Abstracts Submitted From Engineering, Computer Science, and Physics
Undergraduate Summer Research Symposium August 13, 2008

Ordered alphabetically by student's last name

Bocchini Boyd Brew Dalton
Flanagan Hackendorn Hoffmann Jalan McGraw
Myrick Quigley Reinicker Sargianis Steelman
Stengel Wells Woods Zagrobelny

Modification and Subsequent Use of a Gas Phase Reactor for the Study of Propylene Epoxidation Catalysts
Marco A. Bedolla, Joseph C. Dellamorte, Mark A. Barteau
Department of Chemical Engineering

Recent work has shown the presence of an oxametallacycle on Ag catalysts for ethylene epoxidation. This work led to the prediction that the addition of Cu to the catalyst would improve the selectivity to the desired product ethylene oxide. A similar reaction involves the epoxidation of propylene to propylene oxide. In order to study catalysts for this system in a similar fashion to ethylene, the reactor and gas chromatograph were reconfigured. First, possible products from the reaction were researched and the method used for the gas chromatograph was reformulated to separate all reactant and product species from the outlet stream. Preliminary studies of the gas phase reaction were undertaken with silver catalysts supported on -Al2O3 monoliths and doped with either copper or cesium. It was shown that the conversion of propylene to propylene oxide and other products (CO2) was greater for the Cs-Ag catalyst than for the Cu-Ag catalyst. With the Cs-Ag catalyst, the inlet stream to the reactor contained 10% v/v each of propylene and oxygen in nitrogen; however, the Cu-Ag catalyst required much greater oxygen concentrations to be effective (40% v/v O2). It was also observed that the Cs-Ag catalyst produced a still unidentified side product in addition to PO and CO2. The effects of the partial pressure of O2 with the Cs-Ag catalyst were also studied. As the partial pressure of oxygen increased, the activity of the catalyst increased along with the production of PO relative to the other products.

Strategy for Managing the Negative Effects of Carbon-Dioxide Evolution in Direct Methanol Fuel Cells
Peter Bocchini, Srikanth Arisetty, Ajay K. Prasad, and Suresh G. Advani
Department of Mechanical Engineering

Direct methanol fuel cells are considered to be a potential power source for use in portable applications. One of the factors limiting their performance is the blockage of anode catalyst sites by produced carbon-dioxide (CO2) bubbles. In this study we will develop a strategy to flush the stagnant CO2 bubbles with the feedback from pressure drop measurements. The anode side of the cell is made transparent so that we can visualize the dynamics of CO2 bubbles with a video camera. Experiments will be repeated with parallel, serpentine, and interdigitated flow fields. Gas production will also be measured at different current densities as well as different flow rates.

Analyzing Word Usage in Software to Improve Software Maintenance Tools
Haley Boyd, Lori Pollock, Emily Hill, and K. Vijay-Shanker
Department of Computer and Information Science

Currently, many software systems are large and complex. Maintaining these software systems requires that programmers comprehend scattered pieces of code that are often produced by more than one developer. Programmers comprehend code by identifying code segments that are relevant to their particular maintenance task, comprehending the relevant code, and then making modifications to perform the maintenance task. We hypothesize that software maintainers use both the programmers' words, which we call textual clues, and the knowledge of programming language structures, which we call program structure, to identify and understand relevant code segments.  This work focuses on analyzing a large set of real maintenance requests and the corresponding code segments that were changed, with the goal of learning what kinds of textual and structural clues programmers use in the identification and understanding phases of software maintenance.  Particularly, my work this summer involved gathering and analyzing large open-source software projects made available by SourceForge, with the goal of learning by examples.  I automated the process of retrieving the commit messages for each maintenance request from each project's configuration management system's log files.  I manually analyzed the words and program structure involved in the commit messages and maintenance request text, taking note of any clues that might teach us how the programmer would identify the relevant code segments for a given maintenance request.  The information that we learn from this study will be used to develop heuristics to automate the tedious, error-prone tasks and optimize software maintenance tools for reliable software systems as they evolve over time with new features and fixed bugs.

