2017 NSF Research Experiences for Undergraduates posters and presentations
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In operando investigations of lithium-sulfur and lithium-ion battery electrolytes using ATR FT-IR spectroscopyAn in operando spectro-electrochemical Lithium-Sulfur cell is used to show performance benefits of using a LiNO3 additive. Using attenuated total reflection infrared spectroscopy, we are able to track the evolution of lithium polysulfides in a coin cell during cycling. We see that the concentration of polysulfides in electrolyte containing LiNO3 is substantially higher, and capacity retention of the cell is improved. ATR FT-IR spectroscopy is used to monitor thermal decomposition of organic carbonate and room temperature ionic liquid electrolytes. Samples are tested in a flooded coin cell and heated up to a temperature of 175°C. The results will be used to monitor decomposition products and study limitations inherent to RTIL electrolyte.
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Effects of various leaving groups on chain growth condensation mechanism by computational methodsOptimizing polymer mechanisms is a popular area of study and one such mechanism that is still not fully understood is the chain growth condensation. A systematic study of the behavior of different leaving groups on an ester-based monomer was performed for the chain-growth condensation of N-octyl benzamide. Quantum mechanical calculations were performed to determine the energies and charges of each step of the reaction for each of the leaving groups, ranging from extremely electron withdrawing to extremely electron donating. The leaving groups are phenyl oxides with functional groups that were placed in both the para and meta positions on the ring. In both the meta and para positions the functional groups that are electron withdrawing tend to increase reactivity with the exception of the halogens. The halogens tendency to be electron donating through resonance makes them slightly more reactive in the meta position. The most favorable reactions are then tested out by the experimental chemists working on this project.
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In-operando FT-IR spectroscopy of electrolyte decomposition in lithium-ion batteriesOne of the major problems of Li-ion batteries is the decomposition of electrolyte at elevated temperatures. In situ FT-IR spectroscopy can be used to study the health of the electrolyte in Li-ion cells. We used an ATR FT-IR spectro-electrochemical cell to observe thermal decomposition of LiPF6 EC/DEC electrolyte in a LiCoO2 coin cell. Results show that at 70 ℃, several infrared absorption peaks were irreversibly lost. This led to a significant degradation of the electrochemical performance of the battery.
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Simulation of silicon-based solar cells using finite element analysis (FEA)Amorphous silicon (a-Si) and crystalline silicon (c-Si) are some of the most commonly used materials in modern solar cells due to their abundance, inexpensiveness, and performance in photovoltaics. New designs are being tested for enhancing the performance of solar cells that utilize silicon. The ability to accurately model and simulate devices incorporating both a-Si and c-Si allows for more effective and efficient ways of optimizing adjustable parameters and extracting useful information not easily obtainable through experimentation.
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Isolation of an uncharacterized methanogen of class thermoplasma from an anaerobic wastewater treatment reactorConventional wastewater treatment plants account for approximately 3% of the United States’ energy demand1. A potential energy-positive alternative is anaerobic wastewater treatment, which generates methane-rich biogas while producing less biosolids. One challenge of AnWT is ensuring that wastewater is continuously meeting effluent standards. To ensure that this is happening, the mechanism of wastewater transformation in relation to environmental conditions needs to be well understood. At two AnWT in Colorado, namely Plum Creek and Mines Park, established microbial communities consist of numerous anaerobic microbes, including methanogens. Vadin CA 11 is an uncharacterized methanogen of the Thermoplasmata class that could represent up to 7% of the microbial community. Its abundance is different from compartment 2 to compartment 3 of the Mines Park AnWT. Further, Vadin CA 11’s presence has been observed to change with temperature. The goal of this study was to isolate Vadin CA 11 from the Mines Park AnWT. The methanogens with the highest observed relative abundance in the system are Methanobrevibacter, Methanosaeta, and Vadin CA 11. Methanobrevibacter’s metabolism is hydrogeotrophic. Methanosaeta’s metabolism is aceticlastic. Vadin CA 11’s metabolism is expected to be hydrogen dependent methylotrophic.
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Design and construction of a thermal conductivity system for low thermal conductivity materialsModern day laser flash apparatuses can only measure the thermal conductivity of materials if the thermal conductivity (K) is between 0.1 and 100 W/mK. Our goal was to create a system that could relay reliable data for materials with an expanded thermal conductivity range down to 0.001 W/mK. To accomplish this, a more powerful laser flash was used in conjunction with a circuit designed to amplify the signal so that the thermal conductivity could be deduced.
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Performance of and amendments to urban bioretention systems for removal of stormwater contaminantsAs urbanization has expanded, polluted urban stormwater runoff has become a greater concern. While originally installed to control water quantity by smoothing out urban runoff hydrographs, best management practices such as bioretention systems may also remove contaminants in runoff. This project had three primary goals: 1) to evaluate the performance of the Iris Rain Garden with respect to the removal of dissolved trace organic contaminants, 2) to determine the hydraulic conductivity of various geomedia, and 3) to determine the removal of targeted metal contaminants by various geomedia. It was found that the Iris Rain Garden reduced the amount of atrazine, caffeine, carbendazim, and triphenyl phosphate in stormwater runoff. Furthermore, hydraulic conductivity values for various types of geomedia were determined. Currently, work is being done with various geomedia to characterize the removal of heavy metals.
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Neutron shielding capabilities of 3D printing filaments3-D printers have improved significantly as time has passed. This has allowed the cost of printers to go down and has made them more commercially accessible. The increasing accessibility of 3D printing has allowed more and more engineering disciplines to incorporate additive manufacturing. Nuclear engineering is no exception since the costs for any sort of nuclear reactor and apparatus is still quite high, and the ability to create parts that can protect against radiation and be made on-site is very valuable. This research project determined the neutron shielding properties of readily available plastic filaments for 3D printers.
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Electrodeposition of refractory metals from ionic solventsElectrodeposition is a widely used technique in research and industry. We have developed a technique to electrodeposit Niobium (Nb) from an ionic solution. The process was monitored using cyclic voltammetry and electron microscopy.
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Development of a Nuclear Magnetic Resonance (NMR) Mobile Universal Surface Explorer (MOUSE)The purpose of the project is to develop a mobile NMR unit that can be used to determine pore size distribution of geological samples. Standard NMR machines are fairly large, expensive, and have a restricted sample size. A NMR MOUSE can be transported to take quicker preliminary readings on large samples, with decreased cost. This work is focused on the design aspect of creating an NMR MOUSE, future work will go into the build process.