Physical Sciences and Mathematics Commons^™

“Design Of Molecular Mechanics Modeling Techniques For Exploring Molecular Recognition Using Cyclodextrins., Shannon Bradley Fox

Doctoral Dissertations

Molecular mechanics modeling techniques have been developed to study the behavior of cyclodextrins (CDs) in capillary electrophoresis (CE) separations. Using the commercial computational package, Sybyl, the mechanisms of molecular recognition between organic analytes and CDs are investigated.

Cyclodextrin-modified capillary electrochromatography (CDCE) experiments were conducted to separate neutral derivitized naphthalene solutes using carboxymethyl-beta-cyclodextrin (CM-b-CD). Grid conformation-searching programs were developed to explore the interaction space between CD and solute and to calculate their interaction energies using molecular mechanics. The interaction energies correlated remarkably well with the separation behavior. It was found that extensive minimization (more than 3000 iterations) was required at each …

Strategies For Enhancing The Performance Of Chemical Sensors Based On Microcantilever Sensors, Christopher Tipple

Doctoral Dissertations

Microcantilever (MC) based chemical sensors have become more widely used during the past 10 years due to the advantages they possess over other chemical sensors. One of the most significant characteristics is their extremely high surface to volume ratio. This key facet allows surface forces that can be ignored on a macroscale to become a significant sensing transduction mechanism. MC based sensors also exhibit a higher mass sensitivity to adsorbates than do many other chemical sensor platforms. Under many conditions, MC based sensors directly translate changes in Gibbs free energies due to analyte-surface interactions into mechanical responses. However, the widespread …

“Enhancement Of Sensitivity And Selectivity Of Chemical Sensors Through Thin Film Coatings And Surface Modifications, Joseph Jeremy Headrick

Doctoral Dissertations

Chemical sensors have become major analytical tools for how we monitor
and obtain information about the chemical nature of ourselves and our
surroundings. Two characteristics of chemical sensors that are under constant
development and improvement are their selectivity and their sensitivity.
Selectivity is a concern of any chemical sensor, without it the signal obtained by
a chemical sensor cannot be related to the target species concentration with any
confidence. With chemical sensors the selectivity is generally created by the
used of a chemical recognition layer such as a permeable membrane, or a thin
chemical film. The sensitivity of a chemical …

Studies Of Electroosmotic Flow Dynamics During Electrophoretic Separations, Jason Lasseter Pittman

Doctoral Dissertations

Instrumentation and techniques for monitoring electroosmotic flow (EOF) during capillary electrophoretic (CE) separations in both fused-silica capillaries and glass microfluidic devices are presented. These techniques were applied under conventional and sample stacking separation conditions. The instrumentation developed for monitoring EOF was also used to develop optically gated vacancy separations in microfluidic devices.

A recently developed technique for monitoring EOF in capillary electrophoresis by periodic photobleaching of a neutral fluorophore added to the running buffer was further characterized and optimized and then applied to monitoring EOF during a typical capillary electrophoresis separation. The concentration of neutral fluorophore (rhodamine B) added to …

Dipole-Bound Anions, Nathanael Isaac Hammer

Doctoral Dissertations

Any molecule with a dipole moment above approximately 2.5 Debye can form a stable negative ion (dipole-bound anion). These anions are best produced by “resonance” charge exchange from atoms in high Rydberg states (Rydberg electron transfer, RET). RET to form dipole-bound anions occurs over a narrow range of effective principle quantum number, n*. Dipole-bound anions for 32 molecules with dipole moments between 2.5 and 6.0 Debye have been studied. The excess electron in such an anion is very diffuse and weakly bound. Binding energies (electron affinities, EAs) are estimated from the narrow range of n* at which charge exchange occurs …