Hydrothermal Synthesis of Bismuth Molybdate Catalysts
Kevin W. Brew, Joseph C. Dellamorte, and Jochen A. Lauterbach
Department of Chemical Engineering

Bismuth molybdates of the general chemical formula Bi2O3.nMoO3, n = 3, 2, 1, and their metal-ion-doped analogues, have catalytic applications on selective oxidation, oxidative-dehydrogenation, and ammoxidation of lower olefins, as well as unique physical properties with potential technological application as ionic conductors, acousto-optical materials, photoconductors, gas sensors and visible-light responsive photocatalysts. Hydrothermal synthesis is the technique of crystallizing substances from high-temperature aqueous solutions at high vapor pressures. The advantage of hydrothermal synthesis over conventional precipitation and calcination methods is that compounds such as surfactants that may decompose at elevated temperatures can be used to control the crystal size, shape and phase because operating temperatures are below 200 °C. To investigate the effect of the crystal morphology on the catalytic performance, several bismuth molybdate catalysts were synthesized hydrothermally, focusing on three phases: alpha – Bi2Mo3O12, beta– Bi2Mo2O9, gamma – Bi2MoO6. After adjusting the pH of the mixture solution of precursors, the mixture solution was transferred into a reaction vessel and maintained at 413K for 48 hours. A surfactant was introduced to the synthesis process at concentrations of 0.25, 0.5 M. The products were filtered off, washed several times with distilled water and absolute ethanol. Each sample was calcined after hydrothermal synthesis. To ensure formation of pure catalyst phases, samples were analyzed with XRD. Each sample was analyzed with SEM to obtain catalyst morphology as well as a particle size distribution. The SEM images show the crystal size changes with increasing the concentrations of surfactant. Funded by the University of Delaware’s Undergraduate Research Program.

Hurricane Evacuation in Delaware
Sarah Dalton, Sue McNeil, Rachel Davidson, and Earl Rusty Lee
Department of Civil and Environmental Engineering, Disaster Research Center

Delaware is located on the Delmarva Peninsula, bordered on the east by the Atlantic Ocean and on the west by the Chesapeake Bay. Because of this location Delaware is a state vulnerable to many natural hazards. Sussex County, the southernmost county in Delaware, is at risk for seventeen of the twenty-one hazards defined by the federal government, the most threatening of these being floods and hurricanes. Although hurricanes do not pass through this area often, they do occasionally, and the state is in a very vulnerable position when it happens. Evacuation plans exist, but with limited experience we do not know how effective or efficient these plans are. This research hopes to determine if Delaware's pre-existing evacuation plans are adequate and up to current practices if a mass evacuation were to be ordered in the state. To do thi! ! s, a state of the art and practice review was completed by reviewing evacuation plans from both hurricane prone states and non hurricane prone states. A review was also done on engineering and sociological literature relating to evacuations to bridge the gap between the two disciplines. Finally, the research examined the gaps between Delaware's plans, model, assumptions, etc. and the aforementioned research.

A Path to Pico-Tesla Magnetic Tunnel Junction Sensors
T. C. Flanagan1, E. R. Nowak1, R. D. McMichael2, J. Unguris2, P. Pong3, and W. F. Egelhoff, Jr3.
1UD Department of Physics and Astronomy, 2Center for Nanoscale Science and Technology,
3Metallurgy Division, National Institute of Standards and Technology

The extension of small, inexpensive, low-power, low frequency, ultra-sensitive magnetic sensors to fields between 1 nano-Tesla and 1 pico-Tesla, an area currently dominated by fluxgates, optically-pumped magnetometers, and SQUIDS, would be a paradigm shift for the field of magnetic sensors. The necessary elements for pico-Tesla MTJ sensors have been identified by modeling the noise characteristics.  The results help identify the experimental challenges involved in the integration of these necessary elements into actual sensors and illustrate the trade-offs faced if there are losses in performance upon integration. Scanning electron microscopy with polarization analysis (SEMPA) of the pinned layer provides insights into problems and possible solutions. Issues associated with real-world applications of these sensors to ultra-low field measurements are discussed.

