Dissertations / Theses on the topic 'Nuclear magnetic resonance'
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1
Sklar, Howard Fred. "Nuclear magnetic resonance logging." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10503.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1997.Includes bibliographical references (leaves 119-121).
by Howard Fred Sklar.
M.S.
2
Tang, Xiao-wu 1972. "Nuclear magnetic resonance microscopy." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9542.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1999.Includes bibliographical references (leaves 96-100).
This thesis describes the design and applications of an improved Nuclear Magnetic Resonance (NMR) microscope, which permits MRI to study small sample sizes ( < 2mm) at high resolution (up to 2[mu]m). The effects of molecular diffusion and local variations in the magnetic susceptibility in NMR microscopy are described, which, along with the intrinsic low sensitivity of NMR, are the fundamental limitations to resolution. Molecular diffusion in the presence of a magnetization grating not only broadens the point spread function but also reduces the signal intensity. The significance of these effects depends strongly on the magnetic field gradient strengths and imaging protocols. A NMR microscope for a standard bore 14.lT magnet was developed, it is equipped with a highly efficient. solenoidal RF coil and three orthogonal gradients with strengths of 1260G / cm for Gz , 760G/cm for Gy , and 410G/cm for Gx at 15A. A modified CTI sequence is presented which incorporates strong pulsed gradients, Ernst angle excitation, CP coherent detection and reduced k-space sampling. It is the optimal pulse sequence for acquiring high-resolution ( < 5[mu]m) NMR images (best signal-to-noise ratio per unit time) when the effect of molecular diffusion is significant. It is demonstrated that this new sequence makes it possible to acquire images with a high resolution of 2[mu]m x 2[mu]m x 8[mu]m within a few hours. A wide variety of images have been acquired using the new microscope, and representative images are presented to demonstrate the potential of NMR microscopy as a new tool in developmental biology research. In particular, used in combination with other biological techniques, NMR microscopy can provide a robust, non-invasive, 3D imaging approach to quantifying changes in structure due for instance to radiative exposure, therapy, and natural growth or genetic modifications.
by Xiao-wu Tang.
Ph.D.
3
Norwood, Timothy John. "Nuclear magnetic resonance in inhomogeneous magnetic fields." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24875.
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The work described in this thesis was initiated in an attempt to overcome the limitations imposed upon NMR spectroscopy by magnetic field inhomogeneity in two specific areas: high resolution spectroscopy in isotropic liquids, and chemical shift resolved NMR imaging in isotropic liquids.
In both cases magnetic field inhomogeneity may degrade the resolution of spectra to such an extent that no useful information can be obtained from them. In high resolution NMR spectroscopy it is necessary to be able to extract accurately the parameters present within the spectrum such as chemical shifts, coupling constants and peak areas. In chemical shift resolved imaging experiments the requirements are less stringent; and it is only necessary that the resonances of different chemical species be resolved. However, even the less stringent requirements of NMR imaging are often difficult to meet as the sample volumes required are often several orders of magnitude larger than those required in conventional high resolution NMR spectroscopy.
The use of zero-quantum coherence has been investigated as a potential solution to the magnetic field inhomogeneity problem in both of these areas. Zero-quantum coherences are independent of magnetic field inhomogeneity and contain the parameters desired in both cases, though they are displayed in a way which differs from conventional NMR spectra.
In this thesis, existing zero-quantum coherence experiments have been evaluated for use with inhomogeneous magnetic fields, and, where necessary, adapted for this purpose. Several completely new experiments have been developed for producing broad-band decoupled zero-quantum coherence spectra and also for presenting coupling constants and chemical shifts in a manner which is as close to conventional NMR spectra as possible, hence facilitating ease of use. Zero-quantum coherence has been evaluated as a tool for identifying unknown compounds and also for identifying the components of complex mixtures by "signature" recognition.
Both decoupled and non-decoupled zero-quantum coherence experiments are adapted to provide imaging experiments which allow the separation of the images of different chemical species in inhomogeneous magnetic fields. The two-dimensional J-resolved experiment is also adapted for this purpose.Science, Faculty of
Chemistry, Department of
Graduate
4
Briand, Jacques. "Spatially localized nuclear magnetic resonance." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/29062.
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The work presented in this thesis has involved the development and experimental implementation of a new method incorporating Nuclear Magnetic Resonance (NMR) methodology, and which enables a volume to be accurately defined and non-invasively interrogated within a larger object, by a sequence of radiofrequency (RF) and linear magnetic field gradient pulses.
The most important feature of the VOISINER (volume of interest by selective inversion, excitation and refocusing) sequence is its flexibility with respect to the location and size of the region of interest. The spatial coordinates and the size of the volume of interest can be directly selected from conventional NMR images and then converted into the VOISINER sequence by an appropriate setting of the radiofrequency carrier frequencies of the frequency-selective RF pulses and an appropriate scaling of the field gradient strengths used during those RF pulses. As part of the experimental protocol, the VOISINER sequence was actually combined with conventional spin echo imaging in order to facilitate the selection of the region of interest and the optimization of the spatial sensitivity profile of the localization process.
