Matching Items (174)
Description
Climate change is one of the biggest challenges facing today's society.Since the late 19th century, the global average temperature has been rising. In order to minimize the temperature increase of the earth, it is necessary to develop alternative energy technologies that do not depend on fossil fuels. Solar fuels are one potential energy source for the future. Solar fuel technologies use catalysts to convert low energy molecules into fuels via artificial photosynthesis. TiO2, or titania, is an important model photocatalyst for studying these reactions. It is also important to use remaining fossil fuel resources efficiently and with the lowest possible greenhouse gas emissions. Fuel cells are electrochemical devices that aim to accomplish this goal and CeO2, or ceria, is an important material used in these devices. One way to observe the atomic structure of a material is with a transmission electron microscope (TEM). A traditional transmission electron microscope employs a beam of fast electrons to form atomic resolution images of a material. While imaging gives information about the positions of the atoms in the material, spectroscopy gives information about the composition and bonding of the material. A type of spectroscopy that can be performed inside the transmission electron microscope is electron energy loss spectroscopy (EELS), which provides a fundamental understanding of the electronic structure of a material. The energy loss spectrum also contains information on the chemical bonding in the material, and theoretical calculations that model the spectra are essential to correctly interpreting this bonding information. FEFF is a software that performs EELS calculations. Calculations of the oxygen K edges of TiO2 and CeO2 were made using FEFF in order to understand the changes that occur in the spectrum when oxygen vacancies are introduced as well as the changes near a grain boundary.
ContributorsHussaini, Zahra (Author) / Crozier, Peter (Thesis director) / Rez, Peter (Committee member) / Jorissen, Kevin (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Materials Science and Engineering Program (Contributor) / Department of Physics (Contributor)
Created2013-12
Description
Journalism, by its very nature, is limited, often adhering to a repetitive format and narration style. Consequently, the depth of journalistic stories will always hit a barrier. Fiction, on the other hand, provides an elegant solution by exploring the world through a myriad point of views including complete omniscience. This thesis explores the link between journalism and fiction by taking real-world scenarios and exploring them without journalism's limitations. It includes three novellas totaling 25,000 words drawn from true-to-life research papers, news stories and manifestos to paint a realistic picture of a technological reality in the near future, a style of writing one might call futurecasting. The thesis also contains an analysis of the techniques used in contemporary fiction and an analysis of their implementation within the novellas. The goal of the novellas is to let researchers to explore the impact of their work before its mass dissemination in order to shape societal, national and international policy responsibly. Similarly, novellas like this and others similar allow society to discover the beauty of science through fiction. These are some of fiction's greatest roles in science and society.
ContributorsPacini, Jason Daniel (Author) / Zachary, Gregg (Thesis director) / Russell, Dennis (Committee member) / Giarrusso, Theresa Walsh (Committee member) / Barrett, The Honors College (Contributor) / Department of Physics (Contributor) / Walter Cronkite School of Journalism and Mass Communication (Contributor)
Created2013-05
Description
In this project, we introduce a type of microscopy which produces correlated topography and fluorescence lifetime images with nanometer resolution. This technique combines atomic force microscopy (AFM) and time resolved confocal fluorescence microscopy to conduct biological and materials research. This method is used to investigate nanophotonic effects on single fluorophores, including quantum dots and fluorescent molecules. For single fluorescent molecules, we investigate the effects of quenching of fluorescence with the probe of an atomic force microscope which is combined and synchronized with a confocal fluorescence lifetime microscope. For quantum dots, we investigate the correlation between the topographic and fluorescence data. With this method of combining an atomic force microscope with a confocal microscope, it is anticipated that there will be applications in nanomaterial characterization and life sciences; such as the determination of the structure of small molecular systems on surfaces, molecular interactions, as well as the structure and properties of fluorescent nanomaterials.
