events, but interpretation is often qualitative and follows chemical intuition. In this study, we compare the effects of intramolecular hydrogen bonding and solvation on two chiral 2,6-pyridinediyl-dialkylamides. In comparison with 1 H NMR spectroscopy, vibrational circular dichroism (VCD) spectroscopy proved to be more sensitive to conformational changes. In fact, the change of the solvent from CDCl 3 to [D 6 ]DMSO generates mirror-image VCD spectra for the same enantiomer. Here, the common sense that the sterically less hindered group is more prone to solvation proved to be wrong according predicted VCD spectra, which clearly show that both asymmetric amide hydrogens are equally likely to be solvated, but never simultaneously. The competition between intra- and intermolecular hydrogen bonding and their importance for a correct prediction of spectral properties are discussed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamic NMR Study of Model CMP Slurry Containing Silica Particles as Abrasives

NASA Astrophysics Data System (ADS)

Odeh, F.; Al-Bawab, A.; Li, Y.

2018-02-01

Chemical mechanical planarization (CMP) should provide a good surface planarity with minimal surface defectivity. Since CMP slurries are multi-component systems, it is very important to understand the various processes and interactions taking place in such slurries. Several techniques have been employed for such task, however, most of them lack the molecular recognition to investigate molecular interactions without adding probes which in turn increase complexity and might alter the microenvironment of the slurry. Nuclear magnetic resonance (NMR) is a powerful technique that can be employed in such study. The longitudinal relaxation times (T1) of the different components of CMP slurries were measured using Spin Echo-NMR (SE-NMR) at a constant temperature. The fact that NMR is non-invasive and gives information on the molecular level gives more advantage to the technique. The model CMP slurry was prepared in D2O to enable monitoring of T1 for the various components' protons. SE-NMR provide a very powerful tool to study the various interactions and adsorption processes that take place in a model CMP silica based slurry which contains BTA and/or glycine and/or Cu+2 ions. It was found that BTA is very competitive towards complexation with Cu+2 ions and BTA-Cu complex adsorbs on silica surface.

NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-02-02

This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-02-02

This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not? by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

Monoterpene Unknowns Identified Using IR, [to the first power]H-NMR, [to the thirteenth power]C-NMR, DEPT, COSY, and HETCOR

ERIC Educational Resources Information Center

Alty, Lisa T.

2005-01-01

A study identifies a compound from a set of monoterpenes using infrared (IR) and one-dimensional (1D) nuclear magnetic resonance (NMR) techniques. After identifying the unknown, each carbon and proton signal can be interpreted and assigned to the structure using the information in the two-dimensional (2D) NMR spectra, correlation spectroscopy…

Refinement of NMR structures using implicit solvent and advanced sampling techniques.

PubMed

Chen, Jianhan; Im, Wonpil; Brooks, Charles L

2004-12-15

NMR biomolecular structure calculations exploit simulated annealing methods for conformational sampling and require a relatively high level of redundancy in the experimental restraints to determine quality three-dimensional structures. Recent advances in generalized Born (GB) implicit solvent models should make it possible to combine information from both experimental measurements and accurate empirical force fields to improve the quality of NMR-derived structures. In this paper, we study the influence of implicit solvent on the refinement of protein NMR structures and identify an optimal protocol of utilizing these improved force fields. To do so, we carry out structure refinement experiments for model proteins with published NMR structures using full NMR restraints and subsets of them. We also investigate the application of advanced sampling techniques to NMR structure refinement. Similar to the observations of Xia et al. (J.Biomol. NMR 2002, 22, 317-331), we find that the impact of implicit solvent is rather small when there is a sufficient number of experimental restraints (such as in the final stage of NMR structure determination), whether implicit solvent is used throughout the calculation or only in the final refinement step. The application of advanced sampling techniques also seems to have minimal impact in this case. However, when the experimental data are limited, we demonstrate that refinement with implicit solvent can substantially improve the quality of the structures. In particular, when combined with an advanced sampling technique, the replica exchange (REX) method, near-native structures can be rapidly moved toward the native basin. The REX method provides both enhanced sampling and automatic selection of the most native-like (lowest energy) structures. An optimal protocol based on our studies first generates an ensemble of initial structures that maximally satisfy the available experimental data with conventional NMR software using a simplified force field and then refines these structures with implicit solvent using the REX method. We systematically examine the reliability and efficacy of this protocol using four proteins of various sizes ranging from the 56-residue B1 domain of Streptococcal protein G to the 370-residue Maltose-binding protein. Significant improvement in the structures was observed in all cases when refinement was based on low-redundancy restraint data. The proposed protocol is anticipated to be particularly useful in early stages of NMR structure determination where a reliable estimate of the native fold from limited data can significantly expedite the overall process. This refinement procedure is also expected to be useful when redundant experimental data are not readily available, such as for large multidomain biomolecules and in solid-state NMR structure determination.

Nuclear magnetic resonance technology in acupoint catgut embedding therapy for the treatment of menopausal panic disorder: its applications

NASA Astrophysics Data System (ADS)

Chen, Gui-zhen; Zhang, Sha-sha; Xu, Yun-xiang; Wang, Xiao-yun

2011-11-01

Nuclear Magnetic Resonance (NMR) is a diagnostic method which is non-invasive and non-ionizing irradiative to the human body. It not only suits structural, but also functional imaging. The NMR technique develops rapidly in its application in life science, which has become the hotspot in recent years. Menopausal panic disorder (MPD) is a typical psychosomatic disease during climacteric period, which may affect physical and mental health. Looking for a convenient, effective, and safe method, which is free of toxic-side effects to control the disease, is a modern medical issue. Based on reviewing the etiology and pathogenesis of MPD according to dual traditional Chinese medicine (TCM) and western medicine, further analyzed the advantages and principles for selecting acupoint prescription by tonifying kidney and benefiting marrow therapy for acupoint catgut-embedding to this disease. The application of Nuclear Magnetic Resonance Spectroscopy (NMRS) and Magnetic Resonance Imaging (MRI) technologies in mechanism research on acupoint catgut embedding for the treatment of MPD was discussed. It's pointed out that this intervention method is safe and effective to treat MPD. Breakthrough will be achieved from the research of the selection of acupoint prescription and therapeutic mechanism of acupoint catgut embedding for the treatment of menopausal panic disorder by utilizing the Functional Nuclear Magnetic Resonance Imaging (fMRI) and Metabonomics technologies.

Nuclear magnetic resonance technology in acupoint catgut embedding therapy for the treatment of menopausal panic disorder: its applications

NASA Astrophysics Data System (ADS)

Chen, Gui-zhen; Zhang, Sha-sha; Xu, Yun-xiang; Wang, Xiao-yun

2012-03-01

Nuclear Magnetic Resonance (NMR) is a diagnostic method which is non-invasive and non-ionizing irradiative to the human body. It not only suits structural, but also functional imaging. The NMR technique develops rapidly in its application in life science, which has become the hotspot in recent years. Menopausal panic disorder (MPD) is a typical psychosomatic disease during climacteric period, which may affect physical and mental health. Looking for a convenient, effective, and safe method, which is free of toxic-side effects to control the disease, is a modern medical issue. Based on reviewing the etiology and pathogenesis of MPD according to dual traditional Chinese medicine (TCM) and western medicine, further analyzed the advantages and principles for selecting acupoint prescription by tonifying kidney and benefiting marrow therapy for acupoint catgut-embedding to this disease. The application of Nuclear Magnetic Resonance Spectroscopy (NMRS) and Magnetic Resonance Imaging (MRI) technologies in mechanism research on acupoint catgut embedding for the treatment of MPD was discussed. It's pointed out that this intervention method is safe and effective to treat MPD. Breakthrough will be achieved from the research of the selection of acupoint prescription and therapeutic mechanism of acupoint catgut embedding for the treatment of menopausal panic disorder by utilizing the Functional Nuclear Magnetic Resonance Imaging (fMRI) and Metabonomics technologies.

Osmotic and aging effects in caviar oocytes throughout water and lipid changes assessed by 1H NMR T1 and T2 relaxation and MRI.

PubMed

Gussoni, Maristella; Greco, Fulvia; Vezzoli, Alessandra; Paleari, Maria Antonietta; Moretti, Vittorio Maria; Lanza, Barbara; Zetta, Lucia

2007-01-01

By combining NMR relaxation spectroscopy and magnetic resonance imaging techniques, unsalted (us) and salted (s) caviar (Acipenser transmontanus) oocytes were characterized over a storage period of up to 90 days. The aging and the salting effects on the two major cell constituents, water and lipids, were separately assessed. T1 and T2 decays were interpreted by assuming a two-site exchange model. At Day 0, two water compartments that were not in fast exchange were identified by the T1 relaxation measurements on the us oocytes. In the s samples, T1 decay was monoexponential. During the time of storage, an increment of the free water amount was found for the us oocytes, ascribed to an increased metabolism. T1 and T2 of the s oocytes shortened as a consequence of the osmotic stress produced by salting. Selective images showed the presence of water endowed with different regional mobility that severely changed during the storage. Lipid T1 relaxation decays collected on us and s samples were found to be biexponential, and the T1 values lengthened during storage. In us and s oocytes, the increased lipid mobility with the storage was ascribed to lipolysis. Selective images of us samples showed lipids that were confined to the cytoplasm for up to 60 days of storage.

NMR Studies of Low-Gamma Nuclei in Solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wasylishen, Roderick E.; Forgeron, Michelle A.; Siegel, Renee

2006-07-24

Over the past five years we have devoted considerable time to solid-state NMR investigaitons of nuclei, which are traditionally known as "difficult" because of their small magnetic moments. These include quadrupolar nuclei such as 35Cl, 53 Cr, 91Zr, 95Mo, 99Ru, 131 Xe, as well as spin-1/2 nuclei such as 109Ag. While NMR studies of such isotopes remain challenging, the use of moderate to high magnetic field strengths together with a variety of enhancement techniques is leading to many interesting applications. In this talk some of our successes in studying these isotopes will be presented. For example, we will present preliminarymore » results of 131Xe NMR studies of solid sodium perxenate, as well as 109Ag NMR studies of silver dialkylphosphites. Our experience using population enhancement techniques that utilize hyperbolic secant pulses will also be discussed.« less

Heteronuclear Multidimensional Protein NMR in a Teaching Laboratory

ERIC Educational Resources Information Center

Wright, Nathan T.

2016-01-01

Heteronuclear multidimensional NMR techniques are commonly used to study protein structure, function, and dynamics, yet they are rarely taught at the undergraduate level. Here, we describe a senior undergraduate laboratory where students collect, process, and analyze heteronuclear multidimensional NMR experiments using an unstudied Ig domain (Ig2…

Automated Solid Phase Extraction (SPE) LC/NMR Applied to the Structural Analysis of Extractable Compounds from a Pharmaceutical Packaging Material of Construction.

PubMed

Norwood, Daniel L; Mullis, James O; Davis, Mark; Pennino, Scott; Egert, Thomas; Gonnella, Nina C

2013-01-01

The structural analysis (i.e., identification) of organic chemical entities leached into drug product formulations has traditionally been accomplished with techniques involving the combination of chromatography with mass spectrometry. These include gas chromatography/mass spectrometry (GC/MS) for volatile and semi-volatile compounds, and various forms of liquid chromatography/mass spectrometry (LC/MS or HPLC/MS) for semi-volatile and relatively non-volatile compounds. GC/MS and LC/MS techniques are complementary for structural analysis of leachables and potentially leachable organic compounds produced via laboratory extraction of pharmaceutical container closure/delivery system components and corresponding materials of construction. Both hyphenated analytical techniques possess the separating capability, compound specific detection attributes, and sensitivity required to effectively analyze complex mixtures of trace level organic compounds. However, hyphenated techniques based on mass spectrometry are limited by the inability to determine complete bond connectivity, the inability to distinguish between many types of structural isomers, and the inability to unambiguously determine aromatic substitution patterns. Nuclear magnetic resonance spectroscopy (NMR) does not have these limitations; hence it can serve as a complement to mass spectrometry. However, NMR technology is inherently insensitive and its ability to interface with chromatography has been historically challenging. This article describes the application of NMR coupled with liquid chromatography and automated solid phase extraction (SPE-LC/NMR) to the structural analysis of extractable organic compounds from a pharmaceutical packaging material of construction. The SPE-LC/NMR technology combined with micro-cryoprobe technology afforded the sensitivity and sample mass required for full structure elucidation. Optimization of the SPE-LC/NMR analytical method was achieved using a series of model compounds representing the chemical diversity of extractables. This study demonstrates the complementary nature of SPE-LC/NMR with LC/MS for this particular pharmaceutical application. The identification of impurities leached into drugs from the components and materials associated with pharmaceutical containers, packaging components, and materials has historically been done using laboratory techniques based on the combination of chromatography with mass spectrometry. Such analytical techniques are widely recognized as having the selectivity and sensitivity required to separate the complex mixtures of impurities often encountered in such identification studies, including both the identification of leachable impurities as well as potential leachable impurities produced by laboratory extraction of packaging components and materials. However, while mass spectrometry-based analytical techniques have limitations for this application, newer analytical techniques based on the combination of chromatography with nuclear magnetic resonance spectroscopy provide an added dimension of structural definition. This article describes the development, optimization, and application of an analytical technique based on the combination of chromatography and nuclear magnetic resonance spectroscopy to the identification of potential leachable impurities from a pharmaceutical packaging material. The complementary nature of the analytical techniques for this particular pharmaceutical application is demonstrated.

NMR and MRI apparatus and method

DOEpatents

Clarke, John; Kelso, Nathan; Lee, SeungKyun; Moessle, Michael; Myers, Whittier; McDermott, Robert; ten Haken, Bernard; Pines, Alexander; Trabesinger, Andreas

2007-03-06

Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. Additional signal to noise benefits are obtained by use of a low noise polarization coil, comprising litz wire or superconducting materials. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

Investigations of structure and metabolism within Shewanella oneidensis MR-1 biofilms.

PubMed

McLean, Jeffrey S; Majors, Paul D; Reardon, Catherine L; Bilskis, Christina L; Reed, Samantha B; Romine, Margaret F; Fredrickson, James K

2008-07-01

Biofilms possess spatially and temporally varying metabolite concentration profiles at the macroscopic and microscopic scales. This results in varying growth environments that may ultimately drive species diversity, determine biofilm structure and the spatial distribution of the community members. Using non-invasive nuclear magnetic resonance (NMR) microscopic imaging/spectroscopy and confocal imaging, we investigated the kinetics and stratification of anaerobic metabolism within live biofilms of the dissimilatory metal-reducing bacterium Shewanella oneidensis strain MR-1. Biofilms were pre-grown using a defined minimal medium in a constant-depth film bioreactor and subsequently transferred to an in-magnet sample chamber under laminar flow for NMR measurements. Biofilms generated in this manner were subjected to changing substrate/electron acceptor combinations (fumarate, dimethyl sulfoxide, and nitrate) and the metabolic responses measured. Localized NMR spectroscopy was used to non-invasively measure hydrogen-containing metabolites at high temporal resolution (4.5 min) under O(2)-limited conditions. Reduction of electron acceptor under anaerobic conditions was immediately observed upon switching feed solutions indicating that no gene induction (transcriptional response) was needed for MR-1 to switch metabolism from O(2) to fumarate, dimethyl sulfoxide or nitrate. In parallel experiments, confocal microscopy was used with constitutively expressed fluorescent reporters to independently investigate changes in population response to the availability of electron acceptor and to probe metabolic competition under O(2)-limited conditions. A clearer understanding of the metabolic diversity and plasticity of the biofilm mode of growth as well as how these factors relate to environmental fitness is made possible through the use of non-invasive and non-destructive techniques such as described herein.

One dimensional spatial resolution optimization on a hybrid low field MRI-gamma detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agulles-Pedrós, L., E-mail: lagullesp@unal.edu.co; Abril, A., E-mail: ajabrilf@unal.edu.co

Hybrid systems like Positron Emission Tomography/Magnetic Resonance Imaging (PET/MRI) and MRI/gamma camera, offer advantages combining the resolution and contrast capability of MRI with the better contrast and functional information of nuclear medicine techniques. However, the radiation detectors are expensive and need an electronic set-up, which can interfere with the MRI acquisition process or viceversa. In order to improve these drawbacks, in this work it is presented the design of a low field NMR system made up of permanent magnets compatible with a gamma radiation detector based on gel dosimetry. The design is performed using the software FEMM for estimation ofmore » the magnetic field, and GEANT4 for the physical process involved in radiation detection and effect of magnetic field. The homogeneity in magnetic field is achieved with an array of NbFeB magnets in a linear configuration with a separation between the magnets, minimizing the effect of Compton back scattering compared with a no-spacing linear configuration. The final magnetic field in the homogeneous zone is ca. 100 mT. In this hybrid proposal, although the gel detector do not have spatial resolution per se, it is possible to obtain a dose profile (1D image) as a function of the position by using a collimator array. As a result, the gamma detector system described allows a complete integrated radiation detector within the low field NMR (lfNMR) system. Finally we present the better configuration for the hybrid system considering the collimator parameters such as height, thickness and distance.« less

ATOMIC RESOLUTION CRYO ELECTRON MICROSCOPY OF MACROMOLECULAR COMPLEXES

PubMed Central

ZHOU, Z. HONG

2013-01-01

Single-particle cryo electron microscopy (cryoEM) is a technique for determining three-dimensional (3D) structures from projection images of molecular complexes preserved in their “native,” noncrystalline state. Recently, atomic or near-atomic resolution structures of several viruses and protein assemblies have been determined by single-particle cryoEM, allowing ab initio atomic model building by following the amino acid side chains or nucleic acid bases identifiable in their cryoEM density maps. In particular, these cryoEM structures have revealed extended arms contributing to molecular interactions that are otherwise not resolved by the conventional structural method of X-ray crystallography at similar resolutions. High-resolution cryoEM requires careful consideration of a number of factors, including proper sample preparation to ensure structural homogeneity, optimal configuration of electron imaging conditions to record high-resolution cryoEM images, accurate determination of image parameters to correct image distortions, efficient refinement and computation to reconstruct a 3D density map, and finally appropriate choice of modeling tools to construct atomic models for functional interpretation. This progress illustrates the power of cryoEM and ushers it into the arsenal of structural biology, alongside conventional techniques of X-ray crystallography and NMR, as a major tool (and sometimes the preferred one) for the studies of molecular interactions in supramolecular assemblies or machines. PMID:21501817

Imaging secondary structure of individual amyloid fibrils of a β2-microglobulin fragment using near-field infrared spectroscopy.

PubMed

Paulite, Melissa; Fakhraai, Zahra; Li, Isaac T S; Gunari, Nikhil; Tanur, Adrienne E; Walker, Gilbert C

2011-05-18

Amyloid fibril diseases are characterized by the abnormal production of aggregated proteins and are associated with many types of neuro- and physically degenerative diseases. X-ray diffraction techniques, solid-state magic-angle spinning NMR spectroscopy, circular dichroism (CD) spectroscopy, and transmission electron microscopy studies have been utilized to detect and examine the chemical, electronic, material, and structural properties of amyloid fibrils at up to angstrom spatial resolution. However, X-ray diffraction studies require crystals of the fibril to be analyzed, while other techniques can only probe the bulk solution or solid samples. In the work reported here, apertureless near-field scanning infrared microscopy (ANSIM) was used to probe the secondary structure of individual amyloid fibrils made from an in vitro solution. Simultaneous topographic and infrared images of individual amyloid fibrils synthesized from the #21-31 peptide fragment of β(2)-microglobulin were acquired. Using this technique, IR spectra of the amyloid fibrils were obtained with a spatial resolution of less than 30 nm. It is observed that the experimental scattered field spectrum correlates strongly with that calculated using the far-field absorption spectrum. The near-field images of the amyloid fibrils exhibit much lower scattering of the IR radiation at approximately 1630 cm(-1). In addition, the near-field images also indicate that composition and/or structural variations among individual amyloid fibrils were present. © 2011 American Chemical Society

A novel method for the investigation of liquid/liquid distribution coefficients and interface permeabilities applied to the water-octanol-drug system.

PubMed

Stein, Paul C; di Cagno, Massimiliano; Bauer-Brandl, Annette

2011-09-01

In this work a new, accurate and convenient technique for the measurement of distribution coefficients and membrane permeabilities based on nuclear magnetic resonance (NMR) is described. This method is a novel implementation of localized NMR spectroscopy and enables the simultaneous analysis of the drug content in the octanol and in the water phase without separation. For validation of the method, the distribution coefficients at pH = 7.4 of four active pharmaceutical ingredients (APIs), namely ibuprofen, ketoprofen, nadolol, and paracetamol (acetaminophen), were determined using a classical approach. These results were compared to the NMR experiments which are described in this work. For all substances, the respective distribution coefficients found with the two techniques coincided very well. Furthermore, the NMR experiments make it possible to follow the distribution of the drug between the phases as a function of position and time. Our results show that the technique, which is available on any modern NMR spectrometer, is well suited to the measurement of distribution coefficients. The experiments present also new insight into the dynamics of the water-octanol interface itself and permit measurement of the interface permeability.

Profiling planktonic biomass using element-specific, multicomponent nuclear magnetic resonance spectroscopy.

PubMed

Komatsu, Takanori; Kobayashi, Toshiya; Hatanaka, Minoru; Kikuchi, Jun

2015-06-02

Planktonic metabolism plays crucial roles in Earth's elemental cycles. Chemical speciation as well as elemental stoichiometry is important for advancing our understanding of planktonic roles in biogeochemical cycles. In this study, a multicomponent solid-state nuclear magnetic resonance (NMR) approach is proposed for chemical speciation of cellular components, using several advanced NMR techniques. Measurements by ssNMR were performed on (13)C and (15)N-labeled Euglena gracilis, a flagellated protist. 3D dipolar-assisted rotational resonance, double-cross-polarization (1)H-(13)C correlation spectroscopy, and (1)H-(13)C solid-state heteronuclear single quantum correlation spectroscopy successively allowed characterization of cellular components. These techniques were then applied to E. gracilis cultured in high and low ammonium media to demonstrate the power of this method for profiling and comparing cellular components. Cellular NMR spectra indicated that ammonium induced both paramylon degradation and amination. Arginine was stored as a nitrogen reserve and ammonium replaced by arginine catabolism via the arginine dihydrolase pathway. (15)N and (31)P cellular ssNMR indicated arginine and polyphosphate accumulation in E. gracilis, respectively. This chemical speciation technique will contribute to environmental research by providing detailed information on environmental chemical properties.

Diffusion MRI in the heart.

PubMed

Mekkaoui, Choukri; Reese, Timothy G; Jackowski, Marcel P; Bhat, Himanshu; Sosnovik, David E

2017-03-01

Diffusion MRI provides unique information on the structure, organization, and integrity of the myocardium without the need for exogenous contrast agents. Diffusion MRI in the heart, however, has proven technically challenging because of the intrinsic non-rigid deformation during the cardiac cycle, displacement of the myocardium due to respiratory motion, signal inhomogeneity within the thorax, and short transverse relaxation times. Recently developed accelerated diffusion-weighted MR acquisition sequences combined with advanced post-processing techniques have improved the accuracy and efficiency of diffusion MRI in the myocardium. In this review, we describe the solutions and approaches that have been developed to enable diffusion MRI of the heart in vivo, including a dual-gated stimulated echo approach, a velocity- (M 1 ) or an acceleration- (M 2 ) compensated pulsed gradient spin echo approach, and the use of principal component analysis filtering. The structure of the myocardium and the application of these techniques in ischemic heart disease are also briefly reviewed. The advent of clinical MR systems with stronger gradients will likely facilitate the translation of cardiac diffusion MRI into clinical use. The addition of diffusion MRI to the well-established set of cardiovascular imaging techniques should lead to new and complementary approaches for the diagnosis and evaluation of patients with heart disease. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

Magic Angle Spinning NMR Metabolomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhi Hu, Jian

Nuclear Magnetic Resonance (NMR) spectroscopy is a non-destructive, quantitative, reproducible, untargeted and unbiased method that requires no or minimal sample preparation, and is one of the leading analytical tools for metabonomics research [1-3]. The easy quantification and the no need of prior knowledge about compounds present in a sample associated with NMR are advantageous over other techniques [1,4]. 1H NMR is especially attractive because protons are present in virtually all metabolites and its NMR sensitivity is high, enabling the simultaneous identification and monitoring of a wide range of low molecular weight metabolites.

Intermediate couplings: NMR at the solids-liquids interface

NASA Astrophysics Data System (ADS)

Spence, Megan

2006-03-01

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

Mechanisms of amyloid formation revealed by solution NMR

PubMed Central

Karamanos, Theodoros K.; Kalverda, Arnout P.; Thompson, Gary S.; Radford, Sheena E.

2015-01-01

Amyloid fibrils are proteinaceous elongated aggregates involved in more than fifty human diseases. Recent advances in electron microscopy and solid state NMR have allowed the characterization of fibril structures to different extents of refinement. However, structural details about the mechanism of fibril formation remain relatively poorly defined. This is mainly due to the complex, heterogeneous and transient nature of the species responsible for assembly; properties that make them difficult to detect and characterize in structural detail using biophysical techniques. The ability of solution NMR spectroscopy to investigate exchange between multiple protein states, to characterize transient and low-population species, and to study high molecular weight assemblies, render NMR an invaluable technique for studies of amyloid assembly. In this article we review state-of-the-art solution NMR methods for investigations of: (a) protein dynamics that lead to the formation of aggregation-prone species; (b) amyloidogenic intrinsically disordered proteins; and (c) protein–protein interactions on pathway to fibril formation. Together, these topics highlight the power and potential of NMR to provide atomic level information about the molecular mechanisms of one of the most fascinating problems in structural biology. PMID:26282197

Characterization of ferrous-methylthymol blue-polyvinyl alcohol gel dosimeters using nuclear magnetic resonance and optical techniques

NASA Astrophysics Data System (ADS)

Rabaeh, Khalid A.; Eyadeh, Molham M.; Hailat, Tariq F.; Aldweri, Feras M.; Alheet, Samer M.; Eid, Rania M.

2018-07-01

A new composition of Ferrous sulphate-Metheylthymol blue (MTB)-Polyvinyl alcohol (PVA) dosimeter is introduced in this work and evaluated using nuclear magnetic resonance (NMR) and absorbance spectrophotometry techniques. The Fricke-MTB-PVA dosimeters were irradiated using a medical linear accelerator in a cubic water phantom. The dose response of the dosimeters was investigated using NMR in terms of spin-spin relaxation rate (R2), and ultraviolet and visible regions (UV-Vis) spectrophotometry in terms of absorbance. The dosimeter presents a linear dose response for doses up to 20 Gy with UV-Vis and 40 Gy with NMR method. The sample with 0.1 mM MTB, 5% PVA by weight showed highest dose sensitivity for both techniques. The Fricke-MTB-PVA dosimeter developed in this work has a significant advance over the Fricke-MTB-gelatin system: the NMR sensitivity was remarkably improved; the auto-oxidation rate was seven times lower, and no significant dose rate or photon energy effects were observed.

NMR in Pulsed Magnetic Fields on the Orthogonal Shastry-Sutherland spin system SrCu2 (BO3)2

NASA Astrophysics Data System (ADS)

Stern, Raivo; Kohlrautz, Jonas; Kühne, Hannes; Greene, Liz; Wosnitza, Jochen; Haase, Jügen

2015-03-01

SrCu2(BO3)2 is a quasi-two-dimensional spin system consisting of Cu2+ ions which form orthogonal spin singlet dimers, also known as the Shastry-Sutherland lattice, in the ground state. Though this system has been studied extensively using a variety of techniques to probe the spin triplet excitations, including recent magnetization measurements over 100 T, microscopic techniques, such as nuclear magnetic resonance (NMR), could provide further insight into the spin excitations and spin-coupling mechanisms. We demonstrate the feasibility of performing NMR on real physics system in pulsed magnets. We present 11B NMR spectra measured in pulsed magnetic fields up to 53 T, and compare those with prior results obtained in static magnetic fields. Herewith we prove the efficacy of this technique and then extend to higher fields to fully explore the spin structure of the 1/3 plateau. Support by EMFL, DFG, ETAg (EML+ & PUT210).

An Analytical Technique to Elucidate Field Impurities From Manufacturing Uncertainties of an Double Pancake Type HTS Insert for High Field LTS/HTS NMR Magnets

PubMed Central

Hahn, Seung-yong; Ahn, Min Cheol; Bobrov, Emanuel Saul; Bascuñán, Juan; Iwasa, Yukikazu

2010-01-01

This paper addresses adverse effects of dimensional uncertainties of an HTS insert assembled with double-pancake coils on spatial field homogeneity. Each DP coil was wound with Bi2223 tapes having dimensional tolerances larger than one order of magnitude of those accepted for LTS wires used in conventional NMR magnets. The paper presents: 1) dimensional variations measured in two LTS/HTS NMR magnets, 350 MHz (LH350) and 700 MHz (LH700), both built and operated at the Francis Bitter Magnet Laboratory; and 2) an analytical technique and its application to elucidate the field impurities measured with the two LTS/HTS magnets. Field impurities computed with the analytical model and those measured with the two LTS/HTS magnets agree quite well, demonstrating that this analytical technique is applicable to design a DP-assembled HTS insert with an improved field homogeneity for a high-field LTS/HTS NMR magnet. PMID:20407595

Experimental determination of pore shapes using phase retrieval from q -space NMR diffraction

NASA Astrophysics Data System (ADS)

Demberg, Kerstin; Laun, Frederik Bernd; Bertleff, Marco; Bachert, Peter; Kuder, Tristan Anselm

2018-05-01

This paper presents an approach to solving the phase problem in nuclear magnetic resonance (NMR) diffusion pore imaging, a method that allows imaging the shape of arbitrary closed pores filled with an NMR-detectable medium for investigation of the microstructure of biological tissue and porous materials. Classical q -space imaging composed of two short diffusion-encoding gradient pulses yields, analogously to diffraction experiments, the modulus squared of the Fourier transform of the pore image which entails an inversion problem: An unambiguous reconstruction of the pore image requires both magnitude and phase. Here the phase information is recovered from the Fourier modulus by applying a phase retrieval algorithm. This allows omitting experimentally challenging phase measurements using specialized temporal gradient profiles. A combination of the hybrid input-output algorithm and the error reduction algorithm was used with dynamically adapting support (shrinkwrap extension). No a priori knowledge on the pore shape was fed to the algorithm except for a finite pore extent. The phase retrieval approach proved successful for simulated data with and without noise and was validated in phantom experiments with well-defined pores using hyperpolarized xenon gas.

Experimental determination of pore shapes using phase retrieval from q-space NMR diffraction.

PubMed

Demberg, Kerstin; Laun, Frederik Bernd; Bertleff, Marco; Bachert, Peter; Kuder, Tristan Anselm

2018-05-01

This paper presents an approach to solving the phase problem in nuclear magnetic resonance (NMR) diffusion pore imaging, a method that allows imaging the shape of arbitrary closed pores filled with an NMR-detectable medium for investigation of the microstructure of biological tissue and porous materials. Classical q-space imaging composed of two short diffusion-encoding gradient pulses yields, analogously to diffraction experiments, the modulus squared of the Fourier transform of the pore image which entails an inversion problem: An unambiguous reconstruction of the pore image requires both magnitude and phase. Here the phase information is recovered from the Fourier modulus by applying a phase retrieval algorithm. This allows omitting experimentally challenging phase measurements using specialized temporal gradient profiles. A combination of the hybrid input-output algorithm and the error reduction algorithm was used with dynamically adapting support (shrinkwrap extension). No a priori knowledge on the pore shape was fed to the algorithm except for a finite pore extent. The phase retrieval approach proved successful for simulated data with and without noise and was validated in phantom experiments with well-defined pores using hyperpolarized xenon gas.

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

PubMed

Yoon, Ji Won

2014-11-01

Projection reconstruction nuclear magnetic resonance (PR-NMR) is a technique for generating multidimensional NMR spectra. A small number of projections from lower-dimensional NMR spectra are used to reconstruct the multidimensional NMR spectra. In our previous work, it was shown that multidimensional NMR spectra are efficiently reconstructed using peak-by-peak based reversible jump Markov chain Monte Carlo (RJMCMC) algorithm. We propose an extended and generalized RJMCMC algorithm replacing a simple linear model with a linear mixed model to reconstruct close NMR spectra into true spectra. This statistical method generates samples in a Bayesian scheme. Our proposed algorithm is tested on a set of six projections derived from the three-dimensional 700 MHz HNCO spectrum of a protein HasA. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lithium Visibility in Rat Brain and Muscle in Vivoby 7Li NMR Imaging

NASA Astrophysics Data System (ADS)

Komoroski, Richard A.; Pearce, John M.; Newton, Joseph E. O.

1998-07-01

The apparent concentration of lithium (Li)in vivowas determined for several regions in the brain and muscle of rats by7Li NMR imaging at 4.7 T with inclusion of an external standard of known concentration and visibility. The average apparent concentrations were 10.1 mM for muscle, and 4.2-5.3 mM for various brain regions under the dosing conditions used. The results were compared to concentrations determinedin vitroby high-resolution7Li NMR spectroscopy of extracts of brain and muscle tissue from the same rats. The comparison provided estimates of the7Li NMR visibility of the Li cation in each tissue region. Although there was considerable scatter of the calculated visibilities among the five rats studied, the results suggested essentially full visibility (96%) for Li in muscle, and somewhat reduced visibility (74-93%) in the various brain regions.

NMR imaging of cell phone radiation absorption in brain tissue

PubMed Central

Gultekin, David H.; Moeller, Lothar

2013-01-01

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

NMR imaging of cell phone radiation absorption in brain tissue.

PubMed

Gultekin, David H; Moeller, Lothar

2013-01-02

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

[SECOT consensus on medial femorotibial osteoarthritis].

PubMed

Moreno, A; Silvestre, A; Carpintero, P

2013-01-01

A consensus, prepared by SECOT, is presented on the management of medial knee compartment osteoarthritis, in order to establish clinical criteria and recommendations directed at unifying the criteria in its management, dealing with the factors involved in the pathogenesis of medial femorotibial knee osteoarthritis, the usefulness of diagnostic imaging techniques, and the usefulness of arthroscopy. Conservative and surgical treatments are also analysed. The experts consulted showed a consensus (agreed or disagreed) in 65.8% of the items considered, leaving 14items where no consensus was found, which included the aetiopathogenesis of the osteoarthritis, the value of NMR in degenerative disease, the usefulness of COX-2 and the chondroprotective drugs, as well as on the ideal valgus tibial osteotomy technique. © 2013 SECOT. Published by Elsevier Espana. All rights reserved.

Expanding Your Laboratory by Accessing Collaboratory Resources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoyt, David W.; Burton, Sarah D.; Peterson, Michael R.

2004-03-01

The Environmental Molecular Sciences Laboratory (EMSL) in Richland, Washington, is the home of a research facility setup by the United States Department of Energy (DOE). The facility is atypical because it houses over 100 cutting-edge research systems for the use of researchers all over the United States and the world. Access to the lab is requested through a peer-review proposal process and the scientists who use the facility are generally referred to as ‘users’. There are six main research facilities housed in EMSL, all of which host visiting researchers. Several of these facilities also participate in the EMSL Collaboratory, amore » remote access capability supported by EMSL operations funds. Of these, the High-Field Magnetic Resonance Facility (HFMRF) and Molecular Science Computing Facility (MSCF) have a significant number of their users performing remote work. The HFMRF in EMSL currently houses 12 NMR spectrometers that range in magnet field strength from 7.05T to 21.1T. Staff associated with the NMR facility offers scientific expertise in the areas of structural biology, solid-state materials/catalyst characterization, and magnetic resonance imaging (MRI) techniques. The way in which the HFMRF operates, with a high level of dedication to remote operation across the full suite of High-Field NMR spectrometers, has earned it the name “Virtual NMR Facility”. This review will focus on the operational aspects of remote research done in the High-Field Magnetic Resonance Facility and the computer tools that make remote experiments possible.« less

Use of earth field spin echo NMR to search for liquid minerals

DOEpatents

Stoeffl, Wolfgang

2001-01-01

An instrument for measuring the spatial, qualitative and quantitative parameters of an underground nuclear magnetic resonance (NMR) active liquid mineral deposit, including oil and water. A phased array of excitation and receiver antennas on the surface and/or in a borehole excites the NMR active nuclei in the deposit, and using known techniques from magnetic resonance imaging (MRI), the spatial and quantitative distribution of the deposit can be measured. A surface array may utilize, for example, four large (50-500 diameter) diameter wire loops laid on the ground surface, and a weak (1.5-2.5 kHz) alternating current (AC) field applied, matching the NMR frequency of hydrogen in the rather flat and uniform earth magnetic field. For a short duration (a few seconds) an additional gradient field can be generated, superimposed to the earth field, by applying direct current (DC) to the grid (wire loops), enhancing the position sensitivity of the spin-echo and also suppressing large surface water signals by shifting them to a different frequency. The surface coil excitation can be combined with downhole receivers, which are much more radio-quiet compared to surface receivers, and this combination also enhances the position resolution of the MRI significantly. A downhole receiver module, for example, may have a 5.5 inch diameter and fit in a standard six inch borehole having a one-quarter inch thick stainless steel casing. The receiver module may include more than one receiver units for improved penetration and better position resolution.

NMR Spin-Lock Induced Crossing (SLIC) Dispersion and Long-Lived Spin States of Gaseous Propane at Low Magnetic Field (0.05 T)

PubMed Central

Barskiy, Danila A.; Salnikov, Oleg G.; Romanov, Alexey S.; Feldman, Matthew A.; Coffey, Aaron M.; Kovtunov, Kirill V.; Koptyug, Igor V.; Chekmenev, Eduard Y.

2017-01-01

When parahydrogen reacts with propylene in low magnetic fields (e.g., 0.05 T), the reaction product propane develops an overpopulation of pseudo-singlet nuclear spin states. We studied how the spin-lock induced crossing (SLIC) technique can be used to convert these pseudo-singlet spin states of hyperpolarized gaseous propane into observable magnetization and to detect 1H NMR signal directly at 0.05 T. The theoretical simulation and experimental study of the NMR signal dependence on B1 power (SLIC amplitude) exhibits a well-resolved dispersion, which is induced by the spin-spin couplings in the eight-proton spin system of propane. We also measured the exponential decay time constants (TLLSS or TS) of these pseudo-singlet long-lived spin states (LLSS) by varying the time between hyperpolarized propane production and SLIC detection. We have found that, on average, TS is approximately 3 times longer than the corresponding T1 value under the same conditions in the range of pressures studied (up to 7.6 atm). Moreover, TS may exceed 13 seconds at pressures above 7 atm in the gas phase. These results are in agreement with the previous reports, and they corroborate a great potential of long-lived hyperpolarized propane as an inhalable gaseous contrast agent for lung imaging and as a molecular tracer to study porous media using low-field NMR and MRI. PMID:28152435

NMR Spin-Lock Induced Crossing (SLIC) dispersion and long-lived spin states of gaseous propane at low magnetic field (0.05 T)

NASA Astrophysics Data System (ADS)

Barskiy, Danila A.; Salnikov, Oleg G.; Romanov, Alexey S.; Feldman, Matthew A.; Coffey, Aaron M.; Kovtunov, Kirill V.; Koptyug, Igor V.; Chekmenev, Eduard Y.

2017-03-01

When parahydrogen reacts with propylene in low magnetic fields (e.g., 0.05 T), the reaction product propane develops an overpopulation of pseudo-singlet nuclear spin states. We studied how the Spin-Lock Induced Crossing (SLIC) technique can be used to convert these pseudo-singlet spin states of hyperpolarized gaseous propane into observable magnetization and to detect 1H NMR signal directly at 0.05 T. The theoretical simulation and experimental study of the NMR signal dependence on B1 power (SLIC amplitude) exhibits a well-resolved dispersion, which is induced by the spin-spin couplings in the eight-proton spin system of propane. We also measured the exponential decay time constants (TLLSS or TS) of these pseudo-singlet long-lived spin states (LLSS) by varying the time between hyperpolarized propane production and SLIC detection. We have found that, on average, TS is approximately 3 times longer than the corresponding T1 value under the same conditions in the range of pressures studied (up to 7.6 atm). Moreover, TS may exceed 13 s at pressures above 7 atm in the gas phase. These results are in agreement with the previous reports, and they corroborate a great potential of long-lived hyperpolarized propane as an inhalable gaseous contrast agent for lung imaging and as a molecular tracer to study porous media using low-field NMR and MRI.

RF-SABRE: A Way to Continuous Spin Hyperpolarization at High Magnetic Fields.

PubMed

Pravdivtsev, Andrey N; Yurkovskaya, Alexandra V; Vieth, Hans-Martin; Ivanov, Konstantin L

2015-10-29

A new technique is developed that allows one to carry out the signal amplification by reversible exchange (SABRE) experiments at high magnetic field. SABRE is a hyperpolarization method, which utilizes transfer of spin order from para-hydrogen to the spins of a substrate in transient iridium complexes. Previously, it has been thought that such a transfer of spin order is only efficient at low magnetic fields, notably, at level anti-crossing (LAC) regions. Here it is demonstrated that LAC conditions can also be fulfilled at high fields under the action of a RF field. The high-field RF-SABRE experiment can be implemented using commercially available nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) machines and does not require technically demanding field-cycling. The achievable NMR enhancements are around 100 for several substrates as compared to their NMR signals at thermal equilibrium conditions at 4.7 T. The frequency dependence of RF-SABRE is comprised of well pronounced peaks and dips, whose position and amplitude are conditioned solely by the magnetic resonance parameters such as chemical shifts and scalar coupling of the spin system involved in the polarization transfer and by the amplitude of the RF field. Thus, the proposed method can serve as a new sensitive tool for probing transient complexes. Simulations of the dependence of magnetization transfer (i.e., NMR signal amplifications) on the frequency and amplitude of the RF field are in good agreement with the developed theoretical approach. Furthermore, the method enables continuous re-hyperpolarization of the SABRE substrate over a long period of time, giving a straightforward way to repetitive NMR experiments.

Multiscale approach to (micro)porosity quantification in continental spring carbonate facies: Case study from the Cakmak quarry (Denizli, Turkey)

NASA Astrophysics Data System (ADS)

De Boever, Eva; Foubert, Anneleen; Oligschlaeger, Dirk; Claes, Steven; Soete, Jeroen; Bertier, Pieter; Özkul, Mehmet; Virgone, Aurélien; Swennen, Rudy

2016-07-01

Carbonate spring deposits gained renewed interest as potential contributors to subsurface reservoirs and as continental archives of environmental changes. In contrast to their fabrics, petrophysical characteristics - and especially the importance of microporosity (< 1µm) - are less understood. This study presents the combination of advanced petrophysical and imaging techniques to investigate the pore network characteristics of three, common and widespread spring carbonate facies, as exposed in the Pleistocene Cakmak quarry (Denizli, Turkey): the extended Pond, the dipping crystalline Proximal Slope Facies and the draping Apron and Channel Facies deposits formed by encrustation of biological substrate. Integrating mercury injection capillary pressure, bulk and diffusion Nuclear Magnetic Resonance (NMR), NMR profiling and Brunauer-Emmett-Teller (BET) measurements with microscopy and micro-computer tomography (µ-CT), shows that NMR T2 distributions systematically display a single group of micro-sized pore bodies, making up between 6 and 33% of the pore space (average NMR T2 cut-off value: 62 ms). Micropore bodies are systematically located within cloudy crystal cores of granular and dendritic crystal textures in all facies. The investigated properties therefore do not reveal differences in micropore size or shape with respect to more or less biology-associated facies. The pore network of the travertine facies is distinctive in terms of (i) the percentage of microporosity, (ii) the connectivity of micropores with meso- to macropores, and (ii) the degree of heterogeneity at micro- and macroscale. Results show that an approach involving different NMR experiments provided the most complete view on the 3-D pore network especially when microporosity and connectivity are of interest.

NMR study on (1alpha, 2beta, 4beta, 5alpha, 7beta)-7-[(hydroxydi-2-thienylacetyl) oxy]-9,9-dimethyl-3-oxa-9-azoniatricyclo [3.3.1.0(2,4)] nonane bromide monohydrate.

PubMed

Lin, Zhenguang; Mu, Yingdi; Liu, Yihui; Ren, Yeming; Lin, Jimao

2010-03-01

The structure of (1alpha, 2beta, 4beta, 5alpha, 7beta)-7-[(hydroxydi-2-thienylacetyl) oxy]-9,9-dimethyl-3-oxa-9-azoniatricyclo [3.3.1.0(2,4)] nonane bromide monohydrate was studied using 1D and 2D NMR techniques. Complete NMR assignments of the compound were obtained using DEPT, H-H COSY, as well as HMQC and HMBC heteronuclear correlation techniques. Copyright 2010 Elsevier B.V. All rights reserved.

Enhanced detection of aldehydes in Extra-Virgin Olive Oil by means of band selective NMR spectroscopy

NASA Astrophysics Data System (ADS)

Dugo, Giacomo; Rotondo, Archimede; Mallamace, Domenico; Cicero, Nicola; Salvo, Andrea; Rotondo, Enrico; Corsaro, Carmelo

2015-02-01

High resolution Nuclear Magnetic Resonance (NMR) spectroscopy is a very powerful tool for comprehensive food analyses and especially for Extra-Virgin Olive Oils (EVOOs). We use the NMR technique to study the spectral region of aldehydes (8-10 ppm) for EVOOs coming from the south part of Italy. We perform novel experiments by using mono and bidimensional band selective spin-echo pulse sequences and identify four structural classes of aldehydes in EVOOs. For the first time such species are identified in EVOOs without any chemical treatment; only dilution with CDCl3 is employed. This would allow the discrimination of different EVOOs for the aldehydes content increasing the potentiality of the NMR technique in the screening of metabolites for geographical characterization of EVOOs.

Online monitoring of fermentation processes via non-invasive low-field NMR.

PubMed

Kreyenschulte, Dirk; Paciok, Eva; Regestein, Lars; Blümich, Bernhard; Büchs, Jochen

2015-09-01

For the development of biotechnological processes in academia as well as in industry new techniques are required which enable online monitoring for process characterization and control. Nuclear magnetic resonance (NMR) spectroscopy is a promising analytical tool, which has already found broad applications in offline process analysis. The use of online monitoring, however, is oftentimes constrained by high complexity of custom-made NMR bioreactors and considerable costs for high-field NMR instruments (>US$200,000). Therefore, low-field (1) H NMR was investigated in this study in a bypass system for real-time observation of fermentation processes. The new technique was validated with two microbial systems. For the yeast Hansenula polymorpha glycerol consumption could accurately be assessed in spite of the presence of high amounts of complex constituents in the medium. During cultivation of the fungal strain Ustilago maydis, which is accompanied by the formation of several by-products, the concentrations of glucose, itaconic acid, and the relative amount of glycolipids could be quantified. While low-field spectra are characterized by reduced spectral resolution compared to high-field NMR, the compact design combined with the high temporal resolution (15 s-8 min) of spectra acquisition allowed online monitoring of the respective processes. Both applications clearly demonstrate that the investigated technique is well suited for reaction monitoring in opaque media while at the same time it is highly robust and chemically specific. It can thus be concluded that low-field NMR spectroscopy has a great potential for non-invasive online monitoring of biotechnological processes at the research and practical industrial scales. © 2015 Wiley Periodicals, Inc.

An Introduction to Biological NMR Spectroscopy*

PubMed Central

Marion, Dominique

2013-01-01

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

A Multidisciplinary Approach to High Throughput Nuclear Magnetic Resonance Spectroscopy

PubMed Central

Pourmodheji, Hossein; Ghafar-Zadeh, Ebrahim; Magierowski, Sebastian

2016-01-01

Nuclear Magnetic Resonance (NMR) is a non-contact, powerful structure-elucidation technique for biochemical analysis. NMR spectroscopy is used extensively in a variety of life science applications including drug discovery. However, existing NMR technology is limited in that it cannot run a large number of experiments simultaneously in one unit. Recent advances in micro-fabrication technologies have attracted the attention of researchers to overcome these limitations and significantly accelerate the drug discovery process by developing the next generation of high-throughput NMR spectrometers using Complementary Metal Oxide Semiconductor (CMOS). In this paper, we examine this paradigm shift and explore new design strategies for the development of the next generation of high-throughput NMR spectrometers using CMOS technology. A CMOS NMR system consists of an array of high sensitivity micro-coils integrated with interfacing radio-frequency circuits on the same chip. Herein, we first discuss the key challenges and recent advances in the field of CMOS NMR technology, and then a new design strategy is put forward for the design and implementation of highly sensitive and high-throughput CMOS NMR spectrometers. We thereafter discuss the functionality and applicability of the proposed techniques by demonstrating the results. For microelectronic researchers starting to work in the field of CMOS NMR technology, this paper serves as a tutorial with comprehensive review of state-of-the-art technologies and their performance levels. Based on these levels, the CMOS NMR approach offers unique advantages for high resolution, time-sensitive and high-throughput bimolecular analysis required in a variety of life science applications including drug discovery. PMID:27294925

A method to improve the B0 homogeneity of the heart in vivo.

PubMed

Jaffer, F A; Wen, H; Balaban, R S; Wolff, S D

1996-09-01

A homogeneous static (B0) magnetic field is required for many NMR experiments such as echo planar imaging, localized spectroscopy, and spiral scan imaging. Although semi-automated techniques have been described to improve the B0 field homogeneity, none has been applied to the in vivo heart. The acquisition of cardiac field maps is complicated by motion, blood flow, and chemical shift artifact from epicardial fat. To overcome these problems, an ungated three-dimensional (3D) chemical shift image (CSI) was collected to generate a time and motion-averaged B0 field map. B0 heterogeneity in the heart was minimized by using a previous algorithm that solves for the optimal shim coil currents for an input field map, using up to third-order current-bounded shims (1). The method improved the B0 homogenelty of the heart in all 11 normal volunteers studied. After application of the algorithm to the unshimmed cardiac field maps, the standard deviation of proton frequency decreased by 43%, the magnitude 1H spectral linewidth decreased by 24%, and the peak-peak gradient decreased by 35%. Simulations of the high-order (second- and third-order) shims in B0 field correction of the heart show that high order shims are important, resulting for nearly half of the improvement in homogeneity for several subjects. The T2* of the left ventricular anterior wall before and after field correction was determined at 4.0 Tesis. Finally, results show that cardiac shimming is of benefit in cardiac 31P NMR spectroscopy and cardiac echo planar imaging.

