Digital Commons Network^™

Imaging And Molecular Analysis Of Murine Dissecting Abdominal Aortic Aneurysms, Evan H. Phillips

Open Access Dissertations

An abdominal aortic aneurysm (AAA) is a localized expansion of the aorta. This disease can sometimes be caused by aortic dissections where the layers of the vessel wall separate, creating a false channel for blood to flow. AAAs are life-threatening because weakening of the vessel wall can lead to aortic rupture and internal bleeding. Unfortunately, most AAAs are associated with no signs or symptoms. Early diagnosis is therefore often not possible and recommendation for life-saving surgery could be delayed. As a result, the mortality rate for patients who experience aortic rupture is up to 90%. Currently we have an incomplete …

Conversion Of Municipal Organic Waste Into Higher Value Acids And Sugars, Raymond M. Redcorn

Open Access Dissertations

Food waste and sewage sludge were studied for their ability to be up-convert to higher value products under three different scenarios; food waste conversion to lactic acid, glycogen quantification in waste activated sludge from municipal wastewater treatment facilities performing enhanced biological phosphorous removal, and finally the conversion of either food waste or sewage sludge to rhamnose biofilm via acid phase digestion.

In studying the conversion of food waste to lactic acid, three factors where opportunities exist for process improvement; freezing of samples during storage, discontinuous pH control, and holdover of fermentation broth between fermentations, were studied. Freezing samples prior to …

Contested “Chineseness” In Transnational Narratives: Works By Post-1979 Chinese/American Immigrant Writers Ha Jin And Geling Yan, Ping Qiu

Open Access Dissertations

This dissertation aims to claim immigrant literature as an essential part of Chinese American studies. It responds to the challenge by considering how “Chineseness” is negotiated, challenged, and transformed in the literary texts produced by both writers. I argue that “Chineseness” as presented by post-1979 immigrant writers Ha Jin and Geling Yan is a transnational process of defamiliarization, radicalization, and transformation. In their work, new immigrant writers are self-consciously and strategically positioning themselves as both insider and outsider. They engage in, negotiate, and challenge the troubling term “Chineseness” as defined in either U.S-centric/Eurocentric or Sinocentric points of view. For writers, …

Low Temperature Simulations Framework For Quantum Dots And Point Contacts., Harshad Sahasrabudhe

Open Access Dissertations

Quantum computing is becoming increasingly important due to its potential in solving complex optimization problems such as protein folding, and the ability to model correlated electronic systems. Designing of semiconductor based quantum computers is challenging due to the vast number of parameters that need to be optimized from fabrication to their operation. Simulations of these devices could help with the design process. A computational modeling framework is presented that can model quantum point contacts and quantum dots, which are the building blocks of semiconductor based quantum computers. Care was taken to minimize the number of parameters, and use only those …

Spectral And Directional Control Of Thermal Emission With Nanophotonics, Enas S. Sakr

Open Access Dissertations

Thermal emission is a ubiquitous phenomenon required in many applications, including thermophotovoltaics (TPV), selective solar absorption, and infrared spectroscopy. Making it selective can greatly improve application performance. Here, selectivity is achieved using engineered photonic structures. Two specific design scenarios are discussed for different applications. The first scenario considers angular and spectral selectivity for TPV heat-to-electricity conversion. The second scenario excludes emission towards specific directions, with potential applications in daytime radiative cooling and sensitive IR detectors. In both scenarios, optical modeling is performed using rigorous coupled wave analysis, finite-difference time domain simulations, plus Kirchhoffs law of thermal radiation. In the first …

Urban Atmospheric Water Vapor And Its Stable Isotopologues, Olivia E. Salmon

Open Access Dissertations

Water vapor (H2Ov) is known to be a key agent in global scale processes, including: atmospheric circulation, weather, radiative forcing, and energy transfer. Anthropogenic modification of atmospheric H2Ov, and the processes it influences are not as thoroughly studied on the urban or regional scale, in comparison. Airborne measurements made aboard the Purdue University Airborne Laboratory for Atmospheric Research (ALAR) investigated a series of science questions tied to atmospheric H2Ov concentrations in Indianapolis, IN, and the near megacity-sized urban area connecting the Washingon, D.C.-Baltimore, MD area.