ContributorsWard, Alex Mark (Author) / Ros, Robert (Thesis director) / Shumway, John (Committee member) / Schulz, Olaf (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor)
Created2013-05
Description
Dry and steam NanoBonding™ are conceived and researched to bond Si-based surfaces, via nucleation and growth of a two-dimensional SiOxHy or hydrated SiOxHy interphase connecting surfaces at the nanoscale across macroscopic domains. The motivation is to create strong, long lasting, hermetically bonded sensors with their electronics for the development of an artificial pancreas and to bond solar cells to glass panels for robust photovoltaic technology. The first step in NanoBonding™ is to synthesize smooth surfaces with 20 nm wide atomic terraces via a precursor phase, ß-cSiO2 on Si(100) and oxygen-deficient SiOx on the silica using the Herbots-Atluri process and Entrepix’s spin etching. Smooth precursor phases act as geometric and chemical template to nucleate and grow macroscopic contacting domains where cross bridging occurs via arrays of molecular strands in the hydrated SiOxHy interphase. Steam pressurization is found to catalyze NanoBonding™ consistently, eliminating the need for direct mechanical compression that limits the size and shape of wafers to be bonded in turn, reducing the cost of processing. Total surface energy measurements via 3 Liquids Contact Angle Analysis (3L CAA) enables accurate quantitative analysis of the total surface energy and each of its components. 3L CAA at each step in the process shows that surface energy drops to 42.4 ± 0.6 mJ/m2 from 57.5 ± 1.4 mJ/m2 after the Herbots-Atluri clean of an “As Received” wafer. 3L CAA after steam pressurization Nanobonding™ shows almost complete elimination from 13.8 mJ/m2 ± 1.0 to 0.002 ±- 0.0002 mJ/m2 in the contribution of acceptors to the total free surface energy, and an increase from 0.2 ± .03 to 23.8± 1.6 mJ/m2 in the contribution of donors. This is consistent with an increase in hydroxylation of the ß-cSiO2 surface as a consistent precursor phase for cross-bridging. This research optimizes the use of glycerin, water, and α-bromo-naphtalene in the use of 3L CAA to effectively quantify the components of total free surface energy which helps to better understand the most consistent method for NanoBonding™.
ContributorsBennett-Kennett, Ross Buchanan (Author) / Culbertson, Robert (Thesis director) / Herbots, Nicole (Committee member) / Foy, Joseph (Committee member) / Barrett, The Honors College (Contributor) / Materials Science and Engineering Program (Contributor) / Department of Physics (Contributor) / School of Historical, Philosophical and Religious Studies (Contributor)
Created2013-05
Description
In this experiment, an attempt was made to measure the index of refraction of a thin glass microscope slide, with a known thickness of 1.01 mm. A monochromatic laser with wavelength of 532nm was employed to generate the interference pattern through the use of a Michelson interferometer. The slide was placed in the path of one of the beams. The slide could then be rotated through a series of angles, and, from the resulting changes in the interference pattern, the index of refraction of the slide could be extracted. The index of refraction was found to be 1.5±0.02.
ContributorsSwenson, Jordan (Author) / Sukharev, Maxim (Thesis director) / Bennett, Peter (Committee member) / Barrett, The Honors College (Contributor) / Department of Physics (Contributor)
Created2014-05
Description
We designed and constructed a cryostat setup for MKID detectors. The goal for the cryostat is to have four stages: 40K, 4K, 1K and 250mK. Prior to the start of my thesis, the cryostat was reaching 70K and 9K on the first and second stages respectively. During the first semester of my thesis I worked on getting the second stage to reach below 4K such that it would be cold enough to add a sorption fridge to reach 250mK. Various parts were machined for the cryostat and some tweaks were made to existing pieces. The largest changes were we thinned our stainless steel supports from 2mm to 10mil and we added roughly 6-10 layers of multi-layer insulation to the first and second stages. Our result was that we now reach temperatures of 36K and 2.6K on the first and second stages respectively. Next we added the sorption fridge to the 4K stage by having the 4K stage remachined to allow the sorption fridge to be mounted to the stage. Then I designed a final, two stage, setup for the 1K and 250mK stages that has maximum capabilities of housing a six inch wafer for testing. The design was sent to a machinist, but the parts were unfinished by the end of my thesis, so the parts and stage were not tested. Once the cryostat was fully tested and proven to reach the necessary temperatures, preliminary testing was done on a Microwave Kinetic Inductance Detector (MKID) provided by Stanford. Data was collected on the resonance and quality factor as they shifted with final stage temperature (5K to 285mK) and with input power (60dB to 15dB). The data was analyzed and the results agreed within expectations, as the resonant frequency and quality factor shifted down with increased temperature on the MKID. Finally, a noise characterization setup was designed to test the noise of devices, but was not fully implemented.
