This dissertation describes kinetic and mechanistic studies of high performance polyimide formation, synthesis and characterization of fully cyclized, molecular weight and end group controlled polyimides, and investigations of high performance polymer blends based upon polyimides and polybenzimidazole. Imidization kinetics were successfully followed by the quantitative non-aqueous titration of the amic acid functional groups as a function of reaction conditions. The homogeneous solution imidization processes were described by auto-acid catalyzed second order kinetics. The effects of heteroatom bridging groups in the diamines and dianhydrides on reaction rates have been investigated and a possible reaction mechanism for the solution imidization processes has been proposed. Detailed mechanistic investigations of the thermal solution imidization of polyamic acids were performed. A small amount of hydrolysis and possibly some unimolecular decomposition of amide bonds in the polyamic acid during thermal solution imidization processes were observed via combination of NMR and intrinsic viscosity measurements. However, complete "recombination" of the degraded polymer chains and their further cycloimidization could be achieved under proper imidization conditions. Potential side reactions involving intermolecular imide formation reaction were also investigated using a well characterized polyimide and also a model imide. For polyimide systems containing benzophenone tetracarboxylic acid dianhydride (BTDA), direct evidence for network formation involving imine crosslinking, was observed by high field lH-NMR spectroscopy. The gel formation was a strong function of reaction conditions, occurring under extremely dry reaction conditions and being favored at moderate reaction temperatures. Various polyimide homo- and copolymers with controlled molecular weight and end groups were synthesized by the classic two step method and their thermal properties and solution viscosities were evaluated. Further, miscibility behavior of high performance polymer blends based upon polyimide (PI) and polybenzimidazole (PBI) was investigated. Several miscible PI/PBI blend material systems were identified, some of which showed a lower critical solution temperature (LCST), which was consistent with earlier observations. It was found that miscibility was a strong function of polarity and possible specific interactions with the polyimide components. Thus, miscibility was possible over a wide composition range with polyimides containing polar groups such as ketones, sulfones and ethers. However, immiscible blends were obtained when these polar polyimide components were replaced by non-polar groups such as the hexafluoroisopropylidene linkages. / Ph. D.

The effects of dietary broccoli on the body's ability to detoxify were studied in 18 male subjects between the ages of 22-40 years. The biological parameters used for measuring detoxification were the four major urinary conjugates, namely, mercapturates, sulfoconjugates, glucuronides, and amino acid conjugates. Dietary broccoli increased the urinary excretion of mercapturates and sulfoconjugates, but did not influence the excretion of glucuronides and amino acid conjugates. A significant linear trend was observed over the six-day broccoli diet treatment for both urinary mercapturate (P<0.005) and sulfoconjugate (P<0.0001) excretion. The linear trend for the mercapturate excretion was in a dose-dependent manner, resulting in a 1.3 and 2.1 fold increase by the third and sixth days, respectively, of the broccoli diet, compared to the control. For sulfoconjugates, an unexpected decrease was observed on the first day of the broccoli diet. However, within the six-day broccoli dietary treatment, a continuous increase in conjugate excretion was observed, resulting in a 2.5 fold increase by the sixth day compared to the first day. The excretion of sulfoconjugates was not necessarily dose-dependent, and increased excretion at the highest level of broccoli (500 g) could be due to a time effect. Overall, sulfoconjugate excretion was the highest (3.98-8.91 mmole/24 h) followed by the amino acid conjugates (3.06-5.99 mmole/24 h) and glucuronides (2.85-3.54 mmole/24 h). Mercapturate excretion was the lowest (0.16-0.34 mmole/24 h). In spite of its low excretion level, the level of urinary mercapturates appeared to be the most responsive urinary conjugate to the different levels of broccoli diet. / Ph. D.

