scholarly journals New Methods for Studying Materials Under Shear with Nuclear Magnetic Resonance

2021 ◽  
Author(s):  
◽  
Timothy Brox
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Structural Changes ◽  
Shear Banding ◽  
Relaxation Times ◽  
Experimental Parameter ◽  
Exciting Field ◽  
Study Materials ◽  
Open Questions ◽  
Nuclear Magnetic

<p>For over 30 years, nuclear magnetic resonance (NMR) techniques have been used to study materials under shear. Collectively referred to as Rheo-NMR, these methods measure material behaviour due to external stimuli and provide spatially and temporally resolved maps of NMR spectra, intrinsic NMR parameters (e.g. relaxation times) or motion (e.g. diffusion or flow). As a consequence, Rheo-NMR has been established as a complementary technique to conventional rheological measurements. In this thesis, new hardware and experimental methods are presented with the goal of advancing this exciting field through further integration of traditional rheometry techniques with NMR experiments.  Three key areas of hardware development have been addressed, including: 1) integrating torque sensing into the Rheo-NMR experiment for simultaneous bulk shear stress measurements, 2) constructing shear devices with geometric parameters closer to those used on commercial rheometers and 3) implementing an advanced drive system which allows for new shear profiles including oscillatory shear.  In addition to presenting the design and construction of various prototype instruments, results from validation and proof of concept studies are discussed. This information demonstrates that the hardware operates as expected and establishes an experimental parameter space for these new techniques.  Furthermore, these methods have been applied to open questions in various physical systems. This includes exploring the influence of shear geometry curvature on the onset of shear banding in a wormlike micelle surfactant system, observing shear induced structural changes in a lyotropic nonionic surfactant simultaneously via deuterium spectroscopy and bulk viscosity as well as studying interactions of flowing granular materials. The interpretation and implication of these observations are discussed in addition to motivating further studies.</p>

scholarly journals New Methods for Studying Materials Under Shear with Nuclear Magnetic Resonance

2021 ◽  
Author(s):  
◽  
Timothy Brox
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Structural Changes ◽  
Shear Banding ◽  
Relaxation Times ◽  
Experimental Parameter ◽  
Exciting Field ◽  
Study Materials ◽  
Open Questions ◽  
Nuclear Magnetic

<p>For over 30 years, nuclear magnetic resonance (NMR) techniques have been used to study materials under shear. Collectively referred to as Rheo-NMR, these methods measure material behaviour due to external stimuli and provide spatially and temporally resolved maps of NMR spectra, intrinsic NMR parameters (e.g. relaxation times) or motion (e.g. diffusion or flow). As a consequence, Rheo-NMR has been established as a complementary technique to conventional rheological measurements. In this thesis, new hardware and experimental methods are presented with the goal of advancing this exciting field through further integration of traditional rheometry techniques with NMR experiments.  Three key areas of hardware development have been addressed, including: 1) integrating torque sensing into the Rheo-NMR experiment for simultaneous bulk shear stress measurements, 2) constructing shear devices with geometric parameters closer to those used on commercial rheometers and 3) implementing an advanced drive system which allows for new shear profiles including oscillatory shear.  In addition to presenting the design and construction of various prototype instruments, results from validation and proof of concept studies are discussed. This information demonstrates that the hardware operates as expected and establishes an experimental parameter space for these new techniques.  Furthermore, these methods have been applied to open questions in various physical systems. This includes exploring the influence of shear geometry curvature on the onset of shear banding in a wormlike micelle surfactant system, observing shear induced structural changes in a lyotropic nonionic surfactant simultaneously via deuterium spectroscopy and bulk viscosity as well as studying interactions of flowing granular materials. The interpretation and implication of these observations are discussed in addition to motivating further studies.</p>

An emerging technology: Nuclear magnetic resonance microscopy

1988 ◽  
Vol 46 ◽  
pp. 1000-1001
Author(s):  
M.J. Hennessy ◽  
E. Kwok
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Basic Research ◽  
Local Environment ◽  
Magnetic Resonance Images ◽  
Nmr Microscopy ◽  
Mri Scans ◽  
Temperature Relaxation ◽  
Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