ContributorsAbers, Paul (Author) / Mauskopf, Phil (Thesis director) / Groppi, Chris (Committee member) / Department of Physics (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This project details the learning of processes in nanofabrication and sensor detection fields. We sought to apply this knowledge to develop a processing procedure to fabricate sensors used to detect high energy protons. We seek to create such a sensor to be applied to aid Mayo Clinic’s Proton Beam Therapy center for cancer treatment through providing beam detection measurements. Developed plans would allow for proton beam detectors to be able to measure beam intensity and direction which would allow for more accurate beam treatments. Current detectors require much calibration and solid state detectors can’t withstand the high-energy exposure of the proton beam for long durations. By fabricating pixelated diamond sensors we expect to produce sensitive beam readings, while extending detector length time due to diamonds durable crystalline lattice. We report processing procedures for simple 2-3 contact detectors as well as more complex multi-contact pixelated sensors used for spatial resolution of the beam. Testing of simple sensors is additionally reported with successful radioactive source detection.
ContributorsVan Engelhoven, Trevor James (Author) / Nemanich, Robert (Thesis director) / Zaniewski, Anna (Committee member) / Department of Physics (Contributor, Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The LOw Frequency ARray (LOFAR) is a new and innovative radio telescope designed and constructed by the Netherlands Institute for Radio Astronomy (ASTRON). LOFAR unique capable of operating in very low frequencies (10-240 MHz) and consists of an extensive interferometry array of dipole antenna stations distributed throughout the Netherlands and Europe which allows it to achieve superb angular resolution. I investigate a part of the northern sky to search for rare radio objects such as radio haloes and radio relics that may have not been able to have been resolved by other radio telescopes.
ContributorsNguyen, Dustin Dinh (Author) / Scannapieco, Evan (Thesis director) / Butler, Nathaniel (Committee member) / School of Earth and Space Exploration (Contributor) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Radio astronomy is a subfield in astronomy that deals with objects emitting frequencies around 10 MHz to 100 GHz. The Low Frequency Array (LOFAR) is a array of radio antennas in Europe that can reach very low frequencies, roughly between 10-240 MHz. Our project was to image and clean a field from LOFAR. The data was a 10 degree square in the sky centered at a right ascension of 10:19:34.608 and a declination +49.36.52.482. It was observed for 600 seconds at 141 MHz. To clean the field, we had to flag and remove any stations that were not responding. Using a program called FACTOR, we cleaned the image and reduced the residuals. Next we checked the validity of our sources. We checked positional offsets for our sources using the TGSS survey at 150 MHz, and corrected the declination of our LOFAR sources by a factor of 0.0002 degrees. We also fixed the LOFAR fluxes by a factor of 1.15. After this systematic check, we calculated the spectral index of our sources using the FIRST survey at 1435 MHz. We plotted this spectral index against LOFAR flux as well as redshift of the sources, and compared these to literature.
ContributorsStawinski, Stephanie Mae (Author) / Scannapieco, Evan (Thesis director) / Windhorst, Rogier (Committee member) / Karen, Olsen (Committee member) / Department of Physics (Contributor) / School of International Letters and Cultures (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Solid-state lithium-ion batteries are a major area of research due to their increased safety characteristics over conventional liquid electrolyte batteries. Lithium lanthanum zirconate (LLZO) is a promising garnet-type ceramic for use as a solid-state electrolyte due to its high ionic conductivity. The material exists in two dierent phases, one that is cubic in structure and one that is tetragonal. One potential synthesis method that results in LLZO in the more useful, cubic phase, is electrospinning, where a mat of nanowires is spun and then calcined into LLZO. A phase containing lanthanum zirconate (LZO) and amorphous lithium occursas an intermediate during the calcination process. LZO has been shown to be a sintering aid for LLZO, allowing for lower sintering temperatures. Here it is shown the eects of internal LZO on the sintered pellets. This is done by varying the 700C calcination time to transform diering amounts of LZO and LLZO in electrospun nanowires, and then using the same sintering parameters for each sample. X-ray diraction was used to get structural and compositional analysis of both the calcined powders and sintered pellets. Pellets formed from wires calcined at 1 hour or longer contained only LLZO even if the calcined powder had only undergone the rst phase transformation. The relative density of the pellet with no initial LLZO of 61.0% was higher than that of the pellet with no LZO, which had a relative density of 57.7%. This allows for the same, or slightly higher, quality material to be synthesized with a shorter amount of processing time.
ContributorsLondon, Nathan Harry (Author) / Chan, Candace (Thesis director) / Tongay, Sefaattin (Committee member) / Department of Physics (Contributor) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05