Sb Doped Ti02-Ge Nanocomposites for Thermoelectric Applications
R. Andrew Hackendorn, Emre Yassitepe, and S. Ismat Shah
Department of Material Science

The field of Thermoelectrics is being explored to use the waste heat of nearly every system to obtain usable electrical energy. The principle nanocomposite investigated is Sb doped TiO2-Ge. The material was deposited onto a quartz substrate using an rf magnetron sputtering technique. Deposition occurred at 600 oC for approximately 2 hours with varied rf power. The amount of titanium dioxide, germanium and antimony were varied which altered the properties of the thin film. The films are characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The electrical conductivity has been measured up to 100 C for each prepared sample. Electrical conductivity has been improved by altering the rf power for one composition of the nanocomposite.

Mathematical Models for the Simulation of Gene Expression
Kyle Q. Hoffmann, Tobin A. Driscoll, and Prasad Dhurjati
Departments of Chemical Engineering and Mathematical Sciences

The ability to simulate networks of genes will allow researchers to better study existing networks and to create more efficient experiments. The existing C based simulation eXPatGen allows a user to create a gene network via an on-line interface and to view the results as they would appear in a microarray. This program was repaired and placed on-line. Its code was then translated into the Matlab programming language. An interface was created for inputting gene networks and for displaying the data either as it would appear in a series of microarrays, or the mRNA concentration as a function of time. This program was then used to simulate several simple gene networks. Currently, there is a substantial set of microarray data for various organisms under different contexts. Methodologies for interpretation of this information can lead to new diagnostic techniques and also aid in discovery of new drugs. Some microarray data from simple simulated gene networks were interpreted to address the inverse problem of going from data to gene networks. This provided insight into the enormous complexity of the problem. The Howard Hughes Medical Institute funded this work.

Effects of Promoter Loadings on KRu4O8 Hollandite-based NH3 Decomposition Catalysts
Parag Jalan, Elizabeth M. D’Addio, and Jochen A. Lauterbach
Department of Chemical Engineering

Because of issues associated with H2 storage, materials with a high H2 density have been proposed for use in mobile fuel cell applications. Ammonia is an attractive choice because it can be catalytically decomposed to form CO-free hydrogen. However, current catalysts require high temperatures to attain a satisfactory conversion. This challenge necessitates exploration of novel catalytic materials that will be highly active at low temperatures for energy efficient ammonia decomposition.   Results of previously conducted experiments have shown that ruthenium has the highest catalytic activity of all single metals. A significant increase in its activity is achieved by promoting the single metal with potassium. A series of unpromoted and K-promoted Ru catalysts from different precursors was tested using a home-built single reactor and Fourier Transform Infrared (FTIR) spectroscopy. Potassium loadings ranging from 0 wt% to 50 wt% were tested and it was found that the addition of 12 wt% K to 4 wt% Ru increases the NH3 conversion by 30-50% at temperatures around 350°C. The high conversion was related to the formation of KRu4O8 Hollandite “nano-whiskers” on the K-promoted Ru catalyst. SEM analysis of the catalysts after calcinations suggests that increased formation of these nano-whiskers corresponds to higher activity.  At this time, the role of the Hollandite is still under investigation. It is likely that the Hollandite acts as a structural promoter that decomposes to form a highly active metallic Ru phase in close proximity to promoting K.  Funded by the University of Delaware’s Undergraduate Research Program and the Department of Energy.

Efficiency Improvement for Time-Domain Integral Equation Methods for Electromagnetic Scattering
Garret McGraw and Daniel Weile
Department of Electrical and Computer Engineering

Computational electromagnetics involve the solving of time or frequency domain forms of Maxwell's equations to predict the behavior of electromagnetic fields.  While many approaches have been used over the years, one that has proved most problematic has been solving the integral form of Maxwell's equations in the time domain.  Since the beginning, the computational nature of the project required a more optimized platform than the ones traditionally used by engineers such as Matlab or Labview.  For a variety of reasons, including speed, object orientation, and the availability of programming tools, C++ was chosen. Now that much of the C++ code has been written and a library of functions has been established,  it became necessary to maintain and comb through the code, analyzing the methodologies used for basic parts of the code to ensure that performance was not sacrificed in the name of clarity. Under this project, the code is bein documented and made more efficient in anticipation of future practical computations and research.  / Funding was provided through NSF.

