University of Texas at Austin

Permanent URI for this collection

Welcome to The University of Texas at Austin, the largest institution of The University of Texas System. The University of Texas at Austin is a major research university home to more than 48,000 students, 2,700 faculty and 17,000 staff members. This collection contains the theses and dissertations produced at the University of Texas.


Recent Submissions

Now showing 1 - 20 of 20102
  • Item
    Doctoral thesis recital (clarinet) chamber
    (2017-04-20) Sarmiento, Luz; Not available
    Divertissement pour hautbois, clarinette et basson / Jean Françaix -- Trio for clarinet, violin and piano / Aram Khachaturian -- Divertissement pour trio d'anches, op. 107 / Louis Durey -- Contrasts : for violin, clarinet and piano / Béla Bartók -- Encore & remarks. (Ruby Chou, violin ; Antonio Cevallos, violin ; Bethany Lawrence, oboe ; Adam Drake, bassoon).
  • Item
    The effects of carbohydrate and protein supplementation on signaling pathways regulating protein turnover and muscle mass following chronic resistance training
    (2016-12) Huang, Lu, M. S. in Kinesiology; Farrar, Roger P.; Stone, Audrey
    Skeletal muscle is important for physical activity and regulation of metabolism. Increase or maintenance of muscle mass is pursued by different populations ranging from athletes to people suffering from severe muscular diseases causing muscle atrophy/wasting. In this study, four animal groups were generated: sedentary group (No supplements or exercise) (SED); resistance training (RE) and whey supplements (WP); RE and combo (Carbohydrate and whey) supplements (CP); RE and placebo (DI water) (PLA). Flexor hallucis longus (FHL) muscles were collected after 8 weeks of training. Expression of several key proteins controlling muscle mass and protein turnover were measured in order to compare how different combinations affect muscle growth. It was found that resistance training induced reductions in myostatin protein expression compared with sedentary controls (p<0.05) and that MuRF was elevated in the CP group compared with sedentary group (p<0.05). We conclude that resistance training may upregulate protein synthesis through suppressing myostatin and that resistance training may increase muscle protein breakdown.
  • Item
    Travel demand forecasting models : development, application, and comparison of aggregate and activity-based approaches for the Austin, Texas Region
    (2007-08) Lemp, Jason David; Kockelman, Kara
    A great disparity exists between the direction of travel demand forecasting by researchers, and the travel demand models used by transportation planning organizations. Activity-based models of travel demand have become increasingly studied in the academic realm and vast developments have been made over the past many years. However, travel demand forecasting tools used in practice by transportation planning organizations, and the like, have lagged behind, relying on the tried and true traditional, aggregate 4-step approach to travel demand modeling. Many reasons for such a paradox are possible, but one cause is that there is little work that directly relates these two approaches from a model performance perspective. The aim of this research is provide just such a comparison. A traditional, aggregate model and an activity-based microsimulation model of travel demand are developed in parallel using the same data for Austin, Texas. The models are applied for both a base scenario and several policy scenarios to test model performance and sensitivity to inputs. Aggregate outputs indicate that there are many key differences between the ways these two models perform, and some evidence suggests that the activity-based model may boast a greater sensitivity to inputs. Additional outputs are produced to demonstrate the level of segmentation that can be attained in the generated outputs using microsimulation methods. The analysis performed in this research serves as a comparison of these two competing approaches to travel demand forecasting and offers some insight into the benefits of the activity-based approach from a practical standpoint.
  • Item
    Risk reduction in the manufacturing of interference fits for laminated rotating cores of electrical machines
    (2007-08) Lewis, Michael Christopher; Nichols, Steven Parks, 1950-
    Electric drive systems are becoming increasingly popular in all areas from personal automobiles to naval ships. Electric motors and generators are being pushed to higher power and energy densities. The increase in power and energy results in increased rotor speeds, placing more importance on the interference fit between the rotor core and its shaft. Traditional manufacturing methods for rotor cores, such as thermal fits or keying, typically fall short of the interference fit requirements of the rotor or present undesirable manufacturing conditions. The more common methods used for motors are also inherently risky operations that are irreversible. This thesis examines how a hydraulic expansion fit provides a solution to the traditional manufacturing problems of interference fits for laminated rotating cores of electrical machines. Hydraulic expansion fits have been implemented successfully in the coupling industry for several years; however, their application to rotating cores of electrical machines is a novel approach that is beneficial in many respects. The hydraulic expansion fit is a robust manufacturing technique capable of large interference fit pressures. It can be controlled and monitored during installation, thereby reducing manufacturing risks. Additionally, the rotor can be removed after installation using the hydraulic expansion methods. The paper outlines traditional methods and details the design issues associated with a hydraulic expansion fit for a laminated motor core. In addition, the installation method is implemented on a prototype induction motor rotor core and documented measurements from an installation are presented.