Textural and pore size analysis of carbonates from integrated core and nuclear magnetic resonance logging: An Arbuckle study

2015 ◽  
Vol 3 (1) ◽  
pp. SA77-SA89 ◽  
Author(s):  
John Doveton ◽  
Lynn Watney
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Pore Size ◽  
Relaxation Times ◽  
T2 Relaxation Time ◽  
T2 Relaxation ◽  
Nmr Logging ◽  
The Core ◽  
Nuclear Magnetic

The T2 relaxation times recorded by nuclear magnetic resonance (NMR) logging are measures of the ratio of the internal surface area to volume of the formation pore system. Although standard porosity logs are restricted to estimating the volume, the NMR log partitions the pore space as a spectrum of pore sizes. These logs have great potential to elucidate carbonate sequences, which can have single, double, or triple porosity systems and whose pores have a wide variety of sizes and shapes. Continuous coring and NMR logging was made of the Cambro-Ordovician Arbuckle saline aquifer in a proposed CO2 injection well in southern Kansas. The large data set gave a rare opportunity to compare the core textural descriptions to NMR T2 relaxation time signatures over an extensive interval. Geochemical logs provided useful elemental information to assess the potential role of paramagnetic components that affect surface relaxivity. Principal component analysis of the T2 relaxation time subdivided the spectrum into five distinctive pore-size classes. When the T2 distribution was allocated between grainstones, packstones, and mudstones, the interparticle porosity component of the spectrum takes a bimodal form that marks a distinction between grain-supported and mud-supported texture. This discrimination was also reflected by the computed gamma-ray log, which recorded contributions from potassium and thorium and therefore assessed clay content reflected by fast relaxation times. A megaporosity class was equated with T2 relaxation times summed from 1024 to 2048 ms bins, and the volumetric curve compared favorably with variation over a range of vug sizes observed in the core. The complementary link between grain textures and pore textures was fruitful in the development of geomodels that integrates geologic core observations with petrophysical log measurements.

scholarly journals Preliminary magnetic resonance relaxometric analysis of Fricke gel dosimeters produced with polyvinyl alcohol and glutaraldehyde

2017 ◽  
Vol 32 (3) ◽  
pp. 242-249 ◽  
Author(s):  
Salvatore Gallo ◽  
Giorgio Collura ◽  
Giuseppina Iacoviello ◽  
Anna Longo ◽  
Luigi Tranchina ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Polyvinyl Alcohol ◽  
Dose Range ◽  
Relaxation Times ◽  
Ion Concentration ◽  
Nuclear Magnetic Resonance Relaxometry ◽  
New Formulation ◽  
Nuclear Magnetic

This work describes the preliminary analysis of Fricke gels dosimeters characterized by a new formulation making use of a matrix of polyvinyl alcohol cross-linked by adding glutaraldehyde and analyzed by means of nuclear magnetic resonance relaxometry. In previous optical studies, these gels have shown promising dosimetric features in terms of photon sensitivity and low diffusion of ferric ions produced after irradiation. In this work, we used a portable nuclear magnetic resonance relaxometer to measure the relaxation times (which are important for dosimetric applications) of these gel materials. For this purpose, we performed a study for optimizing the acquisition parameters with a nuclear magnetic resonance relaxometer. Gel samples were exposed to clinical 6 MV photons in the dose range between 0 and 20 Gy. Nuclear magnetic resonance relaxometry measurements were per- formed and the sensitivity to photon beams was measured for various values of the Fe2+ ion concentration. The analyses pointed out that the MR signal increases as the Fe2+ content in- creases and the increase is about 75 % when the concentration of Fe2+ ions is increased from 0.5 mM to 2.5 mM. Furthermore, the sensitivity improvement achieved with increasing the Fe2+ concentration is about 60 %. This paper shows that the portable nuclear magnetic resonance relaxometer used for analysis of porous materials can be used for characterization of these dosimetric gels and this study can be considered as the first step for the characterization of these dosimeters which in future could be used for 3-D dose mapping in clinical applications.

