Browsing by Author "Ho, Christopher"

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    HK Assembly in the E and B Experiment
    (2011-04-13) Ho, Christopher
    It has always been human nature to try to understand how the world works and EBEX is no different. Many theories regarding the origin of the universe have been formed. However, there are very few ways to test these theories. My research will be directed toward understanding what happened to the universe during its infancy by analyzing the cosmic microwave background radiation it emitted long ago. Right after the Big Bang, the universe was at such a high temperature that everything in it was plasma. As the universe cooled, atomic particles became stable enough to form permanent bonds with each other. This led the particles to emit their excess energy in the form of photons, thus starting an age when matter and light were separate entities. I am working with researchers in the EBEX project to try to detect the faint B-mode signal created by gravity waves due to inflation during the early universe. In addition, measurements on the polarization of dust will be taken to help calibrate instruments in future cosmology experiments. The information gathered from the project will be able to tell us if the inflationary model is a valid description of the moments after the Big Bang.
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    Kinetics, Mechanism, and Site Requirements of Ethanol Dehydration on γ-Al2O3
    (2013-04-20) Ho, Christopher
    Over 140 million tonnes of ethylene are produced annually by the cracking of petroleum feedstocks. A greener alternative to ethylene production from petroleum involves the dehydration of biomass-derived ethanol over a solid catalyst. In this work, the kinetics, mechanism, and site requirements of dehydration of ethanol to ethylene and diethyl ether on γ-alumina (γ‑Al2O3) were investigated at 215 °C. Pyridine titration showed that the active sites for ethylene and diethyl ether formation are acidic and non-equivalent. Kinetic isotope measurements using C2H5OD and C2D5OD revealed that ethylene formation is kinetically limited by the cleavage of a Cβ-H bond in ethanol while diethyl ether formation is kinetically limited by cleavage of the Cα-O bond. Steady state kinetic measurements at various ethanol and water pressures (1.1-7.1 kPa and 0.4-2.3 kPa, respectively) revealed that the surface sites responsible for ethylene formation are populated by ethanol monomers, ethanol-water complexes, ethanol dimers, and water dimers. The surface sites responsible for diethyl ether formation are predominantly populated by ethanol‑water complexes and ethanol dimers. Mechanisms and rate equations consistent with these observations were proposed for ethanol dehydration to ethylene and diethyl ether.