  • Item
    Performance of pile foundations for fixed-type platforms during Hurricane Katrina
    (2007-08) Lee, Yonghoon, 1977-; Gilbert, Robert B. (Robert Bruce), 1965-
    According to increasing demand for oil, numerous offshore oil producing structures have been constructed in the Gulf of Mexico. A jacket-type platform is one of the oil producing structures, which has deck structures, jacket frames and foundation structures. For foundation structures, driven steel pipe piles are typically used. From Hurricane Katrina, no known collapses of offshore oil jacket platforms occurred because of foundation failure even though foundations were subjected to environmental loads greater than their design capacity. Conservatism in pile design significantly impacts on the cost of the jacket platforms. This research intends to study the bias between the predicted and the observed capacity of pile foundations. To investigate the bias, a plastic model of pile system collapse is adapted and extended. The model is useful to account for an interaction between axial and lateral capacities of individual piles and also to consider interactions between multiple piles. Analyses of foundation capacity for 8-leg and 6-leg jacket platforms using the plastic model result in an interaction collapse diagram for the foundation. Compared with the loads from Katrina the plastic model indicates that the pile systems should have collapsed under the loads. Finally, sensitivity studies regarding pile geometry, loading, soil properties and pile-soil interaction are conducted to identify and study the potential sources of bias in the pile design. The potential sources of the bias include (1) uncertainty from soil sampling and field/lab testing, (2) the contributions of mudline elements to vertical resistance of pile system, (3) rate of loading, (4) reverse end bearing, (5) hardening of sands at pile tips and (6) set-up effect. When the effects of these potential sources are considered to increase axial and lateral capacity of individual piles, the interaction diagram for the two example platforms expands beyond the estimated environmental loads from Hurricane Katrina and therefore the survival of the two platforms from the hurricane may be explained.
  • Item
    Microstructure and processing effects on stress and reliability for through-silicon vias (TSVs) in 3D integrated circuits
    (2015-05) Jiang, Tengfei; Ho, Paul S.; Huang, Rui; Im, Jang-Hi; Shi, Li; Zhao, Jie-Hua
    Copper (Cu) Through-silicon via (TSV) is a key enabling element that provides the vertical connection between stacked dies in three-dimensional (3D) integration. The thermal expansion mismatch between Cu and Si induces complex stresses in and around the TSV structures, which can degrade the performance and reliability of 3DICs and are key concerns for technology development. In this dissertation, the effects of Cu microstructure and processing conditions on the stress characteristics and reliability of the TSV structure are studied. First, the stress characteristics of Cu TSV structures are investigated using the substrate curvature method. The substrate curvature measurement was supplemented by microstructure and finite element analyses (FEA) to investigate the mechanisms for the linear and nonlinear stress-temperature behaviors observed for the TSV structure. Implications of the near surface stress on carrier mobility change and device keep-out zone (KOZ) are discussed. Second, via extrusion, an important yield and reliability issue for 3D integration, is analyzed. Synchrotron x-ray microdiffraction technique was introduced for direct measurements of local stress and material behaviors in and around the TSV. Local plasticity near the top of the via was observed which provided direct experimental evidence to support the plasticity mechanism of via extrusion. An analytical model and FEA were used to analyze via extrusion based on local plasticity. Next, the effect of Cu microstructure effect on the thermomechanical behaviors of TSVs is investigated. The contribution from grain boundary and interfacial diffusion on via extrusion and the relaxation mechanisms are discussed. Potential approaches to minimize via extrusion are proposed. Finally, the stress characteristics of 3D die stack structures are studied using synchrotron x-ray microdiffraction. High resolution stress mappings were performed and verified by finite element analysis (FEA). FEA was further developed to estimate the stress effect on device mobility changes and the warpage of the integrated structure.
