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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.
361

Experimental phase retrieval using coherent X-ray diffraction

Mancuso, Adrian P. Unknown Date (has links) (PDF)
Coherent Diffractive Imaging (CDI) has become an increasingly popular frame work in which to solve the classic phase problem in imaging due to benefits in resolution and the facility of collecting data in this modality. In particular, there is considerable interest in using the short wavelength and high coherence of fourth generation x-ray sources with CDI techniques to phase non-crystalline, or nano-crystalline biomolecular samples. CDI provides an opportunity to determine the structure of proteins and other biological samples which are unable to be phased with the standard techniques of protein crystallography, typically due to lack of adequate crystalline samples. Methods of non-crystalline phase retrieval are legion, however many suffer from limitations in resolution or the inability to recover phase fields containing a pathological singularity. Wavefields containing phase singularities are common in optical fields. The creation of an x-ray wavefield containing a pathological phase singularity is demonstrated. In this thesis a form of CDI termed astigmatic diffraction is presented, that is able tophase uniquely this class of wavefield. This is achieved by illuminating the sample with beams containing known phase curvature. The theory of the method and simulations of its application to a nano-crystalline biomolecule are presented. The experimental recovery of the direction of the phase gradient of a sample illuminated with coherent x-rays produced by a synchrotron source is shown to verify this method.
362

Comparative X-ray Structure Analyses of Multidentate Transition Metal Complexes

Flood, Kelly-Jayne January 2006 (has links)
The biological significance of macrocyclic complexes has been recognized since they were first synthesized by Neil Curtis. They have the potential to play a critical role in mimicking metalloprotein active sites. Nine Curtis macrocyclic complexes have been studied using X-ray crystallographic techniques. Their structures have been solved and comparisons of the results have been made. Biological importance is also true of the macrocyclic counterpart; side-off and end-off compartmental ligands. In some circumstances these types of ligands are more appropriate because they have extra flexibility due to their pendant arms not being fixed in place by another head-unit, like a traditional macrocycle. The synthesis of a proposed compartmental ligand; 2,2-(N,Nʼ-bis(benzimidazole-2-ylmethyl)methylamine-5,5ʼ-di-tert-butyl-3,3ʼmethanediyl-dibenzyl alcohol (Ligand 1(L1)), has been proposed and outlined. The pendant arms: bis(benzimidazole-2-ylmethyl)amine (BBIM), were successfully synthesized and characterized with 1H NMR, IR and X-ray crystallography. The head-unit: 5,5ʼ-Di-tert-butyl-2,2ʼ-dihydroxy-3,3ʼ-methanediyl-dibenzene methanol (DHTMBA), of L1 was synthesized and characterized using 1H NMR, IR and mass spectrometry. A similar head-unit; 5,5ʼ-Di-methyl-2,2ʼ-dihydroxy-3,3ʼ-methanediyl-dibenzene methanol (DHMMBA), was synthesized in an effort to shorten the synthetic time of the head-unit. This was consequently converted to the chlorine analogue; 3,3ʼ-Bis(chloromethyl)-5,5ʼ-dimethyl-2,2ʼ-methane-diyldiphenol (Cl-DHMMB), and characterized with 1H NMR, IR and X-ray crystallography. Efforts were made to synthesize Ligand 1, but due to synthetic difficulties and time restraints this proved unsuccessful. Suggestions have been made to develop this synthesis.
363

X-ray densitometric measurement of climatic influence on the intra-annual characteristics of southwestern semiarid conifer tree rings

Cleaveland, Malcolm Kent. January 1983 (has links) (PDF)
Thesis (Ph. D. - Geosciences)--University of Arizona, 1983. / Includes bibliographical references (leaves 168-177).
364

The crystal structure of 1,1,4,4-tetramethyl-1,4-diaza-2,5-diboracyclohexane and structural studies of some faujasite-type zeolites.

Hseu, Tzong-hsiung, January 1972 (has links)
Thesis (Ph. D.)--University of Washington. / Bibliography: l. 50-52, 192-195.
365

Crystallographic studies on two structures of a kanamycin kinase : a Mg-AMPPNP and a Mg-ADP complex /

Hon, Wai-Ching. January 1998 (has links)
Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (p. 134-135). Also available via World Wide Web.
366

Biochemical and structural studies on the adaptor protein p130Cas /

Nasertorabi, Fariborz, January 2005 (has links)
Diss. (sammanfattning) Uppsala : Uppsala universitet, 2005. / Härtill 4 uppsatser.
367

"PyrH and PrnB crystal structures" /

De Laurentis, Walter. January 2006 (has links)
Thesis (Ph.D.) - University of St Andrews, November 2006.
368

X-ray crystallographic studies of heat-labile enterotoxins from Escherichia coli /

Vandenakker, Focco. January 1997 (has links)
Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [170]-193).
369

Bremsstrahlung x-ray holography /

Bompadre, Silvia G. January 1998 (has links)
Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [120]-123).
370

Combining hydrodynamic modeling with nonthermal test particle tracking to improve flare simulations

Winter, Henry deGraffenried January 2009 (has links) (PDF)
Thesis (PhD)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Petrus Martens. Includes bibliographical references (leaves 160-170).

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