Physical and Mathematical Sciences

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0101. Synthesis of Photoswitchable Triptan Derivatives and Evaluation of their Activity on Serotonin Receptors
Undergraduate Presentation. Author(s): Chelsea Sainsbury. Mentor(s): Michael Kienzler.
Abstract: Serotonin (5HT) is a neurotransmitter in the human body that is used to control a variety of functions such as regulating heart rate. Serotonin targets serotonin receptors that are linked to diseases such as depression and migraines. Triptans are a series of compounds that bind to the 5HT1B or 5HT1D receptors to treat migraines. The structures of these compounds are the basis for this project. The synthesis of a series of azobenzene functionalized triptan derivatives will be achieved through the reaction of 5-nitroindole with both dimethylamine and diethylamine to produce two key indole intermediates. A set of functionalized azobenzenes will then be used to generate a series of photoswitchable triptan compounds. An azobenzene is a photoswitch, which is a compound that changes conformation upon the application of UV light. The photochemical properties of the ligands will be characterized and then their activity will be tested on the serotonin receptors. The hypothesized products are photoswitchable triptan derivatives that we expect to bind to the 5HT1B or 5HT1D receptors in one conformation, but not the other. From this, we hope to achieve the photocontrol of the 5HT1B/D receptors.

0105. Enantioselectivity Determination of Lactic Acid Synthesized Using a Tungsten Oxide Catalyst
Undergraduate Presentation. Author(s): Megan Arsenault, Brian Frederick. Mentor(s): Brian Frederick.
Abstract: Polylactic acid (PLA) is a sustainable, biodegradable bioplastic but is limited by its high flexibility and low temperature threshold, which means that it is not as durable as fossil fuel-based plastics in holding hot food or beverages. PLA is typically produced through the fermentation of glucose. Scale-up of fermentation is economically unfavorable and the properties of PLA would be improved if a source of the pure D-lactic acid were found.1 In previous experiments, where woody biomass was converted to an alternative fuel, glucose was reacted over a tungsten oxide (m-WO3) catalyst and produced lactic acid, along with formic acid and fructose. Lactic acid, if in a 1:1 ratio of L and D conformers, can be used to make PLA that has better thermal and mechanical stability. Lactic acid exists in the form of enantiomers, which are mirror images of each other. Enantiomers are nearly identical in identifying properties except optical rotation. A method was successfully developed to determine the enantioselectivity of lactic acid by isolating and analyzing the lactic acid byproduct of the m-WO3 catalyzed reaction. The lactic acid and the other byproducts were derivatized and analyzed using gas chromatography and mass spectrometry, without the need for a chiral column. Preliminary data indicates the product has some enantiomeric excess of the L-lactic acid.

0108.* Second-Order Derivatives of Nonsmooth Functions with Applications in Engineering
Undergraduate Presentation. Author(s): Abram Karam, Peter Stechlinski. Mentor(s): Peter Stechlinski.
Abstract: Derivative information is a fundamental tool widely used in solving practical problems in engineering and the sciences. Such information is used in classical theory and methods for equation solving, differential equations, and optimization. However, many real-world problems, such as those found in process systems engineering and civil engineering, exhibit nonsmoothness in the form of discrete events, which often means derivative information is unavailable or inaccurate. This has necessitated generalizations of the classical derivative which have been made by a number of authors. Clarke’s generalized derivative is useful in nonsmooth equation solving and optimization, but was hard to calculate in general until a recently developed tool in lexicographic differentiation. The aim of this project is to extend the theory of generalized derivatives to evaluate second-order generalized derivatives in an accurate and automatable way. Motivated by applications of interest in engineering, this project aims to extend results from classical differentiation and first-order generalized derivatives theory for the purpose of improving accuracy and convergence of nonsmooth methods.

0110.* Finding Appropriate Mass Functions and Other Internal Structures for Galactic Dark Matter in Simulation
Graduate Presentation. Author(s): Zachary Smith, Neil F. Comins. Mentor(s): Neil Comins.
Abstract: Experimental observation of galaxies and galaxy clusters have consistently provided evidence that they do not behave as expected in the current theory of gravity. The amount of mass that is calculated from luminosity, and therefore stars, is significantly smaller than what is required for the systems to be gravitationally bound. The additional mass that theories of gravitation need to describe the motion is called dark matter, since it does not seem to interact with electromagnetic radiation. The many candidates for dark matter have theories that usually attempt to explain most of the mass as their own, singular candidate. However, reality could easily have a mixture of the proposed forms and phenomena, even if in relatively small amounts. As a result, the parameter space defining the mass function and other characteristics of dark matter halos is less strictly confined. This project will explore many variations of a simulated galaxy with MACHOs (MAssive Compact Halo Objects), a central SMBH (SuperMasive Black Hole), a scalar field, a formationless gas, a star-forming gas, and stars. Each of these variations will be allowed to relax into a stable configuration, which will then restructured to agree with observations, and then allowed to relax again in a Monte Carlo fashion. Eventually, a convergence should emerge that will provide, among other things, a better upper limit on the galactic population of black holes or other MACHOs as a component of dark matter.