  • Item
    Battle between influenza A virus and a newly identified ZAPL antiviral activity
    (2015-05) Liu, Chien-Hung; Krug, Robert M.; Huibregtse, Jon M; Russell, Rick; Sullivan, Christopher S; Upton, Jason
    Influenza A virus infection causes a highly contagious annual respiratory disease in humans as well as periodic pandemics with higher mortality rates. The Krug laboratory has shown that one of the major ways that the influenza virus NS1 protein counteracts host antiviral responses is to bind the 30 kDa subunit of the cleavage and polyadenylation specificity factor (CPSF30). As a consequence, 3’ end processing of cellular pre-mRNAis is inhibited, leading to reduced production of cellular mRNAs, including interferon mRNAs. I showed that NS1-CPSF30 complexes contain an array of cellular proteins. I purified the NS1-CPSF30 complexes from virus infected cells by affinity selection of CPSF30 and the NS1 protein. I identified the associated cellular proteins by mass spectrometry. Two cellular RNA helicases, DDX21 and DHX30, were identified. SiRNA knockdown of either RNA helicase enhanced virus replication, indicating that DDX21 and DHX30 inhibit influenza A virus replication. Further study demonstrated that DDX21 RNA helicase inhibits viral RNA synthesis, and is countered by the NS1 protein. The cellular ZAPL antiviral protein was also identified in the NS1-CPSF30 complexes. Previous studies have shown that ZAPL antiviral activity is mediated by its N-terminal zinc-fingers, which targets viral mRNA of several viruses for degradation. Little is known about the antiviral role of the ZAPL C-terminal PARP domain. Here I discovered the antiviral role of ZAPL C-terminal PARP domain against influenza A virus. I showed that the ZAPL PARP domain targets the viral polymerase PA and PB2 proteins. These two viral polymerases are poly(ADP-ribosylated), presumably by other PARP protein(s). The ZAPL-associated, poly(ADP-ribosylated) PA and PB2 are then ubiquitinated and proteasomally degraded. This ZAPL antiviral activity is counteracted by the binding of polymerase PB1 protein to the WWE region adjacent to the PARP domain, and causes PA and PB2 to dissociate from ZAPL and thus escape degradation. Because PB1 displaces PA and PB2 and protects them from ZAPL-mediated degradation, endogenous ZAPL only moderately inhibits influenza A virus replication (20-30-fold), as determined by siRNA knockdown experiment. These results suggest that influenza A virus has partially won the battle against the newly identified ZAPL antiviral activity.
  • Item
    Development of a measure of the process of informed decision-making about prenatal genetic screening in expectant women
    (2015-05) Kaur, Mandeep, Ph. D.; Rew, Lynn; Walker, Lorraine; Brown, Adama; Champion, Jane; Bonevac, Daniel
    Existing literature shows low levels of informed decision-making regarding prenatal genetic screening (IDM-PGS) in expectant women. In an attempt to increase autonomy and promote more ethical healthcare, this study aims to develop an instrument to measure of an expectant woman’s informed decision-making regarding prenatal genetic screening. The instrument was developed based on review of the literature. Thorough psychometric testing including content validity analysis, cognitive interviewing, and readability analysis, as well as exploratory administration for criterion-related validity, construct validity, factor analysis and reliability was performed. The population of interest is women who are pregnant or may become pregnant, between the ages of 18 and 34, with no known genetic predispositions. A sample of eight women was recruited for the cognitive interviews, 433 for the exploratory administration and 111 participants in the two-week retest. Results show the instrument is a valid and reliable measure of IDM-PGS. Content validity was achieved after two rounds of expert review and feedback. Cognitive interviews showed high understanding of items in the instrument. Readability analysis resulted in a high grade level, but was justified in the highly technological nature of the information. Criterion-related validity showed a statistically significant ability for the instrument to predict participant action based on results from the IDM-PGS. Construct validity was validated by exploratory factor analysis and known group analysis. Factor analysis resulted in factor loading in line with the developed conceptual model. Known group analysis showed individuals with medical training were significantly more likely to measure high on the IDM-PGS. Reliability was confirmed. The highly valid and reliable nature of this instrument shows its general applicability to various settings. Thus, healthcare providers can apply this instrument in clinical settings to measure the IDM-PGS in expectant women. The instrument is adaptable and should be adapted in diverse populations. In addition to future implementation and study, the results of this study indicate policy implications as well. Policy level changes and implementation of this instrument could increase IDM-PGS for all expectant couples.