Magnetic resonance imaging (MRI) and relaxation spectrum analysis as methods to investigate swelling in whey protein gels.

PubMed

Oztop, Mecit H; Rosenberg, Moshe; Rosenberg, Yael; McCarthy, Kathryn L; McCarthy, Michael J

2010-10-01

Effective means for controlled delivery of nutrients and nutraceuticals are needed. Whey protein-based gels, as a model system and as a potential delivery system, exhibit pH-dependent swelling when placed in aqueous solutions. Understanding the physics that govern gel swelling is thus important when designing gel-based delivery platforms. The extent of swelling over time was monitored gravimetrically. In addition to gravimetric measurements, magnetic resonance imaging (MRI) a real-time noninvasive imaging technique that quantified changes in geometry and water content of these gels was utilized. Heat-set whey protein gels were prepared at pH 7 and swelling was monitored in aqueous solutions with pH values of 2.5, 7, and 10. Changes in dimension over time, as characterized by the number of voxels in an image, were correlated to gravimetric measurements. Excellent correlations between mass uptake and volume change (R(2)= 0.99) were obtained for the gels in aqueous solutions at pH 7 and 10, but not for gels in the aqueous solution at pH 2.5. To provide insight into the mechanisms for water uptake, nuclear magnetic resonance (NMR) relaxation times were measured in independent experiments. The relaxation spectrum for the spin-spin relaxation time (T(2)) showed the presence of 3 proton pools for pH 7 and 10 trials and 4 proton pools for pH 2.5 trials. Results demonstrate that MRI and NMR relaxation measurements provided information about swelling in whey protein gels that can constitute a new means for investigating and developing effective delivery systems for foods.

Structure determination of helical filaments by solid-state NMR spectroscopy

PubMed Central

Ahmed, Mumdooh; Spehr, Johannes; König, Renate; Lünsdorf, Heinrich; Rand, Ulfert; Lührs, Thorsten; Ritter, Christiane

2016-01-01

The controlled formation of filamentous protein complexes plays a crucial role in many biological systems and represents an emerging paradigm in signal transduction. The mitochondrial antiviral signaling protein (MAVS) is a central signal transduction hub in innate immunity that is activated by a receptor-induced conversion into helical superstructures (filaments) assembled from its globular caspase activation and recruitment domain. Solid-state NMR (ssNMR) spectroscopy has become one of the most powerful techniques for atomic resolution structures of protein fibrils. However, for helical filaments, the determination of the correct symmetry parameters has remained a significant hurdle for any structural technique and could thus far not be precisely derived from ssNMR data. Here, we solved the atomic resolution structure of helical MAVSCARD filaments exclusively from ssNMR data. We present a generally applicable approach that systematically explores the helical symmetry space by efficient modeling of the helical structure restrained by interprotomer ssNMR distance restraints. Together with classical automated NMR structure calculation, this allowed us to faithfully determine the symmetry that defines the entire assembly. To validate our structure, we probed the protomer arrangement by solvent paramagnetic resonance enhancement, analysis of chemical shift differences relative to the solution NMR structure of the monomer, and mutagenesis. We provide detailed information on the atomic contacts that determine filament stability and describe mechanistic details on the formation of signaling-competent MAVS filaments from inactive monomers. PMID:26733681

Application of pulsed field gradient NMR techniques for investigating binding of flavor compounds to macromolecules.

PubMed

Jung, Da-Mi; De Ropp, Jeffrey S; Ebeler, Susan E

2002-07-17

Two diffusion-based NMR techniques are presented and used to investigate the binding of selected flavor compounds to macromolecules. A pulsed field gradient NMR (PFG-NMR) method was applied to measure the apparent diffusion coefficients of four alkanone compounds as they associated with bovine serum albumin (BSA). The change in the apparent diffusion coefficient as a function of the BSA/alkanone ratio was fitted to yield binding constants (K(a)()) and binding stoichiometry (n) for each alkanone. The results showed that the apparent diffusion coefficients of alkanones increased with a decrease in the BSA/alkanone ratios, and the measured values of K(a)() and n were comparable with those obtained with other methods and depended on the alkanone structure. A diffusion-based nuclear Overhauser effect (called diffusion NOE pumping) method was also applied to screen mixtures of flavor compounds and identify those that have a binding affinity to complex macromolecules. Using this technique benzaldehyde and vanillin were observed to bind with bovine serum albumin, whereas 2-phenylethanol was identified as a nonbinding or weakly binding ligand with BSA. The diffusion NOE pumping method was also applied to a hydro alcoholic solution of cacao bean tannin extracts to which a mixture of ethylbenzoate, benzaldehyde, and 2-phenylethanol was added. The diffusion NOE pumping technique clearly indicated that ethylbenzoate had a stronger binding affinity to the polymeric (-)-epicatechin units of the cacao bean tannin extracts than the other two flavor compounds. The results successfully demonstrate the potential applications of diffusion-based NMR techniques for studying flavors and nonvolatile food matrix interactions.

Which kind of aromatic structures are produced during biomass charring? New insights provided by modern solid-state NMR spectroscopy

NASA Astrophysics Data System (ADS)

Knicker, Heike; Paneque-Carmona, Marina; Velasco-Molina, Marta; de la Rosa, José Maria; León-Ovelar, Laura Regina; Fernandez-Boy, Elena

2017-04-01

Intense research on biochar and charcoal of the last years has revealed that depending on the production conditions, the chemical and physical characteristics of their aromatic network can greatly vary. Since such variations are determining the behavior and stability of charred material in soils, a better understanding of the structural changes occurring during their heating and the impact of those changes on their function is needed. One method to characterize pyrogenic organic matter (PyOM) represents solid-state 13C NMR spectroscopy applying the cross polarization (CP) magic angle spinning technique (MAS). A drawback of this technique is that the quantification of NMR spectra of samples with highly condensed and proton-depleted structures is assumed to be bias. Typical samples with such attributes are charcoals produced at temperatures above 700°C under pyrolytic conditions. Commonly their high condensation degree leads to graphenic structures that are not only reducing the CP efficiency but create also a conductive lattice which acts as a shield and prevents the entering of the excitation pulse into the sample during the NMR experiments. Since the latter can damage the NMR probe and in the most cases the obtained NMR spectra show only one broad signal assignable to aromatic C, this technique is rarely applied for characterizing high temperature chars or soot. As a consequence, a more detailed knowledge of the nature of the aromatic ring systems is still missing. The latter is also true for the aromatic domains of PyOM produced at lower temperatures, since older NMR instruments operating at low magnetic fields deliver solid-state 13C NMR spectra with low resolution which turns a more detailed analysis of the aromatic chemical shift region into a challenging task. In order to overcome this disadvantages, modern NMR spectroscopy offers not only instruments with greatly improved resolution but also special pulse sequences for NMR experiments which allow a more detailed chemical shift assignment. Applying the latter to various charcoals and biochars, we intended to test their usefulness for a better characterization of PyOM and elucidation how specific aromatic features can affect their behavior in soils. We could demonstrate that furans represent the major compound class of low temperature chars produced from woody material. As indicated by 2D techniques, residual alkyl C in such chars has minor covalent binding to the aromatic network. Reducing the electrical conductivity of high-temperature chars by addition of aluminum oxide permitted the application of the cross CP technique. Determination of the relaxation and CP dynamics confirmed high rigidity of their aromatic domains which were dominated by coronene-type moieties. In contrast to common view, we could demonstrate that quantifiable CP NMR spectra can be obtained from high temperature chars with contact times of 3 to 5 ms and pulse delays > 3 s.

Velocity distributions in a micromixer measured by NMR imaging.

PubMed

Ahola, Susanna; Telkki, Ville-Veikko; Stapf, Siegfried

2012-04-24

Velocity distributions (so-called propagators) with two-dimensional spatial resolution inside a chemical micromixer were measured by pulsed-field-gradient spin-echo (PGSE) nuclear magnetic resonance (NMR). A surface coil matching the volume of interest was built to enhance the signal-to-noise ratio. This enabled the acquisition of velocity maps with a very high spatial resolution of 29 μm × 39 μm. The measured propagators are compared with theoretical distributions and a good agreement is found. The results show that the propagator data provide much richer information about flow behaviour than conventional NMR velocity imaging and the information is essential for understanding the performance of a micromixer. It reveals, for example, deviations in the shape and size of the channel structures and multicomponent flow velocity distribution of overlapping channels. Propagator data efficiently compensate lost information caused by insufficient 3D resolution in conventional velocity imaging.

Characterization and elimination of undesirable protein residues in plant cell walls for enhancing lignin analysis by solution-state 2D gel-NMR methods

USDA-ARS?s Scientific Manuscript database

Proteins exist in every plant cell wall. Certain protein residues interfere with lignin characterization and quantification. The current solution-state 2D-NMR technique (gel-NMR) for whole plant cell wall structural profiling provides detailed information regarding cell walls and proteins. However, ...

qHNMR Analysis of Purity of Common Organic Solvents--An Undergraduate Quantitative Analysis Laboratory Experiment

ERIC Educational Resources Information Center

Bell, Peter T.; Whaley, W. Lance; Tochterman, Alyssa D.; Mueller, Karl S.; Schultz, Linda D.

2017-01-01

NMR spectroscopy is currently a premier technique for structural elucidation of organic molecules. Quantitative NMR (qNMR) methodology has developed more slowly but is now widely accepted, especially in the areas of natural product and medicinal chemistry. However, many undergraduate students are not routinely exposed to this important concept.…

Solid-Cryogen Cooling Technique for Superconducting Magnets of NMR and MRI

NASA Astrophysics Data System (ADS)

Iwasa, Yukikazu; Bascuñán, Juan; Hahn, Seungyong; Park, Dong Keun

This paper describes a solid-cryogen cooling technique currently being developed at the M.I.T. Francis Bitter Magnet Laboratory for application to superconducting magnets of NMR and MRI. The technique is particularly appropriate for "dry" magnets that do not rely on liquid cryogen, e.g., liquid helium (LHe), as their primary cooling sources. In addition, the advantages of a cryocirculator (a combination of a cryocooler and a working fluid circulator) over a cryocooler as the primary cooling source for dry magnets are described. The four magnets described here, all incorporating this cooling technique described and currently being developed at the FBML, are: 1) a solid-nitrogen (SN2)-cooled Nb3Sn 500-MHz/200-mm MRI magnet with an operating temperature range between 4.2 K (nominal) and 6.0 K (maximum with its primary cooling source off); 2) an SN2-cooled MgB2 0.5-T/800-mm MRI magnet, 1015 K; 3) an SN2-cooled compact YBCO "annulus" 100-MHz/9-mm NMR magnet, 10-15 K; 4) an SN2-cooled 1.5T/75-mm NbTi magnet for slow magic-angle-spinning NMR/MRI, 4.5-5.5 K.

Recent Advances in Characterization of Lignin Polymer by Solution-State Nuclear Magnetic Resonance (NMR) Methodology

PubMed Central

Wen, Jia-Long; Sun, Shao-Long; Xue, Bai-Liang; Sun, Run-Cang

2013-01-01

The demand for efficient utilization of biomass induces a detailed analysis of the fundamental chemical structures of biomass, especially the complex structures of lignin polymers, which have long been recognized for their negative impact on biorefinery. Traditionally, it has been attempted to reveal the complicated and heterogeneous structure of lignin by a series of chemical analyses, such as thioacidolysis (TA), nitrobenzene oxidation (NBO), and derivatization followed by reductive cleavage (DFRC). Recent advances in nuclear magnetic resonance (NMR) technology undoubtedly have made solution-state NMR become the most widely used technique in structural characterization of lignin due to its versatility in illustrating structural features and structural transformations of lignin polymers. As one of the most promising diagnostic tools, NMR provides unambiguous evidence for specific structures as well as quantitative structural information. The recent advances in two-dimensional solution-state NMR techniques for structural analysis of lignin in isolated and whole cell wall states (in situ), as well as their applications are reviewed. PMID:28809313

NMR Techniques in Metabolomic Studies: A Quick Overview on Examples of Utilization.

PubMed

Kruk, Joanna; Doskocz, Marek; Jodłowska, Elżbieta; Zacharzewska, Anna; Łakomiec, Joanna; Czaja, Kornelia; Kujawski, Jacek

2017-01-01

Metabolomics is a rapidly developing branch of science that concentrates on identifying biologically active molecules with potential biomarker properties. To define the best biomarkers for diseases, metabolomics uses both models (in vitro, animals) and human, as well as, various techniques such as mass spectroscopy, gas chromatography, liquid chromatography, infrared and UV-VIS spectroscopy and nuclear magnetic resonance. The last one takes advantage of the magnetic properties of certain nuclei, such as 1 H, 13 C, 31 P, 19 F, especially their ability to absorb and emit energy, what is crucial for analyzing samples. Among many spectroscopic NMR techniques not only one-dimensional (1D) techniques are known, but for many years two-dimensional (2D, for example, COSY, DOSY, JRES, HETCORE, HMQS), three-dimensional (3D, DART-MS, HRMAS, HSQC, HMBC) and solid-state NMR have been used. In this paper, authors taking apart fundamental division of nuclear magnetic resonance techniques intend to shown their wide application in metabolomic studies, especially in identifying biomarkers.

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

Novel nuclear magnetic resonance techniques for studying biological molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laws, David Douglas

2000-06-01

Over the fifty-five year history of Nuclear Magnetic Resonance (NMR), considerable progress has been made in the development of techniques for studying the structure, function, and dynamics of biological molecules. The majority of this research has involved the development of multi-dimensional NMR experiments for studying molecules in solution, although in recent years a number of groups have begun to explore NMR methods for studying biological systems in the solid-state. Despite this new effort, a need still exists for the development of techniques that improve sensitivity, maximize information, and take advantage of all the NMR interactions available in biological molecules. Inmore » this dissertation, a variety of novel NMR techniques for studying biomolecules are discussed. A method for determining backbone (Φ/Ψ) dihedral angles by comparing experimentally determined 13C a, chemical-shift anisotropies with theoretical calculations is presented, along with a brief description of the theory behind chemical-shift computation in proteins and peptides. The utility of the Spin-Polarization Induced Nuclear Overhauser Effect (SPINOE) to selectively enhance NMR signals in solution is examined in a variety of systems, as are methods for extracting structural information from cross-relaxation rates that can be measured in SPINOE experiments. Techniques for the production of supercritical and liquid laser-polarized xenon are discussed, as well as the prospects for using optically pumped xenon as a polarizing solvent. In addition, a detailed study of the structure of PrP 89-143 is presented. PrP 89-143 is a 54 residue fragment of the prion proteins which, upon mutation and aggregation, can induce prion diseases in transgenic mice. Whereas the structure of the wild-type PrP 89-143 is a generally unstructured mixture of α-helical and β-sheet conformers in the solid state, the aggregates formed from the PrP 89-143 mutants appear to be mostly β-sheet.« less

Producing >60,000-fold room-temperature 89Y NMR signal enhancement

NASA Astrophysics Data System (ADS)

Lumata, Lloyd; Jindal, Ashish; Merritt, Matthew; Malloy, Craig; Sherry, A. Dean; Kovacs, Zoltan

2011-03-01

89 Y in chelated form is potentially valuable in medical imaging because its chemical shift is sensitive to local factors in tumors such as pH. However, 89 Y has a low gyromagnetic ratio γn thus its NMR signal is hampered by low thermal polarization. Here we show that we can enhance the room-temperature NMR signal of 89 Y up to 65,000 times the thermal signal, which corresponds to 10 % nuclear polarization, via fast dissolution dynamic nuclear polarization (DNP). The relatively long spin-lattice relaxation time T1 (~ 500 s) of 89 Y translates to a long polarization lifetime. The 89 Y NMR enhancement is optimized by varying the glassing matrices and paramagnetic agents as well as doping the samples with a gadolinium relaxation agent. Co-polarization of 89 Y-DOTA with a 13 C sample shows that both nuclear spin species acquire the same spin temperature Ts , consistent with thermal mixing mechanism of DNP. The high room-temperature NMR signal enhancement places 89 Y, one of the most challenging nuclei to detect by NMR, in the list of viable magnetic resonance imaging (MRI) agents when hyperpolarized under optimized conditions. This work is supported in part by the National Institutes of Health grant numbers 1R21EB009147-01 and RR02584.

Peptide Conformation and Supramolecular Organization in Amylin Fibrils: Constraints from Solid State NMR

PubMed Central

Luca, Sorin; Yau, Wai-Ming; Leapman, Richard; Tycko, Robert

2008-01-01

The 37-residue amylin peptide, also known as islet amyloid polypeptide, forms fibrils that are the main peptide or protein component of amyloid that develops in the pancreas of type 2 diabetes patients. Amylin also readily forms amyloid fibrils in vitro that are highly polymorphic under typical experimental conditions. We describe a protocol for the preparation of synthetic amylin fibrils that exhibit a single predominant morphology, which we call a striated ribbon, in electron microscope and atomic force microscope images. Solid state nuclear magnetic resonance (NMR) measurements on a series of isotopically labeled samples indicate a single molecular structure within the striated ribbons. We use scanning transmission electron microscopy and several types of one-dimensional and two-dimensional solid state NMR techniques to obtain constraints on the peptide conformation and supramolecular structure in these amylin fibrils, and derive molecular structural models that are consistent with the experimental data. The basic structural unit in amylin striated ribbons, which we call the protofilament, contains four-layers of parallel β-sheets, formed by two symmetric layers of amylin molecules. The molecular structure of amylin protofilaments in striated ribbons closely resembles the protofilament in amyloid fibrils with similar morphology formed by the 40-residue β-amyloid peptide that is associated with Alzheimer's disease. PMID:17979302

Monitoring mechanistic details in the synthesis of pyrimidines via real-time, ultrafast multidimensional NMR spectroscopy

PubMed Central

Pardo, Zulay D.; Olsen, Greg; Fernández-Valle, María Encarnación; Frydman, Lucio; Martínez-Álvarez, Roberto; Herrera, Antonio

2016-01-01

Recent years have witnessed unprecedented advances in the development of fast multidimensional NMR acquisition techniques. This progress could open valuable new opportunities for the elucidation of chemical and biochemical processes. This study demonstrates one such capability, with the first real-time 2D dynamic analysis of a complex organic reaction relying on unlabeled substrates. Implementing such measurements required the development of new ultrafast 2D methods, capable of monitoring multiple spectral regions of interest as the reaction progressed. The alternate application of these acquisitions in an interleaved, excitation-optimized fashion, allowed us to extract new structural and dynamic insight concerning the reaction between aliphatic ketones and triflic anhydride in the presence of nitriles to yield alkylpyrimidines. Up to 2500 2D NMR data sets were thus collected over the course of this nearly 100 min long reaction, in an approach resembling that used in functional magnetic resonance imaging. With the aid of these new frequency-selective low-gradient-strength experiments, supplemented by chemical shift calculations of the spectral coordinates observed in the 2D heteronuclear correlations, previously postulated intermediates involved in the alkylpyrimidine formation process could be confirmed, and hitherto undetected ones were revealed. The potential and limitations of the resulting methods are discussed. PMID:22283498

Nanoscale β-nuclear magnetic resonance depth imaging of topological insulators

PubMed Central

Koumoulis, Dimitrios; Morris, Gerald D.; He, Liang; Kou, Xufeng; King, Danny; Wang, Dong; Hossain, Masrur D.; Wang, Kang L.; Fiete, Gregory A.; Kanatzidis, Mercouri G.; Bouchard, Louis-S.

2015-01-01

Considerable evidence suggests that variations in the properties of topological insulators (TIs) at the nanoscale and at interfaces can strongly affect the physics of topological materials. Therefore, a detailed understanding of surface states and interface coupling is crucial to the search for and applications of new topological phases of matter. Currently, no methods can provide depth profiling near surfaces or at interfaces of topologically inequivalent materials. Such a method could advance the study of interactions. Herein, we present a noninvasive depth-profiling technique based on β-detected NMR (β-NMR) spectroscopy of radioactive 8Li+ ions that can provide “one-dimensional imaging” in films of fixed thickness and generates nanoscale views of the electronic wavefunctions and magnetic order at topological surfaces and interfaces. By mapping the 8Li nuclear resonance near the surface and 10-nm deep into the bulk of pure and Cr-doped bismuth antimony telluride films, we provide signatures related to the TI properties and their topological nontrivial characteristics that affect the electron–nuclear hyperfine field, the metallic shift, and magnetic order. These nanoscale variations in β-NMR parameters reflect the unconventional properties of the topological materials under study, and understanding the role of heterogeneities is expected to lead to the discovery of novel phenomena involving quantum materials. PMID:26124141

Binding Isotherms and Time Courses Readily from Magnetic Resonance.

PubMed

Xu, Jia; Van Doren, Steven R

2016-08-16

Evidence is presented that binding isotherms, simple or biphasic, can be extracted directly from noninterpreted, complex 2D NMR spectra using principal component analysis (PCA) to reveal the largest trend(s) across the series. This approach renders peak picking unnecessary for tracking population changes. In 1:1 binding, the first principal component captures the binding isotherm from NMR-detected titrations in fast, slow, and even intermediate and mixed exchange regimes, as illustrated for phospholigand associations with proteins. Although the sigmoidal shifts and line broadening of intermediate exchange distorts binding isotherms constructed conventionally, applying PCA directly to these spectra along with Pareto scaling overcomes the distortion. Applying PCA to time-domain NMR data also yields binding isotherms from titrations in fast or slow exchange. The algorithm readily extracts from magnetic resonance imaging movie time courses such as breathing and heart rate in chest imaging. Similarly, two-step binding processes detected by NMR are easily captured by principal components 1 and 2. PCA obviates the customary focus on specific peaks or regions of images. Applying it directly to a series of complex data will easily delineate binding isotherms, equilibrium shifts, and time courses of reactions or fluctuations.

Recent advances in nuclear magnetic resonance quantum information processing.

PubMed

Criger, Ben; Passante, Gina; Park, Daniel; Laflamme, Raymond

2012-10-13

Quantum information processors have the potential to drastically change the way we communicate and process information. Nuclear magnetic resonance (NMR) has been one of the first experimental implementations of quantum information processing (QIP) and continues to be an excellent testbed to develop new QIP techniques. We review the recent progress made in NMR QIP, focusing on decoupling, pulse engineering and indirect nuclear control. These advances have enhanced the capabilities of NMR QIP, and have useful applications in both traditional NMR and other QIP architectures.

1H MAS NMR (magic-angle spinning nuclear magnetic resonance) techniques for the quantitative determination of hydrogen types in solid catalysts and supports.

PubMed

Kennedy, Gordon J; Afeworki, Mobae; Calabro, David C; Chase, Clarence E; Smiley, Randolph J

2004-06-01

Distinct hydrogen species are present in important inorganic solids such as zeolites, silicoaluminophosphates (SAPOs), mesoporous materials, amorphous silicas, and aluminas. These H species include hydrogens associated with acidic sites such as Al(OH)Si, non-framework aluminum sites, silanols, and surface functionalities. Direct and quantitative methodology to identify, measure, and monitor these hydrogen species are key to monitoring catalyst activity, optimizing synthesis conditions, tracking post-synthesis structural modifications, and in the preparation of novel catalytic materials. Many workers have developed several techniques to address these issues, including 1H MAS NMR (magic-angle spinning nuclear magnetic resonance). 1H MAS NMR offers many potential advantages over other techniques, but care is needed in recognizing experimental limitations and developing sample handling and NMR methodology to obtain quantitatively reliable data. A simplified approach is described that permits vacuum dehydration of multiple samples simultaneously and directly in the MAS rotor without the need for epoxy, flame sealing, or extensive glovebox use. We have found that careful optimization of important NMR conditions, such as magnetic field homogeneity and magic angle setting are necessary to acquire quantitative, high-resolution spectra that accurately measure the concentrations of the different hydrogen species present. Details of this 1H MAS NMR methodology with representative applications to zeolites, SAPOs, M41S, and silicas as a function of synthesis conditions and post-synthesis treatments (i.e., steaming, thermal dehydroxylation, and functionalization) are presented.

Multidimensional NMR approaches towards highly resolved, sensitive and high-throughput quantitative metabolomics.

PubMed

Marchand, Jérémy; Martineau, Estelle; Guitton, Yann; Dervilly-Pinel, Gaud; Giraudeau, Patrick

2017-02-01

Multi-dimensional NMR is an appealing approach for dealing with the challenging complexity of biological samples in metabolomics. This article describes how spectroscopists have recently challenged their imagination in order to make 2D NMR a powerful tool for quantitative metabolomics, based on innovative pulse sequences combined with meticulous analytical chemistry approaches. Clever time-saving strategies have also been explored to make 2D NMR a high-throughput tool for metabolomics, relying on alternative data acquisition schemes such as ultrafast NMR. Currently, much work is aimed at drastically boosting the NMR sensitivity thanks to hyperpolarisation techniques, which have been used in combination with fast acquisition methods and could greatly expand the application potential of NMR metabolomics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of IRMS and NMR spectrometry for the determination of intramolecular 13C isotope composition: application to ethanol.

PubMed

Gilbert, Alexis; Hattori, Ryota; Silvestre, Virginie; Wasano, Nariaki; Akoka, Serge; Hirano, Satoshi; Yamada, Keita; Yoshida, Naohiro; Remaud, Gérald S

2012-09-15

Isotopic (13)C NMR is a relatively recent technique which allows the determination of intramolecular (13)C isotope composition at natural abundance. It has been used in various scientific fields such as authentication, counterfeiting or plant metabolism. Although its precision has already been evaluated, the determination of its trueness remains still challenging. To deal with that issue, a comparison with another normalized technique must be achieved. In this work, we compare the intramolecular (13)C isotope distribution of ethanol from different origins obtained using both Isotope Ratio Mass Spectrometry (IRMS) and Nuclear Magnetic Resonance (NMR) spectrometry techniques. The IRMS approach consists of the oxidation of ethanol to acetic acid followed by the degradation of the latter for the analysis of each fragments formed. We show here that the oxidation of ethanol to acetic acid does not bring any significant error on the determination of the site-specific δ(13)C (δ(13)C(i)) of ethanol using the IRMS approach. The difference between the data obtained for 16 samples from different origins using IRMS and NMR approaches is not statistically significant and remains below 0.3‰. These results are encouraging for the future studies using isotopic NMR, especially in combination with the IRMS approach. Copyright © 2012. Published by Elsevier B.V.

Improved nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging

DOEpatents

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

1984-01-01

An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

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

DOEpatents

Fukushima, Eiichi; Roeder, Stephen B. W.; Assink, Roger A.; Gibson, Atholl A. V.

1986-01-01

An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio-frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

Measuring surface-area-to-volume ratios in soft porous materials using laser-polarized xenon interphase exchange nuclear magnetic resonance

NASA Technical Reports Server (NTRS)

Butler, J. P.; Mair, R. W.; Hoffmann, D.; Hrovat, M. I.; Rogers, R. A.; Topulos, G. P.; Walsworth, R. L.; Patz, S.

2002-01-01

We demonstrate a minimally invasive nuclear magnetic resonance (NMR) technique that enables determination of the surface-area-to-volume ratio (S/V) of soft porous materials from measurements of the diffusive exchange of laser-polarized 129Xe between gas in the pore space and 129Xe dissolved in the solid phase. We apply this NMR technique to porous polymer samples and find approximate agreement with destructive stereological measurements of S/V obtained with optical confocal microscopy. Potential applications of laser-polarized xenon interphase exchange NMR include measurements of in vivo lung function in humans and characterization of gas chromatography columns.

Structural comparison of Gilsonite and Trinidad Lake Asphalt using 13C-NMR technique

NASA Astrophysics Data System (ADS)

Nciri, Nader; Cho, Namjun

2017-04-01

The recent increased importance of natural asphalt as an alternative binder for sustainable road pavement has dictated that more knowledge should be acquired about its structure and properties. Earlier, Carbon-13 NMR spectroscopy has been applied to very few natural bituminous materials. In this work, two types of raw binders namely Gilsonite and Trinidad Lake asphalt (TLA) have been subjected to an extensive investigation by using 13C-NMR technique. Results have shown that valuable chemical data can be readily withdrawn on aromatic ring structures and ring substituents in natural asphalts derived from different sources. The chemical significance of these findings will be discussed.

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

Carbon-13 and proton nuclear magnetic resonance analysis of shale-derived refinery products and jet fuels and of experimental referee broadened-specification jet fuels

NASA Technical Reports Server (NTRS)

Dalling, D. K.; Bailey, B. K.; Pugmire, R. J.

1984-01-01

A proton and carbon-13 nuclear magnetic resonance (NMR) study was conducted of Ashland shale oil refinery products, experimental referee broadened-specification jet fuels, and of related isoprenoid model compounds. Supercritical fluid chromatography techniques using carbon dioxide were developed on a preparative scale, so that samples could be quantitatively separated into saturates and aromatic fractions for study by NMR. An optimized average parameter treatment was developed, and the NMR results were analyzed in terms of the resulting average parameters; formulation of model mixtures was demonstrated. Application of novel spectroscopic techniques to fuel samples was investigated.

Physics of MRI: a primer.

PubMed

Plewes, Donald B; Kucharczyk, Walter

2012-05-01

This article is based on an introductory lecture given for the past many years during the "MR Physics and Techniques for Clinicians" course at the Annual Meeting of the ISMRM. This introduction is not intended to be a comprehensive overview of the field, as the subject of magnetic resonance imaging (MRI) physics is large and complex. Rather, it is intended to lay a conceptual foundation by which magnetic resonance image formation can be understood from an intuitive perspective. The presentation is nonmathematical, relying on simple models that take the reader progressively from the basic spin physics of nuclei, through descriptions of how the magnetic resonance signal is generated and detected in an MRI scanner, the foundations of nuclear magnetic resonance (NMR) relaxation, and a discussion of the Fourier transform and its relation to MR image formation. The article continues with a discussion of how magnetic field gradients are used to facilitate spatial encoding and concludes with a development of basic pulse sequences and the factors defining image contrast. Copyright © 2012 Wiley Periodicals, Inc.

Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance

NASA Technical Reports Server (NTRS)

Walsworth, Ronald L.

2003-01-01

We pursued advanced technology development of laser-polarized noble gas nuclear magnetic resonance (NMR) as a novel biomedical imaging tool for ground-based and eventually space-based application. This new multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation-as well as studies of tissue perfusion. In addition, laser-polarized noble gases (3He and 129Xe) do not require a large magnetic field for sensitive detection, opening the door to practical MRI at very low magnetic fields with an open, lightweight, and low-power device. We pursued two technology development specific aims: (1) development of low-field (less than 0.01 T) noble gas MRI of humans; and (2) development of functional MRI of the lung using laser-polarized noble gas and related techniques.

Polarization transfer NMR imaging

DOEpatents

Sillerud, Laurel O.; van Hulsteyn, David B.

1990-01-01

A nuclear magnetic resonance (NMR) image is obtained with spatial information modulated by chemical information. The modulation is obtained through polarization transfer from a first element representing the desired chemical, or functional, information, which is covalently bonded and spin-spin coupled with a second element effective to provide the imaging data. First and second rf pulses are provided at first and second frequencies for exciting the imaging and functional elements, with imaging gradients applied therebetween to spatially separate the nuclei response for imaging. The second rf pulse is applied at a time after the first pulse which is the inverse of the spin coupling constant to select the transfer element nuclei which are spin coupled to the functional element nuclei for imaging. In a particular application, compounds such as glucose, lactate, or lactose, can be labeled with .sup.13 C and metabolic processes involving the compounds can be imaged with the sensitivity of .sup.1 H and the selectivity of .sup.13 C.

Polymeric material prepared from Schiff base based on O-carboxymethyl chitosan and its Cu(II) and Pd(II) complexes

NASA Astrophysics Data System (ADS)

Baran, Talat; Menteş, Ayfer

2016-07-01

In this study, a new eco-friendly Schiff base based on O-carboxymethyl chitosan ([OCMCS-7a]) and its copper(II) and palladium(II) complexes were synthesized. Characterizations of [OCMCS-7a] and its metal complexes were conducted using FTIR, 1H NMR, 13C NMR, TG/DTG, XRD, SEM-EDAX, ICP, UV-VIS, GC-MS, elemental analysis, magnetic moment and molar conductivity measurements. The degree of substitution (DS) of [OCMCS-7a] was determined by elemental analysis to be 0.44. It was shown by the solubility test that [OCMCS-7a] was completely soluble in water. Surface images of chitosan, [OCMCS-7a] and its Cu(II) and Pd(II) complexes were investigated using the SEM-EDAX technique. Their thermal behaviors and crystallinities of the synthesized complexes were determined by TG/DTG and X-ray powder diffraction techniques, respectively. The metal contents of the obtained complexes were determined using an ICP-OES instrument. From the analyses, it was noted that the thermal stabilities and crystallinities of [OCMCS-7a] and its complexes decreased compared to chitosan. As a consequence of surface screening, it was also noted that the surface structure of the chitosan was smoother than that of the obtained compounds.

Parahydrogen-induced polarization of carboxylic acids: a pilot study of valproic acid and related structures.

PubMed

Lego, Denise; Plaumann, Markus; Trantzschel, Thomas; Bargon, Joachim; Scheich, Henning; Buntkowsky, Gerd; Gutmann, Torsten; Sauer, Grit; Bernarding, Johannes; Bommerich, Ute

2014-07-01

Parahydrogen-induced polarization (PHIP) is a promising new tool for medical applications of MR, including MRI. The PHIP technique can be used to transfer high non-Boltzmann polarization, derived from parahydrogen, to isotopes with a low natural abundance or low gyromagnetic ratio (e.g. (13)C), thus improving the signal-to-noise ratio by several orders of magnitude. A few molecules acting as metabolic sensors have already been hyperpolarized with PHIP, but the direct hyperpolarization of drugs used to treat neurological disorders has not been accomplished until now. Here, we report on the first successful hyperpolarization of valproate (valproic acid, VPA), an important and commonly used antiepileptic drug. Hyperpolarization was confirmed by detecting the corresponding signal patterns in the (1)H NMR spectrum. To identify the optimal experimental conditions for the conversion of an appropriate VPA precursor, structurally related molecules with different side chains were analyzed in different solvents using various catalytic systems. The presented results include hyperpolarized (13)C NMR spectra and proton images of related systems, confirming their applicability for MR studies. PHIP-based polarization enhancement may provide a new MR technique to monitor the spatial distribution of valproate in brain tissue and to analyze metabolic pathways after valproate administration. Copyright © 2014 John Wiley & Sons, Ltd.

Nuclear quadrupole resonance detection of explosives: an overview

NASA Astrophysics Data System (ADS)

Miller, Joel B.

2011-06-01

Nuclear Quadrupole Resonance (NQR) is a spectroscopic technique closely related to Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI). These techniques, and NQR in particular, induce signals from the material being interrogated that are very specific to the chemical and physical structure of the material, but are relatively insensitive to the physical form of the material. NQR explosives detection exploits this specificity to detect explosive materials, in contrast to other well known techniques that are designed to detect explosive devices. The past two decades have seen a large research and development effort in NQR explosives detection in the United States aimed at transportation security and military applications. Here, I will briefly describe the physical basis for NQR before discussing NQR developments over the past decade, with particular emphasis on landmine detection and the use of NQR in combating IED's. Potential future directions for NQR research and development are discussed.

Augmentation of oxygen transport by various hemoglobins as determined by pulsed field gradient NMR.

PubMed

Budhiraja, Vikas; Hellums, J David; Post, Jan F M

2002-11-01

Diffusion of oxyhemoglobin has been shown to augment the oxygen transport inside the red blood cells. Measurement of hemoglobin diffusion coefficients by pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) technique can be used for estimating this augmentation effect. Self-diffusion coefficients of polymerized and unpolymerized bovine hemoglobin (Hb) and several other proteins were measured using this technique. The Hb diffusion coefficient was used to determine the effective permeability of oxygen and augmentation of oxygen transport through samples of Hb solutions due to diffusion of oxyhemoglobin. The values compared well with our previous diffusion cell measurements of effective diffusivity and augmentation. Our NMR studies show that even at low concentrations the augmentation of oxygen transport due to diffusion can be significant. The PFG NMR technique can thus provide an accurate and easy method for measuring augmentation of oxygen transport, especially in dilute samples of Hb. The results on polyhemoglobin and high-molecular-weight hemoglobin are of both basic interest and practical value in assessing the promise and performance of hemoglobin-based blood substitutes.

Heart MRI

MedlinePlus

Magnetic resonance imaging - cardiac; Magnetic resonance imaging - heart; Nuclear magnetic resonance - cardiac; NMR - cardiac; MRI of the heart; Cardiomyopathy - MRI; Heart failure - MRI; Congenital heart disease - MRI

NMR characterization of weak interactions between RhoGDI2 and fragment screening hits.

PubMed

Liu, Jiuyang; Gao, Jia; Li, Fudong; Ma, Rongsheng; Wei, Qingtao; Wang, Aidong; Wu, Jihui; Ruan, Ke

2017-01-01

The delineation of intrinsically weak interactions between novel targets and fragment screening hits has long limited the pace of hit-to-lead evolution. Rho guanine-nucleotide dissociation inhibitor 2 (RhoGDI2) is a novel target that lacks any chemical probes for the treatment of tumor metastasis. Protein-observed and ligand-observed NMR spectroscopy was used to characterize the weak interactions between RhoGDI2 and fragment screening hits. We identified three hits of RhoGDI2 using streamlined NMR fragment-based screening. The binding site residues were assigned using non-uniformly sampled C α - and H α -based three dimensional NMR spectra. The molecular docking to the proposed geranylgeranyl binding pocket of RhoGDI2 was guided by NMR restraints of chemical shift perturbations and ligand-observed transferred paramagnetic relaxation enhancement. We further validated the weak RhoGDI2-hit interactions using mutagenesis and structure-affinity analysis. Weak interactions between RhoGDI2 and fragment screening hits were delineated using an integrated NMR approach. Binders to RhoGDI2 as a potential anti-cancer target have been first reported, and their weak interactions were depicted using NMR spectroscopy. Our work highlights the powerfulness and the versatility of the integrative NMR techniques to provide valuable structural insight into the intrinsically weak interactions between RhoGDI2 and the fragment screening hits, which could hardly be conceived using other biochemical techniques. Copyright © 2016 Elsevier B.V. All rights reserved.

AEM and NMR: Tools for the Future of Groundwater Management

NASA Astrophysics Data System (ADS)

Abraham, J. D.; Cannia, J. C.; Lawrie, K.

2012-12-01

Within the world, understanding groundwater resources and their management are growing in importance to society as groundwater resources are stressed by drought and continued development. To minimize conflicts, tools and techniques need to be applied to support knowledge-based decisions and management. Airborne electromagnetic (AEM) surveys provide high-quality subsurface data not available from any other source for building the complex hydrogeologic frameworks needed by water-resource managers for effective groundwater management. Traditionally, point data, such as borehole logs, borehole geophysics, surface geophysics, and aquifer tests were interpolated over long distances to create hydrogeologic frameworks. These methods have enjoyed a long history of being the best available technology to inform our understanding of groundwater and how it moves. The AEM techniques proivde pathway for geoscientists to follow to develop more accurate descriptions of the hydrogeological framework. However, the critical and challenging measurements in characterizing aquifers include effective porosity and hydraulic conductivity. These parameters are not reliable derived from AEM. Typically, values for effective porosity and hydraulic conductivity are derived by lithological comparisons with published data; direct measurements of hydraulic conductivity acquired by a few constant head aquifer tests or slug tests; and expensive and time consuming laboratory measurements of cores which can be biased by sampling and the difficulty of making measurements on unconsolidated materials. Aquifer tests are considered to be the best method to gather information on hydraulic conductivity but are rare because of cost and difficult logistics. Also they are unique in design and interpretation from site to site. Nuclear Magnetic Resonance (NMR) can provide a direct measurement of the presence of water in the pore space of aquifer materials. Detection and direct measurement is possible due to the nuclear magnetization of the hydrogen (protons) in the water. These measurements are the basis of the familiar MRI (magnetic resonance imaging) in medical applications. NMR is also widely used in logging applications within the petroleum industry. Effective porosity values were derived directly from the borehole and surface NMR data, and hydraulic conductivity values were calculated using empirical relationships calibrated and verified with few laboratory permeameter and aquifer tests. NMR provides measurements of the effective porosity and hydraulic conductivity at a resolution not possible using traditional methods. Unlike aquifer tests, NMR logs are not unique in design and are applied in similar fashion from borehole to borehole providing a standard way of measuring hydraulic properties. When the hydraulic properties from the NMR are integrated with hydrogeological framework interpretations of AEM data large areas can be characterized. This allows a much more robust method for conceptualizing groundwater models then simply using previously published data for assigning effective porosity and hydraulic conductivity. Examples from the North Platte River Basin in Nebraska and the Murray Darling Basin of Australia illustrate that borehole and surface NMR allows superior, rapid measurements of the complexities of aquifers within when integrated with AEM.

Proton magnetic resonance imaging with para-hydrogen induced polarization.

PubMed

Dechent, Jan F; Buljubasich, Lisandro; Schreiber, Laura M; Spiess, Hans W; Münnemann, Kerstin

2012-02-21

A major challenge in imaging is the detection of small amounts of molecules of interest. In the case of magnetic resonance imaging (MRI) their signals are typically concealed by the large background signal of e.g. the body. This problem can be tackled by hyperpolarization which increases the NMR signals up to several orders of magnitude. However, this strategy is limited for (1)H, the most widely used nucleus in NMR and MRI, because the enormous number of protons in the body screens the small amount of hyperpolarized ones. Here, we describe a method giving rise to high (1)H MRI contrast for hyperpolarized molecules against a large background signal. The contrast is based on the J-coupling induced rephasing of the NMR signal of molecules hyperpolarized via PHIP and it can easily be implemented in common pulse sequences. We discuss several scenarios with different or equal dephasing times T(2)* for the hyperpolarized and thermally polarized compounds and verify our approach by experiments. This method may open up unprecedented opportunities to use the standard MRI nucleus (1)H for e.g. metabolic imaging in the future.

Neuronal Tracing with Magnetic Labels: NMR Imaging Methods, Preliminary Results, and New Optimized Coils.

NASA Astrophysics Data System (ADS)

Ghosh, Pratik

1992-01-01

The investigations focussed on in vivo NMR imaging studies of magnetic particles with and within neural cells. NMR imaging methods, both Fourier transform and projection reconstruction, were implemented and new protocols were developed to perform "Neuronal Tracing with Magnetic Labels" on small animal brains. Having performed the preliminary experiments with neuronal tracing, new optimized coils and experimental set-up were devised. A novel gradient coil technology along with new rf-coils were implemented, and optimized for future use with small animals in them. A new magnetic labelling procedure was developed that allowed labelling of billions of cells with ultra -small magnetite particles in a short time. The relationships among the viability of such cells, the amount of label and the contrast in the images were studied as quantitatively as possible. Intracerebral grafting of magnetite labelled fetal rat brain cells made it possible for the first time to attempt monitoring in vivo the survival, differentiation, and possible migration of both host and grafted cells in the host rat brain. This constituted the early steps toward future experiments that may lead to the monitoring of human brain grafts of fetal brain cells. Preliminary experiments with direct injection of horse radish peroxidase-conjugated magnetite particles into neurons, followed by NMR imaging, revealed a possible non-invasive alternative, allowing serial study of the dynamic transport pattern of tracers in single living animals. New gradient coils were built by using parallel solid-conductor ribbon cables that could be wrapped easily and quickly. Rapid rise times provided by these coils allowed implementation of fast imaging methods. Optimized rf-coil circuit development made it possible to understand better the sample-coil properties and the associated trade -offs in cases of small but conducting samples.

Application of ChemDraw NMR Tool: Correlation of Program-Generated 13C Chemical Shifts and pKa Values of para-Substituted Benzoic Acids

NASA Astrophysics Data System (ADS)

Wang, Hongyi

2005-09-01

An application of ChemDraw NMR Tool was demonstrated by correlation of program-generated 13 C NMR chemical shifts and p K a values of para-substituted benzoic acids. Experimental 13 C NMR chemical shifts were analyzed in the same way for comparison. The project can be used as an assignment at the end of the first-year organic chemistry course to review topics or explore new techniques: Hammett equation, acid base equilibrium theory, electronic nature of functional groups, inductive and resonance effects, structure reactivity relationship, NMR spectroscopy, literature search, database search, and ChemDraw software.

ODIN-object-oriented development interface for NMR.

PubMed

Jochimsen, Thies H; von Mengershausen, Michael

2004-09-01

A cross-platform development environment for nuclear magnetic resonance (NMR) experiments is presented. It allows rapid prototyping of new pulse sequences and provides a common programming interface for different system types. With this object-oriented interface implemented in C++, the programmer is capable of writing applications to control an experiment that can be executed on different measurement devices, even from different manufacturers, without the need to modify the source code. Due to the clear design of the software, new pulse sequences can be created, tested, and executed within a short time. To post-process the acquired data, an interface to well-known numerical libraries is part of the framework. This allows a transparent integration of the data processing instructions into the measurement module. The software focuses mainly on NMR imaging, but can also be used with limitations for spectroscopic experiments. To demonstrate the capabilities of the framework, results of the same experiment, carried out on two NMR imaging systems from different manufacturers are shown and compared with the results of a simulation.

Biological effects and physical safety aspects of NMR imaging and in vivo spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tenforde, T.S.; Budinger, T.F.

1985-08-01

An assessment is made of the biological effects and physical hazards of static and time-varying fields associated with the NMR devices that are being used for clinical imaging and in vivo spectroscopy. A summary is given of the current state of knowledge concerning the mechanisms of interaction and the bioeffects of these fields. Additional topics that are discussed include: (1) physical effects on pacemakers and metallic implants such as aneurysm clips, (2) human health studies related to the effects of exposure to nonionizing electromagnetic radiation, and (3) extant guidelines for limiting exposure of patients and medical personnel to the fieldsmore » produced by NMR devices. On the basis of information available at the present time, it is concluded that the fields associated with the current generation of NMR devices do not pose a significant health risk in themselves. However, rigorous guidelines must be followed to avoid the physical interaction of these fields with metallic implants and medical electronic devices. 476 refs., 5 figs., 2 tabs.« less

Significance of histopathology in pulsed NMR studies on cancer.

PubMed

Ranade, S S; Bharade, S H; Talwalkar, G V; Sujata, G K; Shrinivasan, V T; Singh, B B

1985-04-01

Characterization of tissue by pulsed nuclear magnetic resonance spectrometry opened a new area of research. The differences in the NMR parameters T1 and T2 of normal and malignant tissues constitute the basis for their distinction by pulsed NMR spectrometry and also by NMR imaging in vivo. The present studies were undertaken to correlate the role of constituent histological elements encountered in various malignancy-associated changes and T1 variations and are based on evaluation of samples taken from surgically resected specimens of carcinoma of the esophagus, comprising the uninvolved portions of the esophagus and the gastric end on gross examination. The uninvolved and involved regions showed low and high T1 values, respectively. High T1 values were also encountered in the zones of samples of uninvolved esophagus which histologically revealed areas with dysplasia. This feature, viz., dysplasia representing malignancy-associated changes, has been found to recur in many samples. Detailed histological studies provided further evidence confirming that areas with dysplasia contribute to an increase in T1 values whereas in zones at the gastric end metaplasia and hyperplasia are more common. The results are of value for demarcation of tumor area by in vivo NMR imaging.

Point of care assessment of melanoma tumor signaling and metastatic burden from μNMR analysis of tumor fine needle aspirates and peripheral blood.

PubMed

Gee, Michael S; Ghazani, Arezou A; Haq, Rizwan; Wargo, Jennifer A; Sebas, Matthew; Sullivan, Ryan J; Lee, Hakho; Weissleder, Ralph

2017-04-01

This study evaluates μNMR technology for molecular profiling of tumor fine needle aspirates and peripheral blood of melanoma patients. In vitro assessment of melanocyte (MART-1, HMB45) and MAP kinase signaling (pERK, pS6K) molecule expression was performed in human cell lines, while clinical validation was performed in an IRB-approved study of melanoma patients undergoing biopsy and blood sampling. Tumor FNA and blood specimens were compared with BRAF genetic analysis and cross-sectional imaging. μNMR in vitro analysis showed increased expression of melanocyte markers in melanoma cells as well as increased expression of phosphorylated MAP kinase targets in BRAF-mutant melanoma cells. Melanoma patient FNA samples showed increased pERK and pS6K levels in BRAF mutant compared with BRAF WT melanomas, with μNMR blood circulating tumor cell level increased with higher metastatic burden visible on imaging. These results indicate that μNMR technology provides minimally invasive point-of-care evaluation of tumor signaling and metastatic burden in melanoma patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Comparison of phytate and other organic P forms in Mehlich-3 and Alkaline-EDTA matrices by ICP, NMR and mass spectrometry

USDA-ARS?s Scientific Manuscript database

The favored method of organic P identification over the last few decades has been 31P NMR. While this technique has the distinct advantage of speciating the organic P fraction, it has a relatively poor detection threshold (0.05 mg/ml), which typically limits 31P NMR to qualitative or confirmative ap...

Toward nanomolar detection by NMR through SABRE hyperpolarization.

