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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.
21

Synthesis and characterisation of Bismuth orthovanadate

Wood, Pamela January 1994 (has links)
A wide range of lime green/yellow to mustard/orange bismuth orthovanadate samples were prepared via solid state and precipitation techniques. The materials were characterised using thermal analysis, X-ray diffraction, evolved gas analysis, reflectance infra-red spectroscopy, electron microscopy, colour measurement, wet chemical analysis and ac impedance spectroscopy. This product characterisation identified more complex materials than previously reported, with generally non-stoichiometric compositions established. The fergusonite-type polymorph of BiVO<sub>4</sub> was prepared via solid state synthesis. This phase was found to be slightly V-rich in composition, of BiV<sub>1.025</sub>O<sub>4+x</sub>. It occurs as a line composition and melts congruently at 930°C ± 10°C. A reversible, non-quenchable phase transition from fergusonite to scheelite-type BiV<sub>1.025</sub>O<sub>4 + x</sub> was determined at 240-250°C. The zircon and scheelite-type polymorphs of BiVo<sub>4</sub> were produced by controlled room temperature precipitation, at pH 1-2 and 3-7 respectively, whereas the fergusonite-type polymorph was obtained at pH 1-7 on precipitation from solutions at 95°C. All three precipitated polymorphs were found to contain a proportion of foreign ions, totalling 2.0-3.0, 2.7-3.6 and 0.3-0.9 weight% for the zircon, scheelite and fergusonite-type polymorphs respectively. These foreign ions consist of adsorbed water and structural nitrate, carbonate and hydroxyl constituents. Chemical analysis identified essentially Bi-rich compositions for the precipitated polymorphs. An irreversible phase transition from zircon to scheelite-type BiVO<sub>4</sub> was determined at 500-520°C. BiVO<sub>4</sub> is studied as a possible alternative yellow pigment for the toxic cadmium and chrome-containing traditional yellow colourants. The sample colours obtained were compared with those of the commercial CdS, PbCrO<sub>4</sub> and BiVO<sub>4</sub>/Bi<sub>2</sub>MoO<sub>6</sub> pigments. Polycrystalline, phase pure BiV<sub>1.025</sub>O<sub>4 + x</sub> ceramics, prepared by solid state synthesis were investigated using ac impedance spectroscopy. These materials were found to exhibit mixed oxide ion/electronic conduction at both low and high temperatures, ie. <400°C and >600°C. Oxide ion conductivity dominates the temperature region between 400 and 600°C, with an activation energy of 0.80 + 0.01eV. The bulk conductivity below 400°C was found to be metastable and influenced by the presence of water. The possibility of protonic conduction below 400<sup>O</sup>C is identified.
22

Studies on lettuce necrotic yellows virus

McLean, George Denis January 1969 (has links)
Ph.D. thesis 1970 from the Dept. of Plant Pathology, Waite Institute, University of Adelaide / iii, 97 leaves : ill., graphs / Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
23

Limnological effects of yellow pine watershed litter

Seawell, William Michael, January 1967 (has links) (PDF)
Thesis (M.S.- Fishery Management)--University of Arizona. / Includes bibliographical references (leaves 70-74).
24

Songs of the wild temporal and geographical distinctions in the acoustic properties of the songs of the yellow-breasted chat /

Canterbury, Jacqueline L. January 1900 (has links)
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed Feb. 4, 2008). "November, 2007." Digitized (PDF) and posted Dec. 2007. Includes bibliographical references (p. 85-94). Also available in paper format.
25

An inaugural essay; on the remitting and intermitting bilious fever; of King George & Westmoreland counties, Virginia.

Ashton, Henry. Alexander, Ashton, Parnham, John, January 1803 (has links)
"An inaugural dissertation, for the degree of Doctor of Medicine ... University of Pennsylvania, on the eighth day of June, 1803"--P. (iii). / "Errata."--P. [58]. Dedicated to Ashton Alexander, M.D., and John Parnham, M.D. Microform version available in the Readex Early American Imprints series.
26

Songs of the wild temporal and geographical distinctions in the acoustic properties of the songs of the yellow-breasted chat /

Canterbury, Jacqueline L. January 1900 (has links)
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed May 20, 2008). PDF text: iv, 103 p. : ill. (some col.), maps ; 1 Mb. UMI publication number: AAT 3284212. Includes bibliographical references. Also available in microfilm and microfiche formats.
27

The Japanese invasion a study in the psychology of inter-racial contacts,

Steiner, Jesse Frederick. January 1917 (has links)
Thesis (Ph. D.)--University of Chicago, 1915. / "The trade edition [without thesis note] is published by A.C. McClurg & co., Chicago, 1917. Bibliography: p. 211-224.
28

Yellow perch aquaculture for planning and control

Benning, Therese Ann. January 1984 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 127-131).
29

Factors affecting resistance of potato to the yellow-dwarf virus disease

Hougas, R. W. January 1949 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1949. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 68-69.
30

Sources of variability in the songs of the yellow-headed blackbird Xanthocephalus xanthocephalus

Knoebel, Joan Marie. January 1978 (has links)
Thesis (M.S.)--Wisconsin. / Includes bibliographical references (leaves 39-41).

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