  • Item
    Characterizing the petrophysical properties of shallow marine environments and their potential as methane hydrate reservoirs
    (2015-05) Nole, Michael Anthony; Daigle, Hugh; Mohanty, Kishore
    In shallow marine sedimentary environments, characterization of sediment petrophysical and thermodynamic properties is imperative for understanding the subsurface transport of fluids and their chemical constituents. This work first presents an objective method of scanning electron microscope image analysis that directly quantifies microporosity in clay-rich, fine-grained sediments typical of the shallow marine subsurface. The method is powerful because it is fast, easy, and provides a direct microporosity estimation technique to augment or replace experimental data. When used appropriately, the method can be implemented on microporous sediments and sedimentary rock in general. With an understanding of how microporosity manifests in shallow marine sediments, the impact of small pore sizes on methane hydrate solubility is then examined for core samples taken from 3 sites in the Nankai Trough offshore Japan, an area that has been heavily surveyed in recent years for its potential to host economically recoverable deposits of methane hydrate for use as a natural gas resource. Small pores in fine-grained shaley intervals are shown to significantly increase the aqueous solubility of methane in pore water relative to surrounding coarser-grained sediment strata, which can have broad implications for methane hydrate formation, including lack of formation in the clayey intervals and strong diffusive fluxes of methane into coarser sediment layers. Finally, an existing methane hydrate reservoir simulator is modified to model methane hydrate accumulations in marine environments with heterogeneous layered sediments. The impact of pore size on solubility is included in the model along with steady state microbial methanogenesis and diffusion of salt in the pore water. The simulator is then used to successfully model methane hydrate accumulations in 1D and 2D at Walker Ridge Site 313 in the Gulf of Mexico, where well logs and seismic surveys throughout the region abound. This work is an important step in building a general 3D methane hydrate reservoir simulator for shallow marine environments around the globe.
  • Item
    Exile within borders : a study of complinace with the international regime to proetct internally displaced persons
    (2015-05) Cardona-Fox, Gabriel; Weaver, Catherine, 1971-; Hutchings, Robert L; Stolp, Chandler W; Elkins, Zachary S; Betts, Alexander
    The UN Guiding Principles for the Protection of Internally Displaced Persons (GP), introduced before the UN General Assembly in 1998, are the cornerstone of the international regime for the protection of internally displaced persons (IDPs). Much has been written about their unusual and unlikely development, yet very little is known about their effectiveness in altering state behavior towards their displaced populations. This dissertation takes a systematic and global look at patterns of commitment and compliance with the IDP regime and identifies forces that have driven states to comply with them. This dissertation addresses: (1) when and why countries voluntarily bind their sovereignty by instituting the GP into domestic law, and (2) if countries that have instituted the GP into law in fact comply with them. I tackle these questions using mixed methods. First, I present a large-n statistical analysis of all documented cases of displacement in the past twenty years to test the merits of competing theories of norm diffusion. Then I trace the evolution of Colombia’s response to internal displacement from denial of the crisis to deep compliance with the IDP regime. Both the first and second stages of the dissertation find that, above all, regional factors are key to the diffusion of IDP norms. This is evidenced by the clear pattern of regional clustering of commitment found in the statistical analysis and by the significant influence exerted by Latin American regional politics found in Colombia’s evolving response to its displacement crisis. This study should be of particular interest to policy practitioners and activists involved in addressing the problem of internal displacement and protecting the rights of IDPs.