The first study described herein focuses on the intermittent urban H2Ov excess signal that was …

Efficient Neuromorphic Computing Enabled By Spin-Transfer Torque: Devices, Circuits And Systems, Abhronil Sengupta

Open Access Dissertations

Present day computers expend orders of magnitude more computational resources to perform various cognitive and perception related tasks that humans routinely perform everyday. This has recently resulted in a seismic shift in the field of computation where research efforts are being directed to develop a neurocomputer that attempts to mimic the human brain by nanoelectronic components and thereby harness its efficiency in recognition problems. Bridging the gap between neuroscience and nanoelectronics, this thesis demonstrates the encoding of biological neural and synaptic functionalities in the underlying physics of electron spin. Description of various spin-transfer torque mechanisms that can be potentially utilized …

A Quantitative Study Of Faculty Retention And Promotion In Engineering Across Gender, Matilde L. Sanchez-Pena

Open Access Dissertations

The retention and promotion of a diverse engineering faculty body play a primary role in the advancement of the field. Failure to retain engineering faculty has significant economic implications for institutions. Additionally, the availability of role models and potential mentors for women and other minorities is paramount for the continuing diversification of the field. Prior research has documented additional challenges faced by women faculty in engineering when compared to men; such evidence has resulted in significant attempts to attenuate such disparities among faculty at all ranks. From the institutional perspective, examining retention and promotion times across gender would help to …

Spectroscopy Of Ultracold Lithium-Rubidium Molecules, Ian Stevenson

Open Access Dissertations

I present spectroscopic data on ultracold lithium-rubidium molecules in a dual species magneto-optical-trap in order to find suitable intermediate states to transfer population to the rotational, vibrational and electronic ground state via a stimulated Raman process. First, I improved the accuracy of the energetic location of the ground state by two orders of magnitude using photoassociation as a spectroscopic tool to measure the energy of bound states relative to the scattering continuum. Second, we studied the d 3Π-D 1Π and A 1Σ+ -b 3Π0+ excited electronic manifolds with a combination of resonantly-enhancedmulti-photon-ionization and depletion spectroscopy finding suitable singlet-triplet mixed states …

Iii-V And 2d Devices: From Mosfets To Steep-Slope Transistors, Mengwei Si

Open Access Dissertations

With silicon CMOS technology approaching the scaling limit, alternating channel materials and novel device structures have been extensively studied and attracted a lot of attention in solid-state device research. In this dissertation, solid-state electron devices for post-Si CMOS applications are explored including both new materials such as III-V and 2D materials and new device structures such as tunneling field-effect transistors and negative capacitance field-effect transistors. Multiple critical challenges in applying such new materials and new device structures are addressed and the key achievements in this dissertation are summarized as follows: 1) Development of fabrication process technology for ultra-scaled planar and …

A Study Of Techniques And Mechanisms Of Vagus Nerve Stimulation For Treatment Of Inflammation, Jesse P. Somann

Open Access Dissertations

Vagus nerve stimulation (VNS) has been on the forefront of inflammatory disorder research for the better part of the last three decades and has yielded many promising results. There remains, however, much debate about the actual biological mechanisms of such treatments, as well as, questions about inconsistencies in methods used in many research efforts.

In this work, I identify shortcomings in past VNS methods and submit new developments and findings that can progress the research community towards more selective and relevant VNS research and treatments. In Aim 1, I present the most recent advancements in the capabilities of our fully …

Electrophysiological And Spatial Orientation Ability Differences In Expert And Novice Aircraft Pilots, Karthik Sukumar

Open Access Dissertations

Exploring differences between experts and novices by observing task-specific performance has been an important area of research in several domains. This study examined differences in expert and novice aircraft pilots based on their cortical activity and spatial orientation ability. Twenty-eight aircraft pilots (eight experts, 20 novices) performed 23 in-flight sequences inside a flight simulator while their cortical activity was recorded using an electroencephalographic (EEG) device. Thirty-two aircraft pilots (11 experts, 21 novices) attempted a 30-question multiple-choice spatial orientation ability test. Outcomes of the study revealed significant differences in cortical activity between expert and novice groups. Novice pilots projected higher mental …

Assessing Novel Bioelectric Effects Of Nanosecond Pulsed Electric Fields On Cell Stimulation, Proliferation And Microorganism Inactivation, Ram Anand Vadlamani

Open Access Dissertations

Bioelectrics is the application of electric fields to cells in a conducting media, treating the cell as a circuit comprising resistors and capacitors (membranes and intracellular fluids respectively). Recent advancements in construction of nanosecond pulse generators allow for construction of low cost devices capable of generating nanosecond pulsed electric fields (nsPEFs). These fields are capable of forming pores on the extra and intra cellular membranes, while also affecting intracellular organelles, DNA and the nucleus. With the first generation of nano-signalling devices set to enter the medical field for treatments ranging from carcinomas to regenerative therapy, the intent of this study …

Polymer Solution Rheology And Polymer Synthesis For Enhanced Oil Recovery, Anna Veronica Walter

Open Access Dissertations

Enhanced Oil Recovery (EOR) is used to access the oil within oil basins that remains after traditional recovery methods are deployed. In alkali-surfactant-polymer EOR, aqueous solutions containing surfactants and high molecular weight polymers are injected into oil basins. The most common polymer used in polymer EOR is partially hydrolyzed polyacrylamide (HPAM), a copolymer of polyacrylamide and polyacrylic acid, and in aqueous solutions, HPAM is a polyelectrolyte. The presence of salts in the oil basin and in water used to make industrial injection solutions can alter the interactions of these anionic charges. By knowing the rheological behavior of polymer solutions containing …