PubMed

Eshuis, Nan; Hermkens, Niels; van Weerdenburg, Bram J A; Feiters, Martin C; Rutjes, Floris P J T; Wijmenga, Sybren S; Tessari, Marco

2014-02-19

SABRE is a nuclear spin hyperpolarization technique based on the reversible association of a substrate molecule and para-hydrogen (p-H2) to a metal complex. During the lifetime of such a complex, generally fractions of a second, the spin order of p-H2 is transferred to the nuclear spins of the substrate molecule via a transient scalar coupling network, resulting in strongly enhanced NMR signals. This technique is generally applied at relatively high concentrations (mM), in large excess of substrate with respect to metal complex. Dilution of substrate ligands below stoichiometry results in progressive decrease of signal enhancement, which precludes the direct application of SABRE to the NMR analysis of low concentration (μM) solutions. Here, we show that the efficiency of SABRE at low substrate concentrations can be restored by addition of a suitable coordinating ligand to the solution. The proposed method allowed NMR detection below 1 μM in a single scan.

A structural study of epoxidized natural rubber (ENR-50) and its cyclic dithiocarbonate derivative using NMR spectroscopy techniques.

PubMed

Hamzah, Rosniza; Bakar, Mohamad Abu; Khairuddean, Melati; Mohammed, Issam Ahmed; Adnan, Rohana

2012-09-12

A structural study of epoxidized natural rubber (ENR-50) and its cyclic dithiocarbonate derivative was carried out using NMR spectroscopy techniques. The overlapping (1)H-NMR signals of ENR-50 at δ 1.56, 1.68-1.70, 2.06, 2.15-2.17 ppm were successfully assigned. In this work, the <(13)C-NMR chemical shift assignments of ENR-50 were consistent to the previously reported work. A cyclic dithiocarbonate derivative of ENR-50 was synthesized from the reaction of purified ENR-50 with carbon disulfide (CS(2)), in the presence of 4-dimethylaminopyridine (DMAP) as catalyst at reflux temperature. The cyclic dithiocarbonate formation involved the epoxide ring opening of the ENR-50. This was followed by insertion of the C-S moiety of CS(2) at the oxygen attached to the quaternary carbon and methine carbon of epoxidized isoprene unit, respectively. The bands due to the C=S and C-O were clearly observed in the FTIR spectrum while the (1)H-NMR spectrum of the derivative revealed the peak attributed to the methylene protons had split. The (13)C-NMR spectrum of the derivative further indicates two new carbon peaks arising from the >C=S and quaternary carbon of cyclic dithiocarbonate. All other (1)H- and (13)C-NMR chemical shifts of the derivative remain unchanged with respect to the ENR-50.

Real-time image reconstruction and display system for MRI using a high-speed personal computer.

PubMed

Haishi, T; Kose, K

1998-09-01

A real-time NMR image reconstruction and display system was developed using a high-speed personal computer and optimized for the 32-bit multitasking Microsoft Windows 95 operating system. The system was operated at various CPU clock frequencies by changing the motherboard clock frequency and the processor/bus frequency ratio. When the Pentium CPU was used at the 200 MHz clock frequency, the reconstruction time for one 128 x 128 pixel image was 48 ms and that for the image display on the enlarged 256 x 256 pixel window was about 8 ms. NMR imaging experiments were performed with three fast imaging sequences (FLASH, multishot EPI, and one-shot EPI) to demonstrate the ability of the real-time system. It was concluded that in most cases, high-speed PC would be the best choice for the image reconstruction and display system for real-time MRI. Copyright 1998 Academic Press.

Membrane lateral compressibility determined by NMR and x-ray diffraction: effect of acyl chain polyunsaturation.

PubMed Central

Koenig, B W; Strey, H H; Gawrisch, K

1997-01-01

The elastic area compressibility modulus, Ka, of lamellar liquid crystalline bilayers was determined by a new experimental approach using 2H-NMR order parameters of lipid hydrocarbon chains together with lamellar repeat spacings measured by x-ray diffraction. The combination of NMR and x-ray techniques yields accurate determination of lateral area per lipid molecule. Samples of saturated, monounsaturated, and polyunsaturated phospholipids were equilibrated with polyethylene glycol (PEG) 20,000 solutions in water at concentrations from 0 to 55 wt % PEG at 30 degrees C. This procedure is equivalent to applying 0 to 8 dyn/cm lateral pressure to the bilayers. The resulting reductions in area per lipid were measured with a resolution of +/-0.2 A2 and the fractional area decrease was proportional to applied lateral pressure. For 1,2-dimyristoyl(d54)-sn-glycero-3-phosphocholine, 1-stearoyl(d35)-2-oleoyl-sn-glycero-3-phosphocholine (SOPC-d35), and 1-stearoyl(d35)-2-docosahexaenoyl-sn-glycero-3-phosphocholine (SDPC-d35) cross-sectional areas per molecule in excess water of 59.5, 61.4, and 69.2 A2 and bilayer elastic area compressibility moduli of 141, 221, and 121 dyn/cm were determined, respectively. Combining NMR and x-ray results enables the determination of compressibility differences between saturated and unsaturated hydrocarbon chains. In mixed-chain SOPC-d35 both chains have similar compressibility moduli; however, in mixed-chain polyunsaturated SDPC-d35, the saturated stearic acid chain appears to be far less compressible than the polyunsaturated docosahexaenoic acid chain. Images FIGURE 3 FIGURE 5 PMID:9336191

250 GHz CW Gyrotron Oscillator for Dynamic Nuclear Polarization in Biological Solid State NMR

PubMed Central

Bajaj, Vikram S.; Hornstein, Melissa K.; Kreischer, Kenneth E.; Sirigiri, Jagadishwar R.; Woskov, Paul P.; Mak-Jurkauskas, Melody L.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

2009-01-01

In this paper, we describe a 250 GHz gyrotron oscillator, a critical component of an integrated system for magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments at 9T, corresponding to 380 MHz 1H frequency. The 250 GHz gyrotron is the first gyro-device designed with the goal of seamless integration with an NMR spectrometer for routine DNP-enhanced NMR spectroscopy and has operated under computer control for periods of up to 21 days with a 100% duty cycle. Following a brief historical review of the field, we present studies of the membrane protein bacteriorhodopsin (bR) using DNP-enhanced multidimensional NMR. These results include assignment of active site resonances in [U-13C,15N]-bR and demonstrate the utility of DNP for studies of membrane proteins. Next, we review the theory of gyro-devices from quantum mechanical and classical viewpoints and discuss the unique considerations that apply to gyrotron oscillators designed for DNP experiments. We then characterize the operation of the 250 GHz gyrotron in detail, including its long-term stability and controllability. We have measured the spectral purity of the gyrotron emission using both homodyne and heterodyne techniques. Radiation intensity patterns from the corrugated waveguide that delivers power to the NMR probe were measured using two new techniques to confirm pure mode content: a thermometric approach based on the temperature-dependent color of liquid crystalline media applied to a substrate and imaging with a pyroelectric camera. We next present a detailed study of the mode excitation characteristics of the gyrotron. Exploration of the operating characteristics of several fundamental modes reveals broadband continuous frequency tuning of up to 1.8 GHz as a function of the magnetic field alone, a feature that may be exploited in future tunable gyrotron designs. Oscillation of the 250 GHz gyrotron at the second harmonic of cyclotron resonance begins at extremely low beam currents (as low 12 mA) at frequencies between 320–365 GHz, suggesting an efficient route for the generation of even higher frequency radiation. The low starting currents were attributed to an elevated cavity Q, which is confirmed by cavity thermal load measurements. We conclude with an appendix containing a detailed description of the control system that safely automates all aspects of the gyrotron operation. PMID:17942352

Probing porous media with gas diffusion NMR

NASA Technical Reports Server (NTRS)

Mair, R. W.; Wong, G. P.; Hoffmann, D.; Hurlimann, M. D.; Patz, S.; Schwartz, L. M.; Walsworth, R. L.

1999-01-01

We show that gas diffusion nuclear magnetic resonance (GD-NMR) provides a powerful technique for probing the structure of porous media. In random packs of glass beads, using both laser-polarized and thermally polarized xenon gas, we find that GD-NMR can accurately measure the pore space surface-area-to-volume ratio, S/V rho, and the tortuosity, alpha (the latter quantity being directly related to the system's transport properties). We also show that GD-NMR provides a good measure of the tortuosity of sandstone and complex carbonate rocks.

Quantitative structure parameters from the NMR spectroscopy of quadrupolar nuclei

DOE PAGES

Perras, Frederic A.

2015-12-15

Here, nuclear magnetic resonance (NMR) spectroscopy is one of the most important characterization tools in chemistry, however, 3/4 of the NMR active nuclei are underutilized due to their quadrupolar nature. This short review centers on the development of methods that use solid-state NMR of quadrupolar nuclei for obtaining quantitative structural information. Namely, techniques using dipolar recoupling as well as the resolution afforded by double-rotation are presented for the measurement of spin–spin coupling between quadrupoles, enabling the measurement of internuclear distances and connectivities.

Using NMR to Determine Protein Structure in Solution

NASA Astrophysics Data System (ADS)

Cavagnero, Silvia

2003-02-01

Nuclear magnetic resonance (NMR) is a marvelous spectroscopic technique that chemists, physicists, and biochemists routinely employ for their research around the world. This year half of the Nobel Prize for chemistry went to Kurt Wüthrich, who was recognized for the development of NMR-based techniques that lead to the structure determination of biomolecules in solution. In addition to implementing novel pulse sequences and software packages, Wüthrich also applied his methods to several biological systems of key importance to human health. These include the prion protein, which is heavily involved in the spongiform encephalopathy (best known as 'mad cow disease'), which recently caused numerous human deaths, particularly in the UK, due to ingestion of contaminated meat. Transverse relaxation optimized spectroscopy (TROSY) is the most intriguing new NMR method recently developed by Wüthrich and coworkers. This and other closely related pulse sequences promise to play a pivotal role in the extension of NMR to the conformational analysis of very large (up to the megadalton range) macromolecules and macromolecular complexes. More exciting new developments are expected in the near future.

Pore size distribution calculation from 1H NMR signal and N2 adsorption-desorption techniques

NASA Astrophysics Data System (ADS)

Hassan, Jamal

2012-09-01

The pore size distribution (PSD) of nano-material MCM-41 is determined using two different approaches: N2 adsorption-desorption and 1H NMR signal of water confined in silica nano-pores of MCM-41. The first approach is based on the recently modified Kelvin equation [J.V. Rocha, D. Barrera, K. Sapag, Top. Catal. 54(2011) 121-134] which deals with the known underestimation in pore size distribution for the mesoporous materials such as MCM-41 by introducing a correction factor to the classical Kelvin equation. The second method employs the Gibbs-Thompson equation, using NMR, for melting point depression of liquid in confined geometries. The result shows that both approaches give similar pore size distribution to some extent, and also the NMR technique can be considered as an alternative direct method to obtain quantitative results especially for mesoporous materials. The pore diameter estimated for the nano-material used in this study was about 35 and 38 Å for the modified Kelvin and NMR methods respectively. A comparison between these methods and the classical Kelvin equation is also presented.

Surface characterization of hydrophobic core-shell QDs using NMR techniques

NASA Astrophysics Data System (ADS)

Zhang, Chengqi; Zeng, Birong; Palui, Goutam; Mattoussi, Hedi

2018-02-01

Using a few solution phase NMR spectroscopy techniques, including 1H NMR and 31P NMR, we have characterized the organic shell on CdSe-ZnS core-shell quantum dots and tracked changes in its composition when the QD dispersions are subjected to varying degrees of purification. Combining solution phase NMR with diffusion ordered spectroscopy (DOSY), we were able to distinguish between freely diffusing ligands in the sample from those bound on the surfaces. Additionally, matrix assisted laser desorption ionization (MALDI) and FTIR measurements were used to provide complementary and supporting information on the organic ligand coating for these nanocrystals. We found that the organic shell is dominated by monomeric or oligomeric n-hexylphosphonic acid (HPA), along with small portion of 1-hexadecyl amine (HDA). The presence of TOP/TOPO (tri-n-octylphosphine / tri-noctylphosphine oxide) molecules is much smaller, even though large excess of TOP/TOPO were used during the QD growth. These results indicate that HPA (alkyl phosphonate) exhibits the strongest coordination affinity to ZnS-rich QD surfaces grown using the high temperature injection route.

NMR of samples containing metal foils.

PubMed

Xiong, J; Lock, H; Tao, T; Keeler, C; Maciel, G E

1999-07-01

By using spool configurations of a sample containing aluminum foil, in which the axis of the spool is collinear with the RF coil axis, one can obtain high-quality 13C NMR spectra of static samples of organic material attached to the aluminum foil. By combining such a spool configuration (or, alternatively, analogous samples containing equivalent amounts of fine aluminum powder) with the magic-angle hopping (MAH) technique, one can achieve a high degree of isotropic averaging of the 13C spectrum. This opens to NMR techniques the study of a variety of samples containing macroscopic pieces of metal foils, e.g., thin films deposited on metal foils and electrochemical systems with species adsorbed on metal-foil electrodes.

International NMR-based Environmental Metabolomics Intercomparison Exercise

EPA Science Inventory

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

Unconventional Tight Reservoirs Characterization with Nuclear Magnetic Resonance

NASA Astrophysics Data System (ADS)

Santiago, C. J. S.; Solatpour, R.; Kantzas, A.

2017-12-01

The increase in tight reservoir exploitation projects causes producing many papers each year on new, modern, and modified methods and techniques on estimating characteristics of these reservoirs. The most ambiguous of all basic reservoir property estimations deals with permeability. One of the logging methods that is advertised to predict permeability but is always met by skepticism is Nuclear Magnetic Resonance (NMR). The ability of NMR to differentiate between bound and movable fluids and providing porosity increased the capability of NMR as a permeability prediction technique. This leads to a multitude of publications and the motivation of a review paper on this subject by Babadagli et al. (2002). The first part of this presentation is dedicated to an extensive review of the existing correlation models for NMR based estimates of tight reservoir permeability to update this topic. On the second part, the collected literature information is used to analyze new experimental data. The data are collected from tight reservoirs from Canada, the Middle East, and China. A case study is created to apply NMR measurement in the prediction of reservoir characterization parameters such as porosity, permeability, cut-offs, irreducible saturations etc. Moreover, permeability correlations are utilized to predict permeability. NMR experiments were conducted on water saturated cores. NMR T2 relaxation times were measured. NMR porosity, the geometric mean relaxation time (T2gm), Irreducible Bulk Volume (BVI), and Movable Bulk Volume (BVM) were calculated. The correlation coefficients were computed based on multiple regression analysis. Results are cross plots of NMR permeability versus the independently measured Klinkenberg corrected permeability. More complicated equations are discussed. Error analysis of models is presented and compared. This presentation is beneficial in understanding existing tight reservoir permeability models. The results can be used as a guide for choosing the best permeability estimation model for tight reservoirs data.

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

PubMed

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

2013-10-18

Seeing the big picture: Asymmetric macromolecular complexes that are NMR active in only a subset of their subunits can be prepared, thus decreasing NMR spectral complexity. For the hetero heptameric LSm1-7 and LSm2-8 rings NMR spectra of the individual subunits of the complete complex are obtained, showing a conserved RNA binding site. This LEGO-NMR technique makes large asymmetric complexes accessible to detailed NMR spectroscopic studies. © 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of Creative Commons the Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

An improved 13C-tracer method for the study of lignin structure and reactions : differential 13C-NMR

Treesearch

Noritsugu Terashima; Dmitry Evtuguin; Carlos Pascoal Neto; Jim Parkas; Magnus Paulsson; Ulla Westermark; Sally Ralph; John Ralph

2003-01-01

The technique of selective 13C-enrichment of specific carbons in lignin combined with 13C-NMR differential spectrometry between spectra of 13C-enriched and unenriched lignins (Ä13C-NMR) provides definitive information on the structure of the lignin macromolecule. Improvements were made on, (1) specific 13C-enrichment of almost all carbons involved in inter-unit bonds...

Perspectives on NMR in drug discovery: a technique comes of age

PubMed Central

Pellecchia, Maurizio; Bertini, Ivano; Cowburn, David; Dalvit, Claudio; Giralt, Ernest; Jahnke, Wolfgang; James, Thomas L.; Homans, Steve W.; Kessler, Horst; Luchinat, Claudio; Meyer, Bernd; Oschkinat, Hartmut; Peng, Jeff; Schwalbe, Harald; Siegal, Gregg

2009-01-01

In the past decade, the potential of harnessing the ability of nuclear magnetic resonance (NMR) spectroscopy to monitor intermolecular interactions as a tool for drug discovery has been increasingly appreciated in academia and industry. In this Perspective, we highlight some of the major applications of NMR in drug discovery, focusing on hit and lead generation, and provide a critical analysis of its current and potential utility. PMID:19172689

First principles NMR study of fluorapatite under pressure.

PubMed

Pavan, Barbara; Ceresoli, Davide; Tecklenburg, Mary M J; Fornari, Marco

2012-01-01

NMR is the technique of election to probe the local properties of materials. Herein we present the results of density functional theory (DFT) ab initio calculations of the NMR parameters for fluorapatite (FAp), a calcium orthophosphate mineral belonging to the apatite family, by using the GIPAW method (Pickard and Mauri, 2001). Understanding the local effects of pressure on apatites is particularly relevant because of their important role in many solid state and biomedical applications. Apatites are open structures, which can undergo complex anisotropic deformations, and the response of NMR can elucidate the microscopic changes induced by an applied pressure. The computed NMR parameters proved to be in good agreement with the available experimental data. The structural evaluation of the material behavior under hydrostatic pressure (from -5 to +100 kbar) indicated a shrinkage of the diameter of the apatitic channel, and a strong correlation between NMR shielding and pressure, proving the sensitivity of this technique to even small changes in the chemical environment around the nuclei. This theoretical approach allows the exploration of all the different nuclei composing the material, thus providing a very useful guidance in the interpretation of experimental results, particularly valuable for the more challenging nuclei such as (43)Ca and (17)O. Copyright © 2012 Elsevier Inc. All rights reserved.

First Principles NMR Study of Fluorapatite under Pressure

PubMed Central

Pavan, Barbara; Ceresoli, Davide; Tecklenburg, Mary M. J.; Fornari, Marco

2012-01-01

NMR is the technique of election to probe the local properties of materials. Herein we present the results of density functional theory (DFT) ab initio calculations of the NMR parameters for fluorapatite (FAp), a calcium orthophosphate mineral belonging to the apatite family, by using the GIPAW method [Pickard and Mauri, 2001]. Understanding the local effects of pressure on apatites is particularly relevant because of their important role in many solid state and biomedical applications. Apatites are open structures, which can undergo complex anisotropic deformations, and the response of NMR can elucidate the microscopic changes induced by an applied pressure. The computed NMR parameters proved to be in good agreement with the available experimental data. The structural evaluation of the material behavior under hydrostatic pressure (from −5 to +100 kbar) indicated a shrinkage of the diameter of the apatitic channel, and a strong correlation between NMR shielding and pressure, proving the sensitivity of this technique to even small changes in the chemical environment around the nuclei. This theoretical approach allows the exploration of all the different nuclei composing the material, thus providing a very useful guidance in the interpretation of experimental results, particularly valuable for the more challenging nuclei such as 43Ca and 17O. PMID:22770669

Protein Dynamics from NMR and Computer Simulation

NASA Astrophysics Data System (ADS)

Wu, Qiong; Kravchenko, Olga; Kemple, Marvin; Likic, Vladimir; Klimtchuk, Elena; Prendergast, Franklyn

2002-03-01

Proteins exhibit internal motions from the millisecond to sub-nanosecond time scale. The challenge is to relate these internal motions to biological function. A strategy to address this aim is to apply a combination of several techniques including high-resolution NMR, computer simulation of molecular dynamics (MD), molecular graphics, and finally molecular biology, the latter to generate appropriate samples. Two difficulties that arise are: (1) the time scale which is most directly biologically relevant (ms to μs) is not readily accessible by these techniques and (2) the techniques focus on local and not collective motions. We will outline methods using ^13C-NMR to help alleviate the second problem, as applied to intestinal fatty acid binding protein, a relatively small intracellular protein believed to be involved in fatty acid transport and metabolism. This work is supported in part by PHS Grant GM34847 (FGP) and by a fellowship from the American Heart Association (QW).

Enhancing NMR of insensitive nuclei by transfer of SABRE spin hyperpolarization

NASA Astrophysics Data System (ADS)

Pravdivtsev, Andrey N.; Yurkovskaya, Alexandra V.; Zimmermann, Herbert; Vieth, Hans-Martin; Ivanov, Konstantin L.

2016-09-01

We describe the performance of methods for enhancing NMR (Nuclear Magnetic Resonance) signals of "insensitive", but important NMR nuclei, which are based on the SABRE (Signal Amplification By Reversible Exchange) technique, i.e., on spin order transfer from parahydrogen (H2 molecule in its nuclear singlet spin state) to a substrate in a transient organometallic complex. Here such transfer is performed at high magnetic fields by INEPT-type NMR pulse sequences, modified for SABRE. Signal enhancements up to three orders of magnitude are obtained for 15N nuclei; the possibility of sensitive detection of 2D-NMR 1H-15N spectra of SABRE complexes and substrates is demonstrated.

Structural confirmation of regioisomers of Lopinavir impurities using MS and gradient COSY (1H and 13C NMR assignment of Lopinavir impurities).

PubMed

Siva Lakshmi Devi, A; Srinivasa Rao, Y; Suresh, Y; Yogeswar Reddy, M; Jyothi, G; Rajababu, B; Prasad, V S R; Umamaheswar Rao, V

2007-05-01

We report the complete (1)H and (13)C NMR assignment of impurities of six Lopinavir (2S)-N-[(2S, 4S, 5S)-5-{[2-(2,6-dimethylphenoxy)acetyl]amino}-4-hydroxy-1,6-diphenyl hexan-2-yl]-3-methyl-2-(2-oxo-1,3-diazinan-1-yl)butan- amide. Two of the impurities are regioisomers and GCOSY used to differentiate the two structures. The spectral assignments for all six impurities were achieved by concerted application of one and two-dimensional NMR techniques ((1)H NMR, (13)C NMR, DEPT, GCOSY, GHSQC and GHMBC). Copyright (c) 2007 John Wiley & Sons, Ltd.

Development of techniques in magnetic resonance and structural studies of the prion protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bitter, Hans-Marcus L.

2000-07-01

Magnetic resonance is the most powerful analytical tool used by chemists today. Its applications range from determining structures of large biomolecules to imaging of human brains. Nevertheless, magnetic resonance remains a relatively young field, in which many techniques are currently being developed that have broad applications. In this dissertation, two new techniques are presented, one that enables the determination of torsion angles in solid-state peptides and proteins, and another that involves imaging of heterogenous materials at ultra-low magnetic fields. In addition, structural studies of the prion protein via solid-state NMR are described. More specifically, work is presented in which themore » dependence of chemical shifts on local molecular structure is used to predict chemical shift tensors in solid-state peptides with theoretical ab initio surfaces. These predictions are then used to determine the backbone dihedral angles in peptides. This method utilizes the theoretical chemicalshift tensors and experimentally determined chemical-shift anisotropies (CSAs) to predict the backbone and side chain torsion angles in alanine, leucine, and valine residues. Additionally, structural studies of prion protein fragments are described in which conformationally-dependent chemical-shift measurements were made to gain insight into the structural differences between the various conformational states of the prion protein. These studies are of biological and pathological interest since conformational changes in the prion protein are believed to cause prion diseases. Finally, an ultra-low field magnetic resonance imaging technique is described that enables imaging and characterization of heterogeneous and porous media. The notion of imaging gases at ultra-low fields would appear to be very difficult due to the prohibitively low polarization and spin densities as well as the low sensitivities of conventional Faraday coil detectors. However, Chapter 5 describes how gas imaging at ultra-low fields is realized by incorporating the high sensitivities of a dc superconducting quantum interference device (SQUID) with the high polarizations attainable through optica11y pumping 129Xe gas.« less

Calibration of NMR well logs from carbonate reservoirs with laboratory NMR measurements and μXRCT

DOE PAGES

Mason, Harris E.; Smith, Megan M.; Hao, Yue; ...

2014-12-31

The use of nuclear magnetic resonance (NMR) well log data has the potential to provide in-situ porosity, pore size distributions, and permeability of target carbonate CO₂ storage reservoirs. However, these methods which have been successfully applied to sandstones have yet to be completely validated for carbonate reservoirs. Here, we have taken an approach to validate NMR measurements of carbonate rock cores with independent measurements of permeability and pore surface area to volume (S/V) distributions using differential pressure measurements and micro X-ray computed tomography (μXRCT) imaging methods, respectively. We observe that using standard methods for determining permeability from NMR data incorrectlymore » predicts these values by orders of magnitude. However, we do observe promise that NMR measurements provide reasonable estimates of pore S/V distributions, and with further independent measurements of the carbonate rock properties that universally applicable relationships between NMR measured properties may be developed for in-situ well logging applications of carbonate reservoirs.« less

Calibration of NMR well logs from carbonate reservoirs with laboratory NMR measurements and μXRCT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mason, Harris E.; Smith, Megan M.; Hao, Yue

The use of nuclear magnetic resonance (NMR) well log data has the potential to provide in-situ porosity, pore size distributions, and permeability of target carbonate CO₂ storage reservoirs. However, these methods which have been successfully applied to sandstones have yet to be completely validated for carbonate reservoirs. Here, we have taken an approach to validate NMR measurements of carbonate rock cores with independent measurements of permeability and pore surface area to volume (S/V) distributions using differential pressure measurements and micro X-ray computed tomography (μXRCT) imaging methods, respectively. We observe that using standard methods for determining permeability from NMR data incorrectlymore » predicts these values by orders of magnitude. However, we do observe promise that NMR measurements provide reasonable estimates of pore S/V distributions, and with further independent measurements of the carbonate rock properties that universally applicable relationships between NMR measured properties may be developed for in-situ well logging applications of carbonate reservoirs.« less

Optimal sampling with prior information of the image geometry in microfluidic MRI.

PubMed

Han, S H; Cho, H; Paulsen, J L

2015-03-01

Recent advances in MRI acquisition for microscopic flows enable unprecedented sensitivity and speed in a portable NMR/MRI microfluidic analysis platform. However, the application of MRI to microfluidics usually suffers from prolonged acquisition times owing to the combination of the required high resolution and wide field of view necessary to resolve details within microfluidic channels. When prior knowledge of the image geometry is available as a binarized image, such as for microfluidic MRI, it is possible to reduce sampling requirements by incorporating this information into the reconstruction algorithm. The current approach to the design of the partial weighted random sampling schemes is to bias toward the high signal energy portions of the binarized image geometry after Fourier transformation (i.e. in its k-space representation). Although this sampling prescription is frequently effective, it can be far from optimal in certain limiting cases, such as for a 1D channel, or more generally yield inefficient sampling schemes at low degrees of sub-sampling. This work explores the tradeoff between signal acquisition and incoherent sampling on image reconstruction quality given prior knowledge of the image geometry for weighted random sampling schemes, finding that optimal distribution is not robustly determined by maximizing the acquired signal but from interpreting its marginal change with respect to the sub-sampling rate. We develop a corresponding sampling design methodology that deterministically yields a near optimal sampling distribution for image reconstructions incorporating knowledge of the image geometry. The technique robustly identifies optimal weighted random sampling schemes and provides improved reconstruction fidelity for multiple 1D and 2D images, when compared to prior techniques for sampling optimization given knowledge of the image geometry. Copyright © 2015 Elsevier Inc. All rights reserved.

Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance

NASA Technical Reports Server (NTRS)

Walsworth, Ronald L.

2001-01-01

We are developing laser-polarized noble gas nuclear magnetic resonance (NMR) as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI) (e.g., of lung ventilation) as well as studies of tissue perfusion. In addition, laser-polarized noble gases (He-3 and Xe-129) do not require a large magnetic field for sensitive detection, opening the door to practical MRI at very low magnetic fields with an open, lightweight, and low-power device. We are pursuing two specific aims in this research. The first aim is to develop a low-field (< 0.01 T) instrument for noble gas MRI of humans, and the second aim is to develop functional MRI of the lung using laser-polarized Xe-129 and related techniques.

Measurement of adenosine triphosphate and 2,3-diphosphoglycerate in stored blood with 31P nuclear magnetic resonance spectroscopy.

PubMed

Ambruso, D R; Hawkins, B; Johnson, D L; Fritzberg, A R; Klingensmith, W C; McCabe, E R

1986-06-01

Conditions for blood storage are chosen to assure adequate levels of adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG). Because of the invasive nature of the techniques, biochemical assays are not routinely used to measure levels of these compounds in stored blood. However, 31P NMR spectroscopy measures phosphorylated intermediates in intact cells and could be used without disruption of the storage pack. We compared levels of ATP and 2,3-DPG measured by 31P spectroscopy and standard enzyme-linked biochemical assays in whole blood (WB) and packed red blood cells (PRBCs) at weekly intervals during a 35-day storage period. NMR demonstrated a marked decrease in 2,3-DPG and an increase in inorganic phosphate after the first week of storage. No significant differences in ATP concentrations were seen in WB during the storage period, but a significant decrease in ATP in PRBCs was documented. There was good agreement in levels of ATP and 2,3-DPG measured by NMR and biochemical techniques. 31P NMR spectroscopy is a noninvasive technique for measuring ATP and 2,3-DPG which has a potential use in quality assurance of stored blood.

TU-EF-BRA-01: NMR and Proton Density MRI of the 1D Patient

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolbarst, A.

NMR, and Proton Density MRI of the 1D Patient - Anthony Wolbarst Net Voxel Magnetization, m(x,t). T1-MRI; The MRI Device - Lisa Lemen ‘Classical’ NMR; FID Imaging in 1D via k-Space - Nathan Yanasak Spin-Echo; S-E/Spin Warp in a 2D Slice - Ronald Price Magnetic resonance imaging not only reveals the structural, anatomic details of the body, as does CT, but also it can provide information on the physiological status and pathologies of its tissues, like nuclear medicine. It can display high-quality slice and 3D images of organs and vessels viewed from any perspective, with resolution better than 1 mm.more » MRI is perhaps most extraordinary and notable for the plethora of ways in which it can create unique forms of image contrast, reflective of fundamentally different biophysical phenomena. As with ultrasound, there is no risk from ionizing radiation to the patient or staff, since no X-rays or radioactive nuclei are involved. Instead, MRI harnesses magnetic fields and radio waves to probe the stable nuclei of the ordinary hydrogen atoms (isolated protons) occurring in water and lipid molecules within and around cells. MRI consists, in essence, of creating spatial maps of the electromagnetic environments around these hydrogen nuclei. Spatial variations in the proton milieus can be related to clinical differences in the biochemical and physiological properties and conditions of the associated tissues. Imaging of proton density (PD), and of the tissue proton spin relaxation times known as T1 and T2, all can reveal important clinical information, but they do so with approaches so dissimilar from one another that each is chosen for only certain clinical situations. T1 and T2 in a voxel are determined by different aspects of the rotations and other motions of the water and lipid molecules involved, as constrained by the local biophysical surroundings within and between its cells – and they, in turn, depend on the type of tissue and its state of health. Three other common applications of MRI exploit its capability to detect and image distinct movements of fluids: MR angiography (MRA), which rivals CT angiography but often requires no contrast medium, monitors the bulk flow of blood; functional MRI ( f MRI), distinguishes the perfusion of oxygenated blood from that of de-oxygenated, and lights up parts of the brain that are activated by a stimulus, rather like PET; and diffusion tensor imaging (DTI) indicates the diffusion of free water along tracts of axons, thereby bringing nerve trunks into view. There are variants on all of these themes, and on others as well. Magnetic Resonance Spectroscopy (MRS), for example, can perform non-invasive ‘virtual biopsies’ that allow identification of certain cancers and other lesions. And an MRI-guided needle biopsy can sample brain tissue from a region only millimeters in dimensions. MRI, however, involves deeper and more complex aspects of physics, technology, and biology than do most other imaging modalities, and it is widely considered to be correspondingly more difficult to learn. We could probably cover all of this rather comprehensively if we had 50 hours available rather than 2 ̶ but, to paraphrase a former Secretary of Defense, you tell your story in the time you have allotted. The four presenters and another physicist, Kevin King from GE, have combined their efforts to co-author a single slide show that describes essentials of MRI as simply as possible. It is obviously far from thorough, but hopefully it will succeed in explaining some of the basics in a simplified but still valid fashion; in providing a taste of the numerous capabilities and complexities of the modality; and in whetting your appetite to learn more. Part I. NMR, and Proton Density MRI of the 1D Patient (Wolbarst), begins with an introductory case study that illustrates a half dozen ways in which MRI provides valuable clinical information. It then explores the nuclear magnetic resonance (NMR) phenomenon, which underlies MRI. NMR can be introduced with either of two approaches. In the first, one thinks (loosely) of the nuclei of hydrogen atoms as (rotating and charged and therefore) magnetic objects, whose spin-axes tend to align in a strong external magnetic field, much like a compass needle. As with the Bohr atom, this spin-up/spin-down picture is a highly abridged version of the full quantum mechanical treatment, but still it leads to some useful, legitimate pictures of the NMR process occurring within a voxel: When RF photons of the correct (Larmor) frequency elevate protons in a fixed magnetic field out of their lower-energy spin state into the upper, the NMR phenomenon is indicated by the detectable absorption of RF power. With the addition of a linear gradient field along a multi-voxel, one-dimensional patient/phantom, as well, we can determine the water content of each compartment – an example of a real MRI study, albeit in 1D. Part I concludes with a discussion of the net magnetization at position x, m0(x), under conditions of dynamic thermal equilibrium, which leads into: Part II. Net Voxel Magnetization, m(x,t); T1-MRI; The MRI Device (Lemen), investigates the biophysics of the form of proton spin relaxation process characterized by the time T1. It then moves on to the creation of an MR image that displays the spatial variation in the values of this clinically relevant parameter, again in 1D. Finally, the design and workings of a clinical MRI machine are sketched, in preparation for: Part III. ‘Classical’ NMR; FID Imaging in 1D via k-Space (Yanasak) presents the second standard approach to NMR and MRI, the classical model. It focuses on the time dependence of the net nuclear magnetization, m(x,t), the overall magnetic field generated by the cohort of protons in the voxel at position x. Quite remarkably, this nuclear net magnetization itself acts in a strong magnetic field like a gyroscope in a gravitational field. This tack is better for explaining Free Induction Decay (FID), which involves a brief introduction to the Fourier transform and k-space. This leads to conventional Spin-Echo (S-E) reconstruction techniques for creating clinical images from raw data, and sets the stage for: Part IV. Spin-Echo; S-E / Spin Warp in a 2D Slice (Price) discusses application of the S- E sequence of radiofrequency pulses and gradient magnetic fields to the 1D patient. T2 is introduced but not explained. This Part also considers how to manipulate the image acquisition parameters so as to generate clinical pictures with contrast dominated by spatial variations in PD, T1, or T2. We conclude by demonstrating the spin-warp approach to imaging in 2D with a simple 2×2, 4-voxel example. Much of this material is presented in more detail in the chapter “MRI of the One-dimensional Patient, Part I”, in Advances in Medical Physics, Vol 5 (2014). Copies are on display at the Medical Physics Publishing booth. Learning Objectives: The participant will learn about the processes of NMR and T1 spin relaxation in a tissue voxel in a uniform magnetic field. The participant will learn about combining spin-up/spin-down NMR and T1 processes with a linear gradient to effect frequency-encoding of voxel spatial position. This approach can be used to create proton density and T1 MRI maps, respectively, of the contents of multi-voxel 1D phantoms. The participant will learn about how the ‘classical’ model of NMR it can generate Free Induction Decay (FID) images of 1D phantoms, which involves the use of the Fourier transform in k-space. This can lead simply into standard Spin-Echo images. The participant will learn about extending Spin-Echo imaging into 2 and more dimensions.« less

Decreased Nicotinic Receptor Availability in Smokers with Slow Rates of Nicotine Metabolism.

PubMed

Dubroff, Jacob G; Doot, Robert K; Falcone, Mary; Schnoll, Robert A; Ray, Riju; Tyndale, Rachel F; Brody, Arthur L; Hou, Catherine; Schmitz, Alexander; Lerman, Caryn

2015-11-01

The nicotine metabolite ratio (NMR), a stable measure of hepatic nicotine metabolism via the CYP2A6 pathway and total nicotine clearance, is a predictive biomarker of response to nicotine replacement therapy, with increased quit rates in slower metabolizers. Nicotine binds directly to nicotinic acetylcholine receptors (nAChRs) to exert its psychoactive effects. This study examined the relationship between NMR and nAChR (α4β2* subtype) availability using PET imaging of the radiotracer 2-(18)F-fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2-(18)F-FA-85380, or 2-(18)F-FA). Twenty-four smokers-12 slow metabolizers (NMR < 0.26) and 12 normal metabolizers (NMR ≥ 0.26)-underwent 2-(18)F-FA-PET brain imaging after overnight nicotine abstinence (18 h before scanning), using a validated bolus-plus-infusion protocol. Availability of nAChRs was compared between NMR groups in a priori volumes of interest, with total distribution volume (VT/fP) being the measure of nAChR availability. Cravings to smoke were assessed before and after the scans. Thalamic nAChR α4β2* availability was significantly reduced in slow nicotine metabolizers (P = 0.04). Slow metabolizers exhibited greater reductions in cravings after scanning than normal metabolizers; however, craving was unrelated to nAChR availability. The rate of nicotine metabolism is associated with thalamic nAChR availability. Additional studies could examine whether altered nAChR availability underlies the differences in treatment response between slow and normal metabolizers of nicotine. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Polymer gel dosimeters with reduced toxicity: a preliminary investigation of the NMR and optical dose response using different monomers

NASA Astrophysics Data System (ADS)

Senden, R. J.; DeJean, P.; McAuley, K. B.; Schreiner, L. J.

2006-07-01

In this work, three new polymer gel dosimeter recipes were investigated that may be more suitable for widespread applications than polyacrylamide gel dosimeters, since the extremely toxic acrylamide has been replaced with the less harmful monomers N-isopropylacrylamide (NIPAM), diacetone acrylamide and N-vinylformamide. The new gel dosimeters studied contained gelatin (5 wt%), monomer (3 wt%), N,N'-methylene-bis-acrylamide crosslinker (3 wt%) and tetrakis (hydroxymethyl) phosphonium chloride antioxidant (10 mM). The NMR response (R2) of the dosimeters was analysed for conditions of varying dose, dose rate, time post-irradiation, and temperature during irradiation and scanning. It was shown that the dose-response behaviour of the NIPAM/Bis gel dosimeter is comparable to that of normoxic polyacrylamide gel (PAGAT) in terms of high dose-sensitivity and low dependence on dose rate and irradiation temperature, within the ranges considered. The dose-response (R2) of NIPAM/Bis appears to be linear over a greater dose range than the PAGAT gel dosimeter. The effects of time post-irradiation (temporal instability) and temperature during NMR scanning on the R2 response were more significant for NIPAM/Bis dosimeters. Diacetone acrylamide and N-vinylformamide gel dosimeters possessed considerably lower dose-sensitivities. The optical dose-response, measured in terms of the attenuation coefficient for each polymer gel dosimeter, showed potential for the use of optical imaging techniques in future studies.

Visualizing 3-D microscopic specimens

NASA Astrophysics Data System (ADS)

Forsgren, Per-Ola; Majlof, Lars L.

1992-06-01

The confocal microscope can be used in a vast number of fields and applications to gather more information than is possible with a regular light microscope, in particular about depth. Compared to other three-dimensional imaging devices such as CAT, NMR, and PET, the variations of the objects studied are larger and not known from macroscopic dissections. It is therefore important to have several complementary ways of displaying the gathered information. We present a system where the user can choose display techniques such as extended focus, depth coding, solid surface modeling, maximum intensity and other techniques, some of which may be combined. A graphical user interface provides easy and direct control of all input parameters. Motion and stereo are available options. Many three- dimensional imaging devices give recordings where one dimension has different resolution and sampling than the other two which requires interpolation to obtain correct geometry. We have evaluated algorithms with interpolation in object space and in projection space. There are many ways to simplify the geometrical transformations to gain performance. We present results of some ways to simplify the calculations.

Solution conformation of carbohydrates: a view by using NMR assisted by modeling.

PubMed

Díaz, Dolores; Canales-Mayordomo, Angeles; Cañada, F Javier; Jiménez-Barbero, Jesús

2015-01-01

Structural elucidation of complex carbohydrates in solution is not a trivial task. From the NMR view point, the limited chemical shift dispersion of sugar NMR spectra demands the combination of a variety of NMR techniques as well as the employment of molecular modeling methods. Herein, a general protocol for assignment of resonances and determination of inter-proton distances within the saccharides by homonuclear and heteronuclear experiments (i.e., (1)H and (13)C) is described. In addition, several computational tools and procedures for getting a final ensemble of geometries that represent the structure in solution are presented.

In Situ and Ex Situ Low-Field NMR Spectroscopy and MRI Endowed by SABRE Hyperpolarization**

PubMed Central

Barskiy, Danila A.; Kovtunov, Kirill V.; Koptyug, Igor V.; He, Ping; Groome, Kirsten A.; Best, Quinn A.; Shi, Fan; Goodson, Boyd M.; Shchepin, Roman V.; Truong, Milton L.; Coffey, Aaron M.; Waddell, Kevin W.; Chekmenev, Eduard Y.

2015-01-01

By using 5.75 and 47.5 mT nuclear magnetic resonance (NMR) spectroscopy, up to 105-fold sensitivity enhancement through signal amplification by reversible exchange (SABRE) was enabled, and subsecond temporal resolution was used to monitor an exchange reaction that resulted in the buildup and decay of hyperpolarized species after parahydrogen bubbling. We demonstrated the high-resolution low-field proton magnetic resonance imaging (MRI) of pyridine in a 47.5 mT magnetic field endowed by SABRE. Molecular imaging (i.e. imaging of dilute hyperpolarized substances rather than the bulk medium) was conducted in two regimes: in situ real-time MRI of the reaction mixture (in which pyridine was hyperpolarized), and ex situ MRI (in which hyperpolarization decays) of the liquid hyperpolarized product. Low-field (milli-Tesla range, e.g. 5.75 and 47.5 mT used in this study) parahydrogen-enhanced NMR and MRI, which are free from the limitations of high-field magnetic resonance (including susceptibility-induced gradients of the static magnetic field at phase interfaces), potentially enables new imaging applications as well as differentiation of hyperpolarized chemical species on demand by exploiting spin manipulations with static and alternating magnetic fields. PMID:25367202

A potential nuclear magnetic resonance imaging approach for noncontact temperature measurement

NASA Technical Reports Server (NTRS)

Manatt, Stanley L.

1989-01-01

It is proposed that in a nuclear magnetic resonance (NMR) imaging experiment that it should be possible to measure temperature through an extended volume. The basis for such a measurement would depend upon sensing a temperature dependent on NMR parameter in an inert, volatile molecule (or fluid) filling the volume of interest. Exploratory work suggest that one suitable candidate for such a purpose might be CH3Cl. Possible parameters, other inert gases and feasible measurement schemes that might provide such temperature measurement are discussed.

Selective detection of hyperpolarized NMR signals derived from para-hydrogen using the Only Para-hydrogen SpectroscopY (OPSY) approach.

PubMed

Aguilar, Juan A; Adams, Ralph W; Duckett, Simon B; Green, Gary G R; Kandiah, Rathika

2011-01-01

A new family of NMR pulse sequences is reported for the recording of para-hydrogen enhanced NMR spectra. This Only Para-hydrogen SpectroscopY (OPSY) approach uses coherence selection to separate hyperpolarized signals from those of fully relaxed and thermally equilibrated protons. Sequence design, performance, practical aspects and applicability to other hyperpolarization techniques are discussed. Copyright © 2010 Elsevier Inc. All rights reserved.

NMR doesn't lie or how solid-state NMR spectroscopy contributed to a better understanding of the nature and function of soil organic matter (Philippe Duchaufour Medal Lecture)

NASA Astrophysics Data System (ADS)

Knicker, Heike

2016-04-01

"Nuclear magnetic resonance (NMR) does not lie". More than anything else, this statement of a former colleague and friend has shaped my relation to solid-state NMR spectroscopy. Indeed, if this technique leads to results which contradict the expectations, it is because i) some parts of the instrument are broken, ii) maladjustment of the acquisition parameters or iii) wrong preparation or confusion of samples. However, it may be even simpler, namely that the expectations were wrong. Of course, for researchers, the latter is the most interesting possibility since it forces to reassess accepted views and to search for new explanations. As my major analytical tool, NMR spectroscopy has confronted me with this challenge often enough to turn this issue into the main subject of my talk and to share with the audience how it formed my understanding of function and nature of soil organic matter (SOM). Already shortly after its introduction into soil science in the 1980's, the data obtained with solid-state 13C NMR spectroscopy opened the stage for ongoing discussions, since they showed that in humified SOM aromatic carbon is considerably less important than previously thought. This finding had major implications regarding the understanding of the origin of SOM and the mechanisms by which it is formed. Certainly, the discrepancy between the new results and previous paradigms contributed to mistrust in the reliability of solid-state NMR techniques. The respective discussion has survived up to our days, although already in the 1980's and 1990's fundamental studies could demonstrate that quantitative solid-state NMR data can be obtained if i) correct acquisition parameters are chosen, ii) the impact of paramagnetic compounds is reduced and iii) the presence of soot in soils can be excluded. On the other hand, this mistrust led to a detailed analysis of the impact of paramagnetics on the NMR behavior of C groups which then improved our understanding of the role of carbohydrates for organo-mineral interactions. Since decent solid-state NMR spectra cannot be obtained from graphenic components, the successful acquisition of solid-state 13C and 15N NMR spectra of charcoals challenged the well accepted model of their chemical nature. Application of advanced 2D NMR approaches confirmed the new view of charcoal as a heterogeneous material, the composition of which depends upon the feedstock and charring condition. The respective consequences of this alternative for the understanding of C sequestration are still matter of ongoing debates. Although the sensitivity of 15N for NMR spectroscopy is 50 times lower than that of 13C, first solid-state 15N NMR spectra of soils with natural 15N abundance were already published in the 1990's. They clearly identified peptide-like structures as the main organic N form in unburnt soils. However, in spite of their high contribution to SOM, the role of peptides in soils is far from understood. Considering the new technological developments in the field of NMR spectroscopy, this technique will certainly not stop to contribute to unexpected results.

Comparison of Attenuated Total Reflectance Mid-Infrared, Near Infrared, and 1H-Nuclear Magnetic Resonance Spectroscopies for the Determination of Coffee's Geographical Origin.

PubMed

Medina, Jessica; Caro Rodríguez, Diana; Arana, Victoria A; Bernal, Andrés; Esseiva, Pierre; Wist, Julien

2017-01-01

The sensorial properties of Colombian coffee are renowned worldwide, which is reflected in its market value. This raises the threat of fraud by adulteration using coffee grains from other countries, thus creating a demand for robust and cost-effective methods for the determination of geographical origin of coffee samples. Spectroscopic techniques such as Nuclear Magnetic Resonance (NMR), near infrared (NIR), and mid-infrared (mIR) have arisen as strong candidates for the task. Although a body of work exists that reports on their individual performances, a faithful comparison has not been established yet. We evaluated the performance of 1 H-NMR, Attenuated Total Reflectance mIR (ATR-mIR), and NIR applied to fraud detection in Colombian coffee. For each technique, we built classification models for discrimination by species ( C. arabica versus C. canephora (or robusta )) and by origin (Colombia versus other C. arabica ) using a common set of coffee samples. All techniques successfully discriminated samples by species, as expected. Regarding origin determination, ATR-mIR and 1 H-NMR showed comparable capacity to discriminate Colombian coffee samples, while NIR fell short by comparison. In conclusion, ATR-mIR, a less common technique in the field of coffee adulteration and fraud detection, emerges as a strong candidate, faster and with lower cost compared to 1 H-NMR and more discriminating compared to NIR.

nmrML: A Community Supported Open Data Standard for the Description, Storage, and Exchange of NMR Data.

PubMed

Schober, Daniel; Jacob, Daniel; Wilson, Michael; Cruz, Joseph A; Marcu, Ana; Grant, Jason R; Moing, Annick; Deborde, Catherine; de Figueiredo, Luis F; Haug, Kenneth; Rocca-Serra, Philippe; Easton, John; Ebbels, Timothy M D; Hao, Jie; Ludwig, Christian; Günther, Ulrich L; Rosato, Antonio; Klein, Matthias S; Lewis, Ian A; Luchinat, Claudio; Jones, Andrew R; Grauslys, Arturas; Larralde, Martin; Yokochi, Masashi; Kobayashi, Naohiro; Porzel, Andrea; Griffin, Julian L; Viant, Mark R; Wishart, David S; Steinbeck, Christoph; Salek, Reza M; Neumann, Steffen

2018-01-02

NMR is a widely used analytical technique with a growing number of repositories available. As a result, demands for a vendor-agnostic, open data format for long-term archiving of NMR data have emerged with the aim to ease and encourage sharing, comparison, and reuse of NMR data. Here we present nmrML, an open XML-based exchange and storage format for NMR spectral data. The nmrML format is intended to be fully compatible with existing NMR data for chemical, biochemical, and metabolomics experiments. nmrML can capture raw NMR data, spectral data acquisition parameters, and where available spectral metadata, such as chemical structures associated with spectral assignments. The nmrML format is compatible with pure-compound NMR data for reference spectral libraries as well as NMR data from complex biomixtures, i.e., metabolomics experiments. To facilitate format conversions, we provide nmrML converters for Bruker, JEOL and Agilent/Varian vendor formats. In addition, easy-to-use Web-based spectral viewing, processing, and spectral assignment tools that read and write nmrML have been developed. Software libraries and Web services for data validation are available for tool developers and end-users. The nmrML format has already been adopted for capturing and disseminating NMR data for small molecules by several open source data processing tools and metabolomics reference spectral libraries, e.g., serving as storage format for the MetaboLights data repository. The nmrML open access data standard has been endorsed by the Metabolomics Standards Initiative (MSI), and we here encourage user participation and feedback to increase usability and make it a successful standard.