  • Item
    Coupling photovoltaics and grid-scale energy storage : performance and sitability
    (2015-05) Stoll, Brady Leigh; Deinert, Mark; Baldick, Ross; Edgar, Thomas; Howell, John; Shi, Li; Webber, Michael
    The Fifth Assessment of the International Panel on Climate Change has called for a four fold increase in the use of low-carbon sources of electricity to help stabilize climate change by mid century. Many people look to solar power systems to help reduce carbon intensity, but cost and variability have been significant obstacles to their widespread deployment. However, the cost of photovoltaics has dropped significantly in recent years, and grid-scale energy storage technologies are available to allow for production of dispatchable electricity from photovoltaics. In particular, compressed-air energy storage is both low-cost and can be built in a wide variety of geologies as well as above ground. I show that coupling large-scale photovoltaic arrays and grid-scale storage allows for dispatchable electricity production at costs that are comparable to other low carbon electricity sources. I examine four load curves: base-load generation, on-peak generation, and averaged load curves for the Electric Reliability Council of Texas (ERCOT) and PJM Independent System Operators. I found that on-peak and ERCOT loads typically required the lowest amount of storage, up to 2000 MWh [subscript e] less than that for base-load generation. However, in some regions, and for some storage amounts, baseload output actually provided the lowest cost of electricity. I also show that such coupled systems could provide base-load electricity for ≤ 0.08/kWh [subscript e] on more than 40% of global land surface, with a capacity factor equivalent to that of the US nuclear fleet. Importantly, this is below the projected cost of electricity from new nuclear power systems. While cost is a major factor, also of importance is where systems of photovoltaics and grid-scale storage would provide the most benefit. Locations expected to provide energy at the lowest cost do not necessarily correspond to load and population centers, where the electricity is most needed. I use multi-criteria decision analysis techniques to perform a global study of the optimal locations for siting these coupled systems to maximize their social benefit. I found that the most ideal locations are generally located in Africa, Iraq, and southeast Asia, as these locations have both high irradiance levels as well as expanding populations and low grid connectivity.
  • Item
    Intelligent nanoscale hydrogels for the oral delivery of hydrophobic therapeutics
    (2015-05) Puranik, Amey Shreekant; Peppas, Nicholas A., 1948-; Contreras , Lydia; Sanchez , Isaac; Stachowiak , Jeanne; Yeh, Hsin-Chih
    In this work, novel oral drug delivery formulations were developed for the administration of hydrophobic therapeutics, with the overarching goal of improving their solubility and permeability in the gastrointestinal tract. We have developed a set of four nanoscale hydrogels, formulated by incorporating different hydrophobic monomer components, and screen them for optimal physicochemical properties, drug loading and release, and ability to modulate intestinal permeability and P-glycoprotein related drug efflux. Here, we employ an evolved paradigm of in vitro tests to gauge the potential of these novel nanoscale carriers for the specific application of improving oral solubility and permeability of poorly water-soluble and less permeable therapeutics. All the responsive nanoscale hydrogels are capable of undergoing a transition in size in response to change in pH. We capitalize on the interplay between the incorporated hydrophobic monomer choices and screened resulting physicochemical properties to determine an optimal nanoscale formulation. Depending upon the selection of the hydrophobic monomer, the sizes of the nanoparticles vary widely from 120 nm to about 500 nm at pH 7.4. We also evaluate cytocompatibility of the nanoparticle formulations in vitro in the presence of an intestinal epithelial cell mode to find that all formulations are reasonably cytocompatible. Subsequently, we discuss some of the key findings and results of characterization studies that validate the success of achieving desired molecular architecture and physicochemical properties of the formulation. We then confirm the capacity of the nanocarrier to be able to load and release hydrophobic therapeutics in gastrointestinally relevant environments. Further, the ability of the nanocarriers to transport the hydrophobic therapeutic doxorubicin is determined by evaluating permeability of doxorubicin with intestinal epithelial cell monolayers. Furthermore, demonstrate functional abilities desired from a therapeutically relevant, oral delivery system is tested. Specifically, to overcome problems associated with P-glycoprotein related efflux and reduced drug permeability in the small intestine, we evaluated the ability of the nanoformulation to achieve therapeutic success in relevant and characteristic in vitro cancer cell lines. Finally, we make concluding remarks on the ability of the nanoparticles to function as improved formulations of hydrophobic therapeutics capable of performing and achieving the end-goal of delivering hydrophobic therapeutics orally for the treatment of cancer.
