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Magnetoacoustic Chemical Sensors Based On Swellable Polymer Microspheres, Huqun Liu

Doctoral Dissertations

The goal of this dissertation was to investigate chemical applications of magnetoacoustic sensors based on swellable polymer microspheres. The magnetoacoustic sensor was used to monitor viscosity of starch solution, water loading, and 2-hydroxyethyl methacrylate polymerization.

Poly(vinylbenzyl chloride) (polyVBC) microspheres were prepared by suspension polymerization and then derivatized to introduce dicarboxylate groups onto the polymer backbone. Poly(vinylbenzyl chloride-trichlorophenyl acrylate) (polyVBC-TCPA) microspheres were prepared by dispersion polymerization and then derivatized to introduce amine groups onto the polymer backbone. These derivatized polymer microspheres swell and shrink with changing pH. They were entrapped in a hydrogel membrane and the membrane turbidity was investigated by …

Improved Swellable Polymer Microspheres For Chemical Sensing, Necati Kaval

Doctoral Dissertations

Derivatized lightly crosslinked polymer microspheres that swell and shrink as a function of pH have been investigated to develop polymeric transduction elements for fiber optic sensors and other sensors. The microspheres were immobilized in hydrogels forming a membrane. The membranes look turbid because of the difference between the refractive index of hydrogel and the refractive index of microspheres. As the microspheres swell as a function of pH, their refractive index decreases approaching the refractive index of the hydrogel. As a result, the turbidity of the membrane decreases. The change in the turbidity of the membrane was monitored by a UV-Vis-NIR …

Simultaneous Determination Of Nitrous Oxide And Ammonia For Measurement Of In-Situ Fluxes From Natural Ecosystems By Gas Chromatography With Headspace Autosampler And Electron Capture Detection, Richard Joseph Puk

Doctoral Dissertations

Anthropogenic disturbance of the soil nitrogen cycle by changes in nitrogen and carbon availability influences the production of N2O and NH 3 emissions to the atmosphere affecting the environment and human health. This dissertation presents a new method for automated gas chromatographic analysis of N2O and NH3 and quantifies fluxes from a salt marsh and tropical rain forest.

The automated system used single column gas chromatograhic separation on HayeSep Q and electron capture detection. Air (N2+O 2), N2O and NH3 are separated with retention times of 0.9, 1.7 and 2.15 minutes respectively. Samples were stored in headspace autosampler vials until …