Chemical Exchange Saturation Transfer in Chemical Reactions: A Mechanistic Tool for NMR Detection and Characterization of Transient Intermediates.

PubMed

Lokesh, N; Seegerer, Andreas; Hioe, Johnny; Gschwind, Ruth M

2018-02-07

The low sensitivity of NMR and transient key intermediates below detection limit are the central problems studying reaction mechanisms by NMR. Sensitivity can be enhanced by hyperpolarization techniques such as dynamic nuclear polarization or the incorporation/interaction of special hyperpolarized molecules. However, all of these techniques require special equipment, are restricted to selective reactions, or undesirably influence the reaction pathways. Here, we apply the chemical exchange saturation transfer (CEST) technique for the first time to NMR detect and characterize previously unobserved transient reaction intermediates in organocatalysis. The higher sensitivity of CEST and chemical equilibria present in the reaction pathway are exploited to access population and kinetics information on low populated intermediates. The potential of the method is demonstrated on the proline-catalyzed enamine formation for unprecedented in situ detection of a DPU stabilized zwitterionic iminium species, the elusive key intermediate between enamine and oxazolidinones. The quantitative analysis of CEST data at 250 K revealed the population ratio of [Z-iminium]/[exo-oxazolidinone] 0.02, relative free energy +8.1 kJ/mol (calculated +7.3 kJ/mol), and free energy barrier of +45.9 kJ/mol (ΔG ⧧ calc. (268 K) = +42.2 kJ/mol) for Z-iminium → exo-oxazolidinone. The findings underpin the iminium ion participation in enamine formation pathway corroborating our earlier theoretical prediction and help in better understanding. The reliability of CEST is validated using 1D EXSY-build-up techniques at low temperature (213 K). The CEST method thus serves as a new tool for mechanistic investigations in organocatalysis to access key information, such as chemical shifts, populations, and reaction kinetics of intermediates below the standard NMR detection limit.

Nuclear magnetic resonance and high-performance liquid chromatography techniques for the characterization of bioactive compounds from Humulus lupulus L. (hop).

PubMed

Bertelli, Davide; Brighenti, Virginia; Marchetti, Lucia; Reik, Anna; Pellati, Federica

2018-06-01

Humulus lupulus L. (hop) represents one of the most cultivated crops, it being a key ingredient in the brewing process. Many health-related properties have been described for hop extracts, making this plant gain more interest in the field of pharmaceutical and nutraceutical research. Among the analytical tools available for the phytochemical characterization of plant extracts, quantitative nuclear magnetic resonance (qNMR) represents a new and powerful technique. In this ambit, the present study was aimed at the development of a new, simple, and efficient qNMR method for the metabolite fingerprinting of bioactive compounds in hop cones, taking advantage of the novel ERETIC 2 tool. To the best of our knowledge, this is the first attempt to apply this method to complex matrices of natural origin, such as hop extracts. The qNMR method set up in this study was applied to the quantification of both prenylflavonoids and bitter acids in eight hop cultivars. The performance of this analytical method was compared with that of HPLC-UV/DAD, which represents the most frequently used technique in the field of natural product analysis. The quantitative data obtained for hop samples by means of the two aforementioned techniques highlighted that the amount of bioactive compounds was slightly higher when qNMR was applied, although the order of magnitude of the values was the same. The accuracy of qNMR was comparable to that of the chromatographic method, thus proving to be a reliable tool for the analysis of these secondary metabolites in hop extracts. Graphical abstract Graphical abstract related to the extraction and analytical methods applied in this work for the analysis of bioactive compounds in Humulus lupulus L. (hop) cones.

Temperature dependence of proton NMR relaxation times at earth's magnetic field

NASA Astrophysics Data System (ADS)

Niedbalski, Peter; Kiswandhi, Andhika; Parish, Christopher; Ferguson, Sarah; Cervantes, Eduardo; Oomen, Anisha; Krishnan, Anagha; Goyal, Aayush; Lumata, Lloyd

The theoretical description of relaxation processes for protons, well established and experimentally verified at conventional nuclear magnetic resonance (NMR) fields, has remained untested at low fields despite significant advances in low field NMR technology. In this study, proton spin-lattice relaxation (T1) times in pure water and water doped with varying concentrations of the paramagnetic agent copper chloride have been measured from 6 to 92oC at earth's magnetic field (1700 Hz). Results show a linear increase of T1 with temperature for each of the samples studied. Increasing the concentration of the copper chloride greatly reduced T1 and reduced dependence on temperature. The consistency of the results with theory is an important confirmation of past results, while the ability of an ultra-low field NMR system to do contrast-enhanced magnetic resonance imaging (MRI) is promising for future applicability to low-cost medical imaging and chemical identification. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and the Robert A. Welch Foundation Grant No. AT-1877.

Characterizing Covalently Sidewall-Functionalized SWCNTs by using 1H NMR Spectroscopy

PubMed Central

Nelson, Donna J.; Kumar, Ravi

2013-01-01

Unambiguous evidence for covalent sidewall functionalization of single-walled carbon nanotubes (SWCNTs) has been a difficult task, especially for nanomaterials in which slight differences in functionality structure produce significant changes in molecular characteristics. Nuclear magnetic resonance (NMR) spectroscopy provides clear information about the structural skeleton of molecules attached to SWCNTs. In order to establish the generality of proton NMR as an analytical technique for characterizing covalently functionalized SWCNTs, we have obtained and analyzed proton NMR data of SWCNT-substituted benzenes across a variety of para substituents. Trends obtained for differences in proton NMR chemical shifts and the impact of o-, p-, and m-directing effects of electrophilic aromatic substituents on phenyl groups covalently bonded to SWCNTs are discussed. PMID:24009779

A review of whole cell wall NMR by the direct-dissolution of biomass

DOE PAGES

Foston, Marcus B.; Samuel, Reichel; He, Jian; ...

2016-01-19

To fully realize the potential of lignocellulosic biomass as a renewable resource for the production of fuels, chemicals, and materials, an improved understanding of the chemical and molecular structures within biomass and how those structures are formed during biosynthesis and transformed during (thermochemical and biological) conversion must be developed. This effort will require analytical techniques which are not only in-depth, rapid, and cost-effective, but also leave native cell wall features intact. Whole plant cell wall nuclear magnetic resonance (NMR) analysis facilitates unparalleled structural characterization of lignocellulosic biomass without causing (or with minimal) structural modification. The objective of this review ismore » to summarize research pertaining to solution- or gel-state whole plant cell wall NMR analysis of biomass, demonstrating the capability of NMR to delineate the structural features and transformations of biomass. In particular, this review will focus on the application of a two-dimensional solution-state NMR technique and perdeuterated ionic liquid based organic electrolyte solvents for the direct dissolution and analysis of biomass. Furthermore, we believe this type of analysis will be critical to advancing biofuel research, improving bioprocessing methodology, and enhancing plant bioengineering efforts.« less

A review of whole cell wall NMR by the direct-dissolution of biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foston, Marcus B.; Samuel, Reichel; He, Jian

To fully realize the potential of lignocellulosic biomass as a renewable resource for the production of fuels, chemicals, and materials, an improved understanding of the chemical and molecular structures within biomass and how those structures are formed during biosynthesis and transformed during (thermochemical and biological) conversion must be developed. This effort will require analytical techniques which are not only in-depth, rapid, and cost-effective, but also leave native cell wall features intact. Whole plant cell wall nuclear magnetic resonance (NMR) analysis facilitates unparalleled structural characterization of lignocellulosic biomass without causing (or with minimal) structural modification. The objective of this review ismore » to summarize research pertaining to solution- or gel-state whole plant cell wall NMR analysis of biomass, demonstrating the capability of NMR to delineate the structural features and transformations of biomass. In particular, this review will focus on the application of a two-dimensional solution-state NMR technique and perdeuterated ionic liquid based organic electrolyte solvents for the direct dissolution and analysis of biomass. Furthermore, we believe this type of analysis will be critical to advancing biofuel research, improving bioprocessing methodology, and enhancing plant bioengineering efforts.« less

Re-polarization of nuclear spins using selective SABRE-INEPT.

PubMed

Knecht, Stephan; Kiryutin, Alexey S; Yurkovskaya, Alexandra V; Ivanov, Konstantin L

2018-02-01

A method is proposed for significant improvement of NMR pulse sequences used in high-field SABRE (Signal Amplification By Reversible Exchange) experiments. SABRE makes use of spin order transfer from parahydrogen (pH 2 , the H 2 molecule in its singlet spin state) to a substrate in a transient organometallic Ir-based complex. The technique proposed here utilizes "re-polarization", i.e., multiple application of an NMR pulse sequence used for spin order transfer. During re-polarization only the form of the substrate, which is bound to the complex, is excited by selective NMR pulses and the resulting polarization is transferred to the free substrate via chemical exchange. Owing to the fact that (i) only a small fraction of the substrate molecules is in the bound form and (ii) spin relaxation of the free substrate is slow, the re-polarization scheme provides greatly improved NMR signal enhancement, ε. For instance, when pyridine is used as a substrate, single use of the SABRE-INEPT sequence provides ε≈260 for 15 N nuclei, whereas SABRE-INEPT with re-polarization yields ε>2000. We anticipate that the proposed method is useful for achieving maximal NMR enhancement with spin hyperpolarization techniques. Copyright © 2017 Elsevier Inc. All rights reserved.

Re-polarization of nuclear spins using selective SABRE-INEPT

NASA Astrophysics Data System (ADS)

Knecht, Stephan; Kiryutin, Alexey S.; Yurkovskaya, Alexandra V.; Ivanov, Konstantin L.

2018-02-01

A method is proposed for significant improvement of NMR pulse sequences used in high-field SABRE (Signal Amplification By Reversible Exchange) experiments. SABRE makes use of spin order transfer from parahydrogen (pH2, the H2 molecule in its singlet spin state) to a substrate in a transient organometallic Ir-based complex. The technique proposed here utilizes "re-polarization", i.e., multiple application of an NMR pulse sequence used for spin order transfer. During re-polarization only the form of the substrate, which is bound to the complex, is excited by selective NMR pulses and the resulting polarization is transferred to the free substrate via chemical exchange. Owing to the fact that (i) only a small fraction of the substrate molecules is in the bound form and (ii) spin relaxation of the free substrate is slow, the re-polarization scheme provides greatly improved NMR signal enhancement, ε . For instance, when pyridine is used as a substrate, single use of the SABRE-INEPT sequence provides ε ≈ 260 for 15N nuclei, whereas SABRE-INEPT with re-polarization yields ε > 2000 . We anticipate that the proposed method is useful for achieving maximal NMR enhancement with spin hyperpolarization techniques.

Solid-State NMR Spectroscopy for the Physical Chemistry Laboratory

ERIC Educational Resources Information Center

Kinnun, Jacob J.; Leftin, Avigdor; Brown, Michael F.

2013-01-01

Solid-state nuclear magnetic resonance (NMR) spectroscopy finds growing application to inorganic and organic materials, biological samples, polymers, proteins, and cellular membranes. However, this technique is often neither included in laboratory curricula nor typically covered in undergraduate courses. On the other hand, spectroscopy and…

A Training Program in Breast Cancer Research Using NMR Techniques

DTIC Science & Technology

2004-07-01

student from Biochemistry) and three postdoctoral fellows. The new students have been introduced to the Biomedical NMR Laboratory and the Howard ... University Cancer Center. The trainees have continued to learn the theories and instrumentation behind nuclear MRI. The trainees have rotated through the

TOPICAL REVIEW: Spatial localization in nuclear magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Keevil, Stephen F.

2006-08-01

The ability to select a discrete region within the body for signal acquisition is a fundamental requirement of in vivo NMR spectroscopy. Ideally, it should be possible to tailor the selected volume to coincide exactly with the lesion or tissue of interest, without loss of signal from within this volume or contamination with extraneous signals. Many techniques have been developed over the past 25 years employing a combination of RF coil properties, static magnetic field gradients and pulse sequence design in an attempt to meet these goals. This review presents a comprehensive survey of these techniques, their various advantages and disadvantages, and implications for clinical applications. Particular emphasis is placed on the reliability of the techniques in terms of signal loss, contamination and the effect of nuclear relaxation and J-coupling. The survey includes techniques based on RF coil and pulse design alone, those using static magnetic field gradients, and magnetic resonance spectroscopic imaging. Although there is an emphasis on techniques currently in widespread use (PRESS, STEAM, ISIS and MRSI), the review also includes earlier techniques, in order to provide historical context, and techniques that are promising for future use in clinical and biomedical applications.

NMR Parameters Determination through ACE Committee Machine with Genetic Implanted Fuzzy Logic and Genetic Implanted Neural Network

NASA Astrophysics Data System (ADS)

Asoodeh, Mojtaba; Bagheripour, Parisa; Gholami, Amin

2015-06-01

Free fluid porosity and rock permeability, undoubtedly the most critical parameters of hydrocarbon reservoir, could be obtained by processing of nuclear magnetic resonance (NMR) log. Despite conventional well logs (CWLs), NMR logging is very expensive and time-consuming. Therefore, idea of synthesizing NMR log from CWLs would be of a great appeal among reservoir engineers. For this purpose, three optimization strategies are followed. Firstly, artificial neural network (ANN) is optimized by virtue of hybrid genetic algorithm-pattern search (GA-PS) technique, then fuzzy logic (FL) is optimized by means of GA-PS, and eventually an alternative condition expectation (ACE) model is constructed using the concept of committee machine to combine outputs of optimized and non-optimized FL and ANN models. Results indicated that optimization of traditional ANN and FL model using GA-PS technique significantly enhances their performances. Furthermore, the ACE committee of aforementioned models produces more accurate and reliable results compared with a singular model performing alone.

Using optimal control methods with constraints to generate singlet states in NMR

NASA Astrophysics Data System (ADS)

Rodin, Bogdan A.; Kiryutin, Alexey S.; Yurkovskaya, Alexandra V.; Ivanov, Konstantin L.; Yamamoto, Satoru; Sato, Kazunobu; Takui, Takeji

2018-06-01

A method is proposed for optimizing the performance of the APSOC (Adiabatic-Passage Spin Order Conversion) technique, which can be exploited in NMR experiments with singlet spin states. In this technique magnetization-to-singlet conversion (and singlet-to-magnetization conversion) is performed by using adiabatically ramped RF-fields. Optimization utilizes the GRAPE (Gradient Ascent Pulse Engineering) approach, in which for a fixed search area we assume monotonicity to the envelope of the RF-field. Such an approach allows one to achieve much better performance for APSOC; consequently, the efficiency of magnetization-to-singlet conversion is greatly improved as compared to simple model RF-ramps, e.g., linear ramps. We also demonstrate that the optimization method is reasonably robust to possible inaccuracies in determining NMR parameters of the spin system under study and also in setting the RF-field parameters. The present approach can be exploited in other NMR and EPR applications using adiabatic switching of spin Hamiltonians.

Osmotic dehydration of organic kiwifruit pre-treated by pulsed electric fields and monitored by NMR.

PubMed

Traffano-Schiffo, Maria Victoria; Laghi, Luca; Castro-Giraldez, Marta; Tylewicz, Urszula; Rocculi, Pietro; Ragni, Luigi; Dalla Rosa, Marco; Fito, Pedro J

2017-12-01

Osmotic dehydration (OD) is a widely used preservation technique that consists in the reduction in food water activity by the immersion of the biological tissue in hypertonic solutions. The aim of this work was to analyze the effect of pulsed electric fields (PEF) in mass transfer as a pre-treatment of the OD using NMR. In this sense, PEF pre-treatments were done using three different voltages (100, 250 and 400V/cm) and 60 number of pulse. The OD of kiwifruit was carried out in 61.5% of sucrose solution at 25°C, for a contact period from 0 to 120min. The water distribution into the cellular tissue was studied by NMR relaxometry. In conclusion, NMR is an excellent technique for quantifying water molecules according to their interactions in the fruit tissue, obtaining the adsorbed water and opening the possibility to apply the BET model to fit the adsorbed isotherm over the whole range of water activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Level anti-crossings are a key factor for understanding para-hydrogen-induced hyperpolarization in SABRE experiments.

PubMed

Pravdivtsev, Andrey N; Yurkovskaya, Alexandra V; Vieth, Hans-Martin; Ivanov, Konstantin L; Kaptein, Robert

2013-10-07

Various hyperpolarization methods are able to enhance the sensitivity of nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) by several orders of magnitude. Among these methods are para-hydrogen-induced polarization (PHIP) and signal amplification by reversible exchange (SABRE), which exploit the strong nuclear alignment of para-hydrogen. Several SABRE experiments have been reported but, so far, it has not been possible to account for the experimentally observed sign and magnetic-field dependence of substrate polarization. Herein, we present an analysis based on level anti-crossings (LACs), which provides a complete understanding of the SABRE effect. The field-dependence of both net and anti-phase polarization is measured for several ligands, which can be reproduced by the theory. The similar SABRE field-dependence for different ligands is also explained. In general, the LAC concept allows complex spin dynamics to be unraveled, and is crucial for optimizing the performance of novel hyperpolarization methods in NMR and MRI techniques. Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

New water soluble Hg2 + selective fluorescent calix[4]arenes: Synthesis and application in living cells imaging

NASA Astrophysics Data System (ADS)

Oguz, Mehmet; Bhatti, Asif Ali; Karakurt, Serdar; Aktas, Mehmet; Yilmaz, Mustafa

2017-01-01

The present study demonstrates the synthesis of water-soluble fluorescent calix[4]arenes (6 and 7) and its application in living cell imaging for Hg2 + detection at a low level. The synthesized fluorescent ligands 6 and 7 were characterized by 1H NMR technique. The fluorescent study showed both water soluble ligands were Hg2 + selective and follow photo-induced electron transfer (PET) process. From the fluorimeter titration experiment detection limit was calculated as 1.14 × 10- 5 and 3.42 × 10- 5 for ligand 6 and 7, respectively. From the Benesi-Hildebrand plot binding constant values were evaluated as 666.7 and 733.3 M- 1 for 6 and 7, respectively. The interactions between ligands 6 and 7 and Hg2 + were also demonstrated in living cells, SW-620, using Fluorescent Cell Imager. While ligands 6 and 7 alone show fluorescent properties, they loss their action with the presence of Hg2 + in SW-620 cells.

Autonomous driving in NMR.

PubMed

Perez, Manuel

2017-01-01

The automatic analysis of NMR data has been a much-desired endeavour for the last six decades, as it is the case with any other analytical technique. This need for automation has only grown as advances in hardware; pulse sequences and automation have opened new research areas to NMR and increased the throughput of data. Full automatic analysis is a worthy, albeit hard, challenge, but in a world of artificial intelligence, instant communication and big data, it seems that this particular fight is happening with only one technique at a time (let this be NMR, MS, IR, UV or any other), when the reality of most laboratories is that there are several types of analytical instrumentation present. Data aggregation, verification and elucidation by using complementary techniques (e.g. MS and NMR) is a desirable outcome to pursue, although a time-consuming one if performed manually; hence, the use of automation to perform the heavy lifting for users is required to make the approach attractive for scientists. Many of the decisions and workflows that could be implemented under automation will depend on the two-way communication with databases that understand analytical data, because it is desirable not only to query these databases but also to grow them in as much of an automatic manner as possible. How these databases are designed, set up and the data inside classified will determine what workflows can be implemented. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Method for nuclear magnetic resonance imaging

DOEpatents

Kehayias, J.J.; Joel, D.D.; Adams, W.H.; Stein, H.L.

1988-05-26

A method for in vivo NMR imaging of the blood vessels and organs of a patient characterized by using a dark dye-like imaging substance consisting essentially of a stable, high-purity concentration of D/sub 2/O in a solution with water.

Toward MRI microimaging of single biological cells

NASA Astrophysics Data System (ADS)

Seeber, Derek Allan

There is a great advantage in signal to noise ratio (SNR) that can be obtained in nuclear magnetic resonance (NMR) on very small samples (having spatial dimensions ˜100 mum or less) if one employs NMR "microcoils" that are of similarly small dimensions. These gains in SNR could enable magnetic resonance imaging (MRI) microscopy with spatial resolutions of ˜1--2 mum, much better than currently available. We report the design and testing of a NMR microcoil receiver apparatus, employing solenoidal microcoils of dimensions of tens to hundreds of microns, using an applied field of 9 Tesla (proton frequency 383 MHz). For the smallest receiver coils we attain sensitivity sufficient to observe proton NMR with SNR one in a single scan applied to ˜10 mum3 (10 fl) water sample, containing 7 x 1011 total proton spins. In addition to the NMR applications, microcoils have been applied to MRI producing images with spatial resolutions as low as 2 mum x 3.5 mum x 14.8 mum on phantom images of rods and beads. This resolution can be further improved. MRI imaging of small sample volumes requires significant hardware modifications and improvements, all of which are discussed. Specifically, MRI microscopy requires very strong (>10 T/m), rapidly switchable triaxial magnetic field gradients. We report the design and construction of such a triaxial gradient system, producing gradient substantially greater than 15 T/m in all three directions, x, y, and z (as high as 50 T/m for the x direction). The gradients are power by a custom designed power supply capable of providing currents in excess of 200 amps and switching times of less than 5 mus corresponding to slew rates of greater that 107 T/m/s. The gradients are adequately uniform (within 5% over a volume of 600 mum3) and sufficient for microcoil MRI of small samples.

Combining 27Al Solid-State NMR and First-Principles Simulations To Explore Crystal Structure in Disordered Aluminum Oxynitride.

PubMed

Tu, Bingtian; Liu, Xin; Wang, Hao; Wang, Weimin; Zhai, Pengcheng; Fu, Zhengyi

2016-12-19

The nuclear magnetic resonance (NMR) technique gives insight into the local information in a crystal structure, while Rietveld refinement of powder X-ray diffraction (PXRD) sketches out the framework of a crystal lattice. In this work, first-principles calculations were combined with the solid-state NMR technique and Rietveld refinement to explore the crystal structure of a disordered aluminum oxynitride (γ-alon). The theoretical NMR parameters (chemical shift, δ iso , quadrupolar coupling constants, C Q , and asymmetry parameter, η) of Al 22.5 O 28.5 N 3.5 , predicted by the gauge-including projector augmented wave (GIPAW) algorithm, were used to facilitate the analytical investigation of the 27 Al magic-angle spinning (MAS) NMR spectra of the as-prepared sample, whose formula was confirmed to be Al 2.811 O 3.565 N 0.435 by quantitative analysis. The experimental δ iso , C Q , and η of 27 Al showed a small discrepancy compared with theoretical models. The ratio of aluminum located at the 8a to 16d sites was calculated to be 0.531 from the relative integration of peaks in the 27 Al NMR spectra. The occupancies of aluminum at the 8a and 16d positions were determined through NMR investigations to be 0.9755 and 0.9178, respectively, and were used in the Rietveld refinement to obtain the lattice parameter and anion parameter of Al 2.811 O 3.565 N 0.435 . The results from 27 Al NMR investigations and PXRD structural refinement complemented each other. This work provides a powerful and accessible strategy to precisely understand the crystal structure of novel oxynitride materials with multiple disorder.

Discrete decoding based ultrafast multidimensional nuclear magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Wei, Zhiliang; Lin, Liangjie; Ye, Qimiao; Li, Jing; Cai, Shuhui; Chen, Zhong

2015-07-01

The three-dimensional (3D) nuclear magnetic resonance (NMR) spectroscopy constitutes an important and powerful tool in analyzing chemical and biological systems. However, the abundant 3D information arrives at the expense of long acquisition times lasting hours or even days. Therefore, there has been a continuous interest in developing techniques to accelerate recordings of 3D NMR spectra, among which the ultrafast spatiotemporal encoding technique supplies impressive acquisition speed by compressing a multidimensional spectrum in a single scan. However, it tends to suffer from tradeoffs among spectral widths in different dimensions, which deteriorates in cases of NMR spectroscopy with more dimensions. In this study, the discrete decoding is proposed to liberate the ultrafast technique from tradeoffs among spectral widths in different dimensions by focusing decoding on signal-bearing sites. For verifying its feasibility and effectiveness, we utilized the method to generate two different types of 3D spectra. The proposed method is also applicable to cases with more than three dimensions, which, based on the experimental results, may widen applications of the ultrafast technique.

A (13)C NMR analysis of the effects of electron radiation on graphite/polyetherimide composites

NASA Technical Reports Server (NTRS)

Ferguson, Milton W.

1989-01-01

Initial investigations have been made into the use of high resolution nuclear magnetic resonance (NMR) for the characterization of radiation effects in graphite and Kevlar fibers, polymers, and the fiber/matrix interface in graphite/polyetherimide composites. Sample preparation techniques were refined. Essential equipment has been procured. A new NMR probe was constructed to increase the proton signal-to-noise ratio. Problem areas have been identified and plans developed to resolve them.

Hyperpolarized 13C NMR lifetimes in the liquid-state: relating structures and T1 relaxation times

NASA Astrophysics Data System (ADS)

Parish, Christopher; Niedbalski, Peter; Hashami, Zohreh; Fidelino, Leila; Kovacs, Zoltan; Lumata, Lloyd

Among the various attempts to solve the insensitivity problem in nuclear magnetic resonance (NMR), the physics-based technique dissolution dynamic nuclear polarization (DNP) is probably the most successful method of hyperpolarization or amplifying NMR signals. Using this technique, liquid-state NMR signal enhancements of several thousand-fold are expected for low-gamma nuclei such as carbon-13. The lifetimes of these hyperpolarized 13C NMR signals are directly related to their 13C spin-lattice relaxation times T1. Depending upon the 13C isotopic location, the lifetimes of hyperpolarized 13C compounds can range from a few seconds to minutes. In this study, we have investigated the hyperpolarized 13C NMR lifetimes of several 13C compounds with various chemical structures from glucose, acetate, citric acid, naphthalene to tetramethylallene and their deuterated analogs at 9.4 T and 25 deg C. Our results show that the 13C T1s of these compounds can range from a few seconds to more than 60 s at this field. Correlations between the chemical structures and T1 relaxation times will be discussed and corresponding implications of these results on 13C DNP experiments will be revealed. US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

Tracking Equilibrium and Nonequilibrium Shifts in Data with TREND.

PubMed

Xu, Jia; Van Doren, Steven R

2017-01-24

Principal component analysis (PCA) discovers patterns in multivariate data that include spectra, microscopy, and other biophysical measurements. Direct application of PCA to crowded spectra, images, and movies (without selecting peaks or features) was shown recently to identify their equilibrium or temporal changes. To enable the community to utilize these capabilities with a wide range of measurements, we have developed multiplatform software named TREND to Track Equilibrium and Nonequilibrium population shifts among two-dimensional Data frames. TREND can also carry this out by independent component analysis. We highlight a few examples of finding concurrent processes. TREND extracts dual phases of binding to two sites directly from the NMR spectra of the titrations. In a cardiac movie from magnetic resonance imaging, TREND resolves principal components (PCs) representing breathing and the cardiac cycle. TREND can also reconstruct the series of measurements from selected PCs, as illustrated for a biphasic, NMR-detected titration and the cardiac MRI movie. Fidelity of reconstruction of series of NMR spectra or images requires more PCs than needed to plot the largest population shifts. TREND reads spectra from many spectroscopies in the most common formats (JCAMP-DX and NMR) and multiple movie formats. The TREND package thus provides convenient tools to resolve the processes recorded by diverse biophysical methods. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Low-energy electron holographic imaging of individual tobacco mosaic virions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Longchamp, Jean-Nicolas, E-mail: longchamp@physik.uzh.ch; Latychevskaia, Tatiana; Escher, Conrad

2015-09-28

Modern structural biology relies on Nuclear Magnetic Resonance (NMR), X-ray crystallography, and cryo-electron microscopy for gaining information on biomolecules at nanometer, sub-nanometer, or atomic resolution. All these methods, however, require averaging over a vast ensemble of entities, and hence knowledge on the conformational landscape of an individual particle is lost. Unfortunately, there are now strong indications that even X-ray free electron lasers will not be able to image individual molecules but will require nanocrystal samples. Here, we show that non-destructive structural biology of single particles has now become possible by means of low-energy electron holography. As an example, individual tobaccomore » mosaic virions deposited on ultraclean freestanding graphene are imaged at 1 nm resolution revealing structural details arising from the helical arrangement of the outer protein shell of the virus. Since low-energy electron holography is a lens-less technique and since electrons with a deBroglie wavelength of approximately 1 Å do not impose radiation damage to biomolecules, the method has the potential for Angstrom resolution imaging of single biomolecules.« less

Fractional motion model for characterization of anomalous diffusion from NMR signals.

PubMed

Fan, Yang; Gao, Jia-Hong

2015-07-01

Measuring molecular diffusion has been used to characterize the properties of living organisms and porous materials. NMR is able to detect the diffusion process in vivo and noninvasively. The fractional motion (FM) model is appropriate to describe anomalous diffusion phenomenon in crowded environments, such as living cells. However, no FM-based NMR theory has yet been established. Here, we present a general formulation of the FM-based NMR signal under the influence of arbitrary magnetic field gradient waveforms. An explicit analytic solution of the stretched exponential decay format for NMR signals with finite-width Stejskal-Tanner bipolar pulse magnetic field gradients is presented. Signals from a numerical simulation matched well with the theoretical prediction. In vivo diffusion-weighted brain images were acquired and analyzed using the proposed theory, and the resulting parametric maps exhibit remarkable contrasts between different brain tissues.

Fractional motion model for characterization of anomalous diffusion from NMR signals

NASA Astrophysics Data System (ADS)

Fan, Yang; Gao, Jia-Hong

2015-07-01

Measuring molecular diffusion has been used to characterize the properties of living organisms and porous materials. NMR is able to detect the diffusion process in vivo and noninvasively. The fractional motion (FM) model is appropriate to describe anomalous diffusion phenomenon in crowded environments, such as living cells. However, no FM-based NMR theory has yet been established. Here, we present a general formulation of the FM-based NMR signal under the influence of arbitrary magnetic field gradient waveforms. An explicit analytic solution of the stretched exponential decay format for NMR signals with finite-width Stejskal-Tanner bipolar pulse magnetic field gradients is presented. Signals from a numerical simulation matched well with the theoretical prediction. In vivo diffusion-weighted brain images were acquired and analyzed using the proposed theory, and the resulting parametric maps exhibit remarkable contrasts between different brain tissues.

Microtesla MRI with dynamic nuclear polarization

NASA Astrophysics Data System (ADS)

Zotev, Vadim S.; Owens, Tuba; Matlashov, Andrei N.; Savukov, Igor M.; Gomez, John J.; Espy, Michelle A.

2010-11-01

Magnetic resonance imaging at microtesla fields is a promising imaging method that combines the pre-polarization technique and broadband signal reception by superconducting quantum interference device (SQUID) sensors to enable in vivo MRI at microtesla-range magnetic fields similar in strength to the Earth magnetic field. Despite significant advances in recent years, the potential of microtesla MRI for biomedical imaging is limited by its insufficient signal-to-noise ratio due to a relatively low sample polarization. Dynamic nuclear polarization (DNP) is a widely used approach that allows polarization enhancement by 2-4 orders of magnitude without an increase in the polarizing field strength. In this work, the first implementation of microtesla MRI with Overhauser DNP and SQUID signal detection is described. The first measurements of carbon-13 NMR spectra at microtesla fields are also reported. The experiments were performed at the measurement field of 96 μT, corresponding to Larmor frequency of 4 kHz for protons and 1 kHz for carbon-13. The Overhauser DNP was carried out at 3.5-5.7 mT fields using rf irradiation at 120 MHz. Objects for imaging included water phantoms and a cactus plant. Aqueous solutions of metabolically relevant sodium bicarbonate, pyruvate, alanine, and lactate, labeled with carbon-13, were used for NMR studies. All the samples were doped with TEMPO free radicals. The Overhauser DNP enabled nuclear polarization enhancement by factor as large as -95 for protons and as large as -200 for carbon-13, corresponding to thermal polarizations at 0.33 T and 1.1 T fields, respectively. These results demonstrate that SQUID-based microtesla MRI can be naturally combined with Overhauser DNP in one system, and that its signal-to-noise performance is greatly improved in this case. They also suggest that microtesla MRI can become an efficient tool for in vivo imaging of hyperpolarized carbon-13, produced by low-temperature dissolution DNP.

TU-EF-BRA-02: Longitudinal Proton Spin Relaxation and T1-Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemen, L.

NMR, and Proton Density MRI of the 1D Patient - Anthony Wolbarst Net Voxel Magnetization, m(x,t). T1-MRI; The MRI Device - Lisa Lemen ‘Classical’ NMR; FID Imaging in 1D via k-Space - Nathan Yanasak Spin-Echo; S-E/Spin Warp in a 2D Slice - Ronald Price Magnetic resonance imaging not only reveals the structural, anatomic details of the body, as does CT, but also it can provide information on the physiological status and pathologies of its tissues, like nuclear medicine. It can display high-quality slice and 3D images of organs and vessels viewed from any perspective, with resolution better than 1 mm.more » MRI is perhaps most extraordinary and notable for the plethora of ways in which it can create unique forms of image contrast, reflective of fundamentally different biophysical phenomena. As with ultrasound, there is no risk from ionizing radiation to the patient or staff, since no X-rays or radioactive nuclei are involved. Instead, MRI harnesses magnetic fields and radio waves to probe the stable nuclei of the ordinary hydrogen atoms (isolated protons) occurring in water and lipid molecules within and around cells. MRI consists, in essence, of creating spatial maps of the electromagnetic environments around these hydrogen nuclei. Spatial variations in the proton milieus can be related to clinical differences in the biochemical and physiological properties and conditions of the associated tissues. Imaging of proton density (PD), and of the tissue proton spin relaxation times known as T1 and T2, all can reveal important clinical information, but they do so with approaches so dissimilar from one another that each is chosen for only certain clinical situations. T1 and T2 in a voxel are determined by different aspects of the rotations and other motions of the water and lipid molecules involved, as constrained by the local biophysical surroundings within and between its cells – and they, in turn, depend on the type of tissue and its state of health. Three other common applications of MRI exploit its capability to detect and image distinct movements of fluids: MR angiography (MRA), which rivals CT angiography but often requires no contrast medium, monitors the bulk flow of blood; functional MRI ( f MRI), distinguishes the perfusion of oxygenated blood from that of de-oxygenated, and lights up parts of the brain that are activated by a stimulus, rather like PET; and diffusion tensor imaging (DTI) indicates the diffusion of free water along tracts of axons, thereby bringing nerve trunks into view. There are variants on all of these themes, and on others as well. Magnetic Resonance Spectroscopy (MRS), for example, can perform non-invasive ‘virtual biopsies’ that allow identification of certain cancers and other lesions. And an MRI-guided needle biopsy can sample brain tissue from a region only millimeters in dimensions. MRI, however, involves deeper and more complex aspects of physics, technology, and biology than do most other imaging modalities, and it is widely considered to be correspondingly more difficult to learn. We could probably cover all of this rather comprehensively if we had 50 hours available rather than 2 ̶ but, to paraphrase a former Secretary of Defense, you tell your story in the time you have allotted. The four presenters and another physicist, Kevin King from GE, have combined their efforts to co-author a single slide show that describes essentials of MRI as simply as possible. It is obviously far from thorough, but hopefully it will succeed in explaining some of the basics in a simplified but still valid fashion; in providing a taste of the numerous capabilities and complexities of the modality; and in whetting your appetite to learn more. Part I. NMR, and Proton Density MRI of the 1D Patient (Wolbarst), begins with an introductory case study that illustrates a half dozen ways in which MRI provides valuable clinical information. It then explores the nuclear magnetic resonance (NMR) phenomenon, which underlies MRI. NMR can be introduced with either of two approaches. In the first, one thinks (loosely) of the nuclei of hydrogen atoms as (rotating and charged and therefore) magnetic objects, whose spin-axes tend to align in a strong external magnetic field, much like a compass needle. As with the Bohr atom, this spin-up/spin-down picture is a highly abridged version of the full quantum mechanical treatment, but still it leads to some useful, legitimate pictures of the NMR process occurring within a voxel: When RF photons of the correct (Larmor) frequency elevate protons in a fixed magnetic field out of their lower-energy spin state into the upper, the NMR phenomenon is indicated by the detectable absorption of RF power. With the addition of a linear gradient field along a multi-voxel, one-dimensional patient/phantom, as well, we can determine the water content of each compartment – an example of a real MRI study, albeit in 1D. Part I concludes with a discussion of the net magnetization at position x, m0(x), under conditions of dynamic thermal equilibrium, which leads into: Part II. Net Voxel Magnetization, m(x,t); T1-MRI; The MRI Device (Lemen), investigates the biophysics of the form of proton spin relaxation process characterized by the time T1. It then moves on to the creation of an MR image that displays the spatial variation in the values of this clinically relevant parameter, again in 1D. Finally, the design and workings of a clinical MRI machine are sketched, in preparation for: Part III. ‘Classical’ NMR; FID Imaging in 1D via k-Space (Yanasak) presents the second standard approach to NMR and MRI, the classical model. It focuses on the time dependence of the net nuclear magnetization, m(x,t), the overall magnetic field generated by the cohort of protons in the voxel at position x. Quite remarkably, this nuclear net magnetization itself acts in a strong magnetic field like a gyroscope in a gravitational field. This tack is better for explaining Free Induction Decay (FID), which involves a brief introduction to the Fourier transform and k-space. This leads to conventional Spin-Echo (S-E) reconstruction techniques for creating clinical images from raw data, and sets the stage for: Part IV. Spin-Echo; S-E / Spin Warp in a 2D Slice (Price) discusses application of the S- E sequence of radiofrequency pulses and gradient magnetic fields to the 1D patient. T2 is introduced but not explained. This Part also considers how to manipulate the image acquisition parameters so as to generate clinical pictures with contrast dominated by spatial variations in PD, T1, or T2. We conclude by demonstrating the spin-warp approach to imaging in 2D with a simple 2×2, 4-voxel example. Much of this material is presented in more detail in the chapter “MRI of the One-dimensional Patient, Part I”, in Advances in Medical Physics, Vol 5 (2014). Copies are on display at the Medical Physics Publishing booth. Learning Objectives: The participant will learn about the processes of NMR and T1 spin relaxation in a tissue voxel in a uniform magnetic field. The participant will learn about combining spin-up/spin-down NMR and T1 processes with a linear gradient to effect frequency-encoding of voxel spatial position. This approach can be used to create proton density and T1 MRI maps, respectively, of the contents of multi-voxel 1D phantoms. The participant will learn about how the ‘classical’ model of NMR it can generate Free Induction Decay (FID) images of 1D phantoms, which involves the use of the Fourier transform in k-space. This can lead simply into standard Spin-Echo images. The participant will learn about extending Spin-Echo imaging into 2 and more dimensions.« less

TU-EF-BRA-03: Free Induction Decay (without the Decay) and Spin-Echo Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Price, R.

NMR, and Proton Density MRI of the 1D Patient - Anthony Wolbarst Net Voxel Magnetization, m(x,t). T1-MRI; The MRI Device - Lisa Lemen ‘Classical’ NMR; FID Imaging in 1D via k-Space - Nathan Yanasak Spin-Echo; S-E/Spin Warp in a 2D Slice - Ronald Price Magnetic resonance imaging not only reveals the structural, anatomic details of the body, as does CT, but also it can provide information on the physiological status and pathologies of its tissues, like nuclear medicine. It can display high-quality slice and 3D images of organs and vessels viewed from any perspective, with resolution better than 1 mm.more » MRI is perhaps most extraordinary and notable for the plethora of ways in which it can create unique forms of image contrast, reflective of fundamentally different biophysical phenomena. As with ultrasound, there is no risk from ionizing radiation to the patient or staff, since no X-rays or radioactive nuclei are involved. Instead, MRI harnesses magnetic fields and radio waves to probe the stable nuclei of the ordinary hydrogen atoms (isolated protons) occurring in water and lipid molecules within and around cells. MRI consists, in essence, of creating spatial maps of the electromagnetic environments around these hydrogen nuclei. Spatial variations in the proton milieus can be related to clinical differences in the biochemical and physiological properties and conditions of the associated tissues. Imaging of proton density (PD), and of the tissue proton spin relaxation times known as T1 and T2, all can reveal important clinical information, but they do so with approaches so dissimilar from one another that each is chosen for only certain clinical situations. T1 and T2 in a voxel are determined by different aspects of the rotations and other motions of the water and lipid molecules involved, as constrained by the local biophysical surroundings within and between its cells – and they, in turn, depend on the type of tissue and its state of health. Three other common applications of MRI exploit its capability to detect and image distinct movements of fluids: MR angiography (MRA), which rivals CT angiography but often requires no contrast medium, monitors the bulk flow of blood; functional MRI ( f MRI), distinguishes the perfusion of oxygenated blood from that of de-oxygenated, and lights up parts of the brain that are activated by a stimulus, rather like PET; and diffusion tensor imaging (DTI) indicates the diffusion of free water along tracts of axons, thereby bringing nerve trunks into view. There are variants on all of these themes, and on others as well. Magnetic Resonance Spectroscopy (MRS), for example, can perform non-invasive ‘virtual biopsies’ that allow identification of certain cancers and other lesions. And an MRI-guided needle biopsy can sample brain tissue from a region only millimeters in dimensions. MRI, however, involves deeper and more complex aspects of physics, technology, and biology than do most other imaging modalities, and it is widely considered to be correspondingly more difficult to learn. We could probably cover all of this rather comprehensively if we had 50 hours available rather than 2 ̶ but, to paraphrase a former Secretary of Defense, you tell your story in the time you have allotted. The four presenters and another physicist, Kevin King from GE, have combined their efforts to co-author a single slide show that describes essentials of MRI as simply as possible. It is obviously far from thorough, but hopefully it will succeed in explaining some of the basics in a simplified but still valid fashion; in providing a taste of the numerous capabilities and complexities of the modality; and in whetting your appetite to learn more. Part I. NMR, and Proton Density MRI of the 1D Patient (Wolbarst), begins with an introductory case study that illustrates a half dozen ways in which MRI provides valuable clinical information. It then explores the nuclear magnetic resonance (NMR) phenomenon, which underlies MRI. NMR can be introduced with either of two approaches. In the first, one thinks (loosely) of the nuclei of hydrogen atoms as (rotating and charged and therefore) magnetic objects, whose spin-axes tend to align in a strong external magnetic field, much like a compass needle. As with the Bohr atom, this spin-up/spin-down picture is a highly abridged version of the full quantum mechanical treatment, but still it leads to some useful, legitimate pictures of the NMR process occurring within a voxel: When RF photons of the correct (Larmor) frequency elevate protons in a fixed magnetic field out of their lower-energy spin state into the upper, the NMR phenomenon is indicated by the detectable absorption of RF power. With the addition of a linear gradient field along a multi-voxel, one-dimensional patient/phantom, as well, we can determine the water content of each compartment – an example of a real MRI study, albeit in 1D. Part I concludes with a discussion of the net magnetization at position x, m0(x), under conditions of dynamic thermal equilibrium, which leads into: Part II. Net Voxel Magnetization, m(x,t); T1-MRI; The MRI Device (Lemen), investigates the biophysics of the form of proton spin relaxation process characterized by the time T1. It then moves on to the creation of an MR image that displays the spatial variation in the values of this clinically relevant parameter, again in 1D. Finally, the design and workings of a clinical MRI machine are sketched, in preparation for: Part III. ‘Classical’ NMR; FID Imaging in 1D via k-Space (Yanasak) presents the second standard approach to NMR and MRI, the classical model. It focuses on the time dependence of the net nuclear magnetization, m(x,t), the overall magnetic field generated by the cohort of protons in the voxel at position x. Quite remarkably, this nuclear net magnetization itself acts in a strong magnetic field like a gyroscope in a gravitational field. This tack is better for explaining Free Induction Decay (FID), which involves a brief introduction to the Fourier transform and k-space. This leads to conventional Spin-Echo (S-E) reconstruction techniques for creating clinical images from raw data, and sets the stage for: Part IV. Spin-Echo; S-E / Spin Warp in a 2D Slice (Price) discusses application of the S- E sequence of radiofrequency pulses and gradient magnetic fields to the 1D patient. T2 is introduced but not explained. This Part also considers how to manipulate the image acquisition parameters so as to generate clinical pictures with contrast dominated by spatial variations in PD, T1, or T2. We conclude by demonstrating the spin-warp approach to imaging in 2D with a simple 2×2, 4-voxel example. Much of this material is presented in more detail in the chapter “MRI of the One-dimensional Patient, Part I”, in Advances in Medical Physics, Vol 5 (2014). Copies are on display at the Medical Physics Publishing booth. Learning Objectives: The participant will learn about the processes of NMR and T1 spin relaxation in a tissue voxel in a uniform magnetic field. The participant will learn about combining spin-up/spin-down NMR and T1 processes with a linear gradient to effect frequency-encoding of voxel spatial position. This approach can be used to create proton density and T1 MRI maps, respectively, of the contents of multi-voxel 1D phantoms. The participant will learn about how the ‘classical’ model of NMR it can generate Free Induction Decay (FID) images of 1D phantoms, which involves the use of the Fourier transform in k-space. This can lead simply into standard Spin-Echo images. The participant will learn about extending Spin-Echo imaging into 2 and more dimensions.« less

NMR characterization of polymers: Review and update

USDA-ARS?s Scientific Manuscript database

NMR spectroscopy is a major technique for the characterization and analysis of polymers. A large number of methodologies have been developed in both the liquid and the solid state, and the literature has grown considerably (1-5). The field now covers a broad spectrum of activities, including polym...

Low Cost, High-Throughput 3-D Pulmonary Imager Using Hyperpolarized Contrast Agents and Low-Field MRI

DTIC Science & Technology

2017-10-01

capacitive matching element (see Figs. S3 and S4, SI). The solenoid was constructed with 170 windings using 28 AWG gauge magnet wire with a measured...10.1002/9780470034590.emrstm0491. (59) Minard, K. R.; Wind , R. A. Solenoidal microcoil designPart II: Optimizing winding parameters for maximum...TiO2 catalyst to an NMR tube containing 0.5 mL of acetone-d6. The position of the NMR tube inside the NMR spinner turbine was adjusted for the

Rotating-frame gradient fields for magnetic resonance imaging and nuclear magnetic resonance in low fields

DOEpatents

Bouchard, Louis-Serge; Pines, Alexander; Demas, Vasiliki

2014-01-21

A system and method for Fourier encoding a nuclear magnetic resonance (NMR) signal is disclosed. A static magnetic field B.sub.0 is provided along a first direction. An NMR signal from the sample is Fourier encoded by applying a rotating-frame gradient field B.sub.G superimposed on the B.sub.0, where the B.sub.G comprises a vector component rotating in a plane perpendicular to the first direction at an angular frequency .omega.in a laboratory frame. The Fourier-encoded NMR signal is detected.

Solution state nuclear magnetic resonance spectroscopy for biological metabolism and pathway intermediate analysis.

PubMed

Nealon, Gareth L; Howard, Mark J

2016-12-15

Using nuclear magnetic resonance (NMR) spectroscopy in the study of metabolism has been immensely popular in medical- and health-related research but has yet to be widely applied to more fundamental biological problems. This review provides some NMR background relevant to metabolism, describes why 1 H NMR spectra are complex as well as introducing relevant terminology and definitions. The applications and practical considerations of NMR metabolic profiling and 13 C NMR-based flux analyses are discussed together with the elegant 'enzyme trap' approach for identifying novel metabolic pathway intermediates. The importance of sample preparation and data analysis are also described and explained with reference to data precision and multivariate analysis to introduce researchers unfamiliar with NMR and metabolism to consider this technique for their research interests. Finally, a brief glance into the future suggests NMR-based metabolism has room to expand in the 21st century through new isotope labels, and NMR technologies and methodologies. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

Interlaboratory Comparison Test as an Evaluation of Applicability of an Alternative Edible Oil Analysis by 1H NMR Spectroscopy.

PubMed

Zailer, Elina; Holzgrabe, Ulrike; Diehl, Bernd W K

2017-11-01

A proton (1H) NMR spectroscopic method was established for the quality assessment of vegetable oils. To date, several research studies have been published demonstrating the high potential of the NMR technique in lipid analysis. An interlaboratory comparison was organized with the following main objectives: (1) to evaluate an alternative analysis of edible oils by using 1H NMR spectroscopy; and (2) to determine the robustness and reproducibility of the method. Five different edible oil samples were analyzed by evaluating 15 signals (free fatty acids, peroxides, aldehydes, double bonds, and linoleic and linolenic acids) in each spectrum. A total of 21 NMR data sets were obtained from 17 international participant laboratories. The performance of each laboratory was assessed by their z-scores. The test was successfully passed by 90.5% of the participants. Results showed that NMR spectroscopy is a robust alternative method for edible oil analysis.

Successful Sampling Strategy Advances Laboratory Studies of NMR Logging in Unconsolidated Aquifers

NASA Astrophysics Data System (ADS)

Behroozmand, Ahmad A.; Knight, Rosemary; Müller-Petke, Mike; Auken, Esben; Barfod, Adrian A. S.; Ferré, Ty P. A.; Vilhelmsen, Troels N.; Johnson, Carole D.; Christiansen, Anders V.