  • Item
    The design of halopyridine-based activity-based probes and mechanistic studies of succinylarginine dihydrolase
    (2015-05) Er, Joyce Ai Vee; Fast, Walter L.; Whitman, Christian P; Lee, Seongmin; Liu, Hung-wen; Iverson, Brent L
    An important design aspect of covalent inactivators is the balance between reactivity, or reversibility of reaction, with nucleophiles in solution and reactivity with nucleophiles at a targeted protein site. We previously identified 4-halopyridines as fragment-sized covalent inactivators of the enzyme dimethylarginine dimethylaminohydrolase (DDAH). Binding of these inactivators stabilizes the more reactive pyridinium form while the less reactive neutral form predominates in solution. Herein, we demonstrate that simple 2- and 4-chloropyridines are extensible as covalent modifiers of other proteins within the E. coli proteome, that halogen positioning can impart target selectivity, and that the targets include a subset of Cys-containing purine binding sites. As one specific example, inosine-5’-monophosphate dehydrogenase is shown to be labeled by a 2-chloropyridine at a catalytic Cys305 residue within the inosine binding site. These results indicate that a simple 2- or 4-chloropyridine core can have wider application as a warhead for incorporation into covalent inhibitors of proteins with diverse function. N-succinylarginine dihydrolase (AstB), like DDAH and arginine deiminase, is part of the amidinotransferase (AT) superfamily. AstB shows conservation of the catalytic residues and carries out a similar type of reaction as other hydrolases in the AT superfamily. Herein, we report the mechanistic studies of AstB and provide insights into how this enzyme performs its dihydrolase activity instead of a “mono” hydrolase reaction, which is more prevalent in this superfamily.
  • Item
    Production and analysis of traditional and non-traditional radioxenon isotopes
    (2015-05) Klingberg, Franziska Julietta; Biegalski, Steven R.; Biegalski, Kendra M.F.; Haas, Derek A.; Landsberger, Sheldon; Saey, Paul R.J.; Schneider, Erich
    Radioxenon releases can originate from fission during nuclear detonations (atmospheric, underground, and underwater), research and commercial reactors, and medical isotope production facilities. Their impacts on atmospheric sample analysis have to be well understood to distinguish between clandestine activities and commercial operations. The global community relies on atmospheric monitoring of radioxenon, among other technologies, to monitor emissions from underground nuclear tests. The Comprehensive Nuclear Test-Ban Treaty (CTBT) incorporates radioxenon monitoring within International Monitoring System (IMS) with a focus on the traditional radioxenon isotopes ¹³¹ [superscript m] Xe, ¹³³ [superscript m] Xe, ¹³³Xe, and ¹³⁵Xe. To strengthen environmental monitoring for radioxenon, a method to produce high purity radioxenon samples was developed. The University of Texas’ 1.1 MW TRIGA research reactor was used for radioactive sample production via neutron activation. The reactor facilities include a pneumatic system for precise timing when irradiating samples. In order to use the pneumatic facilities, gaseous samples have been encapsulated in quartz to fit into the polyethylene vials designed for the system; this method also minimizes leakage, and avoids contaminants from entering the sample. Enriched, stable, isotopically pure xenon gas was irradiated with neutrons in order to activate it to radioxenon isotopes, yielding a complete set of radioxenon isotopes including non-traditional – ¹²⁵Xe, ¹²⁷Xe, ¹²⁹ [superscript m] Xe, ¹³⁵ [superscript m] Xe and ¹³⁷Xe – and traditional radioxenon isotopes. The samples were analyzed with a β--γ coincidence detector; the measurement of the non-traditional isotopes in an ARSA-style β--γ coincidence detector were the first of their kind. Measurements of the ¹³¹ [superscript m] Xe, ¹³³ [superscript m] Xe, ¹³³Xe, and ¹³⁵Xe were used to determine the β--γ coincidence efficiency of the detector and the metastable versus ground state production ratio after irradiation of ¹³³Xe and ¹³⁵Xe. Regions of interest (ROI) were defined for ¹²⁵Xe, ¹²⁷Xe, ¹²⁹ [superscript m] Xe, and ¹³⁷Xe to estimate their interference with the traditional isotopes. The newly defined ROIs aid in distinguishing between radioxenon signatures originating from fission and those mainly originating from neutron activation, thus advancing atmospheric sample analysis in the context of CTBT verification.
