The purpose of this study was to perfect a new calorimetric method for identifying and counting ionizable chemical groups on proteins. To do this, calorimetric and electrometric titrations were performed (using HCl and NaOH as titrant) on native carboxypeptidase, carbonic anhydrase and concanavalin A plus their apo and organic ligand bound derivatives. Readily identifiable endpoints were seen in the calorimetric titrations and general agreement was found between ΔH values obtained in this study and literature ΔH values of model compounds undergoing the same reaction. Imidazole groups were those most easily counted. Many assumptions had to be made, however, in concluding that imidazole groups were responsible for metal binding in these proteins. Ways of eliminating these assumptions were discussed, and the ΔH values for the denaturation of carbonic anhydrase and carboxypeptidase (which occurred at a pH of about 4 were determined).

A literature review on the geometry of hydrogen bonding showed that the geometry is often de-emphasized or even ignored, probably because of the inherent flexibility of many systems studied. Examination of molecular models suggested the geometrically constrained bicyclo [2, 2, 1] heptane system wherein hydrogen bond distances and angles might be more easily predicted. Dihydroboration-oxidation of norbornadiene was shown to yield exo, exo-2,5-norbornadiol, thus clarifying uncertainties in the literature. 2, 5-Norbornadiol was oxidized to the corresponding dione, heretofore inadequately characterized. Several derivatives of the dione were prepared, and spectral data were accumulated for the dione, its precursor, and its derivatives. The mono(ethylene ketal) of 2,5-norbornadione was prepared as a key intermediate in projected synthesis schemes. Preliminary work was initiated in converting it to compounds of interest. Although norbornadione was prepared by dihydroboration followed directly with oxidation, the yields were low under all conditions tried. Consequently, a two-step sequence was used.

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Yes / Diffusion brazing of SiC ceramic to IN738 using an Ag-Cu-Ti powder-mixture as an interlayer was carried out for the first time. The impact of the bonding time (30 and 45 min) on metallurgical features and shear strength of the joints was assessed. The results revealed that raising the bonding time resulted in expanding of the brazing layer from 46.98 µm to 55.31 µm. Besides, increasing the bonding time also enhanced the shear strength of the SiC/Ag-Cu-Ti/IN738 joints.

Anodized Ti-6Al-HV/adhesive bonds exhibit improved corrosion resistance and a higher strength-to-weight ratio compared to conventional metal bonding techniques for primary and/or secondary structural applications. This work was conducted to identify chromic acid (CA) anodization and bond process conditions which produced durable, structural anodized Ti-6Al-4V/heat resistant single lap bonds and to understand why these conditions were necessary. A structural single lap bond was defined as a bond tested at 298K ≤ 0.5 month after bonding and with a strength ≥ 6.9 MPa, based upon values reported in structural adhesive manufacturers' product literature. A durable, structural single lap bond was defined as a bond with a strength ≥ 6.9 MPa strength at 298K after 9 months aging at 433K. Heat resistant adhesives tested had reported service temperatures ≥ 423K, and were: polysulfone; eolyethersulfone; polyphenylquinoxaline; polyetherimide, both unfilled and 20% glass filled; and 50% calcium carbonate filled polyimide. Hydrofluoric acid (HF) added to the CA anodization solution was necessary to produce structural bonds. CA/HF oxide was more porous, and thicker than the CA anodic oxide (140 nm vs. 20 nm), perhaps promoting physical and oxide/adhesive interphase mechanical interlock. Structural, durable CA/HF anodized Ti-6Al-4V-adhesive bonds were produced for all adhesives tested except for the filled polyimide (5.5 MPa). The filler may have occluded oxide pores and prevented optimal adhesive/oxide interphase interlock, and there may have been competition of polyimide for calcium carbonate filler and for oxide. Average oxide thickness values of 65 to 410 nm did not affect bond strength; structural bonds were produced in all cases. CA/HF initial current density of 20 Amperes per square meter produced 33% stronger polysulfone bonds than 30 Amperes per square meter. Polysulfone microstructure may have been chemically degraded by the unnecessarily high fluoride concentration in the oxide from the higher current density. Lica® 44 titanate primer did not significantly influence bond strength or durability, except when unfilled polyetherimide was the adhesive. Polyphenylquinoxaline bond processing influenced bond strength. Structural bonds resulted for all the CA/HF anodization and process conditions described above. Single Iap bond fracture initiated in the adhesive (polymer) fillet. Fracture propagation in the bond overlap was through the polymer/anodic oxide interphase and/or cohesively in the polymer. / Ph. D.