Non-Suicidal Self-Injury In First-Year College Students: The Testing Of A Nonlinear Integrated Model, Natasha Pryde Trujillo

Open Access Dissertations

Non-suicidal self-injury (NSSI) is an increasing concern among college students (Whitlock, Muehlenkamp, & Eckenrode, 2008). First-year college students, who are in the midst of transitioning to the college environment, are often at increased risk for problematic behaviors or maladaptive coping as they adjust to the varied changes that take place during this crucial developmental phase (Chickering & Reisser, 1993, Fromme, Corbin, & Krause, 2008). First-year college students may be at particular risk for NSSI engagement because of the developmental, interpersonal, and intrapersonal demands that accompany the transition to college. Further, first-year students who have experienced aversive life events connected to …

Induced Superconductivity In Two Dimensional Electron Gas System, Zhong Wan

Open Access Dissertations

Recently, interest in superconductor-semiconductor interfaces was renewed by the search for non-Abelian states. One of the possible platform is proximity induce superconductivity into an 1D semiconductor system with strong spin orbit (SO) interaction, such system is predicted to support Majorana excitation. Another candidate is superconductivity coupled to the edge of fractional quantum Hall state, in such system, higher order of non-Abelian statistics is predicted. With such non-Abelian states, topological quantum computing can be realized. In this thesis, I will discuss the approach made by us to investigate such system.

The thesis will begin with a brief review of superconducting proximity …

Effects Of Schisandrin B On Rod Photoreceptors In The Pde6c Larval Retina, Prahatha Venkatraman

Open Access Dissertations

Current Rapid prototyping tools although reduce development time, they still have several restrictions such as print volume and print times. Through this thesis, two prototyping kits are proposed, a rod connector based, user controlled computational support system that re-purposes surface models and transforms them into structurally scaffolded constructs with movable joints; and a planar connector based system that implements movable joints to create functional prototypes. The rod based system enables users to interactively personalize scaffolded structures by re-purposing existing surface mesh models; analyze scaffolded constructs in-situ for better structurality, add movable joints to increase functionality, and attach personalized appearances to …

Modulating Wettability Of Layered Materials By Controlling Headgroup Dynamics And Alkyl Chain Conformations, Terry Angelo Villarreal

Open Access Dissertations

Evolution to the next generation of organic photovoltaics and computer processors requires the capability to pattern organic and inorganic materials consistently at interfaces with feature sizes as small as 5-7 nm. A particular challenge is to generate interfaces that display chemical patterns consisting of two or more very different constituents at such scales. Biology routinely orders orthogonal chemical patterns at this scale, as is observed in the structure of the cellular membrane. Phospholipids have also been observed to form repeating striped phases on layered materials, e.g. graphene, molybdenum disulfide (MoS2), and highly oriented pyrolytic graphite (HOPG).

Research performed in the …

Catalytic Conversion Of Light Hydrocarbons To Chemicals And Fuels, Han-Ting Tseng

Open Access Dissertations

The recent surge in shale gas production throughout the United States has led to increased interest in hydrocarbon upgrading such as C—H bond activation and light hydrocarbons conversion to fuels. Methane and other light alkanes in natural gas can be potentially converted into light olefins, which can be further utilized as basic building block for valuable chemicals or upgraded to long-chain hydrocarbons used as fuels.

In the first work, kinetic study on Mn/Na2WO4/SiO2 catalyst for oxidative coupling of methane (OCM) into ethane and ethylene were performed with varying Mn (0-2 wt%) and W (0-3.1 wt%) loadings. When the W loading …

Modeling Electronic Transport In Metal Interconnects, Daniel Valencia

Open Access Dissertations

The improvements in the density of integrated circuits and device performance have been achieved through a long journey of device downscaling and increase in chip size. The tremendous push of the industry to aggressively scale devices has increased parasitic effects generated by an increase in the resistivity of the wire metallization which negatively affects the chip performance. Therefore, a careful design of interconnects is essential to reduce these parasitic effects. This work presents the first study where a fully atomistic basis has been used to describe realistic copper interconnects as used in the industry to identify the effects on resistivity. …

Prompt D0 Meson Nuclear Modification Factor And Azimuthal Anisotropy In Heavy Ion Collisions With Cms, Jian Sun