Design of a Cell-Responsive De-PEGylation DNA Delivery System
Stephanie L. Myrick, Peter G. Millili, Millicent O. Sullivan
Department of Chemical Engineering
(Stephanie also presented her work as a talk in the Sigma Xi competition.)

We are interested in formulating non-viral DNA delivery vehicles with high delivery efficiency by incorporating multiple functional layers that can be sequentially cleaved off during the delivery process to expose new features. We have established a simplified single-layered model vehicle consisting of a polycation-condensed DNA core attached via a linker peptide to a layer of poly(ethylene) glycol (PEG). While PEG has been widely shown to be vital in protecting biomaterials from salt-induced aggregation and attack by the immune system, the presence of PEG ultimately inhibits DNA delivery at the target cell. This project is focused on validating a cell-responsive de-PEGylation of the vehicle prior to delivery via cleavage of the linker peptide, which is sensitive to proteases such as matrix metalloproteinase-1 (MMP-1). MMP-1 is a collagen-degrading enzyme upregulated by fibroblasts as they migrate through the extracellular matrix; such migration is typically observed in tumor stroma and at sites of injury, making MMP-1 secretion a useful signal for targeting these areas. Having already established the conditions that stimulate MMP-1 expression by normal human dermal fibroblasts (NHDFs) via Western blot analysis and immunofluorescence staining, we have begun to investigate the efficiency of vehicle cleavage (and de-PEGylation) by MMP-1 using light scattering in combination with salt aggregation assays to detect PEG layer release following vehicle incubation with recombinant MMP-1. Future work will include further experiments in this area and the investigation of the transfection efficiencies of PEGylated and dePEGylated particles. This project is supported by Howard Hughes Medical Institute, National Science Foundation (CBET-0707583), and the University of Delaware Research Fund (UDRF).

Synthesis and Characterization of Tungsten Monocarbide Thin Films Made by Physical Vapor Deposition
John P. Quigley, Daniel V. Esposito and  J.G. Chen
Department of Chemical Engineering

Platinum catalysts are currently the most commonly used in direct methanol fuel cells due to both their stability and activity in anodic conditions. However, they are very expensive and susceptible to carbon monoxide poisoning which reduces activity during oxidation. A potential alternative to platinum catalysts are tungsten monocarbide(WC). Building on work completed by Weigert & Chen[1], the scope of this research is to synthesize and characterize tungsten monocarbides films on a large surface area carbon paper substrate and test their electrochemical stability and activity. Phase-pure WC films have been successfully deposited on 4x4” carbon paper in a high vacuum environment using a magnetron sputtering source. The partial pressures of hydrogen and ethylene gases as well as the substrate temperature were deposition parameters which have been investigated thus far. After deposition, all samples were annealed to 1250 K before being characterized by x-ray diffraction methods and cyclic voltommetry. XRD revealed that all films had phase pure WC bulk composition except that which was made in the absence of ethylene. Current work is focused on i.) synthesizing WC films modified with Pt and ii.) testing the activity and stability of all WC films as anodic catalysts in aqueous alcoholic environments ex-situ to determine their applicability to current DMFC’s. References [1] Weigert & Chen. J. Vac. Sci. Technol. A. 26(1). 2008. Funding for this research is provided by the Department of Energy, and the National Science Foundation.

Tungsten Carbides and Bimetallic Carbides as Potential Methanol Fuel Cell Anodes
Aaron Reinicker, Jingguang Chen, Zach Mellinger, and Mike Humbert
Department of Chemical Engineering

In the present work, several different potential electrocatalysts were synthesized on carbon paper containing a specific percentage of tungsten carbide mixed with Pt, Ru, and Ta as a thin film on the surface. All catalysts were prepared using an incipient wetness procedure where metallic precursors were dissolved in a solvent and added drop-wise to Carbon Paper. Then the samples were heated in a quartz tube furnace under a stream of CH4 and H2. These catalysts were characterized by X-ray Diffraction (XRD) and Cyclic Voltammetry (CV) in a solution of 0.2M methanol/0.5M H2SO4 to determine their activity to methanol oxidation. Incipient wetness proved to be a successful synthesis technique as XRD showed all samples to have the correct components and atomic ratios. CV tests also showed that 10% WC 10% Pt on Carbon Paper was the best catalyst for methanol oxidation.

