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Defects And Dark Current In Organic Photovoltaics And Impacts On Device Physics, Xin Jiang

Electronic Theses and Dissertations

In this dissertation, we discussed the shape, energy level and density of defects in Organic Photovoltaic (OPV) devices by both theoretical and experimental methods. The energy band structure and intrinsic junctions of general standard and inverted OPV devices are investigated in detail. Transportation of separated holes and electrons in both structures are well analyzed. In chapter II, we developed a Monte-Carlo model to simulate charge transport process in organic materials. Marcus theory is applied to calculate the carrier transfer rate to build up hopping process in ideal lattices. Results of this model showed several properties of carriers regarding mobility, reorganization …

Development Of A Biosensor For Investigating Membrane Curvature Sorting, Joshua C. Black

Electronic Theses and Dissertations

The physical structure of cellular membranes plays a critical role in lipid and protein sorting. A novel biosensor was developed to probe the influence of curvature on sorting. This biosensor mimics large, two-dimensional membranes in dynamic equilibrium, achieves high spatial resolution between curvature and molecules of interest, and has high sensitivity, enough for single particle detection. The biosensor consists of continuous supported lipid bilayer formed over nanoparticles (40 to 200 nm diameter) deposited on a glass substrate. The nanoparticles determine the extent of curvature. This biosensor is the first to observe large-scale 2-dimensional diffusion of biomolecules on a supported lipid …

A Paleoenvironmental Investigation Of Eolian Influx In Lacustrine Sediments Of The Southern Rocky Mountain Region, Rebecca L. Brice

Electronic Theses and Dissertations

Potential indications of long-term trends in paleoclimate, specifically winds, in the Southern Rocky Mountain region of the United States were tested using lacustrine sediment from South Blue Lake in the Wet Mountains of Colorado. This study builds upon existing eolian and lacustrine research, and investigates paleowind in a location not yet studied in this manner. Variability in sediment laminae, particle size, and mineralogy show similar patterns during the mid-Holocene warm period (ca. 5500 cal. yr BP - ca. 6000 cal. yr BP). These patterns indicate a warmer, drier, windier period that is contrasted by a less variable period in the …

Role Of Camkii In Pancreatic Alpha Cells, Brooke A. Buckland

Electronic Theses and Dissertations

Calcium/calmodulin-dependent protein kinase II (CaMKII) has been identified as an important modulator in controlling electrical activity in neurons and the heart; however, a role for CaMKII in pancreatic alpha cell signaling has not been previously reported. Upon activation by calcium/calmodulin, CaMKII phosphorylates proteins involved in intracellular calcium homeostasis by inducing downstream effects such as an increase in AMPA-receptor single channel conductance, potentiation of L-type voltage dependent calcium channels, and enhanced surface expression of inhibitory GABA_A-receptors. In the pancreas, an increase in intracellular calcium drives secretion of glucagon from alpha cells within the Islets of Langerhans. α-cells contain many …

Evolution Of Xenopus Tropicalis Mc2r: Expression And Activation, Perry Victoria Davis

Electronic Theses and Dissertations

The structure and functional relationship between the melanocortin-2 receptor (MC2R) and adrenocorticotropic hormone (ACTH) is the most complex of the melanocortin gene family. Prior studies had been done on amniote tetrapod MC2Rs (e.g., mammals); this study analyzed the expression and activation of MC2R by an anamniote tetrapod, Xenopus tropicalis (xtMC2R). An immunofluorescence approach, done on the expression of xtMC2R in Chinese Hamster Ovary cells (CHO cells), indicated that the trafficking of xtMC2R to the plasma membrane required co-expression with a tetrapod MRAP1(melanocortin-1 receptor accessory protein). A cAMP-reporter assay was used to show that xtMC2R can activated by human ACTH(1-24, but …

Vegetation Response After Invasive Tamarix Spp. Removal In The Riparian Zone And Semi-Arid Rangeland Ecosystems, Hisham Nagi El Waer

Electronic Theses and Dissertations

Removal of Tamarix spp. (a.k.a. tamarisk, saltcedar, Athel) invasion is often involved in restoration of Western, riparian habitat; however monitoring of vegetation after removal is often neglected and thus opportunity for adaptive management lost. To address this need, I have conducted three and half years of monitoring vegetation response after invasive Tamarix removal in twenty-five sites on the East and Western Colorado, starting fall 2009. I am also comparing six different methodologies: Point intercept, line transect, nearest neighbor, meter-square quadrats, nested Whittaker plots, and densitometer with the objective of developing monitoring protocols that can be used by …

