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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
401

Platinum(II) complexes : studied by diffusion NMR

Miyoshi, Emi, University of Western Sydney, College of Health and Science, School of Biomedical and Health Sciences January 2008 (has links)
Six novel platinum(II) intercalators of the form [Pt(AL)(IL)]Cl2, where AL = ethylenediamine (en), 1R,2R-diaminocyclohexane (R,R-dach), or 1S,2S-diaminocyclohexane (S,S-dach) and IL = 4,7-dihydroxy-1,10-phenanthroline (4,7-dhp) or 4,7-dicarboxy-1,10-phenanthroline (4,7-dcp), were synthesised. All complexes were prepared by the addition of the intercalating ligand followed by the addition of the diamine ancillary ligand. The complexes with 4,7-dhp were soluble in DMSO and were characterised by 1H, 13C, and 195Pt NMR, elemental analysis, UV-vis, ESI-MS, and CD. The complexes with 4,7-dcp were only soluble in a highly acidic solution and, therefore, were characterised only by 1H NMR and elemental analysis. The cytotoxicity of the 4,7-dhp complexes was tested in the L1210 murine leukaemia cell line. [Pt(S,S-dach)(4,7-dhp)]Cl2 showed an IC50 value of > 80 μM. The antitumour and antibacterial activities of all six complexes were tested in vitro using the Kirby-Bauer disc diffusion method with Staphylococcus aureus and Agrobacterium tumefaciens. The 4,7-dhp complexes showed no activity to these bacteria strains. The activities of the 4,7-dcp complexes were not able to be tested due to their solubility only in acidic solutions, which itself inhibits cell growth. The diffusion coefficients of the Pt(II) intercalators of the form [Pt(AL)(IL)]Cl2, where AL = en, R,R-dach, or S,S-dach and IL = phen, 4-mp, 4,7-dmp, 4,7-dhp, 4,7-dcp or 3,4,7,8-tmp and various starting materials used during the synthesis of these complexes were measured using pulsed gradient spin-echo (PGSE) NMR. The diffusion coefficients of both 4,7-dcp and [Pt(4,7-dcp)Cl2] were observed to be lower than other compounds with similar molecular weights indicating dimerisation of the compounds. The binding studies of the systems, [Pt(en)(phen)]Cl2 to (i) BSA, (ii) delipidated BSA, and (iii) d(GTCGAC)2 were studied using a simple two-site binding model with diffusion NMR. The binding of [Pt(en)(phen)]Cl2 – BSA was well described by the model giving the values Kd = 0.0021 ± 0.0002 M and n = 5.85 ± 0.31. On the contrary, the binding of [Pt(en)(phen)]Cl2 – delipidated BSA showed a poor fit to the model. From the poor fit of the data, it was speculated that the transverse relaxation of BSA largely affected the system. The binding of [Pt(en)(phen)]Cl2 – d(GTCGAC)2 showed results where the diffusion coefficient decreases as the concentration of the drug increases but an opposite effect was observed from the point where the drug reached equimolar concentrations to d(GTCGAC)2. It was speculated that the drug undergoes allosteric binding to the biomolecule or that a conformational change occurred as the drug concentration increases in the system. A further study of [Pt(en)(phen)]Cl2 and K2PtCl4 using 195Pt diffusion NMR was conducted giving a diffusion coefficient of 3.08 ± 0.04 × 10-10 m2 s-1 for K2PtCl4. The diffusion coefficient of [Pt(en)(phen)]Cl2, however, were unobtainable due to the short transverse relaxation of the Pt complex. / Master of Science (M.Sc.) (Hons)
402

NMR DIFFUSION MEASUREMENTS OF COMPARTMENTALIZED AND MULTICOMPONENT BIOLOGICAL SYSTEMS: Studies of Tropoelastin, the Self Association of N Methylacetamide, and q-Space Analysis of Real and Model Cell Suspensions

Regan, David Gabriel January 2002 (has links)
Molecular diffusion is an inherent feature of all fluid systems. The processes and interactions that characterize these systems are in some way dependent upon the mobility of the component molecules. Pulsed field-gradient spin-echo nuclear magnetic resonance (PGSE NMR) is a powerful tool for the study of molecular diffusion; for heterogeneous systems, such as those typically found in biology, this technique is unsurpassed in the diversity of systems that yield to its probing. The aim of the work presented in this thesis was to use an integrated NMR-based approach, in conjunction with computer modeling, for the study of molecular diffusion in compartmentalized and multicomponent biological systems. Erythrocyte suspensions provided an ideal experimental system for the study of compartmentalized diffusion in cells. Water exchanges rapidly between the intra- and extracellular regions and, as the major constituent of the cell, provides a strong and predominant proton NMR signal. In addition, the cells are known to align in the strong static magnetic field of the spectrometer. As a consequence of these two properties, the signal intensity from a suitably designed series of PGSE NMR experiments exhibits a series of maxima and minima when graphed as a function of the magnitude of the spatial wave number vector q. The apparently periodic phenomenon is mathematically analogous to optical diffraction and interference and is referred to here as diffusion-coherence. It is the characterization of this phenomenon, with the aid of computer-based models, which was the focus of a major section of the work described herein. Two quite distinct molecular systems formed the basis of the work in which I investigated diffusion in multicomponent systems. Both systems involved molecules that undergo self-association such that at equilibrium a population distribution of different oligomeric species is present. The first of these was tropoelastin, the monomeric subunit of elastin, which under certain conditions aggregates to form a coacervate. The second system was N-methylacetamide (NMA) which also undergoes extensive self-association. NMA oligomers have previously been studied as peptide analogues due to the presence in the monomer of a peptide linkage. In this work the aim was to use PGSE NMR diffusion measurements, in a manner that is in many ways analogous to analytical ultracentrifugation, to obtain estimates of hydrodynamic and thermodynamic parameters. Computer modeling was also used extensively in this section of work for the interpretation of the experimental data.
403