Nuclear magnetic resonance microscopy of single neurons under hypotonic perturbation

1996 ◽  
Vol 271 (6) ◽  
pp. C1895-C1900 ◽  
Author(s):  
E. W. Hsu ◽  
N. R. Aiken ◽  
S. J. Blackband
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Single Cells ◽  
Extracellular Volume ◽  
Relaxation Times ◽  
Volume Ratio ◽  
Cell Swelling ◽  
Single Neurons ◽  
Apparent Diffusion Coefficients ◽  
Nuclear Magnetic

Nuclear magnetic resonance (NMR) characteristics of water in perfused single neurons undergoing a 20% hypotonic perturbation were examined quantitatively using NMR microscopy. The transverse relaxation times (T2) in the cytoplasm and nucleus increased by 24.0 +/- 8.5% (average +/- SE, n = 8) and 29.7 +/- 5.3% (n = 6), respectively, whereas the apparent diffusion coefficients (ADC) showed no significant change. These findings are consistent with the behaviors of a perfect osmometer and with accepted molecular relaxation and diffusion models and have significant impacts on current views of properties of cellular water. Furthermore, the results suggest that the increase of tissue intracellular-to-extracellular volume ratio during cell swelling is the predominant mechanism underlying the ADC reduction in acute brain ischemia. These data are the first direct quantitative measurements of the NMR characteristics of water in the cytoplasm and nucleus of single cells undergoing physiological perturbations and may lead to an improved diagnostic capability for NMR imaging in a variety of disease states.

Nuclear Magnetic Resonance Studies of Molecular Motion in Natural Rubber

1963 ◽  
Vol 36 (2) ◽  
pp. 318-324
Author(s):  
W. P. Slichter ◽  
D. D. Davis
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Natural Rubber ◽  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Nmr Studies ◽  
Spin Lattice ◽  
Nuclear Magnetic

Abstract Nuclear magnetic resonance measurements have been made on natural rubber to examine how frequency, temperature, and crystallinity affect the nuclear relaxation. Moecular motions were studied by observing NMR linewidths and spin-lattice relaxation times at temperatures between −100° and 100° C, and at radio frequencies between 2 and 60 Mc. The effect of crystallinity was seen in measurements on stark rubber. The relation between frequency and temperature in the spin-lattice relaxation process is examined in terms of the Arrhenius equation and the WLF expression. The importance of using frequency as a variable in NMR studies of molecular motion is stressed.

On the Structure of Thin diamond Films: A 1H and 13C Nuclear Magnetic Resonance Study

1994 ◽  
Vol 339 ◽  
Author(s):  
J. Shinar ◽  
M. Pruski ◽  
D. P. Lang ◽  
S.-J. Hwang ◽  
H. Jia
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Spin Diffusion ◽  
Natural Diamond ◽  
Relaxation Times ◽  
Diamond Films ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

ABSTRACTThe 1H and 13C nuclear magnetic resonance (NMR) of thin diamond films deposited from naturally abundant (1.1 at.%) as well as 50% and 100% 13C-enriched CH4 heavily diluted in H2is described and discussed. Less than 0.6 at.% of hydrogen is found in the films which contain crystallites up to ∼15 μm across. The 1H NMR consists of a broad 50–65 kHz wide Gaussian line attributed to H atoms bonded to carbon and covering the crystallite surfaces. A narrow Lorentzian line was only occasionally observed and found not to be intrinsic to the diamonds. The 13C NMR demonstrates that >99.5% of the C atoms reside in a quaternary diamond-like configuration. The 13C spin-lattice relaxation times T1 are four orders of magnitude shorter than in natural diamond and believed to be due to 13C spin diffusion to paramagnetic centers, presumably carbon dangling bonds. Analysis of T1 indicates that within the 13C spin diffusion length of ∼0.05 μm these centers are uniformly distributed in the diamond crystallites, possibly concentrated on the internal surfaces of a relatively dense system of nanovoids.

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