A cold-flow model of a vibrated-bed microreactor has been designed and tested with capability for varying the level of gas dispersion (characterized by axial Peclet number) at a fixed weight hourly space velocity (WHSV). A tool has thus been provided whereby an important feature (viz., gas dispersion) of the reaction kinetic scene in large catalytic fluid beds can be simulated on a microscale, using approximately 5 grams of catalyst. Realization of a hot design of the microreactor (a task for another student) should permit the industrial chemist or chemical engineer, working at laboratory bench scale, quickly and inexpensively, to determine the sensitivity of a cataly1ic reaction to fluid-bed gas dispersion. The new microreactor exploits the coherent-expanded (C-E) vibrated-bed state, and is perhaps the first technical use of this state. The C-E state is achieved by subjecting a shallow layer of a fine powder to vertical sinusoidal vibration. The microreactor comprises a rectangular horizontal duct, 12.7 mm in height, 25.4 mm in width, variable in length, and with nonporous floor and walls. The microreactor is charged with a powder, such as fluid cataly1ic cracking (FCC) catalyst, at a compacted depth of I mm, and is vibrated at ~15 Hertz and amplitude of ~3 mm. Under influence of this vibration, the powder expands, displaying the C-E state. Between a phase angle of ~50° and an angle of ~150°, the powder assumes a depth of ~4 mm (i.e., expanded 4-fold from its compacted depth). Later, in each vibration cycle, the powder expands further. At ~300° phase angle, the powder reaches ~12.7 mm (i.e., collides with the roof of the microreactor duct). / Ph. D.

The microbial oxidation of arenes to the corresponding cis-diols has been shown to be a convenient source of optically pure diols which can be used as synthons in asymmetric synthesis of complex, highly oxygenated molecules. The utility of such synthons has been demonstrated by the total synthesis of (-)- Specionin 1. A key transformation in this sequence is a low-temperature rearrangement of vinylcyclopropane 59 to diquinanes 61 and 62. Of additional merit is the development of an efficient preparation of enone 56 from cis arene diol 66. / Ph. D.

The effect of the interphase/interface region on the static mechanical properties, creep and creep rupture behavior of thermoplastic (J2) composites was investigated. The mechanical properties of the J2 composites were altered by systematic changes in fiber surface chemistry. Four fiber systems were used including the AU4, AS4(1) & (2), and AS4CGP fibers. (AS4(1) and AS4(2) represent different batch numbers.) Surface energies and chemistry of carbon fibers were examined using the Dynamic Contact Angle (DCA) method and X-ray Photoelectron Spectroscopy (XPS), respectively. The meso indentation technique was used to measure the interfacial shear strengths (ISS) of the composites. For the same batch of the composites, the ISS ratios for AS4(2)/J2 to AU4/J2 and AS4CGP/J2 to AU4/J2 were 1.22 and 1.24, respectively. The mechanical properties of these composites in the fiber direction were insensitive to the ISS. The transverse and shear moduli of the J2 composites were also not affected by the ISS. The static strengths, in general, ordered themselves from strong to weak as follows: AS4(2)/J2> AS4CGP/J2> AU4/J2. However, the creep rupture strength revealed a different ordering: AS4CGP/J2> AS4(2)/J2> AU4/J2. This suggests that static mechanical properties may not be a good indicator for long term mechanical performance. Experimental results showed that the interphase/interface region did not affect the degradation rates of the creep rupture strength of the J2 composites. DMA creep tests were performed at elevated temperatures for J2 composites. A master curve of each composite was generated. The shift factors obeyed the Arrhenius type equation. The activation energies of composites were approximately the same. The creep response of the AU4/J2, AS4(2)/J2, and AS4CGP/J2 composites were not dependent upon the ISS. Severe delaminations were observed in the AS4(1)/Jd2 composite laminates. The ([±45/90₂]_s) laminate tensile strength of AS4(1)/J2 composite was less than that of AS4(2)/J2 and AS4CGP/J2 composite. The creep rupture strength of the AS4(1)/J2 composite laminates degraded about two times faster than that of the other three composite systems. / Ph. D.

Isoquinoline alkaloids and analogs play an important role in today's pharmaceutical industry. The need to synthesize single stereoisomers of these alkaloids is important. Many times only a single stereoisomer exhibits the desired activity, while other stereoisomers of the alkaloid exhibit undesired side effects. The stereoselective synthesis of 1, 1-disubstituted 1,2,3,4- tetrahydroisoquinolines using Reissert compound chemistry containing chiral acyl auxiliaries was studied with the ultimate goal of synthesizing spirobenzylisoquinoline alkaloids. / Ph. D.