2017-11-01

The nuclear magnetic resonance (NMR) technique has become popular in groundwater studies because it responds directly to the presence and mobility of water in a porous medium. There is a need to conduct laboratory experiments to aid in the development of NMR hydraulic conductivity models, as is typically done in the petroleum industry. However, the challenge has been obtaining high-quality laboratory samples from unconsolidated aquifers. At a study site in Denmark, we employed sonic drilling, which minimizes the disturbance of the surrounding material, and extracted twelve 7.6 cm diameter samples for laboratory measurements. We present a detailed comparison of the acquired laboratory and logging NMR data. The agreement observed between the laboratory and logging data suggests that the methodologies proposed in this study provide good conditions for studying NMR measurements of unconsolidated near-surface aquifers. Finally, we show how laboratory sample size and condition impact the NMR measurements.

Studies of organic paint binders by NMR spectroscopy

NASA Astrophysics Data System (ADS)

Spyros, A.; Anglos, D.

2006-06-01

Nuclear magnetic resonance spectroscopy is applied to the study of aged binding media used in paintings, namely linseed oil, egg tempera and an acrylic medium. High resolution 1D and 2D NMR experiments establish the state of hydrolysis and oxidation of the linseed and egg tempera binders after five years of aging, by determining several markers sensitive to the hydrolytic and oxidative processes of the binder lipid fraction. The composition of the acrylic binder co-polymer is determined by 2D NMR spectroscopy, while the identification of a surfactant, poly(ethylene glycol), found in greater amounts in aged acrylic medium, is reported. The non-destructive nature of the proposed analytical NMR methodology, and minimization of the amount of binder material needed through the use of sophisticated cryoprobes and hyphenated LC-NMR techniques, make NMR attractive for the arts analyst, in view of its rapid nature and experimental simplicity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pease, J.H.

The three dimensional structures of several small peptides were determined using a combination of {sup 1}H nuclear magnetic resonance (NMR) and distance geometry calculations. These techniques were found to be particularly helpful for analyzing structural differences between related peptides since all of the peptides' {sup 1}H NMR spectra are very similar. The structures of peptides from two separate classes are presented. Peptides in the first class are related to apamin, an 18 amino acid peptide toxin from honey bee venom. The {sup 1}H NMR assignments and secondary structure determination of apamin were done previously. Quantitative NMR measurements and distance geometrymore » calculations were done to calculate apamin's three dimensional structure. Peptides in the second class are 48 amino acid toxins from the sea anemone Radianthus paumotensis. The {sup 1}H NMR assignments of toxin II were done previously. The {sup 1}H NMR assignments of toxin III and the distance geometry calculations for both peptides are presented.« less

Challenges and perspectives in quantitative NMR.

PubMed

Giraudeau, Patrick

2017-01-01

This perspective article summarizes, from the author's point of view at the beginning of 2016, the major challenges and perspectives in the field of quantitative NMR. The key concepts in quantitative NMR are first summarized; then, the most recent evolutions in terms of resolution and sensitivity are discussed, as well as some potential future research directions in this field. A particular focus is made on methodologies capable of boosting the resolution and sensitivity of quantitative NMR, which could open application perspectives in fields where the sample complexity and the analyte concentrations are particularly challenging. These include multi-dimensional quantitative NMR and hyperpolarization techniques such as para-hydrogen-induced polarization or dynamic nuclear polarization. Because quantitative NMR cannot be dissociated from the key concepts of analytical chemistry, i.e. trueness and precision, the methodological developments are systematically described together with their level of analytical performance. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Application and Reliability of Solid-State NMR in Environmental Sciences

NASA Astrophysics Data System (ADS)

Knicker, Heike

2010-05-01

For the characterization of soil organic matter, a suite of analytical approaches are available. Chemical degradative methods involve an extraction scheme with which the soluble part of the mixture is isolated and analyzed by colorimetrical or chromatographic means. Macromolecular structures can be subjected to thermolytic or combined thermochemolytic degradation. Because secondary reactions (rearrangement, cracking, hydrogenation and polymerization) in a heterogeneous mixture cannot be excluded, it is obvious that conclusions regarding the original structure in the macromolecular phase have to be drawn with caution. A powerful alternative represents solid-state nuclear magnetic resonance (NMR) spectroscopy, allowing the examination of the bulk sample without major pre-treatment In environmental sciences, this technique mostly involves the isotope 13C to study the chemical composition of organic matter in soils, sediments or compost to study the temporal development of humic material or chemical alterations due to variation in environmental parameters. Due to its low sensibility solid-state 15N NMR studies on such samples are only found occasionally. The emphasis of solid-state NMR spectroscopy is not only to determine the gross chemical composition of the material under study via a chemical shift assignment but also a quantitative correlation between the different signal intensities and the relative contribution of the respective C or N types to the total organic C or N content. However, despite increasing popularity, this approach is still viewed as mysterious techniques, in particular with respect to quantification. Accordingly, the purpose of this review is to give a short overview on the possibilities and limitations of this technique in environmental science and in particular for the study of soil organic matter. In general, solid-state 13C NMR spectra of soil organic matter are obtained with the cross polarization magic angle spinning (CPMAS) technique. This technique increases the sensitivity of 13C by magnetization transfer from the 1H to the 13C spin system during a contact time tc. However, one has to bear in mind that some molecular properties may obscure quantification. Thus, for carbons with large C-H internuclear distances (bigger than four bonds, i.e in graphite structures) and for C in groups with high molecular mobility (i.e. gas) the proton-dipolar interactions are weakened and the polarization transfer may be incomplete. The observed intensity can also be affected by interactions of the protons with paramagnetic compounds. To circumvent this problem, the samples are often demineralized with hydrofluoric acid. Alternatively, the Bloch decay, a technique in which the 13C is directly excited is used. Here, on the other hand, one has to consider long relaxation times which may lead to saturation effects. Nevertheless, as it will be discussed within the presentation those quantification problems can be solved for most soil samples and then solid-state NMR spectroscopy represents a powerful tool for qualitative and quantitative analysis. Special techniques, such as dipolar dephasing or the proton spin relaxation editing can be used to extract additional information about chemical properties or mobility. A more detailed examination of the cross polarization behavior can be used to analyze the interaction of organic matter and paramagnetics but also for obtaining revealing properties on a molecular level. Applications involving isotopic labeling combined with both 13C and/or 15N NMR allows to follow the fate of a specific compound i.e. in a natural matrix and- if the enrichment is high enough - the use of 2D solid-state NMR techniques. In particular with respect to environmental chemistry, this combination of isotopic labeling with the use of corresponding NMR spectroscopy shows great potential for a better understanding of the kind of interaction between pollutants and natural organic matter.

MeRy-B: a web knowledgebase for the storage, visualization, analysis and annotation of plant NMR metabolomic profiles

PubMed Central

2011-01-01

Background Improvements in the techniques for metabolomics analyses and growing interest in metabolomic approaches are resulting in the generation of increasing numbers of metabolomic profiles. Platforms are required for profile management, as a function of experimental design, and for metabolite identification, to facilitate the mining of the corresponding data. Various databases have been created, including organism-specific knowledgebases and analytical technique-specific spectral databases. However, there is currently no platform meeting the requirements for both profile management and metabolite identification for nuclear magnetic resonance (NMR) experiments. Description MeRy-B, the first platform for plant 1H-NMR metabolomic profiles, is designed (i) to provide a knowledgebase of curated plant profiles and metabolites obtained by NMR, together with the corresponding experimental and analytical metadata, (ii) for queries and visualization of the data, (iii) to discriminate between profiles with spectrum visualization tools and statistical analysis, (iv) to facilitate compound identification. It contains lists of plant metabolites and unknown compounds, with information about experimental conditions, the factors studied and metabolite concentrations for several plant species, compiled from more than one thousand annotated NMR profiles for various organs or tissues. Conclusion MeRy-B manages all the data generated by NMR-based plant metabolomics experiments, from description of the biological source to identification of the metabolites and determinations of their concentrations. It is the first database allowing the display and overlay of NMR metabolomic profiles selected through queries on data or metadata. MeRy-B is available from http://www.cbib.u-bordeaux2.fr/MERYB/index.php. PMID:21668943

Recombinant Kinase Production and Fragment Screening by NMR Spectroscopy.

PubMed

Han, Byeonggu; Ahn, Hee-Chul

2016-01-01

During the past decade fragment-based drug discovery (FBDD) has rapidly evolved and several drugs or drug candidates developed by FBDD approach are clinically in use or in clinical trials. For example, vemurafenib, a V600E mutated BRAF inhibitor, was developed by utilizing FBDD approach and approved by FDA in 2011. In FBDD, screening of fragments is the starting step for identification of hits and lead generation. Fragment screening usually relies on biophysical techniques by which the protein-bound small molecules can be detected. NMR spectroscopy has been extensively used to study the molecular interaction between the protein and the ligand, and has many advantages in fragment screening over other biophysical techniques. This chapter describes the practical aspects of fragment screening by saturation transfer difference NMR.

Mass spectrometry for fragment screening.

PubMed

Chan, Daniel Shiu-Hin; Whitehouse, Andrew J; Coyne, Anthony G; Abell, Chris

2017-11-08

Fragment-based approaches in chemical biology and drug discovery have been widely adopted worldwide in both academia and industry. Fragment hits tend to interact weakly with their targets, necessitating the use of sensitive biophysical techniques to detect their binding. Common fragment screening techniques include differential scanning fluorimetry (DSF) and ligand-observed NMR. Validation and characterization of hits is usually performed using a combination of protein-observed NMR, isothermal titration calorimetry (ITC) and X-ray crystallography. In this context, MS is a relatively underutilized technique in fragment screening for drug discovery. MS-based techniques have the advantage of high sensitivity, low sample consumption and being label-free. This review highlights recent examples of the emerging use of MS-based techniques in fragment screening. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Is Low-field NMR a Complementary Tool to GC-MS in Quality Control of Essential Oils? A Case Study: Patchouli Essential Oil.

PubMed

Krause, Andre; Wu, Yu; Tian, Runtao; van Beek, Teris A

2018-04-24

High-field NMR is an expensive and important quality control technique. In recent years, cheaper and simpler low-field NMR has become available as a new quality control technique. In this study, 60 MHz 1 H-NMR was compared with GC-MS and refractometry for the detection of adulteration of essential oils, taking patchouli essential oil as a test case. Patchouli essential oil is frequently adulterated, even today. In total, 75 genuine patchouli essential oils, 10 commercial patchouli essential oils, 10 other essential oils, 17 adulterants, and 1 patchouli essential oil, spiked at 20% with those adulterants, were measured. Visual inspection of the NMR spectra allowed for easy detection of 14 adulterants, while gurjun and copaiba balsams proved difficult and one adulterant could not be detected. NMR spectra of 10 random essential oils differed not only strongly from patchouli essential oil but also from one another, suggesting that fingerprinting by low-field NMR is not limited to patchouli essential oil. Automated chemometric evaluation of NMR spectra was possible by similarity analysis (Mahalanobis distance) based on the integration from 0.1 - 8.1 ppm in 0.01 ppm increments. Good quality patchouli essential oils were recognised as well as 15 of 17 deliberate adulterations. Visual qualitative inspection by GC-MS allowed for the detection of all volatile adulterants. Nonvolatile adulterants, and all but one volatile adulterant, could be detected by semiquantitation. Different chemometric approaches showed satisfactory results. Similarity analyses were difficult with nonvolatile adulterants. Refractive index measurements could detect only 8 of 17 adulterants. Due to advantages such as simplicity, rapidity, reproducibility, and ability to detect nonvolatile adulterants, 60 MHz 1 H-NMR is complimentary to GC-MS for quality control of essential oils. Georg Thieme Verlag KG Stuttgart · New York.

Partial Removal of Pore and Loosely Bound Water by Low-Energy Drying Decreases Cortical Bone Toughness in Young and Old Donors

PubMed Central

Nyman, Jeffry S.; Gorochow, Lacey E.; Horch, R. Adam; Uppuganti, Sasidhar; Zein-Sabatto, Ahbid; Manhard, Mary Katherine; Does, Mark D.

2012-01-01

With an ability to quantify matrix-bound and pore water in bone, 1H nuclear magnetic resonance (NMR) relaxometry can potentially be implemented in clinical imaging to assess the fracture resistance of bone in a way that is independent of current X-ray techniques, which assess bone mineral density as a correlate of bone strength. Working towards that goal, we quantified the effect of partial dehydration in air on the mechanical and NMR properties of human cortical bone in order to understand whether NMR is sensitive to water-bone interactions at low energy and whether such interactions contribute to the age-related difference in the toughness of bone. Cadaveric femurs were collected from male and female donors falling into two age groups: 21 to 60 years of age (young) and 74 to 99 years of age (old). After extracting two samples from the medial cortex of the mid-shaft, tensile tests were conducted on Wet specimens and paired, Partially Dry (PtlD) specimens (prepared by low-energy drying in air to remove ~3% of original mass before testing). Prior analysis by micro-computed tomography found that there were no differences in intra-cortical porosity between the Wet and PtlD specimens nor did an age-related difference in porosity exist. PtlD specimens from young and old donors had significantly less toughness than Wet specimens, primarily due to a dehydration-related decrease in post-yield strain. The low-energy drying protocol did not affect the modulus and yield strength of bone. Subsequent dehydration of the PtlD specimens in a vacuum oven at 62 °C and then 103 °C, with quantification of water loss at each temperature, revealed an age-related shift from more loosely bound water to more tightly bound water. NMR detected a change in both bound and pore water pools with low-energy air-drying, and both pools were effectively removed when bone was oven-dried at 62 °C, irrespective of donor age. Although not strictly significant due to variability in the drying and testing conditions, the absolute difference in toughness between Wet and PtlD tended to be greater for the younger donors that had higher bone toughness and more bound water for the wet condition than did the older donors. With sensitivity to low-energy bone-water interactions, NMR, which underpins magnetic resonance imaging, has potential to assess fracture resistance of bone as it relates to bone toughness. PMID:23631897

Partial removal of pore and loosely bound water by low-energy drying decreases cortical bone toughness in young and old donors.

PubMed

Nyman, Jeffry S; Gorochow, Lacey E; Adam Horch, R; Uppuganti, Sasidhar; Zein-Sabatto, Ahbid; Manhard, Mary Katherine; Does, Mark D

2013-06-01

With an ability to quantify matrix-bound and pore water in bone, (1)H nuclear magnetic resonance (NMR) relaxometry can potentially be implemented in clinical imaging to assess the fracture resistance of bone in a way that is independent of current X-ray techniques, which assess bone mineral density as a correlate of bone strength. Working towards that goal, we quantified the effect of partial dehydration in air on the mechanical and NMR properties of human cortical bone in order to understand whether NMR is sensitive to water-bone interactions at low energy and whether such interactions contribute to the age-related difference in the toughness of bone. Cadaveric femurs were collected from male and female donors falling into two age groups: 21-60 years of age (young) and 74-99 years of age (old). After extracting two samples from the medial cortex of the mid-shaft, tensile tests were conducted on Wet specimens and paired, Partially Dry (PtlD) specimens (prepared by low-energy drying in air to remove ∼3% of original mass before testing). Prior analysis by micro-computed tomography found that there were no differences in intra-cortical porosity between the Wet and PtlD specimens nor did an age-related difference in porosity exist. PtlD specimens from young and old donors had significantly less toughness than Wet specimens, primarily due to a dehydration-related decrease in post-yield strain. The low-energy drying protocol did not affect the modulus and yield strength of bone. Subsequent dehydration of the PtlD specimens in a vacuum oven at 62°C and then 103°C, with quantification of water loss at each temperature, revealed an age-related shift from more loosely bound water to more tightly bound water. NMR detected a change in both bound and pore water pools with low-energy air-drying, and both pools were effectively removed when bone was oven-dried at 62°C, irrespective of donor age. Although not strictly significant due to variability in the drying and testing conditions, the absolute difference in toughness between Wet and PtlD tended to be greater for the younger donors that had higher bone toughness and more bound water for the wet condition than did the older donors. With sensitivity to low-energy bone-water interactions, NMR, which underpins magnetic resonance imaging, has potential to assess fracture resistance of bone as it relates to bone toughness. Published by Elsevier Ltd.

Evidence of a DHA Signature in the Lipidome and Metabolome of Human Hepatocytes.

PubMed

Ghini, Veronica; Di Nunzio, Mattia; Tenori, Leonardo; Valli, Veronica; Danesi, Francesca; Capozzi, Francesco; Luchinat, Claudio; Bordoni, Alessandra

2017-02-08

Cell supplementation with bioactive molecules often causes a perturbation in the whole intracellular environment. Omics techniques can be applied for the assessment of this perturbation. In this study, the overall effect of docosahexaenoic acid (DHA) supplementation on cultured human hepatocyte lipidome and metabolome has been investigated using nuclear magnetic resonance (NMR) in combination with traditional techniques. The effect of two additional bioactives sharing with DHA the lipid-lowering effect-propionic acid (PRO) and protocatechuic acid (PCA)-has also been evaluated in the context of possible synergism. NMR analysis of the cell lipid extracts showed that DHA supplementation, alone or in combination with PCA or PRO, strongly altered the cell lipid profile. The perfect discrimination between cells receiving DHA (alone or in combination) and the other cells reinforced the idea of a global rearrangement of the lipid environment induced by DHA. Notably, gas chromatography and fluorimetric analyses confirmed the strong discrimination obtained by NMR. The DHA signature was evidenced not only in the cell lipidome, but also in the metabolome. Results reported herein indicate that NMR, combined with other techniques, represents a fundamental approach to studying the effect of bioactive supplementation, particularly in the case of molecules with a broad spectrum of mechanisms of action.

129Xe NMR studies of biochar made from biobased materials

USDA-ARS?s Scientific Manuscript database

Biochar is created by pyrolysis of biobased materials under controlled oxidative environments. The product is charcoal-like and can be used as filtration medium, sequestrant for metallic ions, soil conditioner, and other applications. In our work we have found 129Xe NMR to be an excellent technique...

Using NMR-based metabolomics to monitor the biochemical composition of agricultural soils: a pilot study

USDA-ARS?s Scientific Manuscript database

NMR-based metabolomics plays a major role studying complex living systems. However, very few studies describe the application of this technique to the evaluation of soil metabolome. Here, we introduce a protocol for analyzing the biochemical compounds from agricultural soils where the microbial comm...

An NMR Protonation Study of Metal Diethylenetriaminepentaacetic Acid Complexes.

ERIC Educational Resources Information Center

Letkeman, Peter

1979-01-01

This experiment is suitable for an integrated laboratory course for senior chemistry majors. It introduces the student to a study of the relative basicity of different proton accepting sites. It serves as an opportunity to learn about nmr techniques and could extend to infrared, as well. (BB)

Trispyrazolylborate Complexes: An Advanced Synthesis Experiment Using Paramagnetic NMR, Variable-Temperature NMR, and EPR Spectroscopies

ERIC Educational Resources Information Center

Abell, Timothy N.; McCarrick, Robert M.; Bretz, Stacey Lowery; Tierney, David L.

2017-01-01

A structured inquiry experiment for inorganic synthesis has been developed to introduce undergraduate students to advanced spectroscopic techniques including paramagnetic nuclear magnetic resonance and electron paramagnetic resonance. Students synthesize multiple complexes with unknown first row transition metals and identify the unknown metals by…

MRI and unilateral NMR study of reindeer skin tanning processes.

PubMed

Zhu, Lizheng; Del Federico, Eleonora; Ilott, Andrew J; Klokkernes, Torunn; Kehlet, Cindie; Jerschow, Alexej

2015-04-07

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.

Relaxation time estimation in surface NMR

DOEpatents

Grunewald, Elliot D.; Walsh, David O.

2017-03-21

NMR relaxation time estimation methods and corresponding apparatus generate two or more alternating current transmit pulses with arbitrary amplitudes, time delays, and relative phases; apply a surface NMR acquisition scheme in which initial preparatory pulses, the properties of which may be fixed across a set of multiple acquisition sequence, are transmitted at the start of each acquisition sequence and are followed by one or more depth sensitive pulses, the pulse moments of which are varied across the set of multiple acquisition sequences; and apply processing techniques in which recorded NMR response data are used to estimate NMR properties and the relaxation times T.sub.1 and T.sub.2* as a function of position as well as one-dimensional and two-dimension distributions of T.sub.1 versus T.sub.2* as a function of subsurface position.

Modification and intercalation of layered zirconium phosphates: a solid-state NMR monitoring.

PubMed

Bakhmutov, Vladimir I; Kan, Yuwei; Sheikh, Javeed Ahmad; González-Villegas, Julissa; Colón, Jorge L; Clearfield, Abraham

2017-07-01

Several layered zirconium phosphates treated with Zr(IV) ions, modified by monomethoxy-polyethyleneglycol-monophosphate and intercalated with doxorubicin hydrochloride have been studied by solid-state MAS NMR techniques. The organic components of the phosphates have been characterized by the 13 C{ 1 H} CP MAS NMR spectra compared with those of initial compounds. The multinuclear NMR monitoring has provided to establish structure and covalent attachment of organic/inorganic moieties to the surface and interlayer spaces of the phosphates. The MAS NMR experiments including kinetics of proton-phosphorus cross polarization have resulted in an unusual structure of zirconium phosphate 6 combining decoration of the phosphate surface by polymer units and their partial intercalation into the interlayer space. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Metabolic studies with NMR spectroscopy of the alga Dunaliella salina trapped within agarose beads.

PubMed

Bental, M; Pick, U; Avron, M; Degani, H

1990-02-22

A technique for the entrapment of the unicellular algae Dunaliella salina in agarose beads and their perfusion during NMR measurements is presented. The trapped cells maintained their ability to proliferate under normal growth conditions, and remained viable and stable under steady-state conditions for long periods during NMR measurements. Following osmotic shock in the dark, prominent changes were observed in the intracellular level of ATP and polyphosphates, but little to no changes in the intracellular pH or orthoposphate content. When cells were subjected to hyperosmotic shock, the ATP level decreased. The content of NMR-visible polyphosphates decreased as well, presumably due to the production of longer, NMR-invisible structures. Following hypoosmotic shock, the ATP content increased and longer polyphosphates were broken down to shorter, more mobile polymers.

[Non-invasive analysis of proteins in living cells using NMR spectroscopy].

PubMed

Tochio, Hidehito; Murayama, Shuhei; Inomata, Kohsuke; Morimoto, Daichi; Ohno, Ayako; Shirakawa, Masahiro

2015-01-01

NMR spectroscopy enables structural analyses of proteins and has been widely used in the structural biology field in recent decades. NMR spectroscopy can be applied to proteins inside living cells, allowing characterization of their structures and dynamics in intracellular environments. The simplest "in-cell NMR" approach employs bacterial cells; in this approach, live Escherichia coli cells overexpressing a specific protein are subjected to NMR. The cells are grown in an NMR active isotope-enriched medium to ensure that the overexpressed proteins are labeled with the stable isotopes. Thus the obtained NMR spectra, which are derived from labeled proteins, contain atomic-level information about the structure and dynamics of the proteins. Recent progress enables us to work with higher eukaryotic cells such as HeLa and HEK293 cells, for which a number of techniques have been developed to achieve isotope labeling of the specific target protein. In this review, we describe successful use of electroporation for in-cell NMR. In addition, (19)F-NMR to characterize protein-ligand interactions in cells is presented. Because (19)F nuclei rarely exist in natural cells, when (19)F-labeled proteins are delivered into cells and (19)F-NMR signals are observed, one can safely ascertain that these signals originate from the delivered proteins and not other molecules.

The application of NMR and MS methods for detection of adulteration of wine, fruit juices, and olive oil. A review.

PubMed

Ogrinc, N; Kosir, I J; Spangenberg, J E; Kidric, J

2003-06-01

This review covers two important techniques, high resolution nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), used to characterize food products and detect possible adulteration of wine, fruit juices, and olive oil, all important products of the Mediterranean Basin. Emphasis is placed on the complementary use of SNIF-NMR (site-specific natural isotopic fractionation nuclear magnetic resonance) and IRMS (isotope-ratio mass spectrometry) in association with chemometric methods for detecting the adulteration.

The effects of nuclear magnetic resonance on patients with cardiac pacemakers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pavlicek, W.; Geisinger, M.; Castle, L.

1983-04-01

The effect of nuclear magnetic resonance (NMR) imaging on six representative cardiac pacemakers was studied. The results indicate that the threshold for initiating the asynchronous mode of a pacemaker is 17 gauss. Radiofrequency levels are present in an NMR unit and may confuse or possibly inhibit demand pacemakers, although sensing circuitry is normally provided with electromagnetic interference discrimination. Time-varying magnetic fields can generate pulse amplitudes and frequencies to mimic cardiac activity. A serious limitation in the possibility of imaging a patient with a pacemaker would be the alteration of normal pulsing parameters due to time-varying magnetic fields.

TU-EF-BRA-04: Into 2, 3, and 4 Dimensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yanasak, N.

NMR, and Proton Density MRI of the 1D Patient - Anthony Wolbarst Net Voxel Magnetization, m(x,t). T1-MRI; The MRI Device - Lisa Lemen ‘Classical’ NMR; FID Imaging in 1D via k-Space - Nathan Yanasak Spin-Echo; S-E/Spin Warp in a 2D Slice - Ronald Price Magnetic resonance imaging not only reveals the structural, anatomic details of the body, as does CT, but also it can provide information on the physiological status and pathologies of its tissues, like nuclear medicine. It can display high-quality slice and 3D images of organs and vessels viewed from any perspective, with resolution better than 1 mm.more » MRI is perhaps most extraordinary and notable for the plethora of ways in which it can create unique forms of image contrast, reflective of fundamentally different biophysical phenomena. As with ultrasound, there is no risk from ionizing radiation to the patient or staff, since no X-rays or radioactive nuclei are involved. Instead, MRI harnesses magnetic fields and radio waves to probe the stable nuclei of the ordinary hydrogen atoms (isolated protons) occurring in water and lipid molecules within and around cells. MRI consists, in essence, of creating spatial maps of the electromagnetic environments around these hydrogen nuclei. Spatial variations in the proton milieus can be related to clinical differences in the biochemical and physiological properties and conditions of the associated tissues. Imaging of proton density (PD), and of the tissue proton spin relaxation times known as T1 and T2, all can reveal important clinical information, but they do so with approaches so dissimilar from one another that each is chosen for only certain clinical situations. T1 and T2 in a voxel are determined by different aspects of the rotations and other motions of the water and lipid molecules involved, as constrained by the local biophysical surroundings within and between its cells – and they, in turn, depend on the type of tissue and its state of health. Three other common applications of MRI exploit its capability to detect and image distinct movements of fluids: MR angiography (MRA), which rivals CT angiography but often requires no contrast medium, monitors the bulk flow of blood; functional MRI ( f MRI), distinguishes the perfusion of oxygenated blood from that of de-oxygenated, and lights up parts of the brain that are activated by a stimulus, rather like PET; and diffusion tensor imaging (DTI) indicates the diffusion of free water along tracts of axons, thereby bringing nerve trunks into view. There are variants on all of these themes, and on others as well. Magnetic Resonance Spectroscopy (MRS), for example, can perform non-invasive ‘virtual biopsies’ that allow identification of certain cancers and other lesions. And an MRI-guided needle biopsy can sample brain tissue from a region only millimeters in dimensions. MRI, however, involves deeper and more complex aspects of physics, technology, and biology than do most other imaging modalities, and it is widely considered to be correspondingly more difficult to learn. We could probably cover all of this rather comprehensively if we had 50 hours available rather than 2 ̶ but, to paraphrase a former Secretary of Defense, you tell your story in the time you have allotted. The four presenters and another physicist, Kevin King from GE, have combined their efforts to co-author a single slide show that describes essentials of MRI as simply as possible. It is obviously far from thorough, but hopefully it will succeed in explaining some of the basics in a simplified but still valid fashion; in providing a taste of the numerous capabilities and complexities of the modality; and in whetting your appetite to learn more. Part I. NMR, and Proton Density MRI of the 1D Patient (Wolbarst), begins with an introductory case study that illustrates a half dozen ways in which MRI provides valuable clinical information. It then explores the nuclear magnetic resonance (NMR) phenomenon, which underlies MRI. NMR can be introduced with either of two approaches. In the first, one thinks (loosely) of the nuclei of hydrogen atoms as (rotating and charged and therefore) magnetic objects, whose spin-axes tend to align in a strong external magnetic field, much like a compass needle. As with the Bohr atom, this spin-up/spin-down picture is a highly abridged version of the full quantum mechanical treatment, but still it leads to some useful, legitimate pictures of the NMR process occurring within a voxel: When RF photons of the correct (Larmor) frequency elevate protons in a fixed magnetic field out of their lower-energy spin state into the upper, the NMR phenomenon is indicated by the detectable absorption of RF power. With the addition of a linear gradient field along a multi-voxel, one-dimensional patient/phantom, as well, we can determine the water content of each compartment – an example of a real MRI study, albeit in 1D. Part I concludes with a discussion of the net magnetization at position x, m0(x), under conditions of dynamic thermal equilibrium, which leads into: Part II. Net Voxel Magnetization, m(x,t); T1-MRI; The MRI Device (Lemen), investigates the biophysics of the form of proton spin relaxation process characterized by the time T1. It then moves on to the creation of an MR image that displays the spatial variation in the values of this clinically relevant parameter, again in 1D. Finally, the design and workings of a clinical MRI machine are sketched, in preparation for: Part III. ‘Classical’ NMR; FID Imaging in 1D via k-Space (Yanasak) presents the second standard approach to NMR and MRI, the classical model. It focuses on the time dependence of the net nuclear magnetization, m(x,t), the overall magnetic field generated by the cohort of protons in the voxel at position x. Quite remarkably, this nuclear net magnetization itself acts in a strong magnetic field like a gyroscope in a gravitational field. This tack is better for explaining Free Induction Decay (FID), which involves a brief introduction to the Fourier transform and k-space. This leads to conventional Spin-Echo (S-E) reconstruction techniques for creating clinical images from raw data, and sets the stage for: Part IV. Spin-Echo; S-E / Spin Warp in a 2D Slice (Price) discusses application of the S- E sequence of radiofrequency pulses and gradient magnetic fields to the 1D patient. T2 is introduced but not explained. This Part also considers how to manipulate the image acquisition parameters so as to generate clinical pictures with contrast dominated by spatial variations in PD, T1, or T2. We conclude by demonstrating the spin-warp approach to imaging in 2D with a simple 2×2, 4-voxel example. Much of this material is presented in more detail in the chapter “MRI of the One-dimensional Patient, Part I”, in Advances in Medical Physics, Vol 5 (2014). Copies are on display at the Medical Physics Publishing booth. Learning Objectives: The participant will learn about the processes of NMR and T1 spin relaxation in a tissue voxel in a uniform magnetic field. The participant will learn about combining spin-up/spin-down NMR and T1 processes with a linear gradient to effect frequency-encoding of voxel spatial position. This approach can be used to create proton density and T1 MRI maps, respectively, of the contents of multi-voxel 1D phantoms. The participant will learn about how the ‘classical’ model of NMR it can generate Free Induction Decay (FID) images of 1D phantoms, which involves the use of the Fourier transform in k-space. This can lead simply into standard Spin-Echo images. The participant will learn about extending Spin-Echo imaging into 2 and more dimensions.« less

TU-EF-BRA-00: MR Basics I

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

NMR, and Proton Density MRI of the 1D Patient - Anthony Wolbarst Net Voxel Magnetization, m(x,t). T1-MRI; The MRI Device - Lisa Lemen ‘Classical’ NMR; FID Imaging in 1D via k-Space - Nathan Yanasak Spin-Echo; S-E/Spin Warp in a 2D Slice - Ronald Price Magnetic resonance imaging not only reveals the structural, anatomic details of the body, as does CT, but also it can provide information on the physiological status and pathologies of its tissues, like nuclear medicine. It can display high-quality slice and 3D images of organs and vessels viewed from any perspective, with resolution better than 1 mm.more » MRI is perhaps most extraordinary and notable for the plethora of ways in which it can create unique forms of image contrast, reflective of fundamentally different biophysical phenomena. As with ultrasound, there is no risk from ionizing radiation to the patient or staff, since no X-rays or radioactive nuclei are involved. Instead, MRI harnesses magnetic fields and radio waves to probe the stable nuclei of the ordinary hydrogen atoms (isolated protons) occurring in water and lipid molecules within and around cells. MRI consists, in essence, of creating spatial maps of the electromagnetic environments around these hydrogen nuclei. Spatial variations in the proton milieus can be related to clinical differences in the biochemical and physiological properties and conditions of the associated tissues. Imaging of proton density (PD), and of the tissue proton spin relaxation times known as T1 and T2, all can reveal important clinical information, but they do so with approaches so dissimilar from one another that each is chosen for only certain clinical situations. T1 and T2 in a voxel are determined by different aspects of the rotations and other motions of the water and lipid molecules involved, as constrained by the local biophysical surroundings within and between its cells – and they, in turn, depend on the type of tissue and its state of health. Three other common applications of MRI exploit its capability to detect and image distinct movements of fluids: MR angiography (MRA), which rivals CT angiography but often requires no contrast medium, monitors the bulk flow of blood; functional MRI (f MRI), distinguishes the perfusion of oxygenated blood from that of de-oxygenated, and lights up parts of the brain that are activated by a stimulus, rather like PET; and diffusion tensor imaging (DTI) indicates the diffusion of free water along tracts of axons, thereby bringing nerve trunks into view. There are variants on all of these themes, and on others as well. Magnetic Resonance Spectroscopy (MRS), for example, can perform non-invasive ‘virtual biopsies’ that allow identification of certain cancers and other lesions. And an MRI-guided needle biopsy can sample brain tissue from a region only millimeters in dimensions. MRI, however, involves deeper and more complex aspects of physics, technology, and biology than do most other imaging modalities, and it is widely considered to be correspondingly more difficult to learn. We could probably cover all of this rather comprehensively if we had 50 hours available rather than 2 ̶ but, to paraphrase a former Secretary of Defense, you tell your story in the time you have allotted. The four presenters and another physicist, Kevin King from GE, have combined their efforts to co-author a single slide show that describes essentials of MRI as simply as possible. It is obviously far from thorough, but hopefully it will succeed in explaining some of the basics in a simplified but still valid fashion; in providing a taste of the numerous capabilities and complexities of the modality; and in whetting your appetite to learn more. Part I. NMR, and Proton Density MRI of the 1D Patient (Wolbarst), begins with an introductory case study that illustrates a half dozen ways in which MRI provides valuable clinical information. It then explores the nuclear magnetic resonance (NMR) phenomenon, which underlies MRI. NMR can be introduced with either of two approaches. In the first, one thinks (loosely) of the nuclei of hydrogen atoms as (rotating and charged and therefore) magnetic objects, whose spin-axes tend to align in a strong external magnetic field, much like a compass needle. As with the Bohr atom, this spin-up/spin-down picture is a highly abridged version of the full quantum mechanical treatment, but still it leads to some useful, legitimate pictures of the NMR process occurring within a voxel: When RF photons of the correct (Larmor) frequency elevate protons in a fixed magnetic field out of their lower-energy spin state into the upper, the NMR phenomenon is indicated by the detectable absorption of RF power. With the addition of a linear gradient field along a multi-voxel, one-dimensional patient/phantom, as well, we can determine the water content of each compartment – an example of a real MRI study, albeit in 1D. Part I concludes with a discussion of the net magnetization at position x, m0(x), under conditions of dynamic thermal equilibrium, which leads into: Part II. Net Voxel Magnetization, m(x,t); T1-MRI; The MRI Device (Lemen), investigates the biophysics of the form of proton spin relaxation process characterized by the time T1. It then moves on to the creation of an MR image that displays the spatial variation in the values of this clinically relevant parameter, again in 1D. Finally, the design and workings of a clinical MRI machine are sketched, in preparation for: Part III. ‘Classical’ NMR; FID Imaging in 1D via k-Space (Yanasak) presents the second standard approach to NMR and MRI, the classical model. It focuses on the time dependence of the net nuclear magnetization, m(x,t), the overall magnetic field generated by the cohort of protons in the voxel at position x. Quite remarkably, this nuclear net magnetization itself acts in a strong magnetic field like a gyroscope in a gravitational field. This tack is better for explaining Free Induction Decay (FID), which involves a brief introduction to the Fourier transform and k-space. This leads to conventional Spin-Echo (S-E) reconstruction techniques for creating clinical images from raw data, and sets the stage for: Part IV. Spin-Echo; S-E / Spin Warp in a 2D Slice (Price) discusses application of the S- E sequence of radiofrequency pulses and gradient magnetic fields to the 1D patient. T2 is introduced but not explained. This Part also considers how to manipulate the image acquisition parameters so as to generate clinical pictures with contrast dominated by spatial variations in PD, T1, or T2. We conclude by demonstrating the spin-warp approach to imaging in 2D with a simple 2×2, 4-voxel example. Much of this material is presented in more detail in the chapter “MRI of the One-dimensional Patient, Part I”, in Advances in Medical Physics, Vol 5 (2014). Copies are on display at the Medical Physics Publishing booth. Learning Objectives: The participant will learn about the processes of NMR and T1 spin relaxation in a tissue voxel in a uniform magnetic field. The participant will learn about combining spin-up/spin-down NMR and T1 processes with a linear gradient to effect frequency-encoding of voxel spatial position. This approach can be used to create proton density and T1 MRI maps, respectively, of the contents of multi-voxel 1D phantoms. The participant will learn about how the ‘classical’ model of NMR it can generate Free Induction Decay (FID) images of 1D phantoms, which involves the use of the Fourier transform in k-space. This can lead simply into standard Spin-Echo images. The participant will learn about extending Spin-Echo imaging into 2 and more dimensions.« less

Phase incremented echo train acquisition applied to magnetic resonance pore imaging

NASA Astrophysics Data System (ADS)

Hertel, S. A.; Galvosas, P.

2017-02-01

Efficient phase cycling schemes remain a challenge for NMR techniques if the pulse sequences involve a large number of rf-pulses. Especially complex is the Carr Purcell Meiboom Gill (CPMG) pulse sequence where the number of rf-pulses can range from hundreds to several thousands. Our recent implementation of Magnetic Resonance Pore Imaging (MRPI) is based on a CPMG rf-pulse sequence in order to refocus the effect of internal gradients inherent in porous media. While the spin dynamics for spin- 1 / 2 systems in CPMG like experiments are well understood it is still not straight forward to separate the desired pathway from the spectrum of unwanted coherence pathways. In this contribution we apply Phase Incremented Echo Train Acquisition (PIETA) to MRPI. We show how PIETA offers a convenient way to implement a working phase cycling scheme and how it allows one to gain deeper insights into the amplitudes of undesired pathways.

Hierarchical automated clustering of cloud point set by ellipsoidal skeleton: application to organ geometric modeling from CT-scan images

NASA Astrophysics Data System (ADS)

Banegas, Frederic; Michelucci, Dominique; Roelens, Marc; Jaeger, Marc

1999-05-01

We present a robust method for automatically constructing an ellipsoidal skeleton (e-skeleton) from a set of 3D points taken from NMR or TDM images. To ensure steadiness and accuracy, all points of the objects are taken into account, including the inner ones, which is different from the existing techniques. This skeleton will be essentially useful for object characterization, for comparisons between various measurements and as a basis for deformable models. It also provides good initial guess for surface reconstruction algorithms. On output of the entire process, we obtain an analytical description of the chosen entity, semantically zoomable (local features only or reconstructed surfaces), with any level of detail (LOD) by discretization step control in voxel or polygon format. This capability allows us to handle objects at interactive frame rates once the e-skeleton is computed. Each e-skeleton is stored as a multiscale CSG implicit tree.

Magnetic Field Gradient Calibration as an Experiment to Illustrate Magnetic Resonance Imaging

ERIC Educational Resources Information Center

Seedhouse, Steven J.; Hoffmann, Markus M.

2008-01-01

A nuclear magnetic resonance (NMR) spectroscopy experiment for the undergraduate physical chemistry laboratory is described that encompasses both qualitative and quantitative pedagogical goals. Qualitatively, the experiment illustrates how images are obtained in magnetic resonance imaging (MRI). Quantitatively, students experience the…

Comparison of Attenuated Total Reflectance Mid-Infrared, Near Infrared, and 1H-Nuclear Magnetic Resonance Spectroscopies for the Determination of Coffee's Geographical Origin

PubMed Central

Caro Rodríguez, Diana; Arana, Victoria A.; Bernal, Andrés; Esseiva, Pierre

2017-01-01

The sensorial properties of Colombian coffee are renowned worldwide, which is reflected in its market value. This raises the threat of fraud by adulteration using coffee grains from other countries, thus creating a demand for robust and cost-effective methods for the determination of geographical origin of coffee samples. Spectroscopic techniques such as Nuclear Magnetic Resonance (NMR), near infrared (NIR), and mid-infrared (mIR) have arisen as strong candidates for the task. Although a body of work exists that reports on their individual performances, a faithful comparison has not been established yet. We evaluated the performance of 1H-NMR, Attenuated Total Reflectance mIR (ATR-mIR), and NIR applied to fraud detection in Colombian coffee. For each technique, we built classification models for discrimination by species (C. arabica versus C. canephora (or robusta)) and by origin (Colombia versus other C. arabica) using a common set of coffee samples. All techniques successfully discriminated samples by species, as expected. Regarding origin determination, ATR-mIR and 1H-NMR showed comparable capacity to discriminate Colombian coffee samples, while NIR fell short by comparison. In conclusion, ATR-mIR, a less common technique in the field of coffee adulteration and fraud detection, emerges as a strong candidate, faster and with lower cost compared to 1H-NMR and more discriminating compared to NIR. PMID:29201055

Structural features of a bituminous coal and their changes during low-temperature oxidation and loss of volatiles investigated by advanced solid-state NMR spectroscopy

USGS Publications Warehouse

Mao, J.-D.; Schimmelmann, A.; Mastalerz, Maria; Hatcher, P.G.; Li, Y.

2010-01-01

Quantitative and advanced 13C solid-state NMR techniques were employed to investigate (i) the chemical structure of a high volatile bituminous coal, as well as (ii) chemical structural changes of this coal after evacuation of adsorbed gases, (iii) during oxidative air exposure at room temperature, and (iv) after oxidative heating in air at 75 ??C. The solid-state NMR techniques employed in this study included quantitative direct polarization/magic angle spinning (DP/MAS) at a high spinning speed of 14 kHz, cross polarization/total sideband suppression (CP/TOSS), dipolar dephasing, CH, CH2, and CHn selection, 13C chemical shift anisotropy (CSA) filtering, two-dimensional (2D) 1H-13C heteronuclear correlation NMR (HETCOR), and 2D HETCOR with 1H spin diffusion. With spectral editing techniques, we identified methyl CCH 3, rigid and mobile methylene CCH2C, methine CCH, quaternary Cq, aromatic CH, aromatic carbons bonded to alkyls, small-sized condensed aromatic moieties, and aromatic C-O groups. With direct polarization combined with spectral-editing techniques, we quantified 11 different types of functional groups. 1H-13C 2D HETCOR NMR experiments indicated spatial proximity of aromatic and alkyl moieties in cross-linked structures. The proton spin diffusion experiments indicated that the magnetization was not equilibrated at a 1H spin diffusion time of 5 ms. Therefore, the heterogeneity in spatial distribution of different functional groups should be above 2 nm. Recoupled C-H long-range dipolar dephasing showed that the fraction of large charcoal-like clusters of polycondensed aromatic rings was relatively small. The exposure of this coal to atmospheric oxygen at room temperature for 6 months did not result in obvious chemical structural changes of the coal, whereas heating at 75 ??C in air for 10 days led to oxidation of coal and generated some COO groups. Evacuation removed most volatiles and caused a significant reduction in aliphatic signals in its DP/MAS spectrum. DP/MAS, but not CP/MAS, allowed us to detect the changes during low-temperature oxidation and loss of volatiles. These results demonstrate the applicability of advanced solid-state NMR techniques in chemical characterization of coal. ?? 2010 American Chemical Society.

Mobile NMR: Measuring Pixels, Images, and Spectra

NASA Astrophysics Data System (ADS)

Bluemich, Bernhard

2007-03-01

The vision of bringing nuclear magnetic resonance out of the lab to the doctor's office, the chemical reactor, or the manufacturing site is becoming reality with the development of mobile NMR. Pioneered for well logging in the oil industry, the concept has been explored for materials testing in a more systematic way since the introduction of the NMR-MOUSE. This is a small, one-sided access NMR sensor which acquires the information of one pixel from a particular spot of a large object. As the sensor explores the stray-fields of a permanent magnet and an rf coil, the magnetic fields are inhomogeneous and the sensitive volume is limited to the region, where both fields are orthogonal and the Larmor frequency lies within the excitation bandwidth. By shaping the magnet and the coil geometries, the shape of the sensitive volume can be tailored to a thin slice or a larger volume a certain distance away from the sensor surface. In the first case, there is a strong field gradient in the depth direction, and in the second case, a homogeneous sweet spot of the field profile is desired. The first case is suitable for measuring high-resolution depth profiles, while the second case is suitable for chemical shift resolved spectroscopy and volume imaging. The basic concepts of open and closed mobile NMR sensors will be discussed along with applications from testing polymer products, cultural heritage, medical tissue, and rock cores.

Interaction of lafutidine in binding to human serum albumin in gastric ulcer therapy: STD-NMR, WaterLOGSY-NMR, NMR relaxation times, Tr-NOESY, molecule docking, and spectroscopic studies.

PubMed

Yang, Hongqin; Huang, Yanmei; He, Jiawei; Li, Shanshan; Tang, Bin; Li, Hui

2016-09-15

In this study, lafutidine (LAF) was used as a model compound to investigate the binding mechanism between antiulcer drugs and human serum albumin (HSA) through various techniques, including STD-NMR, WaterLOGSY-NMR, (1)H NMR relaxation times, tr-NOESY, molecule docking calculation, FT-IR spectroscopy, and CD spectroscopy. The analyses of STD-NMR, which derived relative STD (%) intensities, and WaterLOGSY-NMR, determined that LAF bound to HSA. In particular, the pyridyl group of LAF was in close contact with HSA binding pocket, whereas furyl group had a secondary binding. Competitive STD-NMR and WaterLOGSY-NMR experiments, with warifarin and ibuprofen as site-selective probes, indicated that LAF preferentially bound to site II in the hydrophobic subdomains IIIA of HSA. The bound conformation of LAF at the HSA binding site was further elucidated by transferred NOE effect (tr-NOESY) experiment. Relaxation experiments provided quantitative information about the relationship between the affinity and structure of LAF. The molecule docking simulations conducted with AutoDock and the restraints derived from STD results led to three-dimensional models that were consistent with the NMR spectroscopic data. The presence of hydrophobic forces and hydrogen interactions was also determined. Additionally, FT-IR and CD spectroscopies showed that LAF induced secondary structure changes of HSA. Copyright © 2016 Elsevier Inc. All rights reserved.

LC-UV-solid-phase extraction-NMR-MS combined with a cryogenic flow probe and its application to the identification of compounds present in Greek oregano.

PubMed

Exarchou, Vassiliki; Godejohann, Markus; van Beek, Teris A; Gerothanassis, Ioannis P; Vervoort, Jacques

2003-11-15

Structure elucidation of natural products usually relies on a combination of NMR spectroscopy with mass spectrometry whereby NMR trails MS in terms of the minimum sample amount required. In the present study, the usefulness of on-line solid-phase extraction (SPE) in LC-NMR for peak storage after the LC separation prior to NMR analysis is demonstrated. The SPE unit allows the use of normal protonated solvents for the LC separation and fully deuterated solvents for flushing the trapped compounds to the NMR probe. Thus, solvent suppression is no longer necessary. Multiple trapping of the same analyte from repeated LC injections was utilized to solve the problem of low concentration and to obtain 2D heteronuclear NMR spectra. In addition, a combination of the SPE unit with a recently developed cryoflow NMR probe and an MS was evaluated. This on-line LC-UV-SPE-NMR-MS system was used for the automated analysis of a Greek oregano extract. Combining the data provided by the UV, MS, and NMR spectra, the flavonoids taxifolin, aromadendrin, eriodictyol, naringenin, and apigenin, the phenolic acid rosmarinic acid, and the monoterpene carvacrol were identified. This automated technique is very useful for natural product analysis, and the large sensitivity improvement leads to significantly reduced NMR acquisition times.

Assessment of 1H NMR-based metabolomics analysis for normalization of urinary metals against creatinine.

PubMed

Cassiède, Marc; Nair, Sindhu; Dueck, Meghan; Mino, James; McKay, Ryan; Mercier, Pascal; Quémerais, Bernadette; Lacy, Paige

2017-01-01

Proton nuclear magnetic resonance ( 1 H NMR, or NMR) spectroscopy and inductively coupled plasma-mass spectrometry (ICP-MS) are commonly used for metabolomics and metal analysis in urine samples. However, creatinine quantification by NMR for the purpose of normalization of urinary metals has not been validated. We assessed the validity of using NMR analysis for creatinine quantification in human urine samples in order to allow normalization of urinary metal concentrations. NMR and ICP-MS techniques were used to measure metabolite and metal concentrations in urine samples from 10 healthy subjects. For metabolite analysis, two magnetic field strengths (600 and 700MHz) were utilized. In addition, creatinine concentrations were determined by using the Jaffe method. Creatinine levels were strongly correlated (R 2 =0.99) between NMR and Jaffe methods. The NMR spectra were deconvoluted with a target database containing 151 metabolites that are present in urine. A total of 50 metabolites showed good correlation (R 2 =0.7-1.0) at 600 and 700MHz. Metal concentrations determined after NMR-measured creatinine normalization were comparable to previous reports. NMR analysis provided robust urinary creatinine quantification, and was sufficient for normalization of urinary metal concentrations. We found that NMR-measured creatinine-normalized urinary metal concentrations in our control subjects were similar to general population levels in Canada and the United Kingdom. Copyright © 2016 Elsevier B.V. All rights reserved.