Out of Plane Thermal Expansion of Nafion® Membranes for Fuel Cell Applications
James Sargianis, Michael H. Santare, and Anette M. Karlsson
Mechanical Engineering Department

A critical element of a hydrogen fuel cell is the proton-exchange membrane. Its unique properties allow it to conduct the protons of hydrogen atoms, while trapping the electrons to create an electrical charge. A fuel cell’s overall durability and conductivity is in large part, determined by the properties of the membrane. When any material is heated or cooled, it typically expands or contracts and, if this dimensional change is constrained, it causes stress in the material. This stress, especially applied cyclically over a period of time, leads to damage and eventual failure of the material. Hence over time as the membrane of a fuel cell is subjected to changes in temperatures, the membrane experiences a decrease in its durability and conductivity. Therefore the goal of this research is to understand how Nafion® membrane expands and contracts over a range of temperatures from -40° C to 105° C. In these experiments, Nafion® membrane is used since it has been an industry-standard fuel cell membrane, and most other polymer membrane materials are variations of Nafion® membrane’s basic structure. The Nafion® membrane samples are analyzed using a TA Instruments Thermomechanical Analyzer, which controls the temperature and measures changes in thickness on a micrometer size scale.

Design and Fabrication of Micro Air Vehicles modeled after an Insect Thorax.
Kyle D. Steelman,  Zaeem A. Khan, and Sunil K. Agrawal
Department of Mechanical Engineering

Micro Air Vehicles (MAVs) are emerging as the focal point for aerial vehicle research and funding. This project’s goal is optimizing MAV design and fabrication, based on optimized kinematics, with current designs being modeled after an insect thorax. With an optimized mechanical system, we can then expand the project to controlling flight of the system, thus creating a wide variety of applications. This research will explain Insect flight, how we mimic that motion, and show experimental results of our mechanical system.

Detection of Askaryan Radio Pulses Produced by Cores of Air Showers
Patrick Stengel, David Seckel, and Shahid Hussain
Department of Physics and Astronomy

Cosmic rays and neutrinos give astrophysicists information about a variety of high energy galactic and intergalactic phenomena. Cascades of high energy particles, when traveling through a dense medium (such as ice, rock salt or silica sand), create impulsive radio signals observable over a large distance. Antenna arrays deployed in Antarctic ice utilize this Askaryan Effect to search for cosmic neutrinos interacting inside the icecap. Alternatively, these arrays may detect secondary particles produced in cosmic ray air showers, which impact the ice surface. This project involves modification of a software package, originally developed to simulate neutrino events, for the study of coherent radiation from the multiple secondary particles in an air shower core. Accurate event simulation requires nanosecond accuracy of radiation field propagation through the ice. This requirement is constrained by computational resources, so efficient numerical algorithms must be implemented. The improved simulation will be used to assess the ability of a small antenna array to determine the composition of cosmic ray air shower cores.

Functionalization of Diblock Copolymer Micelles
Peter Wells, Christina Russo, and Thomas H. Epps, III
Department of Chemical Engineering

Amphiphilic diblock copolymer micelles have uses as transport agents in different applications and their efficacy can be increased if they are functionalized. The specific diblock copolymer system polybutadiene-b-poly(ethylene oxide) (PB-PEO) was chosen because the system is biocompatible[1], and the phase behavior has already been characterized[2]. Solutions of water and tetrahydrofuran (THF) containing the PB-PEO micelles were characterized using quasi-elastic light scattering (QLS) and cryogenic transmission electron microscopy (CryoTEM). For copolymer in pure water, CryoTEM data displayed micelle sizes of approximately 50 nm, but QLS displayed sizes of approximately 90 nm. Static light scattering (SLS) and small angle neutron scattering (SANS) experiments were also conducted on the copolymer/water solutions to resolve the size discrepancy, and the data were in good agreement with the CryoTEM micrographs. It is believed that the difference in size is due to the PEO corona causing friction with the solvent, resulting in slower movement than predicted by the simplified Einstein-Stokes equation used in QLS. The micelle size disparity also occurred with the addition of THF to copolymer/water solutions. However, both QLS and CryoTEM supported the trend of increasing micelle size with increasing THF volume. It is theorized that some of the PB chains in the core of the micelle were drawn into the corona (PEO) by the THF and increased the overall size of the micelle. This gives opportunity for these micelles to be functionalized by attaching peptides to the methylene side group on the polybutadiene within the corona. Funding provided by the University of Delaware Research Foundation (UDRF). [1] Savic, R.; Luo, L.; Eisenberg, A.; Maysinger, D., Science 300, 615, 2003. “Micellar nanocontainers distribute to defined cytoplasmic organelles” [2] Jain, S.; Gong, X.; Scriven, L. E.; Bates, F., Physical Review Letters 96, 138304, 2006. “Disordered network state in hydrated block-copolymer surfactants”