Application of modern NMR techniques to structure elucidation of bioactive natural products from tunicates

Sikorska, Justyna 29 August 2012 (has links)
Recent developments in NMR hardware have extended the reach of natural products chemists to structure elucidation of compounds isolated on a nanomolar scale. In parallel with advances in hardware new NMR techniques for structure elucidation have evolved, e.g. quantitative NOEs, residual dipolar couplings (RDCs)and diffusion-ordered spectroscopy (DOSY). The application of recent NMR techniques was utilized in the screening and structural assignment of natural products isolated from a 2004 collection of South African tunicates. Assignment of the planar structures of mandelalides A-D from a new Lissoclinum sp. was feasible only after data acquisition on a 700 MHz magnet equipped with 5 mm ����C cryogenic probe. While relative configuration of the polyketide mandelalides was established after extensive J-coupling and NOE analysis, quantitative ROESY and RDC measurements were also explored before the absolute configuration was accomplished by chemical degradation and comparison with standards. The application of DOSY, a greatly under-appreciated technique in natural products research, led to the identification of new rubrolide analogues, compounds with moderate antibacterial properties from the new species Synoicum globosum. Finally, relative and absolute configuration of new and known unstable amino alcohols from two Pseudodistoma species was based on J-coupling analysis and application of the Mosher method. / Graduation date: 2013
404

Nuclear magnetic resonance study of collagen hydration

January 1962 (has links)
Herman J.C. Berendsen. / "July 2, 1962"--Cover. "Reprinted from the Journal of chemical physics, vol. 36, no. 12, 3297-3305, June 15, 1962." / Bibliography: p. 48. / Army Signal Corps Contract DA36-039 sc-78108. Dept. of the Army Task 3-99-20-001 and Project 3-99-00-000.
405

Study of phase transitions by means of nuclear magnetic resonance phenomena

January 1948 (has links)
Nelson L. Alpert. / "July 31, 1948." "Condensation of a thesis." / Includes bibliographical references. / Army Signal Corps No. W-36-039 sc-32037.
406

Any Dimensional Reconstruction from Hyperplanar Projections

Gennert, Michael A. 01 October 1984 (has links)
In this paper we examine the reconstruction of functions of any dimension from hyperplanar projections. This is a generalization of a problem that has generated much interest recently, especially in the field of medical imaging. Computed Axial Tomography (CAT) and Nuclear Magnetic Resonance (NMR) are two medical techniques that fall in this framework. CAT scans measure the hydrogen density along planes through the body. Here we will examine reconstruction methods that involve backprojecting the projection data and summing this over the entire region of interest. There are two methods for doing this. One method is to filter the projection data first, and then backproject this filtered data and sum over all projection directions. The other method is to backproject and sum the projection data first, and then filter. The two methods are mathematically equivalent, producing very similar equations. We will derive the reconstruction formulas for both methods for any number of dimensions. We will examine the cases of two and three dimensions, since these are the only ones encountered in practice. The equations are very different for these cases. In general, the equations are very different for even and odd dimensionality. We will discuss why this is so, and show that the equations for even and odd dimensionality are related by the Hilbert Transform.
407

Elucidation of molecular recognition mechanisms of a peptide involved in biomineralization using solid state nuclear magnetic resonance spectroscopy /

Raghunathan, Vinodhkumar. January 2006 (has links)
Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 119-136).
408

35C1 nuclear quadrupole resonance spectrometry by means of the Bray-Barnes superregenerative detector / Nuclear quadrupole resonance spectrometry

Keshtvarzi, Abbas 03 June 2011 (has links)
Ball State University LibrariesLibrary services and resources for knowledge buildingMasters ThesesThere is no abstract available for this thesis.
409

Design and fabrication of a miniaturized nuclear quadrupole resonance spectrometer which will operate in liquid nitrogen

Konkle, Guy Clifton 03 June 2011 (has links)
A miniaturized super-regenerative nuclear quadrupole resonance spectrometer was fabricated in this project. The spectrometer was constructed using thin-film chromium resistors, gold-nickel conductors, and field effect transistors. The unit operated at room temperature and at 77º K between the frequencies of 24.860 and 44.300 MHs.The spectrometer was fabricated on a ceramic substrate which was 5.08 x 5.08cm. The films consisted of vacuum deposited chromium, electroless plated nickel, and electroplated gold. The resistor-conductor pattern was photo-etched from the films and the remaining components attached to the films to form the circuit.The spectrometer was encased in a stainless steel belljar with the sample coil extending from the bottom and the signal and power leads extending from the top of the belljar. The unit was immersed in liquid nitrogen and the characteristics monitored as the temperature dropped.The spectrometer operated in the liquid nitrogen, but failed to yield a signal for a paradichlorobenzene sample. The spectrometer exhibited poor frequency selectivity and a frequency change of 2MHz (6%) in going from room temperature to liquid nitrogen (77º K).Ball State UniversityMuncie, IN 47306
410

Nuclear quadrupole resonance analysis with a high level regerative autodyne spectrometer

Werking, Byron M. 03 June 2011 (has links)
This thesis includes a summary of some of the early developments of M.IR and NQR detection. Elementary introduction to NQR detection is also discussed. Finally the construction of a high level NQR Spectrometer operating in the regenerative mode is treated. This regenerative spectrometer, originally designed by D. Sill, M. Hayek, Y. Alon, and A. Simievic and published in Rev. Sci. Instr. 38, 11 (1967), is discussed extensively.Ball State UniversityMuncie, IN 47306

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