In situ and ex situ low-field NMR spectroscopy and MRI endowed by SABRE hyperpolarization.

PubMed

Barskiy, Danila A; Kovtunov, Kirill V; Koptyug, Igor V; He, Ping; Groome, Kirsten A; Best, Quinn A; Shi, Fan; Goodson, Boyd M; Shchepin, Roman V; Truong, Milton L; Coffey, Aaron M; Waddell, Kevin W; Chekmenev, Eduard Y

2014-12-15

By using 5.75 and 47.5 mT nuclear magnetic resonance (NMR) spectroscopy, up to 10(5)-fold sensitivity enhancement through signal amplification by reversible exchange (SABRE) was enabled, and subsecond temporal resolution was used to monitor an exchange reaction that resulted in the buildup and decay of hyperpolarized species after parahydrogen bubbling. We demonstrated the high-resolution low-field proton magnetic resonance imaging (MRI) of pyridine in a 47.5 mT magnetic field endowed by SABRE. Molecular imaging (i.e. imaging of dilute hyperpolarized substances rather than the bulk medium) was conducted in two regimes: in situ real-time MRI of the reaction mixture (in which pyridine was hyperpolarized), and ex situ MRI (in which hyperpolarization decays) of the liquid hyperpolarized product. Low-field (milli-Tesla range, e.g. 5.75 and 47.5 mT used in this study) parahydrogen-enhanced NMR and MRI, which are free from the limitations of high-field magnetic resonance (including susceptibility-induced gradients of the static magnetic field at phase interfaces), potentially enables new imaging applications as well as differentiation of hyperpolarized chemical species on demand by exploiting spin manipulations with static and alternating magnetic fields. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

NMR spectroscopy of Group 13 metal ions: biologically relevant aspects.

PubMed

André, J P; Mäcke, H R

2003-12-01

In spite of the fact that Group 13 metal ions (Al(3+), Ga(3+), In(3+) and Tl(+/3+)) show no main biological role, they are NMR-active nuclides which can be used in magnetic resonance spectroscopy of biologically relevant systems. The fact that these metal ions are quadrupolar (with the exception of thallium) means that they are particularly sensitive to ligand type and coordination geometry. The line width of the NMR signals of their complexes shows a strong dependence on the symmetry of coordination, which constitutes an effective tool in the elucidation of structures. Here we report published NMR studies of this family of elements, applied to systems of biological importance. Special emphasis is given to binding studies of these cations to biological molecules, such as proteins, and to chelating agents of radiopharmaceutical interest. The possibility of in vivo NMR studies is also stressed, with extension to (27)Al-based MRI (magnetic resonance imaging) experiments.

NMR-based diffusion pore imaging by double wave vector measurements.

PubMed

Kuder, Tristan Anselm; Laun, Frederik Bernd

2013-09-01

One main interest of nuclear magnetic resonance (NMR) diffusion experiments is the investigation of boundaries such as cell membranes hindering the diffusion process. NMR diffusion measurements allow collecting the signal from the whole sample. This mainly eliminates the problem of vanishing signal at increasing resolution. It has been a longstanding question if, in principle, the exact shape of closed pores can be determined by NMR diffusion measurements. In this work, we present a method using short diffusion gradient pulses only, which is able to reveal the shape of arbitrary closed pores without relying on a priori knowledge. In comparison to former approaches, the method has reduced demands on relaxation times due to faster convergence to the diffusion long-time limit and allows for a more flexible NMR sequence design, because, e.g., stimulated echoes can be used. Copyright © 2012 Wiley Periodicals, Inc.

Staging research of human lung cancer tissues by high-resolution magic angle spinning proton nuclear magnetic resonance spectroscopy (HRMAS 1 H NMR) and multivariate data analysis.

PubMed

Chen, Wenxue; Lu, Shaohua; Wang, Guifang; Chen, Fener; Bai, Chunxue

2017-10-01

High-resolution magic-angle spinning proton nuclear magnetic resonance (HRMAS 1 H NMR) spectroscopy technique was employed to analyze the metabonomic characterizations of lung cancer tissues in hope to identify potential diagnostic biomarkers for malignancy detection and staging research of lung tissues. HRMAS 1 H NMR spectroscopy technique can rapidly provide important information for accurate diagnosis and staging of cancer tissues owing to its noninvasive nature and limited requirement for the samples, and thus has been acknowledged as an excellent tool to investigate tissue metabolism and provide a more realistic insight into the metabonomics of tissues when combined with multivariate data analysis (MVDA) such as component analysis and orthogonal partial least squares-discriminant analysis in particular. HRMAS 1 H NMR spectra displayed the metabonomic differences of 32 lung cancer tissues at the different stages from 32 patients. The significant changes (P < 0.05) of some important metabolites such as lipids, aspartate and choline-containing compounds in cancer tissues at the different stages had been identified. Furthermore, the combination of HRMAS 1 H NMR spectroscopy and MVDA might potentially and precisely provided for a high sensitivity, specificity, prediction accuracy in the positive identification of the staging for the cancer tissues in contrast with the pathological data in clinic. This study highlighted the potential of metabonomics in clinical settings so that the techniques might be further exploited for the diagnosis and staging prediction of lung cancer in future. © 2016 John Wiley & Sons Australia, Ltd.

Method for nuclear magnetic resonance imaging using deuterum as a contrast agent

DOEpatents

Kehayias, Joseph J.; Joel, Darrel D.; Adams, William H.; Stein, Harry L.

1990-01-01

A method for in vivo NMR imaging of the blood vessels and organs of a patient characterized by using a dark dye-like imaging substance consisting essentially of a stable, high-purity concentration of D.sub.2 O in a solution with water.

Field-cycling NMR with high-resolution detection under magic-angle spinning: determination of field-window for nuclear hyperpolarization in a photosynthetic reaction center.

PubMed

Gräsing, Daniel; Bielytskyi, Pavlo; Céspedes-Camacho, Isaac F; Alia, A; Marquardsen, Thorsten; Engelke, Frank; Matysik, Jörg

2017-09-21

Several parameters in NMR depend on the magnetic field strength. Field-cycling NMR is an elegant way to explore the field dependence of these properties. The technique is well developed for solution state and in relaxometry. Here, a shuttle system with magic-angle spinning (MAS) detection is presented to allow for field-dependent studies on solids. The function of this system is demonstrated by exploring the magnetic field dependence of the solid-state photochemically induced nuclear polarization (photo-CIDNP) effect. The effect allows for strong nuclear spin-hyperpolarization in light-induced spin-correlated radical pairs (SCRPs) under solid-state conditions. To this end, 13 C MAS NMR is applied to a photosynthetic reaction center (RC) of the purple bacterium Rhodobacter (R.) sphaeroides wildtype (WT). For induction of the effect in the stray field of the magnet and its subsequent observation at 9.4 T under MAS NMR conditions, the sample is shuttled by the use of an aerodynamically driven sample transfer technique. In the RC, we observe the effect down to 0.25 T allowing to determine the window for the occurrence of the effect to be between about 0.2 and 20 T.

Phenalenone-type phytoalexins mediate resistance of banana plants (Musa spp.) to the burrowing nematode Radopholus similis.

PubMed

Hölscher, Dirk; Dhakshinamoorthy, Suganthagunthalam; Alexandrov, Theodore; Becker, Michael; Bretschneider, Tom; Buerkert, Andreas; Crecelius, Anna C; De Waele, Dirk; Elsen, Annemie; Heckel, David G; Heklau, Heike; Hertweck, Christian; Kai, Marco; Knop, Katrin; Krafft, Christoph; Maddula, Ravi K; Matthäus, Christian; Popp, Jürgen; Schneider, Bernd; Schubert, Ulrich S; Sikora, Richard A; Svatoš, Aleš; Swennen, Rony L

2014-01-07

The global yield of bananas-one of the most important food crops-is severely hampered by parasites, such as nematodes, which cause yield losses up to 75%. Plant-nematode interactions of two banana cultivars differing in susceptibility to Radopholus similis were investigated by combining the conventional and spatially resolved analytical techniques (1)H NMR spectroscopy, matrix-free UV-laser desorption/ionization mass spectrometric imaging, and Raman microspectroscopy. This innovative combination of analytical techniques was applied to isolate, identify, and locate the banana-specific type of phytoalexins, phenylphenalenones, in the R. similis-caused lesions of the plants. The striking antinematode activity of the phenylphenalenone anigorufone, its ingestion by the nematode, and its subsequent localization in lipid droplets within the nematode is reported. The importance of varying local concentrations of these specialized metabolites in infected plant tissues, their involvement in the plant's defense system, and derived strategies for improving banana resistance are highlighted.

Rapid Catalyst Capture Enables Metal-Free para-Hydrogen-Based Hyperpolarized Contrast Agents.

PubMed

Barskiy, Danila A; Ke, Lucia A; Li, Xingyang; Stevenson, Vincent; Widarman, Nevin; Zhang, Hao; Truxal, Ashley; Pines, Alexander

2018-05-10

Hyperpolarization techniques based on the use of para-hydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of para-hydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals, and their administration in vivo should be avoided. Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 s) Ir-based catalyst capture by metal scavenging agents can produce pure para-hydrogen-based hyperpolarized contrast agents, as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.

Emerging technologies for the non-invasive characterization of physical-mechanical properties of tablets.

PubMed

Dave, Vivek S; Shahin, Hend I; Youngren-Ortiz, Susanne R; Chougule, Mahavir B; Haware, Rahul V

2017-10-30

The density, porosity, breaking force, viscoelastic properties, and the presence or absence of any structural defects or irregularities are important physical-mechanical quality attributes of popular solid dosage forms like tablets. The irregularities associated with these attributes may influence the drug product functionality. Thus, an accurate and efficient characterization of these properties is critical for successful development and manufacturing of a robust tablets. These properties are mainly analyzed and monitored with traditional pharmacopeial and non-pharmacopeial methods. Such methods are associated with several challenges such as lack of spatial resolution, efficiency, or sample-sparing attributes. Recent advances in technology, design, instrumentation, and software have led to the emergence of newer techniques for non-invasive characterization of physical-mechanical properties of tablets. These techniques include near infrared spectroscopy, Raman spectroscopy, X-ray microtomography, nuclear magnetic resonance (NMR) imaging, terahertz pulsed imaging, laser-induced breakdown spectroscopy, and various acoustic- and thermal-based techniques. Such state-of-the-art techniques are currently applied at various stages of development and manufacturing of tablets at industrial scale. Each technique has specific advantages or challenges with respect to operational efficiency and cost, compared to traditional analytical methods. Currently, most of these techniques are used as secondary analytical tools to support the traditional methods in characterizing or monitoring tablet quality attributes. Therefore, further development in the instrumentation and software, and studies on the applications are necessary for their adoption in routine analysis and monitoring of tablet physical-mechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermal convection currents in NMR: flow profiles and implications for coherence pathway selection

PubMed

Jerschow

2000-07-01

Rayleigh-Benard convection currents are visualized in a vertical cylindrical tube by means of magnetic resonance imaging. Axially antisymmetric flow, multiple vertical rolls, and twisted node planes are observed. The flow can also be induced by strong RF irradiation. Its effects on the coherence pathways in NMR experiments employing field gradients are discussed. Copyright 2000 Academic Press.

Los Alamos Team Demonstrates Bottle Scanner Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Espy, Michelle; Schultz, Larry

2014-05-06

Los Alamos scientists are demonstrating a Nuclear Magnetic Resonance Imaging (NMR) technology that may provide a breakthrough for screening liquids at airport security. By adding low-power X-ray data to the NMR mix, scientists believe they have unlocked a new detection technology. Funded in part by the Department of Homeland Security's Science and Technology Directorate, the new technology is called MagRay.

Los Alamos Team Demonstrates Bottle Scanner Technology

ScienceCinema

Espy, Michelle; Schultz, Larry

2018-02-13

Los Alamos scientists are demonstrating a Nuclear Magnetic Resonance Imaging (NMR) technology that may provide a breakthrough for screening liquids at airport security. By adding low-power X-ray data to the NMR mix, scientists believe they have unlocked a new detection technology. Funded in part by the Department of Homeland Security's Science and Technology Directorate, the new technology is called MagRay.

Improving reliability of chemometric models for authentication of species origin of heparin by switching from 1D to 2D NMR experiments.

PubMed

Monakhova, Yulia B; Fareed, Jawed; Yao, Yiming; Diehl, Bernd W K

2018-05-10

Nuclear magnetic resonance (NMR) spectroscopy is regarded as one of the most powerful and versatile analytical approaches to assure the quality of heparin preparations. In particular, it was recently demonstrated that by using 1 H NMR coupled with chemometrics heparin and low molecular weight heparin (LMWH) samples derived from three major animal species (porcine, ovine and bovine) can be differentiated [Y.B. Monakhova et al. J. Pharm. Anal. 149 (2018) 114-119]. In this study, significant improvement of existing chemometric models was achieved by switching to 2D NMR experiments (heteronuclear multiple-quantum correlation (HMQC) and diffusion-ordered spectroscopy (DOSY)). Two representative data sets (sixty-nine heparin and twenty-two LMWH) belonged to different batches and distributed by different commercial companies were investigated. A trend for animal species differentiation was observed in the principal component analysis (PCA) score plot built based on the DOSY data. A superior model was constructed using HMQC experiments, where individual heparin (LMWH) clusters as well as their blends were clearly differentiated. The predictive power of different classification methods as well as unsupervised techniques (independent components analysis, ICA) clearly proved applicability of the model for routine heparin and LMWH analysis. The switch from 1D to 2D NMR techniques provides a wealth of additional information, which is beneficial for multivariate modeling of NMR spectroscopic data for heparin preparations. Copyright © 2018 Elsevier B.V. All rights reserved.

Two-dimensional nuclear magnetic resonance of quadrupolar systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Shuanhu

1997-09-01

This dissertation describes two-dimensional nuclear magnetic resonance theory and experiments which have been developed to study quadruples in the solid state. The technique of multiple-quantum magic-angle spinning (MQMAS) is extensively reviewed and expanded upon in this thesis. Specifically, MQMAS is first compared with another technique, dynamic-angle spinning (DAS). The similarity between the two techniques allows us to extend much of the DAS work to the MQMAS case. Application of MQMAS to a series of aluminum containing materials is then presented. The superior resolution enhancement through MQMAS is exploited to detect the five- and six-coordinated aluminum in many aluminosilicate glasses. Combiningmore » the MQMAS method with other experiments, such as HETCOR, greatly expands the possibility of the use of MQMAS to study a large range of problems and is demonstrated in Chapter 5. Finally, the technique switching-angle spinning (SAS) is applied to quadrupolar nuclei to fully characterize a quadrupolar spin system in which all of the 8 NMR parameters are accurately determined. This dissertation is meant to demonstrate that with the combination of two-dimensional NMR concepts and new advanced spinning technologies, a series of multiple-dimensional NMR techniques can be designed to allow a detailed study of quadrupolar nuclei in the solid state.« less

Visualization of gas flow and diffusion in porous media

PubMed Central

Kaiser, Lana G.; Meersmann, Thomas; Logan, John W.; Pines, Alexander

2000-01-01

The transport of gases in porous materials is a crucial component of many important processes in science and technology. In the present work, we demonstrate how magnetic resonance microscopy with continuous flow laser-polarized noble gases makes it possible to “light up” and thereby visualize, with unprecedented sensitivity and resolution, the dynamics of gases in samples of silica aerogels and zeolite molecular sieve particles. The “polarization-weighted” images of gas transport in aerogel fragments are correlated to the diffusion coefficient of xenon obtained from NMR pulsed-field gradient experiments. The technique provides a unique means of studying the combined effects of flow and diffusion in systems with macroscopic dimensions and microscopic internal pore structure. PMID:10706617

Effect of multiple freeze-thaw cycles on the quality of instant sea cucumber: Emphatically on water status of by LF-NMR and MRI.

PubMed

Tan, Mingqian; Lin, Zhuyi; Zu, Yinxue; Zhu, Beiwei; Cheng, Shasha

2018-07-01

Instant sea cucumber has become one popular product due to its convenience to eat, favourable taste and minimal loss of nutrients and bioactive components. However, there was rare information about the water dynamic of instant sea cucumber subjected to multiple freeze-thaw cycles. In this study, low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance image (MRI) were employed to investigate the effect of freeze-thaw cycles on water status of instant sea cucumber. Four water populations corresponding to strongly bound water, weakly bound water, immobile water and free water were observed in instant sea cucumber. With the increase of freeze-thaw cycles, the transverse relaxation time of immobile and free water increased, while the peak area of free water decreased significantly. MRI enabled the visualization of water migration of instant sea cucumber during multiple freeze-thaw cycles. Multiple freeze-thaw cycles also led to significant changes of other quality properties including thawing loss, WHC, color parameters, texture and protein content, and enlarge the interspace between fiber network in microstructure. Good correlations between T 22 , A 22 , A 23 and thaw loss, WHC, L*, hardness and collagen content (0.873 ≤ r ≤ 0.958) revealed LF-NMR may be an effective real-time monitoring method of these physicochemical parameters as a non-destructive technique. Copyright © 2018 Elsevier Ltd. All rights reserved.

Spectroscopy 101: A Practical Introduction to Spectroscopy and Analysis for Undergraduate Organic Chemistry Laboratories

ERIC Educational Resources Information Center

Morrill, Lucas A.; Kammeyer, Jacquelin K.; Garg, Neil K.

2017-01-01

An undergraduate organic chemistry laboratory that provides an introduction to various spectroscopic techniques is reported. Whereas organic spectroscopy is most often learned and practiced in the context of reaction analyses, this laboratory experiment allows students to become comfortable with [superscript 1]H NMR, [superscript 13]C NMR, and IR…

Chemical compositions of dissolved organic matter from various sources as characterized by solid-state NMR

USDA-ARS?s Scientific Manuscript database

Dissolved organic matter (DOM) in surface waters plays an important role in biogeochemical and ecological processes. This study used solid-state NMR techniques to explore the molecular signatures of riverine DOM in relation to its point and nonpoint sources. DOM samples were isolated from (1) two st...

New mechanistic insights regarding Pd/Cu catalysts for the Sonogashira reaction: HRMAS NMR studies of silica-immobilized systems.

PubMed

Posset, Tobias; Blümel, Janet

2006-07-05

The title technique, high-resolution magic angle spinning NMR of suspensions, constitutes a powerful new tool for investigating the structures and mobilities of immobilized species and, thus, for optimizing heterobimetallic catalyst systems, such as the Sonogashira coupling of terminal alkynes and aryl halides.

Isolation of n-decyl-alpha(1-->6) isomaltoside from a technical APG mixture and its identification by the parallel use of LC-MS and NMR spectroscopy

PubMed

Billian; Hock; Doetzer; Stan; Dreher

2000-10-15

The identification of n-decyl alpha(1-->6)isomaltoside as a main component of technical alkyl polyglucoside (APG) mixtures by the parallel use of liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) spectroscopy is described. Following enrichment on a styrene-divinylbenzene-based solid-phase extraction material, unknown components were separated by reversed-phase liquid chromatography (LC). Chemical characterization was achieved by both mass spectrometry and NMR spectroscopy. It is demonstrated that the combination of LC-MS with various NMR techniques is very suitable for stereochemical assignment of unknown components in technical APG mixtures.

1H NMR investigation of thermally triggered insulin release from poly(N-isopropylacrylamide) microgels.

PubMed

Nolan, Christine M; Gelbaum, Leslie T; Lyon, L Andrew

2006-10-01

We describe investigations of insulin release from thermoresponsive microgels using variable temperature (1)H NMR. Microgel particles composed of poly(N-isopropylacrylamide) were loaded with the peptide via a swelling technique, and this method was compared to simple equilibrium partitioning. Variable temperature (1)H NMR studies suggest that the swelling loading method results in enhanced entrapment of the peptide versus equilibrium partitioning. A centrifugation-loading assay supports this finding. Pseudo-temperature jump (1)H NMR measurements suggest that the insulin release rate is partially decoupled from microgel collapse. These types of direct release investigations could prove to be useful methods in the future design of controlled macromolecule drug delivery devices.

NMR-invisible ATP in heart: fact or fiction?

PubMed

Bak, M I; Ingwall, J S

1992-06-01

31P-nuclear magnetic resonance (31P-NMR) spectroscopy is widely used to monitor sequential changes in the nucleoside triphosphate (NTP) pool in intact tissues. Recently, the validity of this technique to quantitate incremental changes in ATP in heart has been challenged. Accordingly, we compared NTP measured by 31P-NMR and by chemical techniques in isolated isovolumic rat hearts at 16 and 56 min of oxygenated perfusion and in hearts subjected to 28 min of hypoxia, with or without 28 min of reoxygenation, and 12 or 28 min of ischemia, with or without 28 min of reperfusion. NTP content was calculated from 31P-NMR spectra using an external standard. At the end of each protocol the heart was freeze-clamped, and NTP and ATP contents were determined by chemical assay. After 16 min of normoxic perfusion the values for NTP and ATP contents measured by both methods in the same hearts were indistinguishable. Results from all seven experimental conditions show no significant difference between methods (P = 0.262). Thus both methods detect the same incremental change in NTP and ATP.

BetaNMR Experiments on Liquid Samples

NASA Astrophysics Data System (ADS)

Gottberg, A.; Stachura, M.; Hemmingsen, L.; Macfarlane, W. A.; Bio-Beta-Nmr Collaboration; Collaps Collaboration

2016-09-01

In 2012 betaNMR spectroscopy was successfully applied on liquid samples; an achievement which opens new opportunities in the fields of chemistry and biochemistry. This project was motivated by the need for finding a new experimental approach to directly study biologically highly relevant metal ions, such as Mg(II), Cu(I), Ca(II), and Zn(II), which are silent in most spectroscopic techniques. The resonance spectrum recorded for Mg-31 implanted into an ionic liquid sample showed two resonances which originate from Mg ions occupying two different coordination geometries, illustrating that this technique can discriminate between different structures. This proof-of-principle result lays the foundation for studies of these metal ions at low concentrations and in environments of biological relevance where other methods are silent. The prototype chamber for bio-betaNMR allows for experiments not only on different samples such as: liquids, gels and solids, but also operates at different vacuum environments. In order to exploit the potential of betaNMR on liquid samples, tests with polarized beams of Mg-29 and Mg-31 have recently been performed at the ISAC facility at TRIUMF.

NMR of insensitive nuclei enhanced by dynamic nuclear polarization.

PubMed

Miéville, Pascal; Jannin, Sami; Helm, Lothar; Bodenhausen, Geoffrey

2011-01-01

Despite the powerful spectroscopic information it provides, Nuclear Magnetic Resonance (NMR) spectroscopy suffers from a lack of sensitivity, especially when dealing with nuclei other than protons. Even though NMR can be applied in a straightforward manner when dealing with abundant protons of organic molecules, it is very challenging to address biomolecules in low concentration and/or many other nuclei of the periodic table that do not provide as intense signals as protons. Dynamic Nuclear Polarization (DNP) is an important technique that provides a way to dramatically increase signal intensities in NMR. It consists in transferring the very high electron spin polarization of paramagnetic centers (usually at low temperature) to the surrounding nuclear spins with appropriate microwave irradiation. DNP can lead to an enhancement of the nuclear spin polarization by up to four orders of magnitude. We present in this article some basic concepts of DNP, describe the DNP apparatus at EPFL, and illustrate the interest of the technique for chemical applications by reporting recent measurements of the kinetics of complexation of 89Y by the DOTAM ligand.

Robustness of NMR-based metabolomics to generate comparable data sets for olive oil cultivar classification. An inter-laboratory study on Apulian olive oils.

PubMed

Piccinonna, Sara; Ragone, Rosa; Stocchero, Matteo; Del Coco, Laura; De Pascali, Sandra Angelica; Schena, Francesco Paolo; Fanizzi, Francesco Paolo

2016-05-15

Nuclear Magnetic Resonance (NMR) spectroscopy is emerging as a powerful technique in olive oil fingerprinting, but its analytical robustness has to be proved. Here, we report a comparative study between two laboratories on olive oil (1)H NMR fingerprinting, aiming to demonstrate the robustness of NMR-based metabolomics in generating comparable data sets for cultivar classification. Sample preparation and data acquisition were performed independently in two laboratories, equipped with different resolution spectrometers (400 and 500 MHz), using two identical sets of mono-varietal olive oils. Partial Least Squares (PLS)-based techniques were applied to compare the data sets produced by the two laboratories. Despite differences in spectrum baseline, and in intensity and shape of peaks, the amount of shared information was significant (almost 70%) and related to cultivar (same metabolites discriminated between cultivars). In conclusion, regardless of the variability due to operator and machine, the data sets from the two participating units were comparable for the purpose of classification. Copyright © 2015 Elsevier Ltd. All rights reserved.

Visualising substrate-fingermark interactions: Solid-state NMR spectroscopy of amino acid reagent development on cellulose substrates.

PubMed

Spindler, Xanthe; Shimmon, Ronald; Roux, Claude; Lennard, Chris

2015-05-01

Most spectroscopic studies of the reaction products formed by ninhydrin, 1,2-indanedione-zinc (Ind-Zn) and 1,8-diazafluoren-9-one (DFO) when reacted with amino acids or latent fingermarks on paper substrates are focused on visible absorption or luminescence spectroscopy. In addition, structural elucidation studies are typically limited to solution-based mass spectrometry or liquid nuclear magnetic resonance (NMR) spectroscopy, which does not provide an accurate representation of the fingermark development process on common paper substrates. The research presented in this article demonstrates that solid-state carbon-13 magic angle spinning NMR ((13)C-MAS-NMR) is a technique that can not only be utilised for structural studies of fingermark enhancement reagents, but is a promising technique for characterising the effect of paper chemistry on fingermark deposition and enhancement. The latter opens up a research area that has been under-explored to date but has the potential to improve our understanding of how fingermark secretions and enhancement reagents interact with paper substrates. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Photochemical Degradation of the Anticancer Drug Bortezomib by V-UV/UV (185/254 nm) Investigated by (1)H NMR Fingerprinting: A Way to Follow Aromaticity Evolution.

PubMed

Martignac, Marion; Balayssac, Stéphane; Gilard, Véronique; Benoit-Marquié, Florence

2015-06-18

We have investigated the removal of bortezomib, an anticancer drug prescribed in multiple myeloma, using the photochemical advanced oxidation process of V-UV/UV (185/254 nm). We used two complementary analytical techniques to follow the removal rate of bortezomib. Nuclear magnetic resonance (NMR) is a nonselective method requiring no prior knowledge of the structures of the byproducts and permits us to provide a spectral signature (fingerprinting approach). This untargeted method provides clues to the molecular structure changes and information on the degradation of the parent drug during the irradiation process. This holistic NMR approach could provide information for monitoring aromaticity evolution. We use liquid chromatography, coupled with high-resolution mass spectrometry (LC-MS), to correlate results obtained by (1)H NMR and for accurate identification of the byproducts, in order to understand the mechanistic degradation pathways of bortezomib. The results show that primary byproducts come from photoassisted deboronation of bortezomib at 254 nm. A secondary byproduct of pyrazinecarboxamide was also identified. We obtained a reliable correlation between these two analytical techniques.

In situ observations of water production and distribution in an operating H2/O2 PEM fuel cell assembly using 1H NMR microscopy.

PubMed

Feindel, Kirk W; LaRocque, Logan P-A; Starke, Dieter; Bergens, Steven H; Wasylishen, Roderick E

2004-09-22

Proton NMR imaging was used to investigate in situ the distribution of water in a polymer electrolyte membrane fuel cell operating on H2 and O2. In a single experiment, water was monitored in the gas flow channels, the membrane electrode assembly, and in the membrane surrounding the catalysts. Radial gradient diffusion removes water from the catalysts into the surrounding membrane. This research demonstrates the strength of 1H NMR microscopy as an aid for designing fuel cells to optimize water management.

In situ Stripline Electrochemical NMR for Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sorte, Eric Glenn; Banek, Nathan A.; Wagner, Michael J.

Here, there exist some long outstanding technical challenges that continue to be of hindrance to fully harnessing the unique investigative advantages of nuclear magnetic resonance (NMR) spectroscopy in the in situ investigation of rechargeable battery chemistry. For instance, the conducting materials and circuitry necessary for an operational battery always deteriorate the coil–based NMR sensitivity when placed inside the coil, and the shape mismatch between them leads to low sample filling factors and even higher detection limits. We report herein a novel and successful adaptation of stripline NMR detection that integrates seamlessly the NMR detection with construction of an electro–chemical devicemore » in general (or a battery in particular) which leads to a technique with much higher detection sensitivity, higher sample filling factors, and which is particularly suitable for mass–limited samples.« less

In situ Stripline Electrochemical NMR for Batteries

DOE PAGES

Sorte, Eric Glenn; Banek, Nathan A.; Wagner, Michael J.; ...

2018-06-11

Here, there exist some long outstanding technical challenges that continue to be of hindrance to fully harnessing the unique investigative advantages of nuclear magnetic resonance (NMR) spectroscopy in the in situ investigation of rechargeable battery chemistry. For instance, the conducting materials and circuitry necessary for an operational battery always deteriorate the coil–based NMR sensitivity when placed inside the coil, and the shape mismatch between them leads to low sample filling factors and even higher detection limits. We report herein a novel and successful adaptation of stripline NMR detection that integrates seamlessly the NMR detection with construction of an electro–chemical devicemore » in general (or a battery in particular) which leads to a technique with much higher detection sensitivity, higher sample filling factors, and which is particularly suitable for mass–limited samples.« less

Dynamic membrane interactions of antibacterial and antifungal biomolecules, and amyloid peptides, revealed by solid-state NMR spectroscopy.

PubMed

Naito, Akira; Matsumori, Nobuaki; Ramamoorthy, Ayyalusamy

2018-02-01

A variety of biomolecules acting on the cell membrane folds into a biologically active structure in the membrane environment. It is, therefore, important to determine the structures and dynamics of such biomolecules in a membrane environment. While several biophysical techniques are used to obtain low-resolution information, solid-state NMR spectroscopy is one of the most powerful means for determining the structure and dynamics of membrane bound biomolecules such as antibacterial biomolecules and amyloidogenic proteins; unlike X-ray crystallography and solution NMR spectroscopy, applications of solid-state NMR spectroscopy are not limited by non-crystalline, non-soluble nature or molecular size of membrane-associated biomolecules. This review article focuses on the applications of solid-state NMR techniques to study a few selected antibacterial and amyloid peptides. Solid-state NMR studies revealing the membrane inserted bent α-helical structure associated with the hemolytic activity of bee venom melittin and the chemical shift oscillation analysis used to determine the transmembrane structure (with α-helix and 3 10 -helix in the N- and C-termini, respectively) of antibiotic peptide alamethicin are discussed in detail. Oligomerization of an amyloidogenic islet amyloid polypeptide (IAPP, or also known as amylin) resulting from its aggregation in a membrane environment, molecular interactions of the antifungal natural product amphotericin B with ergosterol in lipid bilayers, and the mechanism of lipid raft formation by sphingomyelin studied using solid state NMR methods are also discussed in this review article. This article is part of a Special Issue entitled "Biophysical Exploration of Dynamical Ordering of Biomolecular Systems" edited by Dr. Koichi Kato. Copyright © 2017 Elsevier B.V. All rights reserved.

NVR-BIP: Nuclear Vector Replacement using Binary Integer Programming for NMR Structure-Based Assignments.

PubMed

Apaydin, Mehmet Serkan; Çatay, Bülent; Patrick, Nicholas; Donald, Bruce R

2011-05-01

Nuclear magnetic resonance (NMR) spectroscopy is an important experimental technique that allows one to study protein structure and dynamics in solution. An important bottleneck in NMR protein structure determination is the assignment of NMR peaks to the corresponding nuclei. Structure-based assignment (SBA) aims to solve this problem with the help of a template protein which is homologous to the target and has applications in the study of structure-activity relationship, protein-protein and protein-ligand interactions. We formulate SBA as a linear assignment problem with additional nuclear overhauser effect constraints, which can be solved within nuclear vector replacement's (NVR) framework (Langmead, C., Yan, A., Lilien, R., Wang, L. and Donald, B. (2003) A Polynomial-Time Nuclear Vector Replacement Algorithm for Automated NMR Resonance Assignments. Proc. the 7th Annual Int. Conf. Research in Computational Molecular Biology (RECOMB) , Berlin, Germany, April 10-13, pp. 176-187. ACM Press, New York, NY. J. Comp. Bio. , (2004), 11, pp. 277-298; Langmead, C. and Donald, B. (2004) An expectation/maximization nuclear vector replacement algorithm for automated NMR resonance assignments. J. Biomol. NMR , 29, 111-138). Our approach uses NVR's scoring function and data types and also gives the option of using CH and NH residual dipolar coupling (RDCs), instead of NH RDCs which NVR requires. We test our technique on NVR's data set as well as on four new proteins. Our results are comparable to NVR's assignment accuracy on NVR's test set, but higher on novel proteins. Our approach allows partial assignments. It is also complete and can return the optimum as well as near-optimum assignments. Furthermore, it allows us to analyze the information content of each data type and is easily extendable to accept new forms of input data, such as additional RDCs.

Quartz Crystal Temperature Sensor for MAS NMR

NASA Astrophysics Data System (ADS)

Simon, Gerald

1997-10-01

Quartz crystal temperature sensors (QCTS) were tested for the first time as wireless thermometers in NMR MAS rotors utilizing the NMR RF technique itself for exiting and receiving electro-mechanical quartz resonances. This new tool in MAS NMR has a high sensitivity, linearity, and precision. When compared to the frequently used calibration of the variable temperature in the NMR system by a solid state NMR chemical shift thermometer (CST), such as lead nitrate, QCTS shows a number of advantages. It is an inert thermometer in close contact with solid samples operating parallel to the NMR experiment. QCTS can be manufactured for any frequency to be near a NMR frequency of interest (typically 1 to 2 MHz below or above). Due to the strong response of the crystal, signal detection is possible without changing the tuning of the MAS probe. The NMR signal is not influenced due to the relative sharp crystal resonance, restricted excitation by finite pulses, high probeQvalues, and commonly used audio filters. The quadratic dependence of the temperature increase on spinning speed is the same for the QCTS and for the CST lead nitrate and is discussed in terms of frictional heat in accordance with the literature about lead nitrate and with the results of a simple rotor speed jump experiment with differently radial located lead nitrate in the rotor.

Fluid-Rock Characterization and Interactions in NMR Well Logging

DOE Office of Scientific and Technical Information (OSTI.GOV)

George J. Hirasaki; Kishore K. Mohanty

2005-09-05

The objective of this report is to characterize the fluid properties and fluid-rock interactions that are needed for formation evaluation by NMR well logging. The advances made in the understanding of NMR fluid properties are summarized in a chapter written for an AAPG book on NMR well logging. This includes live oils, viscous oils, natural gas mixtures, and the relation between relaxation time and diffusivity. Oil based drilling fluids can have an adverse effect on NMR well logging if it alters the wettability of the formation. The effect of various surfactants on wettability and surface relaxivity are evaluated for silicamore » sand. The relation between the relaxation time and diffusivity distinguishes the response of brine, oil, and gas in a NMR well log. A new NMR pulse sequence in the presence of a field gradient and a new inversion technique enables the T{sub 2} and diffusivity distributions to be displayed as a two-dimensional map. The objectives of pore morphology and rock characterization are to identify vug connectivity by using X-ray CT scan, and to improve NMR permeability correlation. Improved estimation of permeability from NMR response is possible by using estimated tortuosity as a parameter to interpolate between two existing permeability models.« less

Nuclear magnetic resonance (NMR)-based metabolomics for cancer research.

PubMed

Ranjan, Renuka; Sinha, Neeraj

2018-05-07

Nuclear magnetic resonance (NMR) has emerged as an effective tool in various spheres of biomedical research, amongst which metabolomics is an important method for the study of various types of disease. Metabolomics has proved its stronghold in cancer research by the development of different NMR methods over time for the study of metabolites, thus identifying key players in the aetiology of cancer. A plethora of one-dimensional and two-dimensional NMR experiments (in solids, semi-solids and solution phases) are utilized to obtain metabolic profiles of biofluids, cell extracts and tissue biopsy samples, which can further be subjected to statistical analysis. Any alteration in the assigned metabolite peaks gives an indication of changes in metabolic pathways. These defined changes demonstrate the utility of NMR in the early diagnosis of cancer and provide further measures to combat malignancy and its progression. This review provides a snapshot of the trending NMR techniques and the statistical analysis involved in the metabolomics of diseases, with emphasis on advances in NMR methodology developed for cancer research. Copyright © 2018 John Wiley & Sons, Ltd.

Functionalized multimodal ZnO@Gd2O3 nanosystems to use as perspective contrast agent for MRI

NASA Astrophysics Data System (ADS)

Babayevska, Nataliya; Florczak, Patryk; Woźniak-Budych, Marta; Jarek, Marcin; Nowaczyk, Grzegorz; Zalewski, Tomasz; Jurga, Stefan

2017-05-01

The main aim of this research was the synthesis of the multimodal hybrid ZnO@Gd2O3 nanostructures as prospective contrast agent for Magnetic Resonance Imaging (MRI) for bio-medical applications. The nanoparticles surface was functionalized by organosilicon compounds (OSC) then, by folic acid (FA) as targeting agent and doxorubicin (Dox) as chemotherapeutic agent. Doxorubicin and folic acid were attached to the nanoparticles surface by amino groups as well as due to attractive physical interactions. The morphology and crystallography of the nanostructures were studied by HRTEM and SAXS techniques. After ZnO nanoparticles surface modification by Gd3+ and annealing at 900 °C, ZnO@Gd2O3 nanostructures are polydispersed with size 30-100 nm. NMR (Nuclear Magnetic Resonance) studies of ZnO@Gd2O3 were performed on fractionated particles with size up to 50 nm. Fourier transform infrared spectroscopy (FTIR), UV-vis spectroscopy, zeta-potential measurements and energy dispersive X-ray analysis (EDX) showed that functional groups have been effectively bonded onto the nanoparticles surface. The high adsorption capacity of folic acid (up to 20%) and doxorubicin (up to 40%) on nanoparticles was reached upon 15 min of adsorption process in a temperature-dependent manner. The nuclear magnetic resonance (NMR) relaxation measurements confirmed that the obtained ZnO@Gd2O3 nanostructures could be good contrast agents, useful for magnetic resonance imaging.

The GNAT: A new tool for processing NMR data.

PubMed

Castañar, Laura; Poggetto, Guilherme Dal; Colbourne, Adam A; Morris, Gareth A; Nilsson, Mathias

2018-06-01

The GNAT (General NMR Analysis Toolbox) is a free and open-source software package for processing, visualising, and analysing NMR data. It supersedes the popular DOSY Toolbox, which has a narrower focus on diffusion NMR. Data import of most common formats from the major NMR platforms is supported, as well as a GNAT generic format. Key basic processing of NMR data (e.g., Fourier transformation, baseline correction, and phasing) is catered for within the program, as well as more advanced techniques (e.g., reference deconvolution and pure shift FID reconstruction). Analysis tools include DOSY and SCORE for diffusion data, ROSY T 1 /T 2 estimation for relaxation data, and PARAFAC for multilinear analysis. The GNAT is written for the MATLAB® language and comes with a user-friendly graphical user interface. The standard version is intended to run with a MATLAB installation, but completely free-standing compiled versions for Windows, Mac, and Linux are also freely available. © 2018 The Authors Magnetic Resonance in Chemistry Published by John Wiley & Sons Ltd.

Shear rheology and 1H TD-NMR combined to low-field RheoNMR: Set-up and application to quiescent and flow-induced crystallization of polymers

NASA Astrophysics Data System (ADS)

Räntzsch, Volker; Özen, Mürüvvet Begüm; Ratzsch, Karl-Friedrich; Guthausen, Gisela; Wilhelm, Manfred

2017-05-01

Rheology provides access to the flow properties of soft matter, while 1H TD-NMR is a useful technique for the characterization of molecular dynamics. To achieve greater insight into the interplay of these domains, especially under flow, it is desirable to combine these two methods in one set-up. We present a low-field RheoNMR set-up based on a portable 30 MHz 1H NMR unit that was integrated into a commercial strain-controlled shear rheometer. This unique combination can simultaneously conduct a full rheological characterization (G', G", |η*|, FT-Rheology: I3/1, Q0) while monitoring molecular dynamics in-situ via 1H TD-NMR for temperatures from -15 to +210 °C. Possible applications include the quantitative measurement of the composition in multiphase systems (fats, polymers, etc.) and soft matter during the application of flow, e.g. measurements on the flow-induced crystallization of polymers.

Solution NMR structure of a designed metalloprotein and complementary molecular dynamics refinement.

PubMed

Calhoun, Jennifer R; Liu, Weixia; Spiegel, Katrin; Dal Peraro, Matteo; Klein, Michael L; Valentine, Kathleen G; Wand, A Joshua; DeGrado, William F

2008-02-01

We report the solution NMR structure of a designed dimetal-binding protein, di-Zn(II) DFsc, along with a secondary refinement step employing molecular dynamics techniques. Calculation of the initial NMR structural ensemble by standard methods led to distortions in the metal-ligand geometries at the active site. Unrestrained molecular dynamics using a nonbonded force field for the metal shell, followed by quantum mechanical/molecular mechanical dynamics of DFsc, were used to relax local frustrations at the dimetal site that were apparent in the initial NMR structure and provide a more realistic description of the structure. The MD model is consistent with NMR restraints, and in good agreement with the structural and functional properties expected for DF proteins. This work demonstrates that NMR structures of metalloproteins can be further refined using classical and first-principles molecular dynamics methods in the presence of explicit solvent to provide otherwise unavailable insight into the geometry of the metal center.

Synthesis of 24-phenyl-24-oxo steroids derived from bile acids by palladium-catalyzed cross coupling with phenylboronic acid. NMR characterization and X-ray structures.

PubMed

Mayorquín-Torres, Martha C; Romero-Ávila, Margarita; Flores-Álamo, Marcos; Iglesias-Arteaga, Martin A

2013-11-01

Palladium-catalyzed cross coupling of phenyboronic acid with acetylated bile acids in which the carboxyl functions have been activated by formation of a mixed anhydride with pivalic anhydride afforded moderate to good yield of 24-phenyl-24-oxo-steroids. Unambiguous assignments of the NMR signals were made with the aid of combined 1D and 2D NMR techniques. X-ray diffraction studies confirmed the obtained structures. Copyright © 2013 Elsevier Inc. All rights reserved.

DOSY Analysis of Micromolar Analytes: Resolving Dilute Mixtures by SABRE Hyperpolarization.

PubMed

Reile, Indrek; Aspers, Ruud L E G; Tyburn, Jean-Max; Kempf, James G; Feiters, Martin C; Rutjes, Floris P J T; Tessari, Marco

2017-07-24

DOSY is an NMR spectroscopy technique that resolves resonances according to the analytes' diffusion coefficients. It has found use in correlating NMR signals and estimating the number of components in mixtures. Applications of DOSY in dilute mixtures are, however, held back by excessively long measurement times. We demonstrate herein, how the enhanced NMR sensitivity provided by SABRE hyperpolarization allows DOSY analysis of low-micromolar mixtures, thus reducing the concentration requirements by at least 100-fold. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A chemosensor for micro- to nano-molar detection of Ag+ and Hg2+ ions in pure aqueous media and its applications in cell imaging.

PubMed

Nandre, Jitendra P; Patil, Samadhan R; Sahoo, Suban K; Pradeep, Chullikkattil P; Churakov, Andrei; Yu, Fabiao; Chen, Lingxin; Redshaw, Carl; Patil, Ashok A; Patil, Umesh D

2017-10-24

The pyridine substituted thiourea derivative PTB-1 was synthesized and characterized by spectroscopic techniques as well as by single crystal X-ray crystallography. The metal ion sensing ability of PTB-1 was explored by various experimental (naked-eye, UV-Vis, fluorescence, mass spectrometry and 1 H NMR spectroscopy) and theoretical (B3LYP/6-31G**/LANL2DZ) methods. PTB-1 exhibited a highly selective naked-eye detectable color change from colorless to dark brown and UV-Vis spectral changes for the detection of Ag + with a detection limit of 3.67 μM in aqueous medium. The detection of Ag + ions was achieved by test paper strip and supported silica methods. In contrast, PTB-1 exhibited a 23-fold enhanced emission at 420 nm in the presence of Hg 2+ ions with a nano-molar detection limit of 0.69 nM. Finally, the sensor PTB-1 was applied successfully for the intracellular detection of Hg 2+ ions in a HepG2 liver cell line, which was monitored by the use of confocal imaging techniques.

The physics of spin polarized gases

NASA Astrophysics Data System (ADS)

Cates, Gordon D.

1995-01-01

Most of our research was connected either directly or indirectly to the study of spin polarized atoms and nuclei, and their applications. In most cases we used lasers to optically pump, and hence polarize, alkali-metal vapors. Spin-exchange collisions were used to transfer the angular momentum to other systems. Of particular interest was our continuing study of the polarization of noble gas nuclei, which are characterized by extremely long spin relaxation times of minutes to many days. During this past research period we have demonstrated several applications of polarized noble gas nuclei that may have important implications for such diverse areas as nondestructive testing and medical diagnostics, as well as many areas in fundamental research. Of particular note is the use of spin-exchange polarized He-3 and Xe-129 for magnetic resonance imaging. At present, our imaging work has focused on the lungs of small animals such as mice and guinea pigs. We believe, however, that our technique would also be useful for nondestructive testing. We have also continued our study of Xe that is polarized in the gaseous state, and subsequently frozen. This novel technique for producing a highly polarized solid has received considerable attention in the NMR community.

Statistical total correlation spectroscopy scaling for enhancement of metabolic information recovery in biological NMR spectra.

PubMed

Maher, Anthony D; Fonville, Judith M; Coen, Muireann; Lindon, John C; Rae, Caroline D; Nicholson, Jeremy K

2012-01-17

The high level of complexity in nuclear magnetic resonance (NMR) metabolic spectroscopic data sets has fueled the development of experimental and mathematical techniques that enhance latent biomarker recovery and improve model interpretability. We previously showed that statistical total correlation spectroscopy (STOCSY) can be used to edit NMR spectra to remove drug metabolite signatures that obscure metabolic variation of diagnostic interest. Here, we extend this "STOCSY editing" concept to a generalized scaling procedure for NMR data that enhances recovery of latent biochemical information and improves biological classification and interpretation. We call this new procedure STOCSY-scaling (STOCSY(S)). STOCSY(S) exploits the fixed proportionality in a set of NMR spectra between resonances from the same molecule to suppress or enhance features correlated with a resonance of interest. We demonstrate this new approach using two exemplar data sets: (a) a streptozotocin rat model (n = 30) of type 1 diabetes and (b) a human epidemiological study utilizing plasma NMR spectra of patients with metabolic syndrome (n = 67). In both cases significant biomarker discovery improvement was observed by using STOCSY(S): the approach successfully suppressed interfering NMR signals from glucose and lactate that otherwise dominate the variation in the streptozotocin study, which then allowed recovery of biomarkers such as glycine, which were otherwise obscured. In the metabolic syndrome study, we used STOCSY(S) to enhance variation from the high-density lipoprotein cholesterol peak, improving the prediction of individuals with metabolic syndrome from controls in orthogonal projections to latent structures discriminant analysis models and facilitating the biological interpretation of the results. Thus, STOCSY(S) is a versatile technique that is applicable in any situation in which variation, either biological or otherwise, dominates a data set at the expense of more interesting or important features. This approach is generally appropriate for many types of NMR-based complex mixture analyses and hence for wider applications in bioanalytical science.

NMR/MRI with hyperpolarized gas and high Tc SQUID

DOEpatents

Schlenga, Klaus; de Souza, Ricardo E.; Wong-Foy, Annjoe; Clarke, John; Pines, Alexander

2000-01-01

A method and apparatus for the detection of nuclear magnetic resonance (NMR) signals and production of magnetic resonance imaging (MRI) from samples combines the use of hyperpolarized inert gases to enhance the NMR signals from target nuclei in a sample and a high critical temperature (Tc) superconducting quantum interference device (SQUID) to detect the NMR signals. The system operates in static magnetic fields of 3 mT or less (down to 0.1 mT), and at temperatures from liquid nitrogen (77K) to room temperature. Sample size is limited only by the size of the magnetic field coils and not by the detector. The detector is a high Tc SQUID magnetometer designed so that the SQUID detector can be very close to the sample, which can be at room temperature.

(1)H nuclear magnetic resonance (NMR) as a tool to measure dehydration in mice.

PubMed

Li, Matthew; Vassiliou, Christophoros C; Colucci, Lina A; Cima, Michael J

2015-08-01

Dehydration is a prevalent pathology, where loss of bodily water can result in variable symptoms. Symptoms can range from simple thirst to dire scenarios involving loss of consciousness. Clinical methods exist that assess dehydration from qualitative weight changes to more quantitative osmolality measurements. These methods are imprecise, invasive, and/or easily confounded, despite being practiced clinically. We investigate a non-invasive, non-imaging (1)H NMR method of assessing dehydration that attempts to address issues with existing clinical methods. Dehydration was achieved by exposing mice (n = 16) to a thermally elevated environment (37 °C) for up to 7.5 h (0.11-13% weight loss). Whole body NMR measurements were made using a Bruker LF50 BCA-Analyzer before and after dehydration. Physical lean tissue, adipose, and free water compartment approximations had NMR values extracted from relaxation data through a multi-exponential fitting method. Changes in before/after NMR values were compared with clinically practiced metrics of weight loss (percent dehydration) as well as blood and urine osmolality. A linear correlation between tissue relaxometry and both animal percent dehydration and urine osmolality was observed in lean tissue, but not adipose or free fluids. Calculated R(2) values for percent dehydration were 0.8619 (lean, P < 0.0001), 0.5609 (adipose, P = 0.0008), and 0.0644 (free fluids, P = 0.3445). R(2) values for urine osmolality were 0.7760 (lean, P < 0.0001), 0.5005 (adipose, P = 0.0022), and 0.0568 (free fluids, P = 0.3739). These results suggest that non-imaging (1)H NMR methods are capable of non-invasively assessing dehydration in live animals. Copyright © 2015 John Wiley & Sons, Ltd.