The applicability of the VOISINER sequence was then examined under various experimental conditions in order to evaluate the factors that can deteriorate or improve the efficiency of its spatial selectivity and detection sensitivity.
Potential extensions of the VOISINER technique for extracting a variety of high-resolution NMR information have been explored and experimentally demonstrated by combining it with conventional NMR methodology. In particular, it was combined with the inversion recovery method to measure on a model system, spatially localized spin-lattice (T₁) relaxation times. With regard to imaging, studies of a model system have been used to evaluate the technical prospects for using the VOISINER sequence as the basis for high-resolution imaging of small regions within a large object. Finally, to demonstrate that the technique is applicable for studies of living systems, it was tested on a human forearm and spatially localized ¹H high-resolution spectra were successfully obtained from muscle tissue and bone marrow.Science, Faculty of
Chemistry, Department of
Graduate
5
Broadhurst, R. William. "Flash photolysis nuclear magnetic resonance." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257654.
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Ling, Yibo. "Nuclear magnetic resonance readable sensors." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/57705.
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Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2010.Page 104 blank. Cataloged from PDF version of thesis.
Includes bibliographical references.
The monitoring of physiological biomarkers is fundamental to the diagnosis and treatment of disease. We describe here the development of molecular sensors which can be read by magnetic resonance (MR) relaxometry. MR is an advantageous bio-sensor readout because it can be determined from opaque samples and through intervening layers of matter. Wash steps can therefore be avoided in in vitro MR assays and non-invasive interrogation achieved for in vivo MR sensing. Functionalized magnetic nanoparticles originally developed as in vivo contrast agents have recently been adapted for use in magnetic relaxometry assays. The first half of this thesis describes a simple particle functionalization strategy and its application to the detection of myocardial infarction ("heart attack") associated biomarkers. The particles were subcutaneously implanted in the form of small discrete sensors and shown to be efficacious in measuring the physiological release of three protein biomarkers. Alternative contrast mechanisms may also be employed by MR readable sensors. The second half of this thesis introduces the novel use of 'smart' polymers which produce analyte-responsive changes in MR relaxivity. We show that MR responsive calcium-crosslinked and pH-swelling hydrogels can be incorporated within discrete sensors.
by Yibo Ling.
Ph.D.
7
Meier, Benno. "Nuclear Magnetic Resonance in pulsed high magnetic fields." Doctoral thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-101205.
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Höchste Magnetfelder haben sich zu einem unverzichtbaren Werkzeug der Festkörperphysik entwickelt. Sie werden insbesondere verwendet, um die elektronischen Eigenschaften von modernen Materialien zu erforschen. Da Magnetfelder oberhalb von 45 Tesla nicht mehr mit statischen (z.B. supraleitenden) Feldern zu erreichen sind, haben sich weltweit verschiedene Labore auf die Erzeugung gepulster Magnetfelder mit angestrebten Maximalwerten von 100 Tesla spezialisiert.
In der vorliegenden Arbeit werden Anwendungsmöglichkeiten der kernmagnetischen Resonanz (NMR) in gepulsten Magnetfeldern aufgezeigt. Es ist gelungen, die starke Zeitabhängigkeit der gepulsten Magnetfelder mittels NMR präzise zu vermessen. Die genaue Kenntnis des Magnetfelds nach dem Puls ermöglicht, die Zeitabhängigkeit aus den Daten zu entfernen, sodass auch eine kohärente Signal-Mittelung möglich ist. Davon ausgehend werden erstmalig Messungen der chemischen Verschiebung, der Knight Shift, der Spin-Gitter-Relaxationsrate 1/T1 und der Spin-Spin-Relaxationsrate 1/T2 diskutiert.
Schließlich werden die im Zusammenhang mit gepulsten Magnetfeldern erarbeiteten Gleichungen in vereinfachter Form zur genauen Messung und Analyse des freien Induktions-Zerfalls von 19F Kernspins in Calciumfluorid verwendet. Durch Messung des Zerfalls über sechs Größenordnungen wird eine genaue Analyse bezüglich einer neuartigen Theorie ermöglicht, welche den Zerfall basierend auf der Annahme mikroskopischen Chaos\' erklärt. Diese Theorie hat das Potenzial, zu einem tieferen Verständnis von Quantenchaos in makroskopischen Vielteilchensystemen zu führen.
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Chen, Cheng. "NUCLEAR QUADRUPLE RESONANCE AND LOW-FIELD NUCLEAR MAGNETIC RESONANCE FOR MATERIALS AUTHENTICATION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1567518073598426.
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Munasinghe, B. D. Jeeva P. "Nuclear magnetic resonance imaging of mice." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337912.
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Gao, Yuan. "Nuclear magnetic resonance studies of cytochromes." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292649.
