ENHANCEMENT OF THERMAL INACTIVATION OF CRONOBACTER SAKAZAKII WITH INCLUSION OF PARABENS

Parabens are a family of p-hydroxybenzoic acid esters, which have antimicrobial activity over a broad pH range (4-8). This study was designed to evaluate the enhanced thermal inactivation of Cronobacter sakazakii by the inclusion of “parabens” and to ultimately develop mathematical models to describe this effect. A heat-resistant strain, Cronobacter sakazakii 607, was heated at three mild heating temperatures in combination with treatments with five parabens in various concentrations. Results showed the presence of parabens significantly enhanced thermal inactivation in a concentration-dependent manner, and the effect increased with increasing alkyl chain length. The concentration of parabens, alkyl side chain length, and heating temperature acted synergistically, causing bacterial inactivation even at low temperatures that were not effective in killing C. sakazakii. The survival data were used to develop primary and secondary mathematical models that accurately describe how this synergistic activity can be applied in the food industry.

MICROFLUIDIC ASSAY PERFORMANCE ENHANCEMENT USING POROUS VOLUMETRIC DETECTION ELEMENTS FOR IMPEDEMETRIC AND OPTICAL SENSING

Microfluidic technologies have great potential to help create automated, cost-effective, portable devices for rapid point of care (POC) diagnostics in diverse patient settings. Unfortunately commercialization is currently constrained by the materials, reagents, and instrumentation required and detection element performance. While most microfluidic studies utilize planar detection elements, this dissertation demonstrates the utility of porous volumetric detection elements to improve detection sensitivity and reduce assay times. Impedemetric immunoassays were performed utilizing silver enhanced gold nanoparticle immunoconjugates (AuIgGs) and porous polymer monolith or silica bead bed detection elements within a thermoplastic microchannel. For a direct assay with 10 µm spaced electrodes the detection limit was 0.13 fM AuIgG with a 3 log dynamic range. The same assay was performed with electrode spacing of 15, 40, and 100 µm with no significant difference between configurations. For a sandwich assay the detection limit was10 ng/mL with a 4 log dynamic range. While most impedemetric assays rely on expensive high resolution electrodes to enhance planar senor performance, this study demonstrates the employment of porous volumetric detection elements to achieve similar performance using lower resolution electrodes and shorter incubation times. Optical immunoassays were performed using porous volumetric capture elements perfused with refractive index matching solutions to limit light scattering and enhance signal. First, fluorescence signal enhancement was demonstrated with a porous polymer monolith within a silica capillary. Next, transmission enhancement of a direct assay was demonstrated by infusing aqueous sucrose solutions through silica bead beds with captured silver enhanced AuIgGs yielding a detection limit of 0.1 ng/mL and a 5 log dynamic range. Finally, ex situ functionalized porous silica monolith segments were integrated into thermoplastic channels for a reflectance based sandwich assay yielding a detection limit of 1 ng/mL and a 5 log dynamic range. The simple techniques for optical signal enhancement and ex situ element integration enable development of sensitive, multiplexed microfluidic sensors. Collectively the demonstrated experiments validate the use of porous volumetric detection elements to enhance impedemetric and optical microfluidic assays. The techniques rely on commercial reagents, materials compatible with manufacturing, and measurement instrumentation adaptable to POC diagnostics.

The Performance Practice of Buddhist Baiqi in Contemporary Taiwan

The baiqi (Buddhist percussive instruments), also known as faqi (dharma instruments), are mentioned in the Chinese Buddhist scriptures under many different terms: jianzhi, jiandi, jianzhui, or jianchi. The original function of baiqi in earlier monastic life was to gather people or to call an assembly. With the completion of monasticism and monastic institutions, baiqi have become multifunctional in monasteries, and many baiqi instruments have been developed for different monastic applications. In contemporary Buddhist monasteries in Taiwan, baiqi are used, on the one hand, to mark the time throughout the day, signal the beginning and end of monastic daily activities, and regulate the monastic order; and on the other hand, baiqi are indispensable to the musical practices of all Buddhist rituals, where they are used to accompany fanbai (Buddhist liturgical chants) and to articulate the whole ritual process. This study investigates multiple facets of Buddhist baiqi in their performance practice, function, application, notation, and transmission, exploring the interaction between baiqi and fanbai, baiqi and the practitioner, baiqi and the monastic space, and baiqi and various Buddhist contexts. I draw upon ideas from performance theory as it concerns different disciplines, but I maintain a sharper focus on the musicological dimension of performance practice when analyzing, interpreting, and explaining the performance and music of baiqi in terms of the monastic lifestyle and its rituals. The study not only uncovers the musical system of baiqi, but also encapsulates various issues of performed identity, social interaction, performer/audience, associated behaviors, the musical construction of space, and transmission.