0111. Surface modification of spray dried cellulose nanofiber in supercritical CO2
Graduate Presentation. Author(s): Sabrina Sultana, Douglas J. Gardner, Carl P. Tripp. Mentor(s): Carl Tripp.
Abstract: Cellulose nanofiber (CNF) has found widespread application as filler material for different polymer matrices to enhance mechanical properties. The major obstacle to blend CNF into the polymer matrices is its hydrophilicity. Modifying the cellulose hydroxyl groups with hydrophobic chain can incorporate hydrophobicity in cellulose which can improve the dispersion of CNF in hydrophobic polymer matrices. In this poster, we will present data on the surface modification of cellulose nanofiber through esterification in super critical CO2. The efficiency of the reaction is studied by changing different parameters such as type and chain length of the esterifying agent, temperature of the reaction, catalyst amount and time. The produced material is characterized using FTIR, X-Ray diffraction and Electron Microscopy. Control experiments performed with a vapor phase reaction show that using supercritical CO2 as the medium for performing the reaction leads to a 100 times higher amount of surface reaction is observed. Furthermore, the morphology of the CNF remained unchanged as the supercritical CO2 as a fluid has no surface tension.

0112.* Synthesis and Characterization of Yttria-Stabilized Zirconia Thin Film Materials for Use in Harsh Environment Sensors
Graduate Presentation. Author(s): Firas Mahyob, George Bernhardt, Robert Lad. Mentor(s): Robert Lad.
Abstract: Yttria-stabilized zirconia (YSZ) is widely used as a bulk ceramic in solid oxide fuel cells (SOFC) and high temperature oxygen sensors due to its high ionic conductivity, chemical inertness, and stability up to 1500oC. In thin film form, YSZ is an attractive component for use in miniaturized wireless microwave acoustic sensors to monitor conditions within harsh industrial environments. In this work, RF-magnetron sputter deposition was used to synthesize YSZ (8%Y2O3-92%ZrO2) films with thicknesses from 15nm to 200nm on piezoelectric langasite (La3Ga5SiO14) substrates at growth temperatures from 30oC-600oC. X-ray diffraction indicated that the cubic YSZ films grow with preferred (111) out-of-plane texture on the langasite substrate with random in-plane orientation. Post-deposition thermal annealing up to 1000oC leads to an increase in grain size and strain relief within the films as determined by the Williamson-Hall x-ray diffraction method. Scanning electron microscopy reveals the presence of hillocks on the YSZ film surface due to strain effects across the YSZ/langasite interface, and this strain was minimized using a 400oC deposition temperature where extremely smooth films were obtained as determined by x-ray reflectivity. Post-deposition air annealing caused yttria segregation to the film surface region as evidenced by increases in the Y3d/Zr3d photoelectron peak area ratio upon annealing up to 1000oC. Electrochemical impedance spectroscopy showed that yttria segregation is accompanied by a decrease in thin film ionic conductivity. Ionic conductivity was found to be a function of the deposition temperature and thermal annealing treatments, and is strongly dependent on the film grain size.

0113.* Growth Method for High Quality Piezoelectric AlN Films Used in Acoustic Wave Sensors
Graduate Presentation. Author(s): Morton Greenslit, Robert Lad, Mauricio Pereira da Cunha. Mentor(s): Robert Lad.
Abstract: AlN films offer advantages compared to piezoelectric single crystal substrates for use in Surface Acoustic Wave (SAW) sensor devices, including flexible SAW device configurations, higher operating frequencies, and high temperature performance up to 800oC. In this work, a plasma-assisted epitaxy method is presented to achieve high quality AlN (0002) films on c-sapphire using e-beam evaporation of Al in an RF nitrogen plasma at a growth temperature of 930oC. A pre-nitridation treatment of sapphire was found to be beneficial in creating a seed layer for AlN epitaxy. RHEED analysis and XRD pole figures indicate that (0002) AlN grains also have in-plane registry with the sapphire substrate. SAW resonator devices operating near 450 MHz with different transducer and reflector configurations were patterned on the AlN/sapphire films. Admittance and impedance plots determined from S11 measurements indicate that defects and oxygen impurities in the AlN films strongly influence overall SAW resonator performance. Integration of these AlN films into next-generation sensors are expected to enable higher signal-to-noise and long-term sensor stability in harsh environment applications.