A portable NMR sensor to measure dynamic changes in the amount of water in living stems or fruit and its potential to measure sap flow.

PubMed

Windt, Carel W; Blümler, Peter

2015-04-01

Nuclear magnetic resonance (NMR) and NMR imaging (magnetic resonance imaging) offer the possibility to quantitatively and non-invasively measure the presence and movement of water. Unfortunately, traditional NMR hardware is expensive, poorly suited for plants, and because of its bulk and complexity, not suitable for use in the field. But does it need to be? We here explore how novel, small-scale portable NMR devices can be used as a flow sensor to directly measure xylem sap flow in a poplar tree (Populus nigra L.), or in a dendrometer-like fashion to measure dynamic changes in the absolute water content of fruit or stems. For the latter purpose we monitored the diurnal pattern of growth, expansion and shrinkage in a model fruit (bean pod, Phaseolus vulgaris L.) and in the stem of an oak tree (Quercus robur L.). We compared changes in absolute stem water content, as measured by the NMR sensor, against stem diameter variations as measured by a set of conventional point dendrometers, to test how well the sensitivities of the two methods compare and to investigate how well diurnal changes in trunk absolute water content correlate with the concomitant diurnal variations in stem diameter. Our results confirm the existence of a strong correlation between the two parameters, but also suggest that dynamic changes in oak stem water content could be larger than is apparent on the basis of the stem diameter variation alone. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Analysis of ethanol-soluble extractives in southern pine wood by low-field proton NMR

Treesearch

Thomas L. Eberhardt; Thomas Elder; Nicole Labbe

2007-01-01

Low-field portion NMR was evaluated as a nondestructive and rapid technique for measuring ethanol-soluble extractives in southern pine wood. Matchstick-sized wood specimens were steeped in extractive-containing solutions to generate extractive-enriched samples for analysis. decay curves obtained by the Carr-Purcell-Meiboom-gill (CPMG) pulse sequence were analyzed with...

NMR 1D-imaging of water infiltration into mesoporous matrices.

PubMed

Le Feunteun, Steven; Diat, Olivier; Guillermo, Armel; Poulesquen, Arnaud; Podor, Renaud

2011-04-01

It is shown that coupling nuclear magnetic resonance (NMR) 1D-imaging with the measure of NMR relaxation times and self-diffusion coefficients can be a very powerful approach to investigate fluid infiltration into porous media. Such an experimental design was used to study the very slow seeping of pure water into hydrophobic materials. We consider here three model samples of nuclear waste conditioning matrices which consist in a dispersion of NaNO(3) (highly soluble) and/or BaSO(4) (poorly soluble) salt grains embedded in a bitumen matrix. Beyond studying the moisture progression according to the sample depth, we analyze the water NMR relaxation times and self-diffusion coefficients along its 1D-concentration profile to obtain spatially resolved information on the solution properties and on the porous structure at different scales. It is also shown that, when the relaxation or self-diffusion properties are multimodal, the 1D-profile of each water population is recovered. Three main levels of information were disclosed along the depth-profiles. They concern (i) the water uptake kinetics, (ii) the salinity and the molecular dynamics of the infiltrated solutions and (iii) the microstructure of the water-filled porosities: open networks coexisting with closed pores. All these findings were fully validated and enriched by NMR cryoporometry experiments and by performing environmental scanning electronic microscopy observations. Surprisingly, results clearly show that insoluble salts enhance the water progression and thereby increase the capability of the material to uptake water. Copyright © 2011 Elsevier Inc. All rights reserved.

Structures of glycans bound to receptors from saturation transfer difference (STD) NMR spectroscopy: quantitative analysis by using CORCEMA-ST.

PubMed

Enríquez-Navas, Pedro M; Guzzi, Cinzia; Muñoz-García, Juan C; Nieto, Pedro M; Angulo, Jesús

2015-01-01

Glycan-receptor interactions are of fundamental relevance for a large number of biological processes, and their kinetics properties (medium/weak binding affinities) make them appropriated to be studied by ligand observed NMR techniques, among which saturation transfer difference (STD) NMR spectroscopy has been shown to be a very robust and powerful approach. The quantitative analysis of the results from a STD NMR study of a glycan-receptor interaction is essential to be able to translate the resulting spectral intensities into a 3D molecular model of the complex. This chapter describes how to carry out such a quantitative analysis by means of the Complete Relaxation and Conformational Exchange Matrix Approach for STD NMR (CORCEMA-ST), in general terms, and an example of a previous work on an antibody-glycan interaction is also shown.

Facilitated assignment of large protein NMR signals with covariance sequential spectra using spectral derivatives.

PubMed

Harden, Bradley J; Nichols, Scott R; Frueh, Dominique P

2014-09-24

Nuclear magnetic resonance (NMR) studies of larger proteins are hampered by difficulties in assigning NMR resonances. Human intervention is typically required to identify NMR signals in 3D spectra, and subsequent procedures depend on the accuracy of this so-called peak picking. We present a method that provides sequential connectivities through correlation maps constructed with covariance NMR, bypassing the need for preliminary peak picking. We introduce two novel techniques to minimize false correlations and merge the information from all original 3D spectra. First, we take spectral derivatives prior to performing covariance to emphasize coincident peak maxima. Second, we multiply covariance maps calculated with different 3D spectra to destroy erroneous sequential correlations. The maps are easy to use and can readily be generated from conventional triple-resonance experiments. Advantages of the method are demonstrated on a 37 kDa nonribosomal peptide synthetase domain subject to spectral overlap.

Continuous-wave Submillimeter-wave Gyrotrons

PubMed Central

Han, Seong-Tae; Griffin, Robert G.; Hu, Kan-Nian; Joo, Chan-Gyu; Joye, Colin D.; Mastovsky, Ivan; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Torrezan, Antonio C.; Woskov, Paul P.

2007-01-01

Recently, dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP/NMR) has emerged as a powerful technique to obtain significant enhancements in spin spectra from biological samples. For DNP in modern NMR systems, a high power continuous-wave source in the submillimeter wavelength range is necessary. Gyrotrons can deliver tens of watts of CW power at submillimeter wavelengths and are well suited for use in DNP/NMR spectrometers. To date, 140 GHz and 250 GHz gyrotrons are being employed in DNP spectrometer experiments at 200 MHz and 380 MHz at MIT. A 460 GHz gyrotron, which has operated with 8 W of CW output power, will soon be installed in a 700 MHz NMR spectrometer. High power radiation with good spectral and spatial resolution from these gyrotrons should provide NMR spectrometers with high signal enhancement through DNP. Also, these tubes operating at submillimeter wavelengths should have important applications in research in physics, chemistry, biology, materials science and medicine. PMID:17404605

Separation and identification of phenolic compounds of extra virgin olive oil from Olea europaea L. by HPLC-DAD-SPE-NMR/MS. Identification of a new diastereoisomer of the aldehydic form of oleuropein aglycone.

PubMed

Pérez-Trujillo, Míriam; Gómez-Caravaca, Ana María; Segura-Carretero, Antonio; Fernández-Gutiérrez, Alberto; Parella, Teodor

2010-08-25

The phenolic fraction of a monovarietal extra virgin olive oil (EVOO) from Olea europaea L. var. Cornezuelo was studied by the hyphenated HPLC-DAD-SPE-NMR/MS techniques. This survey led to the identification of 25 main compounds. One was identified as a new diastereoisomer of the aldehydic form of oleuropein aglycone (AOA) and characterized by 1D and 2D NMR techniques. The relative configuration of this new AOA was determined as 5R*,8S*,9S* on the basis of the results obtained from the combination of NOE experiments and Monte Carlo conformational search calculations. Assuming, as for the described diastereoisomers, that the new AOA comes from the natural oleuropein aglycone (OA), the absolute configuration was proposed as 5S,8R,9R.

Practical aspects of NMR signal assignment in larger and challenging proteins

PubMed Central

Frueh, Dominique P.

2014-01-01

NMR has matured into a technique routinely employed for studying proteins in near physiological conditions. However, applications to larger proteins are impeded by the complexity of the various correlation maps necessary to assign NMR signals. This article reviews the data analysis techniques traditionally employed for resonance assignment and describes alternative protocols necessary for overcoming challenges in large protein spectra. In particular, simultaneous analysis of multiple spectra may help overcome ambiguities or may reveal correlations in an indirect manner. Similarly, visualization of orthogonal planes in a multidimensional spectrum can provide alternative assignment procedures. We describe examples of such strategies for assignment of backbone, methyl, and nOe resonances. We describe experimental aspects of data acquisition for the related experiments and provide guidelines for preliminary studies. Focus is placed on large folded monomeric proteins and examples are provided for 37, 48, 53, and 81 kDa proteins. PMID:24534088

H2BC: a new technique for NMR analysis of complex carbohydrates.

PubMed

Petersen, Bent O; Vinogradov, Evguenii; Kay, William; Würtz, Peter; Nyberg, Nils T; Duus, Jens Ø; Sørensen, Ole W

2006-03-20

It is demonstrated that the H2BC NMR pulse sequence (J. Am. Chem. Soc.2005, 127, 6154, Magn. Reson. Chem.2005, 43, 971-974) offers unambiguous assignments and significant simplification of NMR spectra of large and complex carbohydrates compared to other techniques for the establishment of correlations over more than one bond. H2BC almost exclusively correlates protons and proton-bearing carbon spins separated by two covalent bonds and is independent of occasionally vanishing (2)J(CH) coupling constants, which alleviates the problem of missing two-bond correlations in HMBC spectra. H2BC also solves the problem of distinguishing two- and three-bond correlations in HSQC-TOCSY or HMBC. It is a further asset of H2BC that the experiment is significantly shorter than HMBC and HSQC-TOCSY, and hence less sensitive to transverse relaxation. The H2BC experiment is demonstrated on an approximately 30-residue oligosaccharide from Francisella victoria.

Fractionation of bamboo culms by autohydrolysis, organosolv delignification and extended delignification: understanding the fundamental chemistry of the lignin during the integrated process.

PubMed

Wen, Jia-Long; Sun, Shao-Ni; Yuan, Tong-Qi; Xu, Feng; Sun, Run-Cang

2013-12-01

Bamboo (Phyllostachys pubescens) was successfully fractionated using a three-step integrated process: (1) autohydrolysis pretreatment facilitating xylooligosaccharide (XOS) production (2) organosolv delignification with organic acids to obtain high-purity lignin, and (3) extended delignification with alkaline hydrogen peroxide (AHP) to produce purified pulp. The integrated process was comprehensively evaluated by component analysis, SEM, XRD, and CP-MAS NMR techniques. Emphatically, the fundamental chemistry of the lignin fragments obtained from the integrated process was thoroughly investigated by gel permeation chromatography and solution-state NMR techniques (quantitative (13)C, 2D-HSQC, and (31)P-NMR spectroscopies). It is believed that the integrated process facilitate the production of XOS, high-purity lignin, and purified pulp. Moreover, the enhanced understanding of structural features and chemical reactivity of lignin polymers will maximize their utilizations in a future biorefinery industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

A self optimizing synthetic organic reactor system using real-time in-line NMR spectroscopy.

PubMed

Sans, Victor; Porwol, Luzian; Dragone, Vincenza; Cronin, Leroy

2015-02-01

A configurable platform for synthetic chemistry incorporating an in-line benchtop NMR that is capable of monitoring and controlling organic reactions in real-time is presented. The platform is controlled via a modular LabView software control system for the hardware, NMR, data analysis and feedback optimization. Using this platform we report the real-time advanced structural characterization of reaction mixtures, including 19 F, 13 C, DEPT, 2D NMR spectroscopy (COSY, HSQC and 19 F-COSY) for the first time. Finally, the potential of this technique is demonstrated through the optimization of a catalytic organic reaction in real-time, showing its applicability to self-optimizing systems using criteria such as stereoselectivity, multi-nuclear measurements or 2D correlations.

Present and future applications of NMR to medicine and materials science

NASA Astrophysics Data System (ADS)

Morris, Peter

1992-06-01

The phenomenon of nuclear magnetic resonance (NMR) was first observed in the immediate post second-world-war period by two American physicists, working independently: Bloch at Stanford and Purcell at Harvard. Their observations were reported in 1946 in the same volume of Physical Review and led to the joint award of the 1952 Nobel Prize for Physics. Once the details of the interaction had been worked out, and the chemical specificity had been appreciated, a period of instrumentational refinement followed before NMR took its place as arguably the most powerful analytical technique available to the organic chemist. The historical development of NMR and the basis of its analytical power are described in the companion article by Dr. J. Feeney.

Hyperpolarized 89Y NMR spectroscopic detection of yttrium ion and DOTA macrocyclic ligand complexation: pH dependence and Y-DOTA intermediates

NASA Astrophysics Data System (ADS)

Ferguson, Sarah; Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Kovacs, Zoltan; Lumata, Lloyd

Dissolution dynamic nuclear polarization (DNP) is a rapidly emerging physics technique used to enhance the signal strength in nuclear magnetic resonance (NMR) and imaging (MRI) experiments for nuclear spins such as yttrium-89 by >10,000-fold. One of the most common and stable MRI contrast agents used in the clinic is Gd-DOTA. In this work, we have investigated the binding of the yttrium and DOTA ligand as a model for complexation of Gd ion and DOTA ligand. The macrocyclic ligand DOTA is special because its complexation with lanthanide ions such as Gd3+ or Y3+ is highly pH dependent. Using this physics technology, we have tracked the complexation kinetics of hyperpolarized Y-triflate and DOTA ligand in real-time and detected the Y-DOTA intermediates. Different kinds of buffers were used (lactate, acetate, citrate, oxalate) and the pseudo-first order complexation kinetic calculations will be discussed. The authors would like to acknowledge the support by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

The application of NMR-based milk metabolite analysis in milk authenticity identification.

PubMed

Li, Qiangqiang; Yu, Zunbo; Zhu, Dan; Meng, Xianghe; Pang, Xiumei; Liu, Yue; Frew, Russell; Chen, He; Chen, Gang

2017-07-01

Milk is an important food component in the human diet and is a target for fraud, including many unsafe practices. For example, the unscrupulous adulteration of soymilk into bovine and goat milk or of bovine milk into goat milk in order to gain profit without declaration is a health risk, as the adulterant source and sanitary history are unknown. A robust and fit-for-purpose technique is required to enforce market surveillance and hence protect consumer health. Nuclear magnetic resonance (NMR) is a powerful technique for characterization of food products based on measuring the profile of metabolites. In this study, 1D NMR in conjunction with multivariate chemometrics as well as 2D NMR was applied to differentiate milk types and to identify milk adulteration. Ten metabolites were found which differed among milk types, hence providing characteristic markers for identifying the milk. These metabolites were used to establish mathematical models for milk type differentiation. The limit of quantification (LOQ) of adulteration was 2% (v/v) for soymilk in bovine milk, 2% (v/v) for soymilk in goat milk and 5% (v/v) for bovine milk in goat milk, with relative standard deviation (RSD) less than 10%, which can meet the needs of daily inspection. The NMR method described here is effective for milk authenticity identification, and the study demonstrates that the NMR-based milk metabolite analysis approach provides a means of detecting adulteration at expected levels and can be used for dairy quality monitoring. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Standardizing the experimental conditions for using urine in NMR-based metabolomic studies with a particular focus on diagnostic studies: a review.

PubMed

Emwas, Abdul-Hamid; Luchinat, Claudio; Turano, Paola; Tenori, Leonardo; Roy, Raja; Salek, Reza M; Ryan, Danielle; Merzaban, Jasmeen S; Kaddurah-Daouk, Rima; Zeri, Ana Carolina; Nagana Gowda, G A; Raftery, Daniel; Wang, Yulan; Brennan, Lorraine; Wishart, David S

The metabolic composition of human biofluids can provide important diagnostic and prognostic information. Among the biofluids most commonly analyzed in metabolomic studies, urine appears to be particularly useful. It is abundant, readily available, easily stored and can be collected by simple, noninvasive techniques. Moreover, given its chemical complexity, urine is particularly rich in potential disease biomarkers. This makes it an ideal biofluid for detecting or monitoring disease processes. Among the metabolomic tools available for urine analysis, NMR spectroscopy has proven to be particularly well-suited, because the technique is highly reproducible and requires minimal sample handling. As it permits the identification and quantification of a wide range of compounds, independent of their chemical properties, NMR spectroscopy has been frequently used to detect or discover disease fingerprints and biomarkers in urine. Although protocols for NMR data acquisition and processing have been standardized, no consensus on protocols for urine sample selection, collection, storage and preparation in NMR-based metabolomic studies have been developed. This lack of consensus may be leading to spurious biomarkers being reported and may account for a general lack of reproducibility between laboratories. Here, we review a large number of published studies on NMR-based urine metabolic profiling with the aim of identifying key variables that may affect the results of metabolomics studies. From this survey, we identify a number of issues that require either standardization or careful accounting in experimental design and provide some recommendations for urine collection, sample preparation and data acquisition.

High-resolution NMR characterization of low abundance oligomers of amyloid-β without purification

NASA Astrophysics Data System (ADS)

Kotler, Samuel A.; Brender, Jeffrey R.; Vivekanandan, Subramanian; Suzuki, Yuta; Yamamoto, Kazutoshi; Monette, Martine; Krishnamoorthy, Janarthanan; Walsh, Patrick; Cauble, Meagan; Holl, Mark M. Banaszak; Marsh, E. Neil. G.; Ramamoorthy, Ayyalusamy

2015-07-01

Alzheimer’s disease is characterized by the misfolding and self-assembly of the amyloidogenic protein amyloid-β (Aβ). The aggregation of Aβ leads to diverse oligomeric states, each of which may be potential targets for intervention. Obtaining insight into Aβ oligomers at the atomic level has been a major challenge to most techniques. Here, we use magic angle spinning recoupling 1H-1H NMR experiments to overcome many of these limitations. Using 1H-1H dipolar couplings as a NMR spectral filter to remove both high and low molecular weight species, we provide atomic-level characterization of a non-fibrillar aggregation product of the Aβ1-40 peptide using non-frozen samples without isotopic labeling. Importantly, this spectral filter allows the detection of the specific oligomer signal without a separate purification procedure. In comparison to other solid-state NMR techniques, the experiment is extraordinarily selective and sensitive. A resolved 2D spectra could be acquired of a small population of oligomers (6 micrograms, 7% of the total) amongst a much larger population of monomers and fibers (93% of the total). By coupling real-time 1H-1H NMR experiments with other biophysical measurements, we show that a stable, primarily disordered Aβ1-40 oligomer 5-15 nm in diameter can form and coexist in parallel with the well-known cross-β-sheet fibrils.

A Novel Tri-Enzyme System in Combination with Laser-Driven NMR Enables Efficient Nuclear Polarization of Biomolecules in Solution

PubMed Central

Lee, Jung Ho; Cavagnero, Silvia

2013-01-01

NMR is an extremely powerful, yet insensitive technique. Many available nuclear polarization methods that address sensitivity are not directly applicable to low-concentration biomolecules in liquids and are often too invasive. Photochemically induced dynamic nuclear polarization (photo-CIDNP) is no exception. It needs high-power laser irradiation, which often leads to sample degradation, and photosensitizer reduction. Here, we introduce a novel tri-enzyme system that significantly overcomes the above challenges rendering photo-CIDNP a practically applicable technique for NMR sensitivity enhancement in solution. The specificity of the nitrate reductase (NR) enzyme is exploited to selectively in situ re-oxidize the reduced photo-CIDNP dye FMNH2. At the same time, the oxygen-scavenging ability of glucose oxidase (GO) and catalase (CAT) is synergistically employed to prevent sample photodegradation. The resulting tri-enzyme system (NR-GO-CAT) enables prolonged sensitivity-enhanced data collection in 1D and 2D heteronuclear NMR, leading to the highest photo-CIDNP sensitivity enhancement (48-fold relative to SE-HSQC) achieved to date for amino acids and polypeptides in solution. NR-GO-CAT extends the concentration limit of photo-CIDNP NMR down to the low micromolar range. In addition, sensitivity (relative to the reference SE-HSQC) is found to be inversely proportional to sample concentration, paving the way to the future analysis of even more diluted samples. PMID:23560683

Nanodisc-Targeted STD NMR Spectroscopy Reveals Atomic Details of Ligand Binding to Lipid Environments.

PubMed

Muñoz-García, Juan C; Inacio Dos Reis, Rosana; Taylor, Richard J; Henry, Alistair J; Watts, Anthony

2018-05-18

Saturation transfer difference (STD) NMR spectroscopy is one of the most popular ligand-based NMR techniques for the study of protein-ligand interactions. This is due to its robustness and the fact that it is focused on the signals of the ligand, without any need for NMR information on the macromolecular target. This technique is most commonly applied to systems involving different types of ligands (e.g., small organic molecules, carbohydrates or lipids) and a protein as the target, in which the latter is selectively saturated. However, only a few examples have been reported where membrane mimetics are the macromolecular binding partners. Here, we have employed STD NMR spectroscopy to investigate the interactions of the neurotransmitter dopamine with mimetics of lipid bilayers, such as nanodiscs, by saturation of the latter. In particular, the interactions between dopamine and model lipid nanodiscs formed either from charged or zwitterionic lipids have been resolved at the atomic level. The results, in agreement with previous isothermal titration calorimetry studies, show that dopamine preferentially binds to negatively charged model membranes, but also provide detailed atomic insights into the mode of interaction of dopamine with membrane mimetics. Our findings provide relevant structural information for the design of lipid-based drug carriers of dopamine and its structural analogues and are of general applicability to other systems. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-resolution NMR characterization of low abundance oligomers of amyloid-β without purification

PubMed Central

Kotler, Samuel A.; Brender, Jeffrey R.; Vivekanandan, Subramanian; Suzuki, Yuta; Yamamoto, Kazutoshi; Monette, Martine; Krishnamoorthy, Janarthanan; Walsh, Patrick; Cauble, Meagan; Holl, Mark M. Banaszak; Marsh, E. Neil. G.; Ramamoorthy, Ayyalusamy

2015-01-01

Alzheimer’s disease is characterized by the misfolding and self-assembly of the amyloidogenic protein amyloid-β (Aβ). The aggregation of Aβ leads to diverse oligomeric states, each of which may be potential targets for intervention. Obtaining insight into Aβ oligomers at the atomic level has been a major challenge to most techniques. Here, we use magic angle spinning recoupling 1H-1H NMR experiments to overcome many of these limitations. Using 1H-1H dipolar couplings as a NMR spectral filter to remove both high and low molecular weight species, we provide atomic-level characterization of a non-fibrillar aggregation product of the Aβ1-40 peptide using non-frozen samples without isotopic labeling. Importantly, this spectral filter allows the detection of the specific oligomer signal without a separate purification procedure. In comparison to other solid-state NMR techniques, the experiment is extraordinarily selective and sensitive. A resolved 2D spectra could be acquired of a small population of oligomers (6 micrograms, 7% of the total) amongst a much larger population of monomers and fibers (93% of the total). By coupling real-time 1H-1H NMR experiments with other biophysical measurements, we show that a stable, primarily disordered Aβ1-40 oligomer 5–15 nm in diameter can form and coexist in parallel with the well-known cross-β-sheet fibrils. PMID:26138908

High-resolution NMR characterization of low abundance oligomers of amyloid-β without purification.

PubMed

Kotler, Samuel A; Brender, Jeffrey R; Vivekanandan, Subramanian; Suzuki, Yuta; Yamamoto, Kazutoshi; Monette, Martine; Krishnamoorthy, Janarthanan; Walsh, Patrick; Cauble, Meagan; Holl, Mark M Banaszak; Marsh, E Neil G; Ramamoorthy, Ayyalusamy

2015-07-03

Alzheimer's disease is characterized by the misfolding and self-assembly of the amyloidogenic protein amyloid-β (Aβ). The aggregation of Aβ leads to diverse oligomeric states, each of which may be potential targets for intervention. Obtaining insight into Aβ oligomers at the atomic level has been a major challenge to most techniques. Here, we use magic angle spinning recoupling (1)H-(1)H NMR experiments to overcome many of these limitations. Using (1)H-(1)H dipolar couplings as a NMR spectral filter to remove both high and low molecular weight species, we provide atomic-level characterization of a non-fibrillar aggregation product of the Aβ1-40 peptide using non-frozen samples without isotopic labeling. Importantly, this spectral filter allows the detection of the specific oligomer signal without a separate purification procedure. In comparison to other solid-state NMR techniques, the experiment is extraordinarily selective and sensitive. A resolved 2D spectra could be acquired of a small population of oligomers (6 micrograms, 7% of the total) amongst a much larger population of monomers and fibers (93% of the total). By coupling real-time (1)H-(1)H NMR experiments with other biophysical measurements, we show that a stable, primarily disordered Aβ1-40 oligomer 5-15 nm in diameter can form and coexist in parallel with the well-known cross-β-sheet fibrils.

Requirements on paramagnetic relaxation enhancement data for membrane protein structure determination by NMR.

PubMed

Gottstein, Daniel; Reckel, Sina; Dötsch, Volker; Güntert, Peter

2012-06-06

Nuclear magnetic resonance (NMR) structure calculations of the α-helical integral membrane proteins DsbB, GlpG, and halorhodopsin show that distance restraints from paramagnetic relaxation enhancement (PRE) can provide sufficient structural information to determine their structure with an accuracy of about 1.5 Å in the absence of other long-range conformational restraints. Our systematic study with simulated NMR data shows that about one spin label per transmembrane helix is necessary for obtaining enough PRE distance restraints to exclude wrong topologies, such as pseudo mirror images, if only limited other NMR restraints are available. Consequently, an experimentally realistic amount of PRE data enables α-helical membrane protein structure determinations that would not be feasible with the very limited amount of conventional NOESY data normally available for these systems. These findings are in line with our recent first de novo NMR structure determination of a heptahelical integral membrane protein, proteorhodopsin, that relied extensively on PRE data. Copyright © 2012 Elsevier Ltd. All rights reserved.

Functional Characteristics of the Naked Mole Rat μ-Opioid Receptor

PubMed Central

Roth, Clarisse A.

2013-01-01

While humans and most animals respond to µ-opioid receptor (MOR) agonists with analgesia and decreased aggression, in the naked mole rat (NMR) opioids induce hyperalgesia and severe aggression. Single nucleotide polymorphisms in the human mu-opioid receptor gene (OPRM1) can underlie altered behavioral responses to opioids. Therefore, we hypothesized that the primary structure of the NMR MOR may differ from other species. Sequencing of the NMR oprm1 revealed strong homology to other mammals, but exposed three unique amino acids that might affect receptor-ligand interactions. The NMR and rat oprm1 sequences were cloned into mammalian expression vectors and transfected into HEK293 cells. Radioligand binding and 3'-5'-cyclic adenosine monophosphate (cAMP) enzyme immunoassays were used to compare opioid binding and opioid-mediated cAMP inhibition. At normalized opioid receptor protein levels we detected significantly lower [3H]DAMGO binding to NMR compared to rat MOR, but no significant difference in DAMGO-induced cAMP inhibition. Strong DAMGO-induced MOR internalization was detectable using radioligand binding and confocal imaging in HEK293 cells expressing rat or NMR receptor, while morphine showed weak or no effects. In summary, we found minor functional differences between rat and NMR MOR suggesting that other differences e.g. in anatomical distribution of MOR underlie the NMR's extreme reaction to opioids. PMID:24312175

From self-assembly fundamental knowledge to nanomedicine developments.

PubMed

Monduzzi, Maura; Lampis, Sandrina; Murgia, Sergio; Salis, Andrea

2014-03-01

This review highlights the key role of NMR techniques in demonstrating the molecular aspects of the self-assembly of surfactant molecules that nowadays constitute the basic knowledge which modern nanoscience relies on. The aim is to provide a tutorial overview. The story of a rigorous scientific approach to understand self-assembly in surfactant systems and biological membranes starts in the early seventies when the progresses of SAXRD and NMR technological facilities allowed to demonstrate the existence of ordered soft matter, and the validity of Tanford approach concerning self-assembly at a molecular level. Particularly, NMR quadrupolar splittings, NMR chemical shift anisotropy, and NMR relaxation of dipolar and quadrupolar nuclei in micellar solutions, microemulsions, and liquid crystals proved the existence of an ordered polar-apolar interface, on the NMR time scale. NMR data, rationalized in terms of the two-step model of relaxation, allowed to quantify the dynamic aspects of the supramolecular aggregates in different soft matter systems. In addition, NMR techniques allowed to obtain important information on counterion binding as well as on size of the aggregate through molecular self-diffusion. Indeed NMR self-diffusion proved without any doubt the existence of bicontinuous microemulsions and bicontinuous cubic liquid crystals, suggested by pioneering and brilliant interpretation of SAXRD investigations. Moreover, NMR self-diffusion played a fundamental role in the understanding of microemulsion and emulsion nanostructures, phase transitions in phase diagrams, and particularly percolation phenomena in microemulsions. Since the nineties, globalization of the knowledge along with many other technical facilities such as electron microscopy, particularly cryo-EM, produced huge progresses in surfactant and colloid science. Actually we refer to nanoscience: bottom up/top down strategies allow to build nanodevices with applications spanning from ICT to food technology. Developments in the applied fields have also been addressed by important progresses in theoretical skills aimed to understand intermolecular forces, and specific ion interactions. Nevertheless, this is still an open question. Our predictive ability has however increased, hence more ambitious targets can be planned. Nanomedicine represents a major challenging field with its main aims: targeted drug delivery, diagnostic, theranostics, tissue engineering, and personalized medicine. Few recent examples will be mentioned. Although the real applications of these systems still need major work, nevertheless new challenges are open, and perspectives based on integrated multidisciplinary approaches would enable both a deeper basic knowledge and the expected advances in biomedical field. © 2013.

Insights into the distribution of water in a self-humidifying H2/O2 proton-exchange membrane fuel cell using 1H NMR microscopy.

PubMed

Feindel, Kirk W; Bergens, Steven H; Wasylishen, Roderick E

2006-11-01

Proton ((1)H) NMR microscopy is used to investigate in-situ the distribution of water throughout a self-humidifying proton-exchange membrane fuel cell, PEMFC, operating at ambient temperature and pressure on dry H(2)(g) and O(2)(g). The results provide the first experimental images of the in-plane distribution of water within the PEM of a membrane electrode assembly in an operating fuel cell. The effect of gas flow configuration on the distribution of water in the PEM and cathode flow field is investigated, revealing that the counter-flow configurations yield a more uniform distribution of water throughout the PEM. The maximum power output from the PEMFC, while operating under conditions of constant external load, occurs when H(2)O(l) is first visible in the (1)H NMR image of the cathode flow field, and subsequently declines as this H(2)O(l) continues to accumulate. The (1)H NMR microscopy experiments are in qualitative agreement with predictions from several theoretical modeling studies (e.g., Pasaogullari, U.; Wang, C. Y. J. Electrochem. Soc. 2005, 152, A380-A390), suggesting that combined theoretical and experimental approaches will constitute a powerful tool for PEMFC design, diagnosis, and optimization.

NMR of enzymatically synthesized uniformly 13C15N-labeled DNA oligonucleotides.

PubMed Central

Zimmer, D P; Crothers, D M

1995-01-01

A procedure for the enzymatic synthesis of uniformly 13C15N-labeled DNA oligonucleotides in milligram quantities for NMR studies is described. Deoxynucleotides obtained from microorganisms grown on 13C and 15N nutrient sources are enzymatically phosphorylated to dNTPs, and the dNTPs are incorporated into oligonucleotides using a 3'-5' exonuclease-deficient mutant of Klenow fragment of DNA polymerase I and an oligonucleotide template primer designed for efficient separation of labeled product DNA from unlabeled template. The labeling strategy has been used to uniformly label one or the other oligonucleotide strand in the DNA duplex dGGCAAAACGG.dCCGTTTTGCC in order to facilitate assignment and structure determination by NMR. Application of 15N and 13C heteronuclear NMR experiments to isotopically labeled DNA is presented. Images Fig. 2 Fig. 3 Fig. 4 PMID:7724521

Separation and analysis of trace degradants in a pharmaceutical formulation using on-line capillary isotachophoresis-NMR.

PubMed

Eldridge, Stacie L; Almeida, Valentino K; Korir, Albert K; Larive, Cynthia K

2007-11-15

NMR spectroscopy is widely used in the pharmaceutical industry for the structure elucidation of pharmaceutical impurities, especially when coupled to a separation method, such as HPLC. However, NMR has relatively poor sensitivity compared with other techniques such as mass spectrometry, limiting its applicability in impurity analyses. This limitation is addressed here through the on-line coupling of microcoil NMR with capillary isotachophoresis (cITP), a separation method that can concentrate dilute components by 2-3 orders of magnitude. With this approach, 1H NMR spectra can be acquired for microgram (nanomole) quantities of trace impurities in a complex sample matrix. cITP-NMR was used in this work to isolate and detect 4-aminophenol (PAP) in an acetaminophen sample spiked at the 0.1% level, with no interference from the parent compound. Analysis of an acetaminophen thermal degradation sample revealed resonances of several degradation products in addition to PAP, confirming the effectiveness of on-line cITP-NMR for trace analyses of pharmaceutical formulations. Subsequent LC-MS/MS analysis provided complementary information for the structure elucidation of the unknown degradation products, which were dimers formed during the degradation process.

Proton Nuclear Magnetic Resonance Spectroscopy as a Technique for Gentamicin Drug Susceptibility Studies with Escherichia coli ATCC 25922

PubMed Central

García-Álvarez, Lara; Busto, Jesús H.; Avenoza, Alberto; Sáenz, Yolanda; Peregrina, Jesús Manuel

2015-01-01

Antimicrobial drug susceptibility tests involving multiple time-consuming steps are still used as reference methods. Today, there is a need for the development of new automated instruments that can provide faster results and reduce operating time, reagent costs, and labor requirements. Nuclear magnetic resonance (NMR) spectroscopy meets those requirements. The metabolism and antimicrobial susceptibility of Escherichia coli ATCC 25922 in the presence of gentamicin have been analyzed using NMR and compared with a reference method. Direct incubation of the bacteria (with and without gentamicin) into the NMR tube has also been performed, and differences in the NMR spectra were obtained. The MIC, determined by the reference method found in this study, would correspond with the termination of the bacterial metabolism observed with NMR. Experiments carried out directly into the NMR tube enabled the development of antimicrobial drug susceptibility tests to assess the effectiveness of the antibiotic. NMR is an objective and reproducible method for showing the effects of a drug on the subject bacterium and can emerge as an excellent tool for studying bacterial activity in the presence of different antibiotic concentrations. PMID:25972417

Proton Nuclear Magnetic Resonance Spectroscopy as a Technique for Gentamicin Drug Susceptibility Studies with Escherichia coli ATCC 25922.

PubMed

García-Álvarez, Lara; Busto, Jesús H; Avenoza, Alberto; Sáenz, Yolanda; Peregrina, Jesús Manuel; Oteo, José A

2015-08-01

Antimicrobial drug susceptibility tests involving multiple time-consuming steps are still used as reference methods. Today, there is a need for the development of new automated instruments that can provide faster results and reduce operating time, reagent costs, and labor requirements. Nuclear magnetic resonance (NMR) spectroscopy meets those requirements. The metabolism and antimicrobial susceptibility of Escherichia coli ATCC 25922 in the presence of gentamicin have been analyzed using NMR and compared with a reference method. Direct incubation of the bacteria (with and without gentamicin) into the NMR tube has also been performed, and differences in the NMR spectra were obtained. The MIC, determined by the reference method found in this study, would correspond with the termination of the bacterial metabolism observed with NMR. Experiments carried out directly into the NMR tube enabled the development of antimicrobial drug susceptibility tests to assess the effectiveness of the antibiotic. NMR is an objective and reproducible method for showing the effects of a drug on the subject bacterium and can emerge as an excellent tool for studying bacterial activity in the presence of different antibiotic concentrations. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Single-scan 2D NMR: An Emerging Tool in Analytical Spectroscopy

PubMed Central

Giraudeau, Patrick; Frydman, Lucio

2016-01-01

Two-dimensional Nuclear Magnetic Resonance (2D NMR) spectroscopy is widely used in chemical and biochemical analyses. Multidimensional NMR is also witnessing an increased use in quantitative and metabolic screening applications. Conventional 2D NMR experiments, however, are affected by inherently long acquisition durations, arising from their need to sample the frequencies involved along their indirect domains in an incremented, scan-by-scan nature. A decade ago a so-called “ultrafast” (UF) approach was proposed, capable to deliver arbitrary 2D NMR spectra involving any kind of homo- or hetero-nuclear correlations, in a single scan. During the intervening years the performance of this sub-second 2D NMR methodology has been greatly improved, and UF 2D NMR is rapidly becoming a powerful analytical tool witnessing an expanded scope of applications. The present reviews summarizes the principles and the main developments which have contributed to the success of this approach, and focuses on applications which have been recently demonstrated in various areas of analytical chemistry –from the real time monitoring of chemical and biochemical processes, to extensions in hyphenated techniques and in quantitative applications. PMID:25014342

Determination of Structural Topology of a Membrane Protein in Lipid -Bilayers using Polarization Optimized Experiments (POE) for Static and MAS Solid State NMR Spectroscopy

PubMed Central

Mote, Kaustubh R.; Gopinath, T.; Veglia, Gianluigi

2013-01-01

The low sensitivity inherent to both the static and magic angle spinning techniques of solid-state NMR (ssNMR) spectroscopy has thus far limited the routine application of multidimensional experiments to determine the structure of membrane proteins in lipid bilayers. Here, we demonstrate the advantage of using a recently developed class of experiments, polarization optimized experiments (POE), for both static and MAS spectroscopy to achieve higher sensitivity and substantial time-savings for 2D and 3D experiments. We used sarcolipin, a single pass membrane protein, reconstituted in oriented bicelles (for oriented ssNMR) and multilamellar vesicles (for MAS ssNMR) as a benchmark. The restraints derived by these experiments are then combined into a hybrid energy function to allow simultaneous determination of structure and topology. The resulting structural ensemble converged to a helical conformation with a backbone RMSD ∼ 0.44 Å, a tilt angle of 24° ± 1°, and an azimuthal angle of 55° ± 6°. This work represents a crucial first step toward obtaining high-resolution structures of large membrane proteins using combined multidimensional O-ssNMR and MAS-ssNMR. PMID:23963722

SABRE hyperpolarization enables high-sensitivity 1H and 13C benchtop NMR spectroscopy.

PubMed

Richardson, Peter M; Parrott, Andrew J; Semenova, Olga; Nordon, Alison; Duckett, Simon B; Halse, Meghan E

2018-06-19

Benchtop NMR spectrometers operating with low magnetic fields of 1-2 T at sub-ppm resolution show great promise as analytical platforms that can be used outside the traditional laboratory environment for industrial process monitoring. One current limitation that reduces the uptake of benchtop NMR is associated with the detection fields' reduced sensitivity. Here we demonstrate how para-hydrogen (p-H2) based signal amplification by reversible exchange (SABRE), a simple to achieve hyperpolarization technique, enhances agent detectability within the environment of a benchtop (1 T) NMR spectrometer so that informative 1H and 13C NMR spectra can be readily recorded for low-concentration analytes. SABRE-derived 1H NMR signal enhancements of up to 17 000-fold, corresponding to 1H polarization levels of P = 5.9%, were achieved for 26 mM pyridine in d4-methanol in a matter of seconds. Comparable enhancement levels can be achieved in both deuterated and protio solvents but now the SABRE-enhanced analyte signals dominate due to the comparatively weak thermally-polarized solvent response. The SABRE approach also enables the acquisition of 13C NMR spectra of analytes at natural isotopic abundance in a single scan as evidenced by hyperpolarized 13C NMR spectra of tens of millimolar concentrations of 4-methylpyridine. Now the associated signal enhancement factors are up to 45 500 fold (P = 4.0%) and achieved in just 15 s. Integration of an automated SABRE polarization system with the benchtop NMR spectrometer framework produces renewable and reproducible NMR signal enhancements that can be exploited for the collection of multi-dimensional NMR spectra, exemplified here by a SABRE-enhanced 2D COSY NMR spectrum.

Analysis and Synthesis of Robust Data Structures

DTIC Science & Technology

1990-08-01

1.3.2 Multiversion Software. .. .. .. .. .. .... .. ... .. ...... 5 1.3.3 Robust Data Structure .. .. .. .. .. .. .. .. .. ... .. ..... 6 1.4...context are 0 multiversion software, which is an adaptation oi N-modulo redundancy (NMR) tech- nique. * recovery blocks, which is an adaptation of...implementations using these features for such a hybrid approach. 1.3.2 Multiversion Software Avizienis [AC77] was the first to adapt NMR technique into

Isobutylene Dimerization: A Discovery-Based Exploration of Mechanism and Regioselectivity by NMR Spectroscopy and Molecular Modeling

ERIC Educational Resources Information Center

Schuster, Mariah L.; Peterson, Karl P.; Stoffregen, Stacey A.

2018-01-01

This two-period undergraduate laboratory experiment involves the synthesis of a mixture of isomeric unknowns, isolation of the mixture by means of distillation, and characterization of the two products primarily by NMR spectroscopy (1D and 2D) supported with IR spectroscopy and GC-MS techniques. Subsequent calculation and examination of the…

Scaffolding Students' Skill Development by First Introducing Advanced Techniques through the Synthesis and [superscript 15]N NMR Analysis of Cinnamamides

ERIC Educational Resources Information Center

Shuldburg, Sara; Carroll, Jennifer

2017-01-01

An advanced undergraduate experiment involving the synthesis and characterization of a series of six unique cinnamamides is described. This experiment allows for a progressive mastery of skills students need to tackle more complex NMR structure elucidation problems. Characterization of the products involves IR spectroscopy, GCMS, and proton,…

Reaction of [rho]-hydroxycinnamyl alcohols with transition metal salts. 3, Preparation and NMR characterization of improved DHPS

Treesearch

Lawrence L. Landucci

2000-01-01

Dehydropolymerization of [rho]-hydroxycinnamyl alcohols with manganese(III) acetate in either aqueous acetic acid or pyridine resulted in dehydropolymers (DHPs) that more closely approximate the structure of natural lignins than do DHPs produced by enzymic techniques. The 13C NMR spectrum of a "biomimetic" guaiacyl-DHP (G-DHP) from coniferyl alcohol was very...

An Introduction to Drug Discovery by Probing Protein-Substrate Interactions Using Saturation Transfer Difference-Nuclear Magnetic Resonance (STD-NMR)

ERIC Educational Resources Information Center

Guegan, Jean-Paul; Daniellou, Richard

2012-01-01

NMR spectroscopy is a powerful tool for characterizing and identifying molecules and nowadays is even used to characterize complex systems in biology. In the experiment presented here, students learned how to apply this modern technique to probe interactions between small molecules and proteins. With the use of simple organic synthesis, students…

Interest of fluorine-19 nuclear magnetic resonance spectroscopy in the detection, identification and quantification of metabolites of anticancer and antifungal fluoropyrimidine drugs in human biofluids.

PubMed

Martino, Robert; Gilard, Véronique; Desmoulin, Franck; Malet-Martino, Myriam

2006-01-01

The metabolism of fluorouracil and fluorocytosine, two 5-fluoropyrimidine drugs in clinical use, was investigated. (19)F nuclear magnetic resonance (NMR) spectroscopy was used as an analytical technique for the detection, identification and quantification of fluorinated metabolites of these drugs in intact human biofluids as well as fluorinated degradation compounds of fluorouracil in commercial vials. (19)F NMR provides a highly specific tool for the detection and absolute quantification, in a single run, of all the fluorinated species, including unexpected substances, present in biofluids of patients treated with fluorouracil or fluorocytosine. Besides the parent drug and the already known fluorinated metabolites, nine new metabolites were identified for the first time with (19)F NMR in human biofluids. Six of them can only be observed with this technique: fluoride ion, N-carboxy-alpha-fluoro-beta-alanine, alpha-fluoro-beta-alanine conjugate with deoxycholic acid, 2-fluoro-3-hydroxypropanoic acid, fluoroacetic acid, O(2)-beta-glucuronide of fluorocytosine. (19)F NMR studies of biological fluids of patients treated with anticancer fluorouracil or antifungal fluorocytosine have furthered the understanding of their catabolic pathways.

Holistic Analysis Enhances the Description of Metabolic Complexity in Dietary Natural Products1234

PubMed Central

Kulakowski, Daniel; Lankin, David C; McAlpine, James B; Chen, Shao-Nong

2016-01-01

In the field of food and nutrition, complex natural products (NPs) are typically obtained from cells/tissues of diverse organisms such as plants, mushrooms, and animals. Among them, edible fruits, grains, and vegetables represent most of the human diet. Because of an important dietary dependence, the comprehensive metabolomic analysis of dietary NPs, performed holistically via the assessment of as many metabolites as possible, constitutes a fundamental building block for understanding the human diet. Both mass spectrometry (MS) and nuclear magnetic resonance (NMR) are important complementary analytic techniques, covering a wide range of metabolites at different concentrations. Particularly, 1-dimensional 1H-NMR offers an unbiased overview of all metabolites present in a sample without prior knowledge of its composition, thereby leading to an untargeted analysis. In the past decade, NMR-based metabolomics in plant and food analyses has evolved considerably. The scope of the present review, covering literature of the past 5 y, is to address the relevance of 1H-NMR–based metabolomics in food plant studies, including a comparison with MS-based techniques. Major applications of NMR-based metabolomics for the quality control of dietary NPs and assessment of their nutritional values are presented. PMID:27180381

Simple and Inexpensive Classroom Demonstrations of Nuclear Magnetic Resonance and Magnetic Resonance Imaging.

ERIC Educational Resources Information Center

Olson, Joel A.; Nordell, Karen J.; Chesnik, Marla A.; Landis, Clark R.; Ellis, Arthur B.; Rzchowski, M. S.; Condren, S. Michael; Lisensky, George C.

2000-01-01

Describes a set of simple, inexpensive, classical demonstrations of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) principles that illustrate the resonance condition associated with magnetic dipoles and the dependence of the resonance frequency on environment. (WRM)

Ionic Diffusion in Cu6PS5Br Studied by 63Cu NMR

NASA Astrophysics Data System (ADS)

Ohki, H.; Harazono, K.; Erata, T.; Tasaki, A.; Ikeda, R.

1993-10-01

Applying 63Cu NMR technique, we observed exchange between the nonequivalent copper sites in crystalline Cu6PS5Br, known as a member of the mineral "argyrodite". Below 200 K, where the motion of the copper (I) ion is slow, we could distinguish several nonequivalent copper sites. On increasing the temperature, the chemical exchange between the nonequivalent cation sites was seen on the 63Cu NMR spectra. We could determine the activation energy for this motion to be 35 kJ mol-1 , in good agreement with the published ionic conductivity.

NMR at very low fields.

PubMed

Trahms, Lutz; Burghoff, Martin

2010-10-01

Although nuclear magnetic resonance in low fields around or below the Earth's magnetic field is almost as old as nuclear magnetic resonance itself, the recent years have experienced a revival of this technique that is opposed to the common trend towards higher and higher fields. The background of this development is the expectation that the low-field domain may open a new window for the study of molecular structure and dynamics. Here, we will give an overview on the specific features in the low-field domain, both from the technical and from the physical point of view. In addition, we present a short passage on the option of magnetic resonance imaging in fields of the micro-Tesla range. Copyright © 2010 Elsevier Inc. All rights reserved.

The Development of Metabolomic Sampling Procedures for Pichia pastoris, and Baseline Metabolome Data

PubMed Central

Tredwell, Gregory D.; Edwards-Jones, Bryn; Leak, David J.; Bundy, Jacob G.

2011-01-01

Metabolic profiling is increasingly being used to investigate a diverse range of biological questions. Due to the rapid turnover of intracellular metabolites it is important to have reliable, reproducible techniques for sampling and sample treatment. Through the use of non-targeted analytical techniques such as NMR and GC-MS we have performed a comprehensive quantitative investigation of sampling techniques for Pichia pastoris. It was clear that quenching metabolism using solutions based on the standard cold methanol protocol caused some metabolite losses from P. pastoris cells. However, these were at a low level, with the NMR results indicating metabolite increases in the quenching solution below 5% of their intracellular level for 75% of metabolites identified; while the GC-MS results suggest a slightly higher level with increases below 15% of their intracellular values. There were subtle differences between the four quenching solutions investigated but broadly, they all gave similar results. Total culture extraction of cells + broth using high cell density cultures typical of P. pastoris fermentations, was an efficient sampling technique for NMR analysis and provided a gold standard of intracellular metabolite levels; however, salts in the media affected the GC-MS analysis. Furthermore, there was no benefit in including an additional washing step in the quenching process, as the results were essentially identical to those obtained just by a single centrifugation step. We have identified the major high-concentration metabolites found in both the extra- and intracellular locations of P. pastoris cultures by NMR spectroscopy and GC-MS. This has provided us with a baseline metabolome for P. pastoris for future studies. The P. pastoris metabolome is significantly different from that of Saccharomyces cerevisiae, with the most notable difference being the production of high concentrations of arabitol by P. pastoris. PMID:21283710

Protein 19F-labeling using transglutaminase for the NMR study of intermolecular interactions.