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Harvey, I. "Nuclear magnetic resonance scanning in schizophrenia." Thesis, University of Edinburgh, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.652194.
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This work aimed to detect cerebral abnormalities in schizophrenia affecting the volume or T1 relaxation time of specific anatomical structures. Sixty-seven schizophrenics under fifty years of age, recruited from admissions to two teaching hospitals, underwent nuclear magnetic resonance scanning at 0.5 Tesla along with thirty-six matched healthy controls. Twenty coronal and twenty-four transverse contiguous slices were obtained and subsequently viewed blind to group status. Methods of adequate reliability were developed to estimate volumes of the cerebrum, cortex, sulcal fluid, temporal lobes and lateral ventricles and to measure T1 times in the centrum semiovale and basal ganglia. Volumetric data from forty-eight patients, analysed using multiple regression to control for the influenced of intra-cranialvolume, revealed a significant increase in sulcal fluid and diffuse reduction in cerebral volume compared to thirty-four controls. This was primarily due to reduction in cortical rather than subcortical tissue. Patients also had a decreased right temporal lobe volume. These changes bore no close relationship to clinical variables. Factors that influence T1 times in normal subjects were identified, through the additional serial scanning of two healthy males, before comparing the patient and control groups. No group differences in either the white matter or basal ganglia T1 times were found. An animal model was used to assess the effect of neuroleptic drugs on T1 values over four weeks, and no sustained alteration was seen.
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Jones, Jonathan A. "Nuclear magnetic resonance data processing methods." Thesis, University of Oxford, 1992. http://ora.ox.ac.uk/objects/uuid:7df97c9a-4e65-4c10-83eb-dfaccfdccefe.
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This thesis describes the application of a wide variety of data processing methods, in particular the Maximum Entropy Method (MEM), to data from Nuclear Magnetic Resonance (NMR) experiments. Chapter 1 provides a brief introduction to NMR and to data processing, which is developed in chapter 2. NMR is described in terms of the classical model due to Bloch, and the principles of conventional (Fourier transform) data processing developed. This is followed by a description of less conventional techniques. The MEM is derived on several grounds, and related to both Bayesian reasoning and Shannon information theory. Chapter 3 describes several methods of evaluating the quality of NMR spectra obtained by a variety of data processing techniques; the simple criterion of spectral appearance is shown to be completely unsatisfactory. A Monte Carlo method is described which allows several different techniques to be compared, and the relative advantages of Fourier transformation and the MEM are assessed. Chapter 4 describes in vivo NMR, particularly the application of the MEM to data from Phase Modulated Rotating Frame Imaging (PMRFI) experiments. In this case the conventional data processing is highly unsatisfactory, and MEM processing results in much clearer spectra. Chapter 5 describes the application of a range of techniques to the estimation and removal of splittings from NMR spectra. The various techniques are discussed using simple examples, and then applied to data from the amino acid iso-leucine. The thesis ends with five appendices which contain historical and philosophical notes, detailed calculations pertaining to PMRFI spectra, and a listing of the MEM computer program.
13
Powell, Matthew R. "Nuclear magnetic resonance studies of emulsions." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243476.
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Horsfield, Mark Andrew. "Nuclear Magnetic Resonance in petroleum engineering." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334172.
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McIntyre, Lisa. "New techniques in nuclear magnetic resonance." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387033.
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Hancorn, Simon Douglas John. "Nuclear magnetic resonance in inhomogeneous fields." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389838.
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Wilkins, Christine Linda. "Nuclear magnetic resonance studies on myoglobin." Thesis, University of Leicester, 1992. http://hdl.handle.net/2381/33994.
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Nuclear magnetic resonance spectroscopy (NMR) studies of the paramagnetic haemoprotein equine cyanometmyoglobin are presented. Many significant NMR assignments in both the proton and carbon-13 spectra of equine cyanometmyoglobin have been obtained. Notably the full proton and carbon-13 assignments for all four haem methyl groups have been obtained, resolving some previous ambiguity surrounding the assignment of the haem 3-methyl group, and full proton assignments for the haem 4-vinyl group, which is unresolved from the diamagnetic envelope in the one dimensional proton spectrum, have been obtained by use of two dimensional proton-proton shift correlation spectroscopy (COSY). Assignments are also presented for the ubiquitous proximal histidine residue, which plays a role in modulating the activity of the iron centre, as well as for certain other physiologically relevant haem pocket nuclei, providing a valuable basis for future studies of the strueture-function relationships not only of equine cyanometmyoglobin, but also of those other related haemoproteins for which it can be used as a model. It has been demonstrated that the COSY technique, which prior to the commencement of this work was believed to be inapplicable to paramagnetic species, since the line broadening and rapid loss of coherence caused by paramagnetic induced relaxation was thought to interfere with COSY peak detection, may indeed be profitably applied to the study of paramagnetic haemoproteins. The usefulness of other spectroscopic techniques, previously rarely used in the study of biological macromolecules, such as two dimensional heteronuclear shift correlation spectroscopy, and both one and two dimensional techniques involving the editing of the natural abundance carbon-13 spectrum according to the number of attached protons, to the study of paramagnetic haemoproteins has also been demonstrated.
