Graduation date: 1994

No description available.

The effect of acetylene (C(,2)H(,2)) on nitrifying microorganisms and the production of nitrous oxide (N(,2)O) by the ammonia-oxidizing chemoautotroph Nitrosomonas europaea was measured in culture medium and in sterilized soil. / Acetylene strongly inhibited (K(,i) 0.66 Pa) the oxidation of NH(,4)('+) to hydroxylamine (NH(,2)OH) but not of NH(,2)OH to nitrite (NO(,2)('-)) by N. europaea. The oxidation of NH(,4)('+) to NH(,2)OH and NO(,3)('-) by the heterotrophic nitrifier, Arthrobacter sp. was not affected by C(,2)H(,2) (10 kPa). / Observed patterns of N(,2)O production by N. europaea in the presence of various combinations of NH(,4)('+), NO(,2)('-), C(,2)H(,2) and oxygen (O(,2)) supported earlier published suggestions that N(,2)O may be formed via an oxidative route from NH(,4)('+) and (or) NH(,2)OH, or via a reductive route from NO(,2)('-). The former process was O(,2)-dependent and inhibited by C(,2)H(,2), while the latter process was inhibited by O(,2) but not by C(,2)H(,2). / Sodium chlorate (NaClO(,3), 10 mM) inhibited the oxidation of both NH(,4)('+) and NO(,2)('-) in dual axenic suspensions of N. europaea and Nitrobacter winogradskyi. N. winogradskyi reduced ClO(,3)('-) to ClO(,2)('-) under both aerobic and anaerobic conditions. Evidence is presented which suggests that NH(,4)('+) oxidation is inhibited by the ClO(,2)('-) so produced.

This study investigated possible reasons for the failure of the acetylene inhibition assay of denitrification in highly reducing environments and resulted in the isolation of a denitrifying Cytophaga from soil enriched by anaerobic incubation with glucose, nitrous oxide (N(,2)O), acetylene (C(,2)H(,2)), and sulfide (S('2-)). Such soil enrichments and pure cultures of the isolated Cytophaga (Is-11) reduced N(,2)O rapidly even in the presence of a normally inhibitory concentration of C(,2)H(,2) (4 kPa), providing S('2-) was present 8.0 umol (g soil)('-1) or 0.4 umol (mL culture)('-1) . The observed reaction appears to be unique to this soil Cytophaga since other organisms tested, using the same or similar experimental conditions, failed to show this response. / The isolate was characterized, after extensive comparative studies with five Cytophaga johnsonae strains, as a pigmented, Gram-negative, non-motile, gliding filamentous bacillus. Although these features established a taxonomic link with the family Cytophagaceae, the inability of Is-11 to digest chitin and DNA base composition of about 42.5 mol% (G+C) make the organism's specific affiliation uncertain.

Typescript (Photocopy) / Includes bibliographical references / xix, 290 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Dept. of Physical and Inorganic Chemistry, University of Adelaide, 1989

Thesis (M.Sc.) -- University of Adelaide, Dept. of Organic Chemistry, 1975.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisors: Jingguang G. Chen and Raul F. Lobo, Dept. of Chemical Engineering. Includes bibliographical references.

Thesis (Ph. D.)--Virginia Commonwealth University, 2007. / Prepared for: Dept. of Chemistry. Bibliography: leaves 194-206. Also available online via the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 77-79). Available also in a digital version from Dissertation Abstracts.

xxi, 294 p. ill. (some col.) A print copy of this title is available through the UO Libraries under the call number: SCIENCE QD403.O23 2008 / Highly conjugated carbon-rich systems have demonstrated many attractive applications for fundamental and materials science applications, including--but not limited to--probes for aromaticity, charge-transfer complexes, conducting/semi-conducting materials, linear/nonlinear optical materials, and solar cells. The bulk of this research has focused on carbon-rich fullerenes, conjugated polymers, or polycyclic aromatic hydrocarbons; however, with recent developments in cross-coupling chemistry, carbon rich chemistry, particularly dehydrobenzo[ n ]annulenes (DBAs), has grown to yield molecules of great diversity and utility. Concurrently, materials based on conjugated heterocycles have been developed and display similar and often enhanced properties to the aforementioned carbon rich systems. The lone pair of the heterocycle often adds additional stability and polarizablity, creating novel and tunable molecules. Assimilating techniques used to produce DBAs with heteroaromatic molecules, our work has afforded a novel class of conjugated macrocycles with the highly tunable optical-electronic properties of a DBA system. That in turn has led to the systematic study of the diverse structure-property relationships of the thiophene/DBA hybrids reported herein. Chapter I details the synthetic advances in the field of DBA chemistry. The first section discusses the methods of synthesis, inter- vs. intra- molecular approaches, while the remaining sections provide current examples of the DBAs reported. Chapter II briefly discuses conjugated thiophene chemistry, then describes the advantages of utilizing planarized thiophenes. Several examples of thiophene macrocycles are reviewed: both planar and nonplanar. Particular attention in the review focuses on synthesis, optical properties, and some redox properties. Chapters III and IV detail the synthesis and analysis of thiophenes locked into [14]- and [15]annulene scaffolds, respectively. The dehydrothieno[14]annulenes (DTAs) and DTA/DBA hybrids of chapter III serve as aromatic probes and show significant tunabilty with respect to the number and orientation of the thiophenes. Chapter IV's dehydrobenzo[15]annulenes, which are comprised of a cross-conjugated system, also display a structure-property relationship where the optical properties encompass a wider dispersion of wavelengths. Chapter IV also explores the incorporation of pyridines and the affects on conjugation. The electronic properties of the macrocycles were explored using NMR, UV-Vis absorption and fluorescence spectroscopy, and electrochemically (cyclic voltammetry). Chapter V is devoted to further functionalization of DTAs through alkylation and further cycliziation to yield planarized terthiophene units. This dissertation includes my previously published and co-authored material. / Adviser: Michael M. Haley