http://smartech.gatech.edu/handle/1853/5987 Original work by students of Chemical and Biomolecular Engineering Search the Channel search http://smartech.gatech.edu/simple-search http://smartech.gatech.edu/handle/1853/30968 Title: I: Enhanced specificity for aromatics using 2E mass spectrometry II: Evaluation of the proteolytic activity of cathepsin G and elastase upon bacterial cell wall III: Hydrolysis studies of an isocoumar <br/> <br/>Authors: Robinson, Margaret Reybold http://smartech.gatech.edu/handle/1853/29769 Title: Carbon-carbon bond forming reactions of biomass derived aldehydes <br/> <br/>Authors: Hoskins, Travis Justin Christopher <br/> <br/>Abstract: The Knoevenagel reaction was applied to form a carbon-carbon double bond between the aldehydes (HMF, furfual) and an alpha di-carbonyl compound. The alpha di-carbonyl compound used was malonic acid, which can be bio-derived from glucose along fermentation routes. The effects of solvents (THF, water, ethanol, isopropanol, ethyl ether, toluene) and catalysts (e.g. homogeneous and heterogeneous amines, solid basic oxides) on the yields of alpha-beta unsaturated acids were investigated. It was found that the homogeneous amines worked well in THF solvent (90-100% conversion, 99% selectivity for furfural and HMF), while the poly(styrene) supported ethylenediamine gave a higher conversion and selectivity for HMF (65± 5%, 99% selectivity) over furfural (58 ± 7%, 99% selectivity). This trend was also present in competition reactions where both HMF and furfural were reacted in the same vessel. á-â Unsaturated mono-acids for both HMF and furfural were identified as minor side products. However, levulinic acid did not work as well under the conditions studied. Lastly, among the solvents studied, several caused precipitation of the Knoevenagel products. http://smartech.gatech.edu/handle/1853/29768 Title: Quantification and control of ultrasound-mediated cell death modes <br/> <br/>Authors: Hutcheson, Joshua Daniel <br/> <br/>Abstract: Ultrasound has been identified as a possible non-invasive drug delivery device that could avoid many of the problems found in traditional therapeutics. Studies have shown that ultrasound can deliver molecules into cells; however, the applicability of ultrasound has been limited due to uncontrollable cellular viability losses after sonication. In this study, we sought to quantify the heterogeneous bioeffects of ultrasound in order to gain more insight into how ultrasound affects cells. We were also concerned with identifying the causes of and preventing programmed cell death caused by ultrasound exposure. In order to accomplish these objectives, we used flow cytometry to group cells into quantifiable characteristic populations. This allowed us to identify the relative importance of different forms of rapid cell death. We found that up to 65% of cells (at the highest ultrasound pressure studied) can lose viability rapidly and, for the first time, quantified them among three distinct populations: (1) cells that retain normal size but lose plasma membrane integrity; (2) intact nuclei surrounded by plasma membrane remnants; (3) debris resulting from cellular lysis. Our analysis was supported by mechanical sorting of these populations and subsequent imaging using confocal microscopy. We then monitored the viable populations for 6 h after ultrasound exposure. Results indicated that up to 15% of viable cells (at the highest ultrasound pressure studied) underwent apoptosis, which we showed was associated with an influx of intracellular Ca2+; therefore, we developed a method of chelating intracellular Ca2+ after sonication in an effort to maintain viability of those cells. Using this technique, we showed for the first time that cells could be saved, and we were able to prevent apoptosis by 50%, thereby increasing the overall viability of cells exposed to ultrasound. We conclude that ultrasound is a useful method to deliver molecules into cells and that appropriate selection of sonication conditions can minimize cell death by rapid and apoptotic mechanisms. http://smartech.gatech.edu/handle/1853/29759 Title: Crystallization of pseudopolymorphic forms of sodium naproxen in mixed solvent systems <br/> <br/>Authors: Chavez, Krystle J. <br/> <br/>Abstract: Several pseudopolymorphic forms of sodium naproxen were crystallized from methanol-water and ethanol-water solutions, including hydrated and alcohol-solvated forms. Results showed that the transitions of the pseudopolymorphic forms occur at temperatures that depend upon the solvent concentration. Results also revealed that water activity is a controlling factor for the transitions because regardless of which alcohol solvent mixture was used. The heats of solution for each pseudopolymorph were estimated by fitting the solubility data with the van't Hoff equation. The stability of hydrated forms over solvated forms at higher temperatures was proven for enantiotropic systems from a thermodynamic cycle. A 1:1 methanol-solvated form of sodium naproxen was discovered and fully characterized using a variety of analytical techniques. For further analysis, a single crystal was performed and revealed a two to three ratio solvate of sodium naproxen to methanol. The 1.5 solvate was shown to not be representative of the entire sample, but still provided insight into the bonding of the methanol solvent in sodium naproxen. Additionally, the ability of sodium naproxen to solvate with other alcohol solvents was explored, specifically looking at comparisons between pure ethanol, 1-propanol, 2-propanol, 1-butanol, and isobutanol solvents. It was shown that as the size of the alcohol increases and/or branching increases the ability to solvate decreases in relation to the molar amount of the alcohol present in the crystal structure. Additionally larger, branched alcohols required more energy to desolvate.