Synthesis and Characterization of PEG-Peptide Hybrid Hydrogels for Vocal Fold Tissue Engineering
Meghan Woods1, Sarah Grieshaber2, Xinqiao Jia2
1Department of Chemistry and Biochemistry,2Department of Materials Science and Engineering

Material used in vocal fold tissue engineering must possess several properties that enable it to withstand the unique conditions that vocal fold tissue endures. In addition to being flexible and durable, the material should be biocompatible and biodegradable. Polymer-peptide hybrids are promising candidates for vocal fold and other tissue engineering scaffolds because the synthetic polymer segments allow control over the mechanical properties of the material, while the peptide segments allow control over the assembly and biological properties. As the peptide domain, a repeat unit of AKAAAKA was chosen from the hydrophilic, cross-linking domains of elastin. For the polymer domain, poly(ethylene glycol) (PEG) was chosen for its flexibility, biocompatibility, and water solubility. Hydrogels were produced by functionalizing peptides and polymers of various molecular weights and architectures with multiple alkyne and azide groups, respectively, and covalently cross-linking them using “click” chemistry, a copper-catalyzed cycloaddition reaction. It has been shown that an increased number of functional groups leads to more viscous gels that reach their gelation point in a shorter amount of time. In addition, rheological measurements indicate that the storage modulus of these materials increases as the molecular weight increases and as the geometry of the PEG is changed. This project was funded by HHMI.

Alternative Reactor Optimization for Hydrogen Production from Ammonia Decomposition and Water-Gas Shift Reaction
Megan A. Zagrobelny and Dionisios G. Vlachos
Department of Chemical Engineering

The continuing environmental concerns and the recent energy crisis require a paradigm shift in the production and utilization of energy. Hydrogen is the greenest fuel, and fuel cells have much higher energy efficiency than internal combustion engines. Consequently, identifying efficient ways to produce hydrogen production is important. In this research, several routes for hydrogen production are being studied with focus on optimizing the devices (reactors) producing hydrogen. Ammonia is an attractive option for hydrogen storage and transport; however, high temperatures are required for decomposition of ammonia. A model was developed for a membrane reactor for ammonia decomposition over a ruthenium catalyst. Adding a hydrogen-selective membrane caused adsorbed hydrogen to be removed from the catalyst surface, thus freeing active sites and allowing additional ammonia to decompose. The effects of membrane thickness and pressure gradient across the membrane were also studied. The second part of the work conducted focuses on the water-gas shift reaction that plays an important role in obtaining hydrogen from hydrocarbons, both from fossil fuels and from biomass. Because the reaction is exothermic and equilibrium limited, a balance must be achieved between the thermodynamically favorable low temperatures and the kinetically necessary high temperatures. One possible solution is to use multiple reactors that operate at different temperatures. A system of multiple reactors in series was designed and optimized to determine the best temperature to operate each reactor. Conversion of carbon monoxide was improved significantly by using multiple reactors, with lower temperatures in the later reactors. Acknowledgements: This work was sponsored in part by the Northeastern Chemical Association and by the DOE.

Links: Summer 2008 Undergraduate Research Symposium, Symposium Abstracts from other Colleges and Departments,

2008 Undergraduate Research Summer Enrichment ProgramUnversity of Delaware Undergraduate Research Program, Howard Hughes Undergraduate Program.
Created  9 August 2008. Last up dated 2 September 2008 by Hal White
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