18
Sun, Phillip Zhe 1975. "Nuclear magnetic resonance microscopy and diffusion." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29996.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.Includes bibliographical references.
The goal of the work described in this thesis is to develop the methodology and instrumentation for studying neuron physiology and activation in vivo at near cellular resolution. Using biocompatible crosslinked Hemoglobin (xHb) as a contrast agent, we demonstrated partial local oxygen pressure (pO₂) monitoring in vivo with a home-built high resolution microscopy imaging probe. It is one of the most stable microimaging system designed and fully equipped for microscopic fMRI study. This work is an advancement of using MRI to study fundamental neuron science and cell signal pathways in vivo. NMR Microscopy of pancreatic islet of NOD-SCID mice in vitro has shown the feasibility of tracking T-lymphocytes infiltration into islets before the onset of any diabetes symptoms using contrast agents CLIO-Tat. Application of this to in vivo study will not only advance our understanding of the progression IDDM but also help monitor the treatment and prognosis of IDDM patients. Throughout the high resolution imaging studies at high field (14.1 T), a new gradient sequence was developed to suppress the distortion due to the internal fields. This sequence can faithfully measure the displacement propagator in q-space imaging, and provide the proper displacement contrast in k-space imaging. The constant time imaging technique has been used to image a phantom model of a vascular system. It is made up of two glass tubes, filled with solutions of D[sub]y - DTPA and C[sub]uSO₄ respectively and the field mapping showed significant internal field introduced by their susceptibility difference. The new sequence may find applications in clinical Diffusion Tensor Imaging (DTI) and Diffusion Weighted Imaging (DWI).
by Philip Zhe Sun.
Ph.D.
19
Barker, P. B. "New techniques in nuclear magnetic resonance." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375213.
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Patel, Sunil U. "Nuclear magnetic resonance spectroscopy and ultrasound." Thesis, Aston University, 1989. http://publications.aston.ac.uk/9708/.
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The work described in this thesis is directed to the examination of the hypothesis that ultrasound may be used to perturb molecular motion in the liquid phase. These changes can then be detected by nuclear magnetic resonance (NMR) in spin-lattice and spin-spin relaxation times. The objective being to develop a method capable of reducing the pulsed NMR acquisition times of slowly relaxing nuclei. The thesis describes the theoretical principles underlying both NMR spectroscopy and ultrasonics with particular attention being paid to factors that impinge on testing the above hypothesis. Apparatus has been constructed to enable ultrasound at frequencies between 1 and 10 mega-hertz with a variable power up to 100W/cm-2 to be introduced in the NMR sample. A broadband high frequency generator is used to drive PZT piezo-electric transducer via various transducer to liquid coupling arrangements. A commercial instrument of 20 kilo-hertz has also been employed to test the above hypothesis and also to demonstrate the usefulness of ultrasound in sonochemistry. The latter objective being, detection of radical formation in monomer and polymer ultrasonic degradation. The principle features of the results obtained are: Ultrasonic perturbation of T1 is far smaller for pure liquids than is for mixtures. The effects appear to be greater on protons (1H) than on carbon-13 nuclei (13C) relaxation times. The observed effect of ultrasonics is not due to temperature changes in the sample. As the power applied to the transducer is progressively increased T1 decreases to a minimum and then increases. The T1's of the same nuclei in different functional groups are influenced to different extents by ultrasound. Studies of the 14N resonances from an equimolar mixture of N, N-dimethylformamide and deuterated chloroform with ultrasonic frequencies at 1.115, 6, 6.42 and 10 MHz show that as the frequency is increased the NMR signal to noise ratio decreases to zero at the Larmor frequency of 6.42 MHz and then again rises. This reveals the surprising indication that an effect corresponding to nuclear acoustic saturation in the liquid may be observable. Ultrasonic irradiation of acidified ammonium chloride solution at and around 6.42 MHz appears to cause distinctive changes in the proton-nitrogen J coupling resonance at 89.56 MHz. Ultrasonic irradiation of N, N-dimethylacetamide at 2 KHz using the lowest stable power revealed the onset of coalescence in the proton spectrum. The corresponding effect achieved by direct heating required a temperature rise of approximately 30oC. The effects of low frequency (20 KHz) on relaxation times appear to be nil. Detection of radical formation proved difficult but is still regarded as the principle route for monomer and polymer degradation. The initial hypothesis is considered proven with the results showing significant changes in the mega-hertz region and none at 20 KHz.
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Norwood, Timothy John. "Nuclear magnetic resonance in homogeneous and inhomogeneous magnetic fields." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304456.
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Massin, Charles. "Microfabricated planar coils in nuclear magnetic resonance /." [S.l.] : [s.n.], 2004. http://library.epfl.ch/theses/?nr=2913.