Loops And Their Permutation Groups, Mark Greer

Electronic Theses and Dissertations

This dissertation uses the connections between loops and their associated permutation groups to study certain varieties of loops. We first define a variety of loops generalizing commutative automorphic loops and show this new variety is power associative. We show a correspondence to Bruck loops of odd order and use this correspondence to give structural results for our new variety, which in turn hold for commutative automorphic loops. Next, we study a variety of loops that generalize both Moufang and Steiner loops. We extend on known results for Moufang loops and then extend two different doubling constructions for creating Moufang and …

Host Use And Geographic Variation In Fall Webworms (Hyphantria Cunea), Katrina J. Loewy

Electronic Theses and Dissertations

Host use in herbivores is determined by a variety of ecological drivers, including bottom-up and top-down selective pressures such as host abundance, host plant quality, and parasitism pressure. If the relative importance and strength of interactions among these selective conditions change over an herbivore’s geographic range, local patterns of host use should change in response, evident in differing diet breadths. The fall webworm (Hyphantria cunea) is a widespread, polyphagous moth with two color morphs, red and black-headed. In the eastern United States, fall webworms feed on dozens of plant species and previous research demonstrated that host plant abundance …

Impact Of Rail Transit On The Denver Metro Region: Transportation And Land Use, Sutapa Bhattacharjee

Electronic Theses and Dissertations

Among the reasons behind construction of the light rail system in the 1990s and 2000s and currently the FasTracks lines, in Denver metro region, has been reduction of traffic congestion and consolidation of land use. This research analyzes the success of the rail transit system in achieving the above-mentioned goals.

A temporal and spatial analysis of Vehicle Miles Traveled (VMT) data from 1992 to 2008 on the highways in Denver has been conducted to determine if traffic congestion has reduced after the initial light rail service began in 1994. Temporal analysis provides an insight into the changes in the level …

¿Del Mar Quién Es Dueño? Artisanal Fisheries, Tourism Development, And The Struggles Over Access To Marine Resources In Playa Gigante, Nicaragua, Nikolai Alexander Alvarado

Electronic Theses and Dissertations

In post-revolutionary Nicaragua tourism development has been embraced as a way to inject foreign exchange into an ailing economy. Despite rapid growth of the sector, particularly along Nicaragua's southwestern Pacific coast, little attention has been given to the impacts of this development on local producers. This research focuses on the tourism development taking place in the fishing community of Playa Gigante and its impacts on artisanal fisheries. Additionally, I focus on the struggles over access to marine resources, especially with creation of La Anciana Marine Protected Area (MPA), a marine conservation corridor being pushed forth by the largest resort development …

Thermal And Electrical Transport In Ferromagnetic Metal Thin Films, Azure D. Avery

Electronic Theses and Dissertations

The recent emergence of spin caloritronics has focused considerable attention on the interplay between spin, charge, and temperature gradients in magnetic materials. A reliable and energy efficient method for generating pure spin currents would signify an important step toward future spin-based nano-electronics that may offer lower power consumption and greater processing capabilities. To develop new technology using thermoelectric effects in magnetic thin films, it is essential to understand thermal and electrical transport through these films. One possible source of pure spin currents is the so-called spin Seebeck effect (SSE) in which a thermal gradient (∇T) applied to a ferromagnet is …

X-Band Rapid-Scan Epr, Deborah Gale Mitchell

Electronic Theses and Dissertations

The advantages of rapid-scan EPR relative to CW and pulse techniques for samples with long longitudinal relaxation time T₁ (N_s⁰ defects in diamond, N@C₆₀, and amorphous hydrogenated silicon), heterogeneous samples (crystalline 1:1 α,γ-bisdiphenylene-β-phenylallyl (BDPA):benzene), lossy samples (aqueous nitroxyl radicals), and transient radicals (5-tert-butoxycarbonyl-5-methyl-1-pyrroline-N-oxide (BMPO)-superoxide adduct) were studied.

