Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 70-86). Also available via the Internet.

Master of Science / Food Science Institute / J. Scott Smith / Acrylamide is a naturally occurring compound that is formed during the Maillard reaction. The International Agency for Research on Cancer has classified acrylamide as a “probable human carcinogen” as a result of tumor development in laboratory animals when acrylamide is ingested in high concentrations. The amino acid asparagine is particularly important in the formation of acrylamide due to its structural significance; its structure is analogous to that of acrylamide. Potato tubers contain high amounts of asparagine, thus food products such as French fries and potato chips (crisps) have been flagged for their high acrylamide levels and widespread consumption. Acrylamide mitigation in potato products can take place either during raw variety selection (or breeding) or during processing. Heating potatoes at a lower temperature or for a shorter time has shown to significantly decrease acrylamide levels. Numerous studies have shown that use of acidulants, preservatives, and low pH conditions dramatically reduce acrylamide formation by protonation of the asparagine molecule. Hydrolysis and epimerization of sugars during storage, precursor concentrations, and plant physiology are agronomic factors that can be manipulated to decrease acrylamide concentrations. Asparagine has shown to be the rate limiting factor in acrylamide formation, so processing potato cultivars with low asparagine concentrations will result in lower acrylamide levels in the finished product. Continued research areas are focusing on cultivar studies and process optimization to provide a product with lower acrylamide levels but the same sensorial attributes as current products.

The purpose of this work is to frame the main issues one must face in the design of a mobility control process using polyacrylamide and related acrylic polymers under hostile conditions. Proper preliminary lab evaluation techniques, chemical degradation and related calcium tolerance issues, thermal degradation, and economic optimization based upon injectivity are discussed. Emphasis is placed on stability under alkaline conditions, the use of sodium dithionite to prevent thermal degradation, and the beneficial use of in-situ hydrolysis to increase injectivity. Filtration properties are a focus of screening experiments, and though it often takes several days to achieve acceptable filter ratios in the lab, experience from two field observations indicate that even high molecular weight polymers have filtration ratios on the order of 1.2 or less before they are injected, so preparation procedures that do not result in this may not yield results that scale to the field. Chemical stability issues with acrylamide polymers are addressed in two parts, the first describing the kinetics of hydrolysis under neutral and alkaline conditions and the second estimating the calcium tolerance of aged polymers using industrial and lab produced analogues. Under alkaline conditions, hydrolysis is very rapid, even at low temperatures. Though aged copolymers of acrylamide (AM) and 2-acrylamide 2-methyl propane sulfonate (AMPS) exhibit similar calcium tolerances to similarly aged polyacrylamide (PAM), viscosity loss is much higher for the latter as this limit is approached. Thermal, or "oxidative" degradation, is examined using Pourbaix diagrams for iron to understand the commonly reported relationships between pH, Eh, and stability. The beneficial effects of sodium carbonate and sodium dithionite on polymer solutions as well as some inconsistencies in the literature point towards a catalytic role played by ppb level amounts of iron in oxidative degradation mechanisms. It is put forward that addition of sodium dithionite is a conservative approach to all acrylic-backboned polymer floods, and practical issues related to this are discussed. A simple analytical model is developed to take a brief look at economic optimization of polymer viscosity, and this is used to demonstrate the benefits of in-situ hydrolysis in alkaline or high-temperature floods. / text

Thesis (Ph.D.). / Written for the Dept. of Food Science and Agricultural Chemistry. Title from title page of PDF (viewed 2008/02/12). Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2009. / Title from PDF title page (University of Texas Digital Repository, viewed on Sept. 16, 2009). Vita. Includes bibliographical references.

Separation and isolation of a desired analyte from an impure sample solution containing numerous unwanted interfering agents is the first step of nearly every laboratory test performed in medicine and biology. Nucleic acids are often of particular interest to doctors and researchers, and although methods currently exist for their isolation, these procedures are costly in time, man-power, and real-estate. In addition to easing the execution of presently performed tests, mitigation or elimination of these drawbacks would make a large range of currently unperformed tests both practical and feasible. This thesis presents a microfluidics-based approach to the isolation of nucleic acids using transverse isotachophoresis (ITP). A boro-silicate glass chip is used with Poly(Acrylamide) gel electrodes to establish an electric field perpendicular to the direction of sample flow, causing a controlled migration of charged particles. The design and fabrication of the microfluidic chip are addressed, along with the development of a transverse-ITP model which predicts the necessary conditions for the successful separation/concentration of an arbitrary sample. Several proof-of-concept images are provided which demonstrate the effectiveness of transverse ITP using surrogate sample inputs. This thesis proposes a direction for future work which aims toward confirming the model presented and preparing the transverse ITP chip to receive biological samples.

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A method for the preparation of air stable difluoroboryl acrylamides is reported. In contrast to the ubiquitous organotrifluoroborate salts, difluoroboryl acrylamides are relatively nonpolar and are readily purified by silica gel chromatography. Difluoroboryl acrylamides serve as efficient substrates in cross-coupling reactions to afford the corresponding trisubstituted acrylamides in good to excellent yields. The utility of the difluoroboryl group in various chemical transformations is presented. / A new method for the formation of a unique difluorinated boron-based functional group is reported. In contrast to the commonly observed trifluoronated boron species, the difluoroboryl species is relatively nonpolar, which allows for these compounds to be purified by silica gel chromatography, a convenient method for purification of compounds. Similarly to trifluoroborate salts, difluoroboryl species are capable of undergoing cross-coupling reactions, which form carbon-carbon bonds, in good to excellent yields. Additional examples of chemical reactions using difluoroboryl acrylamides are also presented.