If the gas chromatographic retention behavior of a compound is known under isothermal conditions at several temperatures, then it is possible to predict accurately the retention time under temperature programmed conditions. This work details the calculations required to perform such predictions. A discussion of isothermal and temperature programmed retention is presented, along with a discussion of carrier gas flow relationships. These theories are then applied to the problem of predicting temperature programmed retention times from isothermal data. It is shown that accurate and precise predictions are possible for many situations. These predicted retention times are then applied to qualitative analysis by the use of retention indices. An architecture for a retention time or index database is proposed. Finally, the use of gas chromatography for the determination of thermodynamic quantities and gas viscosities is demonstrated. / Ph. D.

Zincosilicate gel chemistry is chosen, a priori, for the synthesis of novel molecular sieves that contain three T-atom rings (three-membered rings, 3MR). Zincosilicate syntheses are performed in the presence of Group I cations. Two molar compositions of reaction mixture are investigated. / Ph. D.

Isozymes of glutathione reductase (GR) have been purified from red spruce. A major isozyme is present throughout the year, while one isozyme is present only during summer in non-hardened needles. A third isozyme is present only during winter in hardened needles. The isozymes present in non-hardened and hardened needles have been designated GR-INH and GR-IH, respectively. The major GR isoform has been designated GR-2NH or GR-H, depending on whether it was purified from nonhardened or hardened needles. GR-2NH and GR-2H have been purified to homogeneity, as judged by SDS polyacrylamide gel electrophoresis. GR-lNH and GR-IH showed several contaminating proteins in the final preparations. GR-2NH and GR-2H could each be further separated into five charge isomers by isoelectric focussing, and the relative abundance of these charge isomers differs between preparations from non-hardened and hardened needles. GR-1NH and GR-1H differ from GR-2NH and GR-2H with respect to their kinetic, immunological, and physical characteristics. GR-1NH appears different from GR-1H based on chromatographic and electrophoretic behaviour. However, no differences in the temperature dependence of kinetic parameters between either isozyme have been found. The amino-terminal sequences of GR-1H and GR-2H show a high degree of homology with GR's from other organisms. Oligonucleotides derived from the amino-terminal sequences of GR-1H and GR-2H, or from conserved regions within other GR's have been derived and used to amplify cDNA by the polymerase chain reaction. A 500 base pair cDNA, produced with oligonucleotides expected to be specific for GR-1H has been used to transform E.coli. The differences between the isozymes are discussed with respect to temperature adaptation of enzyme function in a species that experiences extreme temperature differences during its life cycle. / Ph. D.

A new hybrid method combining moire interferometry, high resolution data-reduction technique, two-dimensional datasmoothing method, and Finite Element Method (FEM) has been successfully developed. This hybrid method has been applied to residual strain analyses of composite panels, strain concentrations around optical fibers embedded in composites, and cruciform composite shear test. This hybrid method allows moire data to be collected with higher precision and accuracy by digitizing overexposed moire patterns (U & V fields) with appropriate carrier fringes. The resolution of the data is ± 20 nm. The data extracted from the moire patterns are interfaced to an FEM package through an automatic mesh generator. This mesh generator produces a nonuniform FEM mesh by connecting the digitized data points into triangles. The mesh, which uses digitized displacement data as boundary conditions, is then fed to and processed by a commercial FEM package. Due to the natural scatter of the displacement data digitized from moire patterns, the accuracy of strain values is significantly affected. A modified finite-element model with linear spring elements is introduced so data-smoothing can be done easily in two dimensional space. The results of the data smoothing are controlled by limiting the stretch of those springs to be less than the resolution of the experimental method. With the full-field hybrid method, the strain contours from moire interferometry can be easily obtained with good accuracy. If the properties of the material are known, the stress patterns can also be obtained. In addition, this method can be used to analyze any two-dimensional displacement data, including the grid method and holography. / Ph. D.