For samples with long relaxation times, CW (continuous wave) EPR is challenging due to power saturation and distortions from passage effects. In rapid-scan EPR, the field is swept through resonance in a time that is short relative to T₂. In rapid-scan EPR, the magnetic field is …

Isolation And Characterization Of A Full Length Retrotransposon: Cr1, Cassandra Michelle Weason

Electronic Theses and Dissertations

Transposable elements (TE) have been found in all genomes and have clearly had a major impact on genomic evolution. The described research takes advantage of an abundant transposable element present in the genomes of Anseriformes, called Chicken Repeat 1 (CR1). Previous studies in Anseriformes suggest that CR1 is presently active in recent evolutionary time (St. John, 2004). A fully functional CR1 element itself is approximately 4.5kb long (Kajikawa, 1997), where almost all inserts are truncated at the 5' end. Because of this, it has been a challenge to isolate a full length, active element. In this study, two CR1 sequences …

Fresh Squeezed: The Dilemma Of Local Food Production Along Colorado's Front Range Urban Corridor, Amanda Jessie Weaver

Electronic Theses and Dissertations

Today, the Front Range Urban Corridor of Colorado is one example from the urban/agricultural battlefield. The history of food production and urbanization in this area is similar to many regions throughout the western United States. Originally an extraction based economy, Colorado later became agriculturally/pastorally based, and more recently became a service-based, urban economy. On the Front Range Urban Corridor specifically, the urban core of Denver and Boulder developed with rich agricultural lands toward the northeast to Weld County along the northern border of the state. Though a semi-arid region, this agricultural zone produces a volume and variety of food-based crops …

Mitochondrial Glutathione Transport: Implications For Bcl-2 And Neuronal Survival, Heather Marie Wilkins

Electronic Theses and Dissertations

Oxidative stress is a contributing factor to many neurodegenerative diseases. In particular, mitochondria are a key source of oxidative stress due to electron leakage at the level of the electron transport chain. To combat the endogenous production of reactive oxygen and reactive nitrogen species mitochondria are equipped with several redox-cycling systems, such as glutathione (GSH). Mitochondrial GSH has been shown to be a critical reservoir of this antioxidant, where selective depletion of mitochondrial GSH can induce apoptosis in several systems. Many studies have intricately linked Bcl-2 to cellular GSH status and it has been previously shown that Bcl-2 is a …

Seeded Propagation Of Tau Fibrils, Paul David Dinkel

Electronic Theses and Dissertations

In various neurodegenerative diseases, including Alzheimer's disease, progressive supranuclear palsy, Pick's disease, and corticobasal degeneration, the deposition of fibrils composed of misfolded tau protein is observed. Recent evidence suggests that tau fibrils transfer between cells and spread throughout the brain, underscoring the significance of fibril propagation.

Six tau isoforms exist in the adult human brain that can be grouped into 4-repeat (4R) tau and 3-repeat (3R) tau based on the presence or absence of the second of four microtubule binding repeats. We demonstrate in vitro that seeded fibril growth, a prerequisite for the spreading of the tau pathology, is crucially …

Regulation Of Actin Dynamics During Drosophila Germband Extension, Ashley M. Motlong

Electronic Theses and Dissertations

Convergent extension is a process that occurs in the development of a wide variety of organisms, including gastrulation in the Drosophila embryo to begin to lay out the adult body plan. In fly embryos, this is known as germband extension and is mainly driven by cell intercalation or neighbor exchange by planar polarized cell-cell interface contraction to shorten the tissue along the dorsal-ventral axis. In this thesis, I show that interface contraction consists of phases of fast interface shortening and intervals of stable interface size. My data also suggests that regulation of F-actin aggregates at these shrinking interfaces is important …

The Urban Heat Island And Its Influence On Precipitation In Denver, Colorado, Diana Thunen

Electronic Theses and Dissertations

Anthropogenic modification of the climate is an unintended yet serious effect of urbanization and it is happening in every city across the globe in the form of the urban heat island. The purpose of this study was to see if Denver, Colorado exhibits evidence of an urban heat island using meteorological data and if there has been a change in precipitation amounts since the urbanization of the city. It was concluded that Denver, Colorado does have an urban heat island that varies seasonally throughout the year with an average magnitude of 3.57°C during the day and 3.82°C at night. The …