0115.* An Improved Method For Detecting Trace Level Phosphate/Arsenate in Water Using Transparent H-PTFE Membrane by UV-VIS Spectroscopy
Graduate Presentation. Author(s): Mohammed Nayeem Ibnul, Carl Tripp. Mentor(s): Carl Tripp.
Abstract: The conventional UV-Vis spectroscopic detection method requires target analytes to be soluble or have enough vapor pressure for analysis in the gas phase. Typically, a Beer Lambert’s law relationship is used where the detection limit is dependent on the pathlength of the beam in the absorbing medium. To circumvent the limit in detection posed by the pathlength of the cell, we have developed a simple, fast and inexpensive method for conversion of target analytes present in solution or the gas phase to a solid for quantification by UV-Vis spectroscopy. The approach involves forming a precipitate with the target compound and then passing a known volume of the suspension through a transparent membrane to capture target analytes from aqueous solutions. We demonstrate this new method with the detection of phosphate and arsenate as both the analytes are essential parameters in determining the quality of water. In this presentation, I will describe how we reached a detection limit of 0.50 µg/L phosphate and 5 µg/L arsenate using a modified approach to the molybdenum blue method to form a precipitate combined with the use of a UV-Vis transparent membrane.

0116. Determining Influential Parameters in Glucose-Insulin Kinetics and Riot Spread
Graduate Presentation. Author(s): Matt Ackley, Peter Stechlinski. Mentor(s): Peter Stechlinski.
Abstract: Dynamical systems are predictive models used to make inferences and gain insights about a wide range of real-world problems in which data collection may be difficult, expensive, or not possible. In many cases, these models contain points where behavioral switches or “tipping points” occur, and such models are therefore referred to as “nonsmooth”. Examples of nonsmoothness are found in models of bodily glucose-insulin kinetics, where insulin release is suddenly triggered by a biochemical threshold; a similar switch is found in models of riot spread in which the likelihood of individuals to join the riot switches at a threshold value. In such applications, it is often of interest to determine which of the model parameters are “most important” – that is, which parameters are the most influential to the long-term behavior of the system. However, in nonsmooth systems, classical methods of determining this information based on derivatives may fail. In this talk, we will discuss how recent advancements in generalized derivative theory make the attainment of this sensitivity information possible. Simulations of the two aforementioned problems are provided and discussed.

0117. Catalytic Carbon-Carbon Bond Coupling for Producing Bio Jet Fuel from Mixed Organic Acids
Graduate Presentation. Author(s): Elnaz Jamalzade, Koorosh Kashkooli, Liam Griffin, G. Peter van Walsum, Thomas J. Schwartz. Mentor(s): Thomas J. Schwartz.
Abstract: Biomass has received considerable attention as a suitable feedstock to replace crude oil for producing both energy and value-added compounds. Our primary research goal is to produce value-added bioproducts from local woody biomass resources using a combination of chemical and biological processing. The mixture of medium-chain-length carboxylic acids obtained from methane-inhibited open-culture anaerobic fermentation of lignocellulosic biomass is suitable for further oligomerization using heterogeneous chemical catalysis. The target product is a mixture of C10 –C20 molecules that is suitable blend-stock for mixing with existing hydrocarbon jet fuel. In this project, we have achieved more than 86% conversion of a model feedstock (ethyl hexanoate) into a wide range of C7-C19 molecules using bifunctional metal/mixed-oxide catalysts. In particular, we found that Pd/CeZrOx is highly selective and stable under reaction conditions. This catalyst achieves more than 90% selectivity to C11 or greater compounds. We have used bulk methods (e.g., XRD) to determine the atomic-scale structure and composition of the catalyst. The XRD pattern of calcined 0.25% Pd/CeZrOX showed mainly the CeO2 fluorite-cubic structure, consistent with other reports. Conversely, there were no reflections in the diffractogram that were attributable to Pd, indicating the presence of small particles. This information will ultimately be used for designing a highly optimized catalyst for biojet fuel production.