  • Item
    The role of surface reactions and solid electrolyte interphase in silicon electrodes for lithium-ion batteries
    (2015-05) Schroder, Kjell William; Stevenson, Keith J.; Webb, Lauren J.; Korgel, Brian A; Milliron, Delia J; Henkelman, Graeme; Goodenough, John B
    In order to utilize renewable energy sources to avoid adverse climate change caused by fossil fuel use, economical, efficient, and long-cycling energy storage means are needed for grid power applications and electric vehicles. Lithium-ion batteries (LIBs) are promising electrochemical energy storage devices for these applications, but capacity, cycle life, and device energy density need to be improved to meet these challenges. Silicon, as a lithium alloy, promises high gravimetric and volumetric charge capacities as a negative electrode in the next generation of LIBs. However silicon has a lithiation potential outside the window of stability of common non-aqueous liquid electrolytes (e.g., lithium hexafluorophosphate in ethylene carbonate and diethyl carbonate mixtures). Consequently, parasitic side reactions occur during continued lithiation and delithiation (cycling) of silicon. However, these side reactions (including electro-reduction and thermal decomposition) form insoluble products that make a solid electrolyte interphase (SEI), passivating an electrode’s surface. Cycling silicon electrodes can entail incomplete passivation (via unstable SEI species) and newly exposed surfaces (due to mechanical wear) and thus continued side reactions that lead to thermal runaway, capacity loss, and cell failure. By understanding interfacial electrode chemistry, it is hoped that novel design suggestions for addressing these problems will be uncovered. Model silicon electrodes studied by X-ray Photoelectron Spectroscopy (XPS), and Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) were used to explore the effects of surface layer conductivity and electrolyte additives on SEI composition and structure. Anhydrous and anoxic techniques showed better reproducibility and accuracy in characterizing the SEI over previous studies of composite electrodes exposed to ambient conditions. By comparing silicon oxide and etched silicon surfaces, electrode conductivity was studied as well as how the co-solvent additive fluoroethylene carbonate (FEC) affects the SEI. Both the etched silicon surface and FEC produced SEI species like lithium fluoride that improved stability by resisting further electro-reduction. However, questions about the oxidative stability of some SEI species were raised (namely lithium oxide), suggesting a more stable artificial SEI could be manufactured compared to those formed during naive device operation.
  • Item
    Consumers' attitudes towards product placement in three media : a cross-cultural study of the U.S. and Korea
    (2007-05) Lee, Taejun, 1977-; Sung, Yongjun
    No previous study has yet examined attitude toward product placement in the U.S. and Korea together. To fill the gap in a body of product placement literature, the current study was conducted to examine any differences and similarities on consumers' attitude toward product placement in three different media: film, television, and music. Further, a previously unexamined element in the literature, genre, was incorporated. The results suggest that both American and Korean consumers have generally positive attitudes toward product placement in films and television. However, with regard to music, both groups express uncertain opinions towards the product placement practice. In addition, specific product types and media genres are considered especially appropriate or inappropriate for the practice. Implications for practitioners and public policy makers are provided.
  • Item
    Demand side load control in residential buildings with HVAC controller for demand response
    (2015-05) Yoon, Ji Hoon; Baldick, Ross; Novoselac, Atila; Arapostathis, Aristotle; Liedl, Petra G; Kwasinski, Alexis
    Demand Response (DR) is a key factor to increase the efficiency of the power grid and has the potential to facilitate supply-demand balance. Demand side load control can contribute to reduce electricity consumption through DR programs. Especially, Heating, Ventilating and Air Conditioning (HVAC) load is one of the major contributors to peak loads. In the United States, HVAC systems are the largest consumers of electrical energy and a major contributor to peak demand. In this research, the Dynamic Demand Response Controller (DDRC) is proposed to reduce peak load as well as saves electricity cost while maintaining reasonable thermal comfort by controlling HVAC system. To reduce both peak load and energy cost, DDRC controls the set-point temperature in a thermostat depending on real-time price of electricity. Residential buildings are modeled with various internal loads using building energy modeling tools. The weather data in different climate zones are used to demonstrate that DDRC decreases peak loads and brings economic benefit in various locations. In addition, two different types of electricity wholesale markets are used to generate DR signals. To assess the performance of DDRC, the control algorithms are improved to consider the characteristics of building envelopes and HVAC equipment. Also, DDRC is designed to be deployed in various areas with different electricity wholesale markets. The indoor thermal comfort on temperature and humidity are considered based on ASHRAE standard 55. Finally, DDRC is developed to a hardware using embedded system. The hardware of DDRC is based on Advanced RISC Microcontroller (ARM) processor and senses both indoor and outdoor environment with Internet connection capability for DR. In addition, user friendly Graphic User Interface (GUI) is generated to control DDRC.