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Podgorsak, Matthew B. "Fricke radiation dosimetry using nuclear magnetic resonance." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59290.
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The spin-lattice relaxation rate R$ sb1$ of irradiated Fricke solution was studied as a function of the absorbed dose D. The R$ sb1$ increases linearly with D up to a dose of $ sim$250 Gy after which the response saturates. A model describing the R$ sb1$ of a solution of either ferrous (Fe$ sp{2+})$ or ferric (Fe$ sp{3+})$ ions is presented; it is based on fast exchange between protons on water molecules in the bulk and protons on water molecules in the coordination shell of the ions. All inherent relaxation parameters of the different proton groups are determined. An extension of the model is made to describe the spin-lattice relaxation behaviour of irradiated Fricke solution. Good agreement between model predictions and experimental results is observed. The model relates the spin-lattice relaxation rate of a Fricke dosimeter to the chemical yield of ferric ion, thus creating an absolute dosimetry technique. Various practical aspects of the NMR-Fricke system are described.
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Xu, Ping. "New methods in nuclear magnetic resonance spectroscopy." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239177.
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Cavanagh, John. "New techniques in nuclear magnetic resonance spectroscopy." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293707.
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Wu, Xi-Li. "New techniques in nuclear magnetic resonance spectroscopy." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385872.
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Badar-Goffer, Ronnitte S. "Nuclear magnetic resonance studies of cerebral metabolism." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335591.
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Gatehouse, Peter David Richard. "Rapid nuclear magnetic resonance imaging of bloodflow." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300967.
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Bowdrey, Mark David. "Implementing quantum circuits using nuclear magnetic resonance." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398155.
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Cummins, Holly Katherine. "Quantum information processing and nuclear magnetic resonance." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393477.
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Claridge, Timothy David William. "Protein studies by nuclear magnetic resonance spectroscopy." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303628.
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Wormald, Philip. "Nuclear magnetic resonance spectroscopy of vinylidenefluoride polymers." Thesis, Durham University, 2005. http://etheses.dur.ac.uk/2615/.
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High-resolution solid- and solution state NMR techniques have been applied in the study of a Semi crystalline fluoropolymer Poly(vinylidienfluoride) (PVDF) and a vinylidienfluoride telomer. The application of standard solution-state experiments with high power decoupling and two-dimensional techniques has provided a greater understanding of the structure of these two fluoropolymers. Specifically, Cosy and Tocsy experiments gave information on signals normally related to end groups and to previously unidentified structures, which suggest the presence of at least a second major structure. 19F solid-state Magic Angle spinning Nuclear Magnetic Resonance (MAs- NMR) using relaxation filters in pulse sequences, has revealed fundamental differences relating to morphology and structure. The location of reverse units in the amorphous and crystalline domains is investigated by fluorine Tip filtered Radio Frequency Driven Recoupling (RFDR) and spin-diffusion experiments. These experiments proved that the reverse units are dominant in the amorphous phase, yet could have association with rigid species. Furthermore, signals generally associated with crystalline domains are not homogenie in character. The presence of a highly mobile species was detected and investigated using the delayed acquisition technique and T2 measurements. This showed the possibility of end-group signal in the spectral region normally associated with reverse groups. Furthermore, proton Tip measurements of nascent and annealed PVDF, recorded at variable temperature are related to molecular motion and debated with respect to the effect of spin diffusion on populations. The relationship between thermal events and thermal history of PVDF and its effect on molecular motion is debated.
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Raven, C. I. "Nuclear magnetic resonance studies of surfactant systems." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235350.
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Jones, David Nigel Mark. "Nuclear magnetic resonance spectroscopy of bacterial polysaccharides." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316713.
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Zimmerman, Clarissa Lynette. "Low-field classroom nuclear magnetic resonance system." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61245.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 109).
The goal of this research was to develop a Low-field Classroom NMR system that will enable hands-on learning of NMR and MRI concepts in a Biological-Engineering laboratory course. A permanent magnet system, designed using finite-element modeling software, was built to produce a static field of Bo = 0.133 Tesla. A single coil was used for both transmitting the excitation pulses and detecting the NMR signal. The probe circuit is essentially an LC tank with a tunable resonant frequency. An FPGA is used to produce the excitation pulses and process the received NMR signals. This research has led to the ability to observe Nuclear Magnetic Resonance. 'Spin- Lattice' and 'Spin-Spin' relaxation times of glycerin samples can easily be measured. Future work will allow further MRI exploration by incorporating gradient magnetic field coils.
by Clarissa Lynette Zimmerman.
M.Eng.
36
Damion, Robin A. "Grassmann variables and pseudoclassical Nuclear Magnetic Resonance." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-214290.
