Date of Award

Fall 1992

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering - (Ph.D.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Samir S. Sofer

Second Advisor

Ching-Rong Huang

Third Advisor

Dana E. Knox

Fourth Advisor

Barbara B. Kebbekus

Fifth Advisor

Arthur Greenberg

Abstract

Several nitroxides have been prepared for study of their image enhancement capability. These nitroxides contain different nitroxyl moieties within one molecule. On MRI examination for the nitroxides prepared, TEMPO and HPTPO are better due to their better water solubility, even though some of the others have more nitroxyl centers available. The intensity response is linear with respect to concentration in the range studied in most of the cases except for HPTPO, whose intensity finally reaches maximum when its concentration is higher than 10 mM.

Three sources of biomass, namely, liver microsomes, whole-cell yeast and a bacterial activated sludge consortium, have been immobilized in calcium alginate gel. These beads are evaluated for contrast as measured on a clinical MRI machine with respect to time. This system is proposed as a hypothetical method to characterize the nitroxide behavior in porous beads containing active biological systems.

Furthermore, the prepared nitroxides are used as model inhibitors. Their inhibition characteristics are studied on styrene polymerization . Molecules with multinitroxyl centers within a single molecule possess stepwise radical killing reactivity. Their induction periods are also found to be proportional to their concentrations studied. Each of these nitroxyl centers exhibits slightly different inhibitory capabilities in terminating the growth of polymer chains. A kinetic model is developed to calculate individual inhibition constants for each molecule's nitroxyl center and to characterize kinetic behavior.

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