PubMed

Hattori, Yoshikazu; Heidenreich, David; Ono, Yuki; Sugiki, Toshihiko; Yokoyama, Kei-Ichi; Suzuki, Ei-Ichiro; Fujiwara, Toshimichi; Kojima, Chojiro

2017-08-01

The preparation of stable isotope-labeled proteins is important for NMR studies, however, it is often hampered in the case of eukaryotic proteins which are not readily expressed in Escherichia coli. Such proteins are often conveniently investigated following post-expression chemical isotope tagging. Enzymatic 15 N-labeling of glutamine side chains using transglutaminase (TGase) has been applied to several proteins for NMR studies. 19 F-labeling is useful for interaction studies due to its high NMR sensitivity and susceptibility. Here, 19 F-labeling of glutamine side chains using TGase and 2,2,2-trifluoroethylamine hydrochloride was established for use in an NMR study. This enzymatic 19 F-labeling readily provided NMR detection of protein-drug and protein-protein interactions with complexes of about 100 kDa since the surface residues provided a good substrate for TGase. The 19 F-labeling method was 3.5-fold more sensitive than 15 N-labeling, and could be combined with other chemical modification techniques such as lysine 13 C-methylation. 13 C-dimethylated- 19 F-labeled FKBP12 provided more accurate information concerning the FK506 binding site.

Coal liquefaction process streams characterization and evaluation: Analysis of Black Thunder coal and liquefaction products from HRI Bench Unit Run CC-15

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pugmire, R.J.; Solum, M.S.

This study was designed to apply {sup 13}C-nuclear magnetic resonance (NMR) spectrometry to the analysis of direct coal liquefaction process-stream materials. {sup 13}C-NMR was shown to have a high potential for application to direct coal liquefaction-derived samples in Phase II of this program. In this Phase III project, {sup 13}C-NMR was applied to a set of samples derived from the HRI Inc. bench-scale liquefaction Run CC-15. The samples include the feed coal, net products and intermediate streams from three operating periods of the run. High-resolution {sup 13}C-NMR data were obtained for the liquid samples and solid-state CP/MAS {sup 13}C-NMR datamore » were obtained for the coal and filter-cake samples. The {sup 1}C-NMR technique is used to derive a set of twelve carbon structural parameters for each sample (CONSOL Table A). Average molecular structural descriptors can then be derived from these parameters (CONSOL Table B).« less

Dynamics and conformations of PEO chains chemically bonded on silica: comparison between 1H and 2H NMR.

PubMed

Tajouri, T; Hommel, H

2007-06-01

1H NMR was used to study the motion of monomer units in a layer of poly(ethylene oxide) chains grafted on silica. First, the dependence of the relaxation times on the grafting ratios is discussed qualitatively from a phenomenological point of view. Next, the NMR line narrowing effect by high-speed rotation is observed in the same samples with different grafting ratios. The magic angle spinning technique permits determination of two correlation times for each grafting ratio: tau(c) characteristic of an environment with a fast motion and tau(l) characteristic of an environment with a slow motion. In addition, the dynamics of these grafted chains are investigated by deuterium NMR (2H NMR), which is sensitive to the anisotropy of molecular motion. The evolution has been studied for two extreme grafting ratios and each time as a function of temperature. The anisotropy is more marked at low temperatures and for a low grafting ratio. The results are consistent with the 1H NMR relaxation times measured as a function of temperature. Copyright 2007 John Wiley & Sons, Ltd.

Modeling an in-register, parallel "iowa" aβ fibril structure using solid-state NMR data from labeled samples with rosetta.

PubMed

Sgourakis, Nikolaos G; Yau, Wai-Ming; Qiang, Wei

2015-01-06

Determining the structures of amyloid fibrils is an important first step toward understanding the molecular basis of neurodegenerative diseases. For β-amyloid (Aβ) fibrils, conventional solid-state NMR structure determination using uniform labeling is limited by extensive peak overlap. We describe the characterization of a distinct structural polymorph of Aβ using solid-state NMR, transmission electron microscopy (TEM), and Rosetta model building. First, the overall fibril arrangement is established using mass-per-length measurements from TEM. Then, the fibril backbone arrangement, stacking registry, and "steric zipper" core interactions are determined using a number of solid-state NMR techniques on sparsely (13)C-labeled samples. Finally, we perform Rosetta structure calculations with an explicitly symmetric representation of the system. We demonstrate the power of the hybrid Rosetta/NMR approach by modeling the in-register, parallel "Iowa" mutant (D23N) at high resolution (1.2Å backbone rmsd). The final models are validated using an independent set of NMR experiments that confirm key features. Copyright © 2015 Elsevier Ltd. All rights reserved.

Observations using Phosphorus-31 nuclear magnetic resonance (31P-NMR) of structural changes in freeze-thawed hen egg yolk.

PubMed

Wakamatsu, Hiroki; Handa, Akihiro; Chiba, Kazuhiro

2018-04-01

Hen egg yolk (EY) has a complicated structure consisting of lipids and proteins, and its structure is deeply related with its functional properties. 31 P-NMR is an efficient technique to non-destructively detect the dynamic behaviour of phospholipids, the main component of bio-membranes. We determined conditions for measuring the 31 P NMR spectra of EY and identified the components. 31 P-NMR was used to detect phosvitin, inorganic phosphate, and lipoprotein as well as structural changes such as granule collapse and freeze-thaw denaturation as signal changes. Freeze-thaw denaturation generated a new denaturation peak. We separated aggregates of LDL from freeze-thawed plasma using centrifugation. TEM and 31 P-NMR observations revealed that the denaturation peak corresponded to LDL aggregates. The 31 P-NMR spectra suggested the formation of multiple forms of LDL aggregates in which the head groups of phospholipid molecules adopt a face-to-face orientation, similar to that observed following the flocculation of lipoproteins or in the lamellar-like structures of phospholipids. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improved classification accuracy in 1- and 2-dimensional NMR metabolomics data using the variance stabilising generalised logarithm transformation

PubMed Central

Parsons, Helen M; Ludwig, Christian; Günther, Ulrich L; Viant, Mark R

2007-01-01

Background Classifying nuclear magnetic resonance (NMR) spectra is a crucial step in many metabolomics experiments. Since several multivariate classification techniques depend upon the variance of the data, it is important to first minimise any contribution from unwanted technical variance arising from sample preparation and analytical measurements, and thereby maximise any contribution from wanted biological variance between different classes. The generalised logarithm (glog) transform was developed to stabilise the variance in DNA microarray datasets, but has rarely been applied to metabolomics data. In particular, it has not been rigorously evaluated against other scaling techniques used in metabolomics, nor tested on all forms of NMR spectra including 1-dimensional (1D) 1H, projections of 2D 1H, 1H J-resolved (pJRES), and intact 2D J-resolved (JRES). Results Here, the effects of the glog transform are compared against two commonly used variance stabilising techniques, autoscaling and Pareto scaling, as well as unscaled data. The four methods are evaluated in terms of the effects on the variance of NMR metabolomics data and on the classification accuracy following multivariate analysis, the latter achieved using principal component analysis followed by linear discriminant analysis. For two of three datasets analysed, classification accuracies were highest following glog transformation: 100% accuracy for discriminating 1D NMR spectra of hypoxic and normoxic invertebrate muscle, and 100% accuracy for discriminating 2D JRES spectra of fish livers sampled from two rivers. For the third dataset, pJRES spectra of urine from two breeds of dog, the glog transform and autoscaling achieved equal highest accuracies. Additionally we extended the glog algorithm to effectively suppress noise, which proved critical for the analysis of 2D JRES spectra. Conclusion We have demonstrated that the glog and extended glog transforms stabilise the technical variance in NMR metabolomics datasets. This significantly improves the discrimination between sample classes and has resulted in higher classification accuracies compared to unscaled, autoscaled or Pareto scaled data. Additionally we have confirmed the broad applicability of the glog approach using three disparate datasets from different biological samples using 1D NMR spectra, 1D projections of 2D JRES spectra, and intact 2D JRES spectra. PMID:17605789

NMR-based investigations into target DNA search processes of proteins.

PubMed

Iwahara, Junji; Zandarashvili, Levani; Kemme, Catherine A; Esadze, Alexandre

2018-05-10

To perform their function, transcription factors and DNA-repair/modifying enzymes must first locate their targets in the vast presence of nonspecific, but structurally similar sites on genomic DNA. Before reaching their targets, these proteins stochastically scan DNA and dynamically move from one site to another on DNA. Solution NMR spectroscopy provides unique atomic-level insights into the dynamic DNA-scanning processes, which are difficult to gain by any other experimental means. In this review, we provide an introductory overview on the NMR methods for the structural, dynamic, and kinetic investigations of target DNA search by proteins. We also discuss advantages and disadvantages of these NMR methods over other methods such as single-molecule techniques and biochemical approaches. Copyright © 2018 Elsevier Inc. All rights reserved.

Metabolic studies of mammalian cells by 31P-NMR using a continuous perfusion technique.

PubMed

Knop, R H; Chen, C W; Mitchell, J B; Russo, A; McPherson, S; Cohen, J S

1984-07-20

Levels of ATP and Pi in metabolically active Chinese hamster lung fibroblasts were monitored noninvasively by 31P-NMR over many hours and under a variety of conditions. The cells were embedded in a matrix of agarose gel in the form of fine threads which were continuously perfused in a standard NMR tube. The small diameter of the thread allows rapid diffusion of metabolites and drugs into the cells. The changes in ATP and Pi levels were followed as a function of time in response to perfusion with a glucose-containing medium, with isotonic saline and with a medium containing 2,4-dinitrophenol, an uncoupler of oxidative phosphorylation. This gel-thread perfusion method should enable routine NMR studies of cellular metabolism, and may have other potential biological applications.

An NMR relaxometry and gravimetric study of gelatin-free aqueous polyacrylamide dosimeters

NASA Astrophysics Data System (ADS)

Babic, Steven; Schreiner, L. John

2006-09-01

In conformal radiation therapy, a high dose of radiation is given to a target volume to increase the probability of cure, and care is taken to minimize the dose to surrounding healthy tissue. The techniques used to achieve this are very complicated and the precise verification of the resulting three-dimensional (3D) dose distribution is required. Polyacrylamide gelatin (PAG) dosimeters with magnetic resonance imaging and optical computed tomography scanning provide the required 3D dosimetry with high spatial resolution. Many basic studies have characterized these chemical dosimeters that polymerize under irradiation. However, the investigation of the fundamental properties of the radiation-induced polymerization in PAG dosimeters is complicated by the presence of the background gelatin matrix. In this work, a gelatin-free model system for the study of the basic radiation-induced polymerization in PAG dosimeters has been developed. Experiments were performed on gelatin-free dosimeters, named aqueous polyacrylamide (APA) dosimeters, containing equal amounts of acrylamide and N,N'-methylene-bisacrylamide. The APA dosimeters were prepared with four different total monomer concentrations (2, 4, 6 and 8% by weight). Nuclear magnetic resonance (NMR) spin-spin and spin-lattice proton relaxation measurements at 20 MHz, and gravimetric analyses performed on all four dosimeters, show a continuous degree of polymerization over the dose range of 0-25 Gy. The developed NMR model explains the relationship observed between the relaxation data and the amount of crosslinked polymer formed at each dose. This model can be extended with gelatin relaxation data to provide a fundamental understanding of radiation-induced polymerization in the conventional PAG dosimeters.

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.

An NMR relaxometry and gravimetric study of gelatin-free aqueous polyacrylamide dosimeters.

PubMed

Babic, Steven; Schreiner, L John

2006-09-07

In conformal radiation therapy, a high dose of radiation is given to a target volume to increase the probability of cure, and care is taken to minimize the dose to surrounding healthy tissue. The techniques used to achieve this are very complicated and the precise verification of the resulting three-dimensional (3D) dose distribution is required. Polyacrylamide gelatin (PAG) dosimeters with magnetic resonance imaging and optical computed tomography scanning provide the required 3D dosimetry with high spatial resolution. Many basic studies have characterized these chemical dosimeters that polymerize under irradiation. However, the investigation of the fundamental properties of the radiation-induced polymerization in PAG dosimeters is complicated by the presence of the background gelatin matrix. In this work, a gelatin-free model system for the study of the basic radiation-induced polymerization in PAG dosimeters has been developed. Experiments were performed on gelatin-free dosimeters, named aqueous polyacrylamide (APA) dosimeters, containing equal amounts of acrylamide and N,N'-methylene-bisacrylamide. The APA dosimeters were prepared with four different total monomer concentrations (2, 4, 6 and 8% by weight). Nuclear magnetic resonance (NMR) spin-spin and spin-lattice proton relaxation measurements at 20 MHz, and gravimetric analyses performed on all four dosimeters, show a continuous degree of polymerization over the dose range of 0-25 Gy. The developed NMR model explains the relationship observed between the relaxation data and the amount of crosslinked polymer formed at each dose. This model can be extended with gelatin relaxation data to provide a fundamental understanding of radiation-induced polymerization in the conventional PAG dosimeters.

Monitoring carbonate dissolution using spatially resolved under-sampled NMR propagators and MRI

NASA Astrophysics Data System (ADS)

Sederman, A. J.; Colbourne, A.; Mantle, M. D.; Gladden, L. F.; Oliveira, R.; Bijeljic, B.; Blunt, M. J.

2017-12-01

The dissolution of a porous rock matrix by an acidic flow causes a change in the pore structure and consequently the pattern of fluid flow and rock permeability. This process is relevant to many areas of practical relevance such as enhanced oil recovery, water contaminant migration and sequestration of supercritical CO2. The most important governing factors for the type of change in the pore space are related by the Péclet (Pe) and Damköhler (Da) dimensionless numbers; these compare the transport properties of the fluid in the porous medium with the reactive properties of the solid matrix and the incident fluid respectively. Variation in Pe and Da can cause very different evolution regimes of the pore space and flow can occur, ranging from a uniform dissolution through different "wormholing" regimes (shown on the left hand side of figure 1) to face dissolution. NMR has a unique capability of measuring both the flow and structural changes during such dissolution whilst the characteristics of flow in the highly heterogeneous matrix that is formed can be predicted by the CTRW modelling approach. Here, NMR measurements of displacement probability distributions, or propagators, have been used to monitor the evolution of fluid flow during a reactive dissolution rock core floods. Developments in the NMR method by undersampling the acquisition data enable spatially resolved measurements of the propagators to be done at sufficient displacement resolution and in a timescale that is short enough to capture the changes in structure and flow. The highly under-sampled (4%) data, which typically reduces the acquisition time from 2 hours to 6 minutes, has been shown to produce equivalent propagator results to the fully sampled experiment. Combining these propagator measurements with quantitative and fast imaging techniques a full time-resolved picture of the dissolution reaction is built up. Experiments have been done for both Ketton and Estaillades carbonate rock cores, which exhibit very different dissolution behaviours, and for which experiments and model comparisons will be shown.

Development of a superconducting bulk magnet for NMR and MRI.

PubMed

Nakamura, Takashi; Tamada, Daiki; Yanagi, Yousuke; Itoh, Yoshitaka; Nemoto, Takahiro; Utumi, Hiroaki; Kose, Katsumi

2015-10-01

A superconducting bulk magnet composed of six vertically stacked annular single-domain c-axis-oriented Eu-Ba-Cu-O crystals was energized to 4.74 T using a conventional superconducting magnet for high-resolution NMR spectroscopy. Shim coils, gradient coils, and radio frequency coils for high resolution NMR and MRI were installed in the 23 mm-diameter room-temperature bore of the bulk magnet. A 6.9 ppm peak-to-peak homogeneous region suitable for MRI was achieved in the central cylindrical region (6.2 mm diameter, 9.1 mm length) of the bulk magnet by using a single layer shim coil. A 21 Hz spectral resolution that can be used for high resolution NMR spectroscopy was obtained in the central cylindrical region (1.3 mm diameter, 4 mm length) of the bulk magnet by using a multichannel shim coil. A clear 3D MR image dataset of a chemically fixed mouse fetus with (50 μm)(3) voxel resolution was obtained in 5.5 h. We therefore concluded that the cryogen-free superconducting bulk magnet developed in this study is useful for high-resolution desktop NMR, MRI and mobile NMR device. Copyright © 2015 Elsevier Inc. All rights reserved.

Development of Laser-Polarized Noble Gas Magnetic Resonance Imaging (MRI) Technology

NASA Technical Reports Server (NTRS)

Walsworth, Ronald L.

2004-01-01

We are developing technology for laser-polarized noble gas nuclear magnetic resonance (NMR), with the aim of enabling it as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation, perfusion, and gas-exchange. In addition, laser-polarized noble gases (3He and 1BXe) do not require a large magnetic field for sensitive NMR detection, opening the door to practical MRI with novel, open-access magnet designs at very low magnetic fields (and hence in confined spaces). We are pursuing two specific aims in this technology development program. The first aim is to develop an open-access, low-field (less than 0.01 T) instrument for MRI studies of human gas inhalation as a function of subject orientation, and the second aim is to develop functional imaging of the lung using laser-polarized He-3 and Xe-129.

Decreased nicotinic receptor availability in smokers with slow rates of nicotine metabolism

PubMed Central

Dubroff, Jacob G.; Doot, Robert K.; Falcone, Mary; R, Robert A. Schnoll; Ray, Riju; Tyndale, Rachel F.; Brody, Arthur L.; Hou, Catherine; Schmitz, Alexander; Lerman, Caryn

2015-01-01

The nicotine metabolite ratio (NMR), a stable measure of hepatic nicotine metabolism via the CYP2A6 pathway and total nicotine clearance, is a predictive biomarker of response to nicotine replacement therapy, with increased quit rates in slower metabolizers. Nicotine binds directly to nicotinic acetylcholine receptors (nAChRs) to exert its psychoactive effects. This study examined the relationship between NMR and nAChR availability (α4β2* subtype) using positron emission tomography (PET) imaging of the radiotracer 2-18F-FA-85380 (2-18F-FA). Methods Twenty four smokers, 12 slow metabolizers (NMR <0.26) and 12 normal metabolizers (NMR ≥0.26), underwent 2-18F-FA-PET brain imaging following overnight nicotine abstinence (18 hours prior to scanning), using a validated bolus plus infusion protocol. Availability of nAChRs was compared between NMR groups in a priori volumes of interest (VOIs), with total distribution volume (VT/fP) being the measure of nAChR availability. Cravings to smoke were assessed prior to and following the scans. Results Thalamic nAChR α4β2* availability was significantly reduced in slow (versus normal) nicotine metabolizers (P=0.04). Slow metabolizers exhibited greater reductions in craving than normal metabolizers from pre- to post-scanning; however, craving was unrelated to availability. Conclusion The rate of nicotine metabolism is associated with thalamic nAChR availability. Additional studies could examine whether altered nAChR availability underlies differences in treatment response between slow and normal metabolizers of nicotine. PMID:26272810

Characterization of the fluid and solid components of cyanogel systems during the gelation process

NASA Astrophysics Data System (ADS)

Fortmeyer, Ivy Camille

The work in this thesis concerns the sol-gel transformation in cyanogel systems comprised of d8 square planar chlorometalates (M=Pd(II), Pt(II)) and d6 octahedral hexacyanometalates (M=Fe(II), Co(III), Ru(II)). The body of this thesis is split into two chapters. The first chapter examines the physical changes in the solvent phase of the sol-gel network, and the second focuses on the polymer backbone of the gel. Studies on the water component of cyanogel systems during the gelation process were carried out with a variety of in situ spectroscopic techniques. The use of high resolution-magic angle spinning nuclear magnetic resonance (HR-MAS NMR) to identify and characterize different water environments was explored, but was ultimately found to disrupt gelation. Standard solution-phase 1H NMR proved sufficient for calculation and qualitative modeling of spin-spin and spin-lattice relaxations, providing distinct spectral markers of the gelation point and subsequent aging process. Vibrational spectroscopy was used to explore the hydrogen bonding environment of the water during gelation. The kinetics of polymerization of the cyanogel backbone was explored using both in situ and ex situ techniques. Data collected by 13C NMR and 195Pt NMR primarily demonstrated first order kinetics, implying a dissociative substitution mechanism at the chlorometalate center. Rate constants for gelation in the presence of various added monopotassium and nitrate salts were calculated. Added chloride was found to significantly slow gelation and was further explored using NMR and vibrational spectroscopy. A mechanism was proposed for the polymerization taking into account the dissociative substitution and the bridging geometries implied by 13C NMR.

Characterization of wet aggregate stability of soils by ¹H-NMR relaxometry.

PubMed

Buchmann, C; Meyer, M; Schaumann, G E

2015-09-01

For the assessment of soil structural stability against hydraulic stress, wet sieving or constant head permeability tests are typically used but rather limited in their intrinsic information value. The multiple applications of several tests is the only possibility to assess important processes and mechanisms during soil aggregate breakdown, e.g. the influences of soil fragment release or differential swelling on the porous systems of soils or soil aggregate columns. Consequently, the development of new techniques for a faster and more detailed wet aggregate stability assessment is required. (1)H nuclear magnetic resonance relaxometry ((1)H-NMR relaxometry) might provide these requirements because it has already been successfully applied on soils. We evaluated the potential of (1)H-NMR relaxometry for the assessment of wet aggregate stability of soils, with more detailed information on occurring mechanisms at the same time. Therefore, we conducted single wet sieving and constant head permeability tests on untreated and 1% polyacrylic acid-treated soil aggregates of different textures and organic matter contents, subsequently measured by (1)H-NMR relaxometry after percolation. The stability of the soil aggregates were mainly depending on their organic matter contents and the type of aggregate stabilization, whereby additional effects of clay swelling on the measured wet aggregate stability were identified by the transverse relaxation time (T2) distributions. Regression analyses showed that only the percentage of water stable aggregates could be determined accurately from percolated soil aggregate columns by (1)H-NMR relaxometry measurements. (1)H-NMR relaxometry seems a promising technique for wet aggregate stability measurements but should be further developed for nonpercolated aggregate columns and real soil samples. Copyright © 2014 John Wiley & Sons, Ltd.

Liquid-State NMR Analysis of Nanocelluloses.

PubMed

King, Alistair W T; Mäkelä, Valtteri; Kedzior, Stephanie A; Laaksonen, Tiina; Partl, Gabriel J; Heikkinen, Sami; Koskela, Harri; Heikkinen, Harri A; Holding, Ashley J; Cranston, Emily D; Kilpeläinen, Ilkka

2018-04-11

Recent developments in ionic liquid electrolytes for cellulose or biomass dissolution has also allowed for high-resolution 1 H and 13 C NMR on very high molecular weight cellulose. This permits the development of advanced liquid-state quantitative NMR methods for characterization of unsubstituted and low degree of substitution celluloses, for example, surface-modified nanocelluloses, which are insoluble in all molecular solvents. As such, we present the use of the tetrabutylphosphonium acetate ([P 4444 ][OAc]):DMSO- d 6 electrolyte in the 1D and 2D NMR characterization of poly(methyl methacrylate) (PMMA)-grafted cellulose nanocrystals (CNCs). PMMA- g-CNCs was chosen as a difficult model to study, to illustrate the potential of the technique. The chemical shift range of [P 4444 ][OAc] is completely upfield of the cellulose backbone signals, avoiding signal overlap. In addition, application of diffusion-editing for 1 H and HSQC was shown to be effective in the discrimination between PMMA polymer graft resonances and those from low molecular weight components arising from the solvent system. The bulk ratio of methyl methacrylate monomer to anhydroglucose unit was determined using a combination of HSQC and quantitative 13 C NMR. After detachment and recovery of the PMMA grafts, through methanolysis, DOSY NMR was used to determine the average self-diffusion coefficient and, hence, molecular weight of the grafts compared to self-diffusion coefficients for PMMA GPC standards. This finally led to a calculation of both graft length and graft density using liquid-state NMR techniques. In addition, it was possible to discriminate between triads and tetrads, associated with PMMA tacticity, of the PMMA still attached to the CNCs (before methanolysis). CNC reducing end and sulfate half ester resonances, from sulfuric acid hydrolysis, were also assignable. Furthermore, other biopolymers, such as hemicelluloses and proteins (silk and wool), were found to be soluble in the electrolyte media, allowing for wider application of this method beyond just cellulose analytics.

DESI-MS imaging and NMR spectroscopy to investigate the influence of biodiesel in the structure of commercial rubbers.

PubMed

Silva, Lorena M A; Alves Filho, Elenilson G; Simpson, André J; Monteiro, Marcos R; Cabral, Elaine; Ifa, Demian; Venâncio, Tiago

2017-10-01

Biodiesel has been introduced as an energetic matrix in several countries around the world. However, the affinity of biodiesel with the components of petrodiesel engines is a growing concern. In order to obtain information regarding the effect of biodiesel on the rubber structure, nuclear magnetic resonance technics under a new technology named as comprehensive multiphase (CMP NMR) and the imaging through desorption electrospray ionization mass spectrometry (DESI-MS imaging) were used. The 1 H CMP-DOSY NMR showed the entrapped fuel into the rubber cavities, which the higher constraint caused by the rubber structure is related to the smaller diffusion coefficient. The less affected type of rubber by biodiesel was ethylene-propylene-diene monomer (EPDM), and the most affected was synthetic rubber nitrile (NBR). The 13 C CMP MAS-SPE experiments also confirmed that the internal region of EPDM was less accessible to the biodiesel molecules (no fuels detected) while other rubbers were more susceptible to the penetration of the fuel. DESI-MS imaging revealed for the first time the topography of the rubbers exposed to fuels. The biodiesel molecules entrapped at the EPDM and NBR pores were in oxidized form, which might degrade the rubber structure at long exposure time. The employed technics enabled the study of dynamic and molecular structure of the mixing complex multiphase. The DOSY under CMP used in this study could prove helpful in assessing the interactions throughout all physical phases (liquid, solid, and gel or semi-solid) by observing swellability caused by the fuel in the rubber. In addition, the DESI-MS was especially valuable to detect the degradation products of biodiesel entangled at the rubber structure. In our knowledge, this was the first report in which chemical changes of commercial rubbers induced by biodiesel and petrodiesel were investigated by means of DESI-MS and DOSY NMR. Copyright © 2017 Elsevier B.V. All rights reserved.

Noninvasive quantification of left ventricular mass by cardiac magnetic resonance imaging: Development of the method and experimental validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddahi, J.; Crues, J.; Berman, D.S.

1985-05-01

Determination of left ventricular myocardial (LV) mass may aid evaluation of hypertrophic cardiomyopathies as well as percent viable myocardium in ischemic heart disease. The validity of cardiac NMR for determination of LV mass was evaluated in 9 dogs using a superconducting magnet operating at 0.35 Tesla. In-vivo gated spin echo pulsing sequences were used obtaining 0.7 cm thick slices of the heart, spaced by 1 cm, in three orthogonal planes. After sacrifice, the nonbeating hearts were imaged in-situ without gating. On each NMR slice, the LV surface area was planimetered and multiplied by slice spacing (1) and myocardial specific gravitymore » (1.05) to obtain slice mass. For total LV mass, slice masses were added on coronal (Method (Meth) 1), transaxial (Meth 2), and sagittal (Meth 3) planes. Mass of the LV portions subject to partial volume effect were derived from an orthogonal plane. Excised LV weight ranged from 27 to 134 grams. The intra- and inter-observer agreement for planimetry of the NMR slices was high (r=.99 and r=.97, respectively). For in-situ imaging, r values of all methods were high (r=.99, .99, and .98); however, the slope and intercept of the regression line were closes to the line of identity with Meth 1 (y=0.94x+0.52). For in-vivo beating heart images, Meth 1 also had the best results (r=.99, y= 0.99x+8.3). Failure to correct for partial volume effect resulted in underestimation of in-situ and in-vivo LV masses as indicated by slope of <1 (r=,.98, y=0.77x+3.9; r=.98, y= 0.88x+0.98, respectively, Meth 1). Thus, cardiac NMR is a reproducible and accurate method for noninvasive determination of LV myocardial mass.« less

Dynamic Adaptive Binning: An Improved Quantification Technique for NMR Spectroscopic Data

DTIC Science & Technology

2010-01-01

Reo 2002). Unlike proteomics and genomics that assess inter- mediate products, metabolomics assesses the end product of cellular function, metabolites...other proteomic , genomic , and metabolomic analyses, NMR spectroscopy is Electronic supplementary material The online version of this article (doi...Changes occurring at the level of genes and proteins (assessed by genomics and proteomics ) may or may not influence a variety of cellular functions

Integrated microchip incorporating atomic magnetometer and microfluidic channel for NMR and MRI

DOEpatents

Ledbetter, Micah P [Oakland, CA; Savukov, Igor M [Los Alamos, NM; Budker, Dmitry [El Cerrito, CA; Shah, Vishal K [Plainsboro, NJ; Knappe, Svenja [Boulder, CO; Kitching, John [Boulder, CO; Michalak, David J [Berkeley, CA; Xu, Shoujun [Houston, TX; Pines, Alexander [Berkeley, CA

2011-08-09

An integral microfluidic device includes an alkali vapor cell and microfluidic channel, which can be used to detect magnetism for nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). Small magnetic fields in the vicinity of the vapor cell can be measured by optically polarizing and probing the spin precession in the small magnetic field. This can then be used to detect the magnetic field of in encoded analyte in the adjacent microfluidic channel. The magnetism in the microfluidic channel can be modulated by applying an appropriate series of radio or audio frequency pulses upstream from the microfluidic chip (the remote detection modality) to yield a sensitive means of detecting NMR and MRI.

"Pulse pair technique in high resolution NMR" a reprint of the historical 1971 lecture notes on two-dimensional spectroscopy.

PubMed

Jeener, Jean; Alewaeters, Gerrit

2016-05-01

The review articles published in "Progress in NMR Spectroscopy" are usually invited treatments of topics of current interest, but occasionally the Editorial Board may take an initiative to publish important historical material that is not widely available. The present article represents just such a case. Jean Jeener gave a lecture in 1971 at a summer school in Basko Polje, in what was then called Yugoslavia. As is now widely known, Jean Jeener laid down the foundations in that lecture of two - and higher - dimensional NMR spectroscopy by proposing the homonuclear COSY experiment. Jeener realized that the new proposal would open the door towards protein NMR and molecular structure determinations, but he felt that useful versions of such experiments could not be achieved with the NMR, computer and electronics technology available at that time, so that copies of the lecture notes were circulated (the Basko Polje lecture notes by J. Jeener and G. Alewaeters), but no formal publication followed. Fortunately, Ernst, Freeman, Griffin, and many others were more far-sighted and optimistic. An early useful extension was Ernst's proposal to replace the original projection/reconstruction technique of MRI by the widely adopted Fourier transform method inspired by the Basko Polje lecture. Later, the pulse method spread over many fields of spectroscopy as soon as the required technology became available. Jean Jeener, Emeritus professor, Université Libre de Bruxelles. Geoffrey Bodenhausen, Ecole Normale Supérieure, Paris. Copyright © 2016 Elsevier B.V. All rights reserved.

Evidence for cross-linking in tomato cutin using HR-MAS NMR spectroscopy.

PubMed

Deshmukh, Ashish P; Simpson, André J; Hatcher, Patrick G

2003-11-01

Cutin is a polyester biopolymer component of plant leaf and fruit cuticles, most often associated with waxes and cuticular polysaccharides, and sometimes with another aliphatic biopolymer called cutan. Insolubility of these cuticular biopolymers has made it difficult to apply traditional analytical techniques for structure determination, because most techniques providing molecular level details require solubility. By using the relatively new technique of one and two-dimensional high-resolution magic angle spinning (HR-MAS) NMR spectroscopy, with added information from solid-state 13C NMR spectroscopy, detailed through-bond connectivities and assignments are made for cutin from Lycopersicon esculentum (tomato) fruit. Based on the data obtained, tomato cutin is found to be predominantly an aliphatic polyester with some olefinic and aromatic moieties, consistent with previous studies that employed various degradative approaches. Aside from esters, there are free primary and secondary alcohol groups, as well as free fatty acids. A significant finding is the presence of alpha-branched fatty acids/esters. Mid-chain hydroxyls appear to be generally unesterified, but esters of mid-chain hydroxyls have been identified. The alpha-branched fatty acids/esters and esters of mid-chain hydroxyls could point towards cross-linking.

Interfacial Ca2+ environments in nanocrystalline apatites revealed by dynamic nuclear polarization enhanced 43Ca NMR spectroscopy

NASA Astrophysics Data System (ADS)

Lee, Daniel; Leroy, César; Crevant, Charlène; Bonhomme-Coury, Laure; Babonneau, Florence; Laurencin, Danielle; Bonhomme, Christian; de Paëpe, Gaël

2017-01-01

The interfaces within bones, teeth and other hybrid biomaterials are of paramount importance but remain particularly difficult to characterize at the molecular level because both sensitive and selective techniques are mandatory. Here, it is demonstrated that unprecedented insights into calcium environments, for example the differentiation of surface and core species of hydroxyapatite nanoparticles, can be obtained using solid-state NMR, when combined with dynamic nuclear polarization. Although calcium represents an ideal NMR target here (and de facto for a large variety of calcium-derived materials), its stable NMR-active isotope, calcium-43, is a highly unreceptive probe. Using the sensitivity gains from dynamic nuclear polarization, not only could calcium-43 NMR spectra be obtained easily, but natural isotopic abundance 2D correlation experiments could be recorded for calcium-43 in short experimental time. This opens perspectives for the detailed study of interfaces in nanostructured materials of the highest biological interest as well as calcium-based nanosystems in general.

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

PubMed Central

Dias, David M.; Ciulli, Alessio

2014-01-01

Nuclear magnetic resonance (NMR) spectroscopy is a pivotal method for structure-based and fragment-based lead discovery because it is one of the most robust techniques to provide information on protein structure, dynamics and interaction at an atomic level in solution. Nowadays, in most ligand screening cascades, NMR-based methods are applied to identify and structurally validate small molecule binding. These can be high-throughput and are often used synergistically with other biophysical assays. Here, we describe current state-of-the-art in the portfolio of available NMR-based experiments that are used to aid early-stage lead discovery. We then focus on multi-protein complexes as targets and how NMR spectroscopy allows studying of interactions within the high molecular weight assemblies that make up a vast fraction of the yet untargeted proteome. Finally, we give our perspective on how currently available methods could build an improved strategy for drug discovery against such challenging targets. PMID:25175337

Automatic 1H-NMR Screening of Fatty Acid Composition in Edible Oils

PubMed Central

Castejón, David; Fricke, Pascal; Cambero, María Isabel; Herrera, Antonio

2016-01-01

In this work, we introduce an NMR-based screening method for the fatty acid composition analysis of edible oils. We describe the evaluation and optimization needed for the automated analysis of vegetable oils by low-field NMR to obtain the fatty acid composition (FAC). To achieve this, two scripts, which automatically analyze and interpret the spectral data, were developed. The objective of this work was to drive forward the automated analysis of the FAC by NMR. Due to the fact that this protocol can be carried out at low field and that the complete process from sample preparation to printing the report only takes about 3 min, this approach is promising to become a fundamental technique for high-throughput screening. To demonstrate the applicability of this method, the fatty acid composition of extra virgin olive oils from various Spanish olive varieties (arbequina, cornicabra, hojiblanca, manzanilla, and picual) was determined by 1H-NMR spectroscopy according to this protocol. PMID:26891323

Selective observation of charge storing ions in supercapacitor electrode materials.

PubMed

Forse, Alexander C; Griffin, John M; Grey, Clare P

2018-02-01

Nuclear magnetic resonance (NMR) spectroscopy has emerged as a useful technique for probing the structure and dynamics of the electrode-electrolyte interface in supercapacitors, as ions inside the pores of the carbon electrodes can be studied separately from bulk electrolyte. However, in some cases spectral resolution can limit the information that can be obtained. In this study we address this issue by showing how cross polarisation (CP) NMR experiments can be used to selectively observe the in-pore ions in supercapacitor electrode materials. We do this by transferring magnetisation from 13 C nuclei in porous carbons to nearby nuclei in the cations ( 1 H) or anions ( 19 F) of an ionic liquid. Two-dimensional NMR experiments and CP kinetics measurements confirm that in-pore ions are located within Ångströms of sp 2 -hybridised carbon surfaces. Multinuclear NMR experiments hold promise for future NMR studies of supercapacitor systems where spectral resolution is limited. Copyright © 2017 University of Cambridge. Published by Elsevier Inc. All rights reserved.

NMR Spectroscopy in Glass Science: A Review of the Elements

PubMed Central

2018-01-01

The study of inorganic glass structure is critically important for basic glass science and especially the commercial development of glasses for a variety of technological uses. One of the best means by which to achieve this understanding is through application of solid-state nuclear magnetic resonance (NMR) spectroscopy, which has a long and interesting history. This technique is element specific, but highly complex, and thus, one of the many inquiries made by non-NMR specialists working in glass science is what type of information and which elements can be studied by this method. This review presents a summary of the different elements that are amenable to the study of glasses by NMR spectroscopy and provides examples of the type of atomic level structural information that can be achieved. It serves to inform the non-specialist working in glass science and technology about some of the benefits and challenges involved in the study of inorganic glass structure using modern, readily-available NMR methods. PMID:29565328

Use of diffusion-ordered NMR spectroscopy and HPLC-UV-SPE-NMR to identify undeclared synthetic drugs in medicines illegally sold as phytotherapies.

PubMed

Silva, Lorena M A; Filho, Elenilson G A; Thomasi, Sérgio S; Silva, Bianca F; Ferreira, Antonio G; Venâncio, Tiago

2013-09-01

The informal (and/or illegal) e-commerce of pharmaceutical formulations causes problems that governmental health agencies find hard to control, one of which concerns formulas sold as natural products. The purpose of this work was to explore the advantages and limitations of DOSY and HPLC-UV-SPE-NMR. These techniques were used to identify the components of a formula illegally marketed in Brazil as an herbal medicine possessing anti-inflammatory and analgesic properties. DOSY was able to detect the major components present at higher concentrations. Complete characterization was achieved using HPLC-UV-SPE-NMR, and 1D and 2D NMR analyses enabled the identification of known synthetic drugs. These were ranitidine and a mixture of orphenadrine citrate, piroxicam, and dexamethasone, which are co-formulated in a remedy called Rheumazim that is used to relieve severe pain, but it is prohibited in Brazil because of a lack of sufficient pharmacokinetic and pharmacodynamic information. Copyright © 2013 John Wiley & Sons, Ltd.

Hypothesis driven assessment of an NMR curriculum

NASA Astrophysics Data System (ADS)

Cossey, Kimberly

The goal of this project was to develop a battery of assessments to evaluate an undergraduate NMR curriculum at Penn State University. As a chemical education project, we sought to approach the problem of curriculum assessment from a scientific perspective, while remaining grounded in the education research literature and practices. We chose the phrase hypothesis driven assessment to convey this process of relating the scientific method to the study of educational methods, modules, and curricula. We began from a hypothesis, that deeper understanding of one particular analytical technique (NMR) will increase undergraduate students' abilities to solve chemical problems. We designed an experiment to investigate this hypothesis, and data collected were analyzed and interpreted in light of the hypothesis and several related research questions. The expansion of the NMR curriculum at Penn State was funded through the NSF's Course, Curriculum, and Laboratory Improvement (CCLI) program, and assessment was required. The goal of this project, as stated in the grant proposal, was to provide NMR content in greater depth by integrating NMR modules throughout the curriculum in physical chemistry, instrumental, and organic chemistry laboratory courses. Hands-on contact with the NMR spectrometer and NMR data and repeated exposure of the analytical technique within different contexts (courses) were unique factors of this curriculum. Therefore, we maintained a focus on these aspects throughout the evaluation process. The most challenging and time-consuming aspect of any assessment is the development of testing instruments and methods to provide useful data. After key variables were defined, testing instruments were designed to measure these variables based on educational literature (Chapter 2). The primary variables measured in this assessment were: depth of understanding of NMR, basic NMR knowledge, problem solving skills (HETCOR problem), confidence for skills used in class (within the hands-on NMR modules), confidence for NMR tasks (not practiced), and confidence for general science tasks. Detailed discussion of the instruments, testing methods and experimental design used in this assessment are provided (Chapter 3). All data were analyzed quantitatively using methods adapted from the educational literature (Chapter 4). Data were analyzed and the descriptive statistics, independent t-tests between the experimental and control groups, and correlation statistics were calculated for each variable. In addition, for those variables included on the pretest, dependent t-tests between pretest and posttest scores were also calculated. The results of study 1 and study 2 were used to draw conclusions based on the hypothesis and research questions proposed in this work (Chapter 4). Data collected in this assessment were used to answer the following research questions: (1) Primary research question: Is depth of understanding of NMR linked to problem solving skills? (2) Are the NMR modules working as intended? Do they promote depth of understanding of NMR? (a) Will students who complete NMR modules have a greater depth of understanding of NMR than students who do not complete the modules? (b) Is depth of understanding increasing over the course of the experiment? (3) Is confidence an intermediary between depth of understanding and problem solving skills? Is it linked to both variables? (4) What levels of confidence are affected by the NMR modules? (a) Will confidence for the NMR class skills used in the modules themselves be greater for those who have completed the modules? (b) Will confidence for NMR tasks not practiced in the course be affected? (c) Will confidence for general science tasks be affected? (d) Are different levels of confidence (class skills, NMR tasks, general science tasks) linked to each other? Results from this NMR curriculum assessment could also have implications outside of the courses studied, and so there is potential to impact the chemical education community (section 5.2.1). In addition to providing reliable testing instruments/measures that could be used outside the university, the results of this research contribute to the study of problem solving in chemistry, learner characteristics within the context of chemical education studies, and NMR specific educational evaluations. Valuable information was gathered through the current method of evaluation for the NMR curriculum. However, improvements could be made to the existing assessment, and an alternate assessment that could supplement the information found in this study has been proposed (Chapter 5).

Phenalenone-type phytoalexins mediate resistance of banana plants (Musa spp.) to the burrowing nematode Radopholus similis

PubMed Central

Hölscher, Dirk; Dhakshinamoorthy, Suganthagunthalam; Alexandrov, Theodore; Becker, Michael; Bretschneider, Tom; Buerkert, Andreas; Crecelius, Anna C.; De Waele, Dirk; Elsen, Annemie; Heckel, David G.; Heklau, Heike; Hertweck, Christian; Kai, Marco; Knop, Katrin; Krafft, Christoph; Maddula, Ravi K.; Matthäus, Christian; Popp, Jürgen; Schneider, Bernd; Schubert, Ulrich S.; Sikora, Richard A.; Svatoš, Aleš; Swennen, Rony L.

2014-01-01

The global yield of bananas—one of the most important food crops—is severely hampered by parasites, such as nematodes, which cause yield losses up to 75%. Plant–nematode interactions of two banana cultivars differing in susceptibility to Radopholus similis were investigated by combining the conventional and spatially resolved analytical techniques 1H NMR spectroscopy, matrix-free UV-laser desorption/ionization mass spectrometric imaging, and Raman microspectroscopy. This innovative combination of analytical techniques was applied to isolate, identify, and locate the banana-specific type of phytoalexins, phenylphenalenones, in the R. similis-caused lesions of the plants. The striking antinematode activity of the phenylphenalenone anigorufone, its ingestion by the nematode, and its subsequent localization in lipid droplets within the nematode is reported. The importance of varying local concentrations of these specialized metabolites in infected plant tissues, their involvement in the plant’s defense system, and derived strategies for improving banana resistance are highlighted. PMID:24324151

Self-assembly of a triangle-shaped, hexaplatinum-incorporated, supramolecular amphiphile in solution and at interfaces.

PubMed

Maran, Umamageswaran; Britt, David; Fox, Christopher B; Harris, Joel M; Orendt, Anita M; Conley, Hiram; Davis, Robert; Hlady, Vladamir; Stang, Peter J

2009-08-24

The self-assembly and characterization of a novel supramolecular amphiphile built from a new 60 degree amphiphilic precursor that incorporates hydrophilic platinum(II) metals and hydrophobic dioctadecyloxy chains is reported. The amphiphilic macrocycle and its precursor compound have been characterized by multinuclear NMR spectroscopy, ESI-MS, and other standard techniques. The coacervate morphology of the amphiphile at the liquid-liquid interface has been studied by using confocal optical microscopy and in situ Raman spectroscopy. The self-assembly of the amphiphilic macrocycle at the air-water interface has been investigated through Langmuir-trough techniques. The study indicates the possible formation of surface micelle-like aggregates. The disparity between the experimental molecular areas and those derived from molecular models support the idea of aggregation. AFM images of the surface aggregates show the formation of a flat topology with arbitrary ridgelike patterns. Reasonable molecular-packing arrangements are proposed to explain the molecular organization within the observed structures.

Ex vivo diffusion MRI of the human brain: Technical challenges and recent advances.

PubMed

Roebroeck, Alard; Miller, Karla L; Aggarwal, Manisha

2018-06-04

This review discusses ex vivo diffusion magnetic resonance imaging (dMRI) as an important research tool for neuroanatomical investigations and the validation of in vivo dMRI techniques, with a focus on the human brain. We review the challenges posed by the properties of post-mortem tissue, and discuss state-of-the-art tissue preparation methods and recent advances in pulse sequences and acquisition techniques to tackle these. We then review recent ex vivo dMRI studies of the human brain, highlighting the validation of white matter orientation estimates and the atlasing and mapping of large subcortical structures. We also give particular emphasis to the delineation of layered gray matter structure with ex vivo dMRI, as this application illustrates the strength of its mesoscale resolution over large fields of view. We end with a discussion and outlook on future and potential directions of the field. © 2018 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

Spectroscopic and Statistical Techniques for Information Recovery in Metabonomics and Metabolomics

NASA Astrophysics Data System (ADS)

Lindon, John C.; Nicholson, Jeremy K.

2008-07-01

Methods for generating and interpreting metabolic profiles based on nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), and chemometric analysis methods are summarized and the relative strengths and weaknesses of NMR and chromatography-coupled MS approaches are discussed. Given that all data sets measured to date only probe subsets of complex metabolic profiles, we describe recent developments for enhanced information recovery from the resulting complex data sets, including integration of NMR- and MS-based metabonomic results and combination of metabonomic data with data from proteomics, transcriptomics, and genomics. We summarize the breadth of applications, highlight some current activities, discuss the issues relating to metabonomics, and identify future trends.

Spectroscopic and statistical techniques for information recovery in metabonomics and metabolomics.

PubMed

Lindon, John C; Nicholson, Jeremy K

2008-01-01

Methods for generating and interpreting metabolic profiles based on nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), and chemometric analysis methods are summarized and the relative strengths and weaknesses of NMR and chromatography-coupled MS approaches are discussed. Given that all data sets measured to date only probe subsets of complex metabolic profiles, we describe recent developments for enhanced information recovery from the resulting complex data sets, including integration of NMR- and MS-based metabonomic results and combination of metabonomic data with data from proteomics, transcriptomics, and genomics. We summarize the breadth of applications, highlight some current activities, discuss the issues relating to metabonomics, and identify future trends.

Automatic NMR field-frequency lock-pulsed phase locked loop approach.

PubMed

Kan, S; Gonord, P; Fan, M; Sauzade, M; Courtieu, J

1978-06-01

A self-contained deuterium frequency-field lock scheme for a high-resolution NMR spectrometer is described. It is based on phase locked loop techniques in which the free induction decay signal behaves as a voltage-controlled oscillator. By pulsing the spins at an offset frequency of a few hundred hertz and using a digital phase-frequency discriminator this method not only eliminates the usual phase, rf power, offset adjustments needed in conventional lock systems but also possesses the automatic pull-in characteristics that dispense with the use of field sweeps to locate the NMR line prior to closure of the lock loop.

Production and NMR signal optimization of hyperpolarized 13C-labeled amino acids

NASA Astrophysics Data System (ADS)

Parish, Christopher; Niedbalski, Peter; Ferguson, Sarah; Kiswandhi, Andhika; Lumata, Lloyd

Amino acids are targeted nutrients for consumption by cancers to sustain their rapid growth and proliferation. 13C-enriched amino acids are important metabolic tracers for cancer diagnostics using nuclear magnetic resonance (NMR) spectroscopy. Despite this diagnostic potential, 13C NMR of amino acids however is hampered by the inherently low NMR sensitivity of the 13C nuclei. In this work, we have employed a physics technique known as dynamic nuclear polarization (DNP) to enhance the NMR signals of 13C-enriched amino acids. DNP works by transferring the high polarization of electrons to the nuclear spins via microwave irradiation at low temperature and high magnetic field. Using a fast dissolution method in which the frozen polarized samples are dissolved rapidly with superheated water, injectable solutions of 13C-amino acids with highly enhanced NMR signals (by at least 5,000-fold) were produced at room temperature. Factors that affect the NMR signal enhancement levels such as the choice of free radical polarizing agents and sample preparation will be discussed along with the thermal mixing physics model of DNP. The authors would like to acknowledge the support by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

Evaluation of phosphorus characterization in broiler ileal digesta, manure, and litter samples: (31)P-NMR vs. HPLC.

PubMed

Leytem, A B; Kwanyuen, P; Plumstead, P W; Maguire, R O; Brake, J

2008-01-01

Using 31-phosphorus nuclear magnetic resonance spectroscopy ((31)P-NMR) to characterize phosphorus (P) in animal manures and litter has become a popular technique in the area of nutrient management. To date, there has been no published work evaluating P quantification in manure/litter samples with (31)P-NMR compared to other accepted methods such as high performance liquid chromatography (HPLC). To evaluate the use of (31)P-NMR to quantify myo-inositol hexakisphosphate (phytate) in ileal digesta, manure, and litter from broilers, we compared results obtained from both (31)P-NMR and a more traditional HPLC method. The quantification of phytate in all samples was very consistent between the two methods, with linear regressions having slopes ranging from 0.94 to 1.07 and r(2) values of 0.84 to 0.98. We compared the concentration of total monoester P determined with (31)P-NMR with the total inositol P content determined with HPLC and found a strong linear relationship between the two measurements having slopes ranging from 0.91 to 1.08 and r(2) values of 0.73 to 0.95. This suggests that (31)P-NMR is a very reliable method for quantifying P compounds in manure/litter samples.