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The concept of a propagator is useful and is a well-known object in diffusion NMR experiments. Here, we investigate the related concept; the propagator for the magnetization or the Green’s function of the Torrey-Bloch equations. The magnetization propagator is constructed by defining functions such as the Hamiltonian and Lagrangian and using these to define a path integral. It is shown that the equations of motion derived from the Lagrangian produce complex-valued trajectories (classical paths) and it is conjectured that the end-points of these trajectories are real-valued. The complex nature of the trajectories also suggests that the spin degrees of freedom are also encoded into the trajectories and this idea is explored by explicitly modeling the spin or precessing magnetization by anticommuting Grassmann variables. A pseudoclassical Lagrangian is constructed by combining the diffusive (bosonic) Lagrangian with the Grassmann (fermionic) Lagrangian, and performing the path integral over the Grassmann variables recovers the original Lagrangian that was used in the construction of the propagator for the magnetization. The trajectories of the pseudoclassical model also provide some insight into the nature of the end-points.
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Brouwer, William J. "Nuclear magnetic resonance studies of relaxor ferroelectrics." W&M ScholarWorks, 2005. https://scholarworks.wm.edu/etd/1539623478.
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This work is devoted to the study of local order in the ferroelectric PbSc1/2Ta1/2O3 (PST) and relaxor ferroelectric solid solutions (1-x)PbSC2/3W1/3O3-(x)PbTiO 3 (PSW-PT), (1x)PbSC2/3W1/3O3-(x)PbZrO 3 (PSW-PZ). Novel Magic Angle Spinning (MAS) Solid State Nuclear Magnetic Resonance (SS-NMR) experiments, including Multiple Quantum MAS (MQMAS) and Double Quantum Filtered Satellite Transition (DQF-STMAS), have been performed on these materials. A gamma function model is proposed for the distribution of quadrupole coupling constants, based on the Poissonian nature of atomic displacements. Moments for distributions may be subsequently extracted through agreement between experimental spectra and simulations implemented in novel programs. Simple crystal compound scandium oxide provides a reasonable analogue and assists in spectral interpretation. Support is given to the Random Site (RS) model for atomic ordering in Relaxor Ferroelectrics. Based on point charge calculations, significant lead displacement takes place as well as oxygen octahedral tilting. In June 2004, Donghua Zhou proposed an experimental scheme to expedite the interpretation of experimental spectra for materials such as those studied here and a realization with analysis is given.
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Luck, Stanley David. "The role of magnetic field gradients in nuclear magnetic resonance." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27541.
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A high resolution NMR probe was modified with gradient coils (31 mm diameter) for the measurement of translational diffusion and for microscopic imaging, and a larger set of gradient coils (15 cm diameter) was constructed for surface coil diffusion measurements. The magnitudes of the gradients produced by these coils were determined from the linewidths and lineshapes of gradient spectra. In diffusion experiments using the pulsed gradient method of Stejskal and Tanner, induced eddy currents and slow variation of the magnetic field at the sample interfered with measurements at short echo times. For these experiments the known diffusion coefficient of water was used to determine the effective gradient in each experiment. The diffusion coefficient of acrylonitrile was measured from the decay of single, double and triple quantum echoes using a modified pulsed field gradient spin echo pulse sequence.
In the second part of this thesis, three examples of living systems were studied. The first involved the application of pulsed gradient spin echo measurements to characterize the motion of water and lipid, in-vivo, in human forearm. Spin echo spectra from human forearm gave a water signal that was attributed to extracellular water because of relatively long spin-spin relaxation time (0.8 s) compared to that of intracellular water (20-30 ms). Comparison of the diffusivity of water, from experiments at two different echo times suggest that the major part of the motion of water, in-vivo, was due to directionally randomized bulk flow rather than molecular diffusion.
The second application involved the chemical shift resolved mapping of the proton distribution, in one-dimension, along the anteroposterior direction, of pupae of the Douglas-fir cone moth Barbara colfaxiana. Proton distribution maps showed that the distribution of the aqueous fluid depended upon the vertical orientation, head pointing upward or downward, of the pupae.
Finally, two dimensional images of mature caps of the marine alga Acetabularia mediterranea were obtained using the normal spin echo sequence as well as with T₁, T₂ and diffusion contrasting. D₂O—contrasting was obtained by briefly submerging the caps in D₂O. All of these images showed features resembling the radial structure of the caps. The resolution was estimated by comparison with microscopic views of the caps and was found to be 0.1 mm, determined as the smallest distinguishable feature in the image.Science, Faculty of
Chemistry, Department of
Graduate
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Chen, Yin-Ching Iris. "A magnetic resonance approach to neurodegeneration." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/44490.
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Sehgal, Akansha. "Methodology for nuclear magnetic resonance and ion cyclotron resonance mass spectrometry." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066491/document.