  • Item
    Probing the effects of backbone ester substitution on self-assembly and biological activity of short depsipeptides
    (2015-05) Eckes, Kevin Michael; Suggs, Laura J.; Iverson, Brent; Ren, Pengyu; Shear, Jason; Stachowiak, Jeanne
    Hydrogel materials composed of self-assembled amphiphilic peptides show great promise for use as injectable, highly biocompatible biomaterials for tissue regeneration applications. However, peptides do not easily degrade naturally without the presence of proteolytic enzymes, which recognize specific peptide sequences and are specific to certain cell and tissue types. In this dissertation, we evaluate the self-assembly and bioactivity of backbone ester-containing depsipeptides that are degradable by alkaline or acid hydrolysis as the basis for hydrogel materials, in order to circumvent any inflammation and immunogenicity caused by peptide materials that persist in the body. The self-assembly of depsipeptides has not been widely explored, thus we first studied the self-assembly of a simple N-protected dipeptide and its depsipeptide analogue both experimentally and computationally to evaluate the relative importance of hydrogen-bonding interactions mediated by the single amide bond in driving and stabilizing self-assembly. We determined that amide-amide hydrogen bonding interactions are not strictly necessary for self-assembly. We next hypothesized that amide-mediated hydrogen bonding may not be necessary for mediating peptide-protein interactions. To test this hypothesis in a simple, well-characterized system, we synthesized a depsipeptide analogue of a peptide containing the Arg-Asp-Gly (RGD) sequence, which is found in extracellular matrix proteins and known to promote cell adhesion through binding of cell surface integrin proteins. As before, the RGD analogue was capable of self-assembly leading to hydrogel formation. However, we found that the depsipeptide did not possess an affinity for the protein high enough to influence cell behavior in the same manner as the peptide. These results suggest that backbone amide hydrogen bonding is crucial in mediating RGD-integrin interaction affinity. Based on these results and other studies in the literature suggesting that amide-to-ester mutations have a complex and context-dependent effect on peptide-protein interactions, further development of depsipeptide-based materials should focus on exploring alternate N-protecting groups that are likely to have higher biocompatibility while driving robust self-assembly, exploring in more depth the ability to tune degradation rates and mechanical properties using alternate side chain chemistries, and exploiting depsipeptide self-assembly and degradability for non-viral gene delivery.
  • Item
    Doctoral thesis recital (trombone) lecture
    (2017-04-19) Sankey, Evan; Not available
    Lecture: The upper register of the trombone : existing methods and suggestions for improvement -- Excerpts from: Bolero / Maurice Ravel ; Deux danses. Danse sacrée / Jean-Michel Defaye ; Concerto pour trombone et orchestra. II., Nocturne / Henri Tomasi ; Fantasy for trombone and orchestra / Paul Creston ; Also sprach Zarathustra / Richard Strauss ; Symphony no. 3, op. 97. IV., Feierlich / Robert Schumann ; Symphonie fantastique. IV., Marche au supplice / Hector Berlioz.
  • Item
    Doctoral thesis recital (guitar) lecture
    (2017-04-19) Milovanov, Alexander; Not available
    Lecture and performance: Ten etudes for guitar / Giulio Regondi.
This site provides access to materials, licensed or otherwise, for which the copyright is held by owners other than the University of Texas at Austin. Unless assigned to another entity, the copyright in a thesis or dissertation is owned by its author. Use of these materials and resources is restricted by applicable license agreement and copyright law.