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Pendant ma thèse de doctorat, j’ai eu la grande chance de travailler sur le développement de nouvelles méthodes de deux techniques spectroscopiques complétement différentes : la Résonance Magnétique Nucléaire (RMN) et la Spectroscopie de Masse par Résonance Cyclotronique Ionique à Transformée de Fourier (FT-ICR/MS). En tant que méthodologiste, mon but principal a été d’améliorer les méthodes existantes et la théorie. En RMN, l’outil fantastique de la manipulation des spins permet la mise en place des séquences d’impulsions, et en FT-ICR, les rapports masse sur charge (m/z) des ions et des fragments d’ions obtenus par différents chemins de fragmentation peuvent être appliqués à des problèmes en chimie, biochimie et médecine. Le manuscrit de ma thèse de doctorat comporte deux parties. Les sujets abordés étant différents, ce manuscrit a été rédigé pour que chaque chapitre puisse être lu indépendamment. La première partie aborde la RMN dans le chapitre I. Dans ce chapitre, nous avons amélioré une méthode développée précédemment dans l’equipe pour l’étude de l’échange rapide des protons par RMN. Nous avons adapté la méthode à l’étude de l’acide aminé histidine, système en apparence simple mais qui s’est avéré très compliqué à l’étude. La deuxième partie de ma thèse de doctorat aborde la spectroscopie de masse et comprend deux chapitres. Dans le chapitre II, nous avons essayé de faire revivre et de mettre en œuvre une méthode longtemps oubliée ; il s’agit de la méthode d’isolement d’ions par éjection sélective (‘notch ejection’) par spectroscopie de masse FT-ICR. Un autre sujet abordé pendant ma thèse, qui est décrit dans le chapitre III, concerne l’utilisation de trois impulsions rf dans une expérience à deux dimensions (2D) ICR. Notre objectif a été de mieux comprendre la complexité du comportement des ions pendant cette expérience 2D ICR, en particulier pour le cas d’impulsions courtesThis thesis encompasses methodological developments in both nuclear magnetic resonance and Fourier transform ion cyclotron resonance mass spectrometry. The NMR section explores the effects of scalar relaxation on a coupled nucleus to measure fast exchange rates. In order to quantify these rates accurately, a precise knowledge of the chemical shifts of the labile protons and of the scalar couplings is normally required. We applied the method to histidine where no such information was available a priori, neither about the proton chemical shifts nor about the one-bond scalar coupling constants J(1H15N), since the protons were invisible due to fast exchange. We have measured the exchange rates of the protons of the imidazole ring and of amino protons in histidine by indirect detection via 15N. Not only the exchange rate constants, but also the elusive chemical shifts of the protons and the coupling constants could be determined. For the mass spectrometry section, the ion isolation project was initiated to study the effect of phase change of radiofrequency pulses. Excitation of ions in the ICR cell is a linear process, so that the pulse voltage required for ejecting ions must be inversely proportional to the pulse duration. A continuous sweep pulse propels the ion to a higher radius, whereas a phase reversal causes the ion to come to the centre. This represents the principle of ‘notch ejection’, wherein the ion for which the phase is reversed is retained in the ICR cell, while the remaining ions are ejected. The manuscript also contains a theoretical chapter, wherein the ion trajectories are plotted by solving the Lorentzian equation for the three-pulse scheme used for two-dimensional ICR. Through our simulations we mapped the ion trajectories for different pulse durations and for different phase relations
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Urban, Jeffry Todd. "Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects." Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2004. http://www.osti.gov/servlets/purl/836811-joXo6p/native/.
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Thesis (Ph.D.); Submitted to the University of California, Berkeley, CA (US); 21 Dec 2004.Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--56768" Urban, Jeffry Todd. USDOE Director. Office of Science. Office of Basic Energy Sciences (US) 12/21/2004. Report is also available in paper and microfiche from NTIS.
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Meng, Jiqun J. "Line scan proton magnetic resonance spectroscopic imaging." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36963.
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Goloshevsky, Artem. "Development of a micro nuclear magnetic resonance system /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Cousin, Samuel. "Two-field nuclear magnetic resonance : spectroscopy and relaxation." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066354/document.
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Cette thèse traite de la RMN en phase liquide à champs multiples, pour la détermination de la structure et de la dynamique de petites molécules et de protéines. La dynamique ps-ns des chaînes latérales de la protéine ubiquitine a été étudiée par la relaxation du 13C des groupes méthyles δ1 des isoleucines, marqués sélectivement. Les vitesses de relaxation mesurées à plusieurs hauts champs magnétiques et les vitesses de relaxation longitudinale de 0.29 T à 9 T obtenues par relaxométrie haute résolution ont été analysées à l'aide du programme ICARUS, adapté à l’occasion pour les groupes méthyle. La matrice de relaxation a été calculée par un programme inédit, nommé RedKite. Un modèle de fonction de densité spectrale a été proposé pour prendre en compte les mouvements complexes des groupes méthyles. Nous avons ainsi pu accéder à une description de la dynamique des groupes méthyle sur trois ordres de grandeur d’échelles de temps. La spectroscopie RMN à deux champs magnétiques a été développée en collaboration avec Bruker. Le spectromètre à deux champs permet le contrôle des spins dans deux centres magnétiques avec une homogénéité suffisante et le transfert rapide de l’échantillon entre ces deux centres. Grâce à l'utilisation de cohérences à zéro-quantum, nous avons mesuré des spectres de corrélation homo- et hétéronucléaires à haute résolution dans lesquels les deux dimensions sont obtenues à deux champs très différents. Cette approche a été utilisée pour réduire considérablement la contribution de l’échange chimique à la relaxation transverse, permettant l’observation des signaux de noyaux en échange chimique invisibles à haut champWe present the development of multiple-field liquid-state NMR spectroscopy for the determination of the structure and dynamics of small molecules and proteins. Dynamics of proteins side-chains in the pico- to nanosecond range have been studied in the protein ubiquitin, by measuring the relaxation of carbon-13 nuclei in isoleucine-δ1 methyl groups, with site-specific isotope labelling. High-field relaxation rates and longitudinal relaxation rates obtained using high-resolution relaxometry have been analysed using a new version of the program ICARUS, adapted for methyl groups. The relaxation matrix has been calculated with a homemade program called RedKite. Models of spectral density function have been proposed to account for all motions of methyl groups. This unprecedented dataset allows for the description of motions in methyl groups over 3 orders of magnitudes of correlation times. Two-field NMR has been developed in collaboration with Bruker. The two-field NMR spectrometer allows for the control of nuclear spins in two magnetic centres with vastly different magnetic fields, coupled with a sample shuttle. Using zero-quantum coherences, homo and heteronuclear two-field high-resolution spectra have been obtained, where the two dimensions are acquired at very different magnetic fields. Such pulse sequences have been used to reduce the contribution of chemical exchange to transverse relaxation, even when this exchange makes signals invisible at high field. The reduced bandwidth of signals at low field has also been used to perform efficient isotropic mixing in a two-field TOCSY experiment. Correlations have been observed for carbon-13 signals separated by more than 150 ppm
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Gjersing, Erica Lee. "Nuclear Magnetic Resonance Microscopy of Staphylococcus epidermidis Biofilms." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/gjersing/GjersingE04.pdf.
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Nuclear Magnetic Resonance (NMR) microscopy is well-suited for investigating living systems since it is innocuous and non-invasive. In addition to imaging internal structures of systems, NMR microscopy techniques can be used to obtain information about transport phenomena, such as fluid velocities and diffusion. The goal of this research was to determine the applicability of NMR imaging techniques to studying transport properties in biofilms. Staphylococcus epidermidis biofilms were investigated because of their importance in medical implant infections. NMR experiments were used to image biofilm structure and the fluid flow patterns in one millimeter square glass capillaries. Results showing the heterogeneous structure of biofilms are congruent with confocal laser microscopy images. The advantage of using the NMR techniques to image biofilm structures is that there are no light or laser penetration barriers and the innermost regions of the structures can be easily revealed. In addition to imaging the biofilms, velocity distributions have been mapped for the one millimeter capillary system. Laminar flows in clean, square capillaries display axial velocities that are both uniform and symmetrical while non-axial components of velocity are not present. In contrast, a biofilm fouled capillary displays irregular flow patterns in the axial direction along with distinct non-axial secondary flow perturbations. These results demonstrate that biofilms impact bulk flow in ways that cannot be ignored when modeling their impact on transport in bioreactors and medial devices. This work establishes NMR microscopy as an important biofilm research tool which can spatially resolve structural characteristics and transport processes in biofilm fouled systems.
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Corum, Curtis A. "Nuclear Magnetic Resonance with the Distant Dipolar Field." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1108%5F1%5Fm.pdf&type=application/pdf.
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Meißner, Thomas. "Exploring Nuclear Magnetic Resonance at the Highest Pressures." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-115023.
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Die vorliegende Arbeit beschäftigt sich mit der Entwicklung und Anwendung der Kernmagnetresonanz (NMR) unter extremen Drücken bis 101 kbar. Es wird gezeigt, dass die Empfindlichkeit von NMR Experimenten unter hohen Drücken in Diamantstempel- und ähnlichen Hochdruckzellen im Vergleich zu früheren experimentellen Versuchsanordnungen durch Verwendung von Mikrospulen um mehrere Größenordnungen verbessert werden kann. Die neue Versuchsanordnung wird dann zum einen bei der Untersuchung der Druckabhängigkeit elektronischer Eigenschaften von metallischem Aluminium bis 101 kbar verwendet. Zum anderen wird damit der Pseudogap des Hochtemperatursupraleiters YBa2Cu4O8 bei Drücken bis zu 63 kbar untersucht.
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Duce, Suzanne Louise. "Nuclear magnetic resonance imaging and spectroscopy of food." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240194.
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Gates, Andrew R. C. "Blood flow studies using nuclear magnetic resonance imaging." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260496.
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Hodgkinson, Paul. "Non-linear sampling of nuclear magnetic resonance data." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294326.
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