Open Access Dissertations

The primary goal of heavy ion physics is to study the properties of the Quark Gluon Plasma (QGP), a state of matter comprising deconfined quarks and gluons. Heavy quarks (charm and bottom) are effective probes to study the properties of the QGP produced in heavy ion collisions. Because of their large masses, heavy quarks are primarily produced via initial hard scatterings in heavy ion collisions. They are expected to interact with the QGP differently than light quarks and gluons. The comparison between the nuclear modification factors of heavy flavor and light hadrons can provide insights into the expected flavor dependence …

Environmental Life Cycle Impact And Complexity Assessment Of Rare Earth Production, Ehsan Vahidi Movassagh

Open Access Dissertations

Rare Earth Elements (REEs) find applications in clean energy technology, including wind turbines, electric vehicles, and high efficiency lighting therefore, as the renewable energy market expands, demand of REEs is anticipated to rise. However, it is well known that the production of REEs carries large environmental burden and as a result, reducing environmental footprints of REE production becomes critical. The first action towards reducing the environmental degradation during production of REEs is the thorough examination of the energy requirements and environmental emissions. To date, Life Cycle Assessment (LCA) is the standard methodology to evaluate the environmental performance of a system, …

Program Transformation For Secure And Sustainable Web Applications, Weihang Wang

Open Access Dissertations

Web advertising is a multi-billion-dollar industry. As a primary source of income for many Internet companies, web advertising (ads) has a profound impact on the security and sustainability of today’s web ecosystem. Web advertising, however, is extremely complex and highly vulnerable to attacks. In fact, attackers using the web advertising system as a channel to spread malware has become some of today’s largest web-based attacks. To protect users from malicious advertising, we develop a memory randomization system, PAD, that effectively prevents malicious advertising (malvertising) attacks exploiting zero-day vulnerabilities.

To reduce the risk of malicious ads and remove unwanted ads, recent …

Materials Design With Molecular Dynamics: Novel Properties In Martensitic Alloys Through Free Energy Landscape Engineering, Samuel Temple Reeve

Open Access Dissertations

Novel properties in martensitic alloys are predicted using molecular dynamics (MD) simulations, the uncertainty from input models in MD is explored and quantified, and new data infrastructure for MD is developed.

The possible regimes of material properties are extended through free energy landscape engineering (FELE), where coherent, epitaxial integration of two materials at the nanoscale can result in metamaterials with fundamentally different behavior. Free energy as a function of strain is calculated using MD simulations and analytically combined to predict potential new properties for a Ni 63% - Al 37% martensitic alloy combined with B2 NiAl, shown to be an …

Analytical Methods For Structured Matrix Computations, Xin Ye

Open Access Dissertations

The design of fast algorithms is not only about achieving faster speeds but also about retaining the ability to control the error and numerical stability. This is crucial to the reliability of computed numerical solutions. This dissertation studies topics related to structured matrix computations with an emphasis on their numerical analysis aspects and algorithms. The methods discussed here are all based on rich analytical results that are mathematically justified. In chapter 2, we present a series of comprehensive error analyses to an analytical matrix compression method and it serves as a theoretical explanation of the proxy point method. These results …

Tuning Thermal Transport In Thin Films, Yuqiang Zeng

Open Access Dissertations

Decades of research have enabled new understanding of thermal transport at the nanoscale. Leveraging this new understanding to tune heat conduction in thin films (TFs) is of significant interest for both fundamental and applications. This work explores tuning thermal conduction in TFs by structuring, strain engineering, and annealing. Specifically, three approaches are interrogated: 1) nanostructuring to achieve significant in-plane thermal conduction anisotropy in TFs; 2) strain engineering of thermal conductivity (k) of a basic structure in flexible electronics, Au-on-polyimide films, and a representative 2D material, graphene; and 3) high temperature annealing of reduced graphene oxide (RGO) films to enhance k. …

Characterization Of The Human Dead-Box Rna Helicase Ddx5, Zheng Xing

Open Access Dissertations

Gene expression in eukaryotes is highly complex. The central player in gene expression is the messenger RNA (mRNA). After transcription, the mRNA is bound by numerous RNA binding proteins to form a messenger ribonucleoprotein complex (mRNP) that dictates the function and fate of the messengers. Proper mRNP formation is critical for gene expression. DEAD-box proteins are the largest class of RNA helicases that play fundamental roles in RNA and RNP structure remodeling. However, the precise biological roles of the vast majority of them are not well described. To fill in this gap, my research focused on the characterization of the …

Mapping Underground Utilities With Complex Spatial Configurations Using Ground Penetrating Radar, Chenxi Yuan

Open Access Dissertations

Records of the locations, measures, and properties of over 20 million mileage underground utility networks in the US are incomplete, inaccurate, and many times unavailable. This lack of information of underground pipes and cables is a primary reason for over six million of utility interruptions every year that cause injuries, fatalities, property damages, and environmental pollutions, amounting to over eight billions of dollars in loss. It also poses a critical challenge to maintaining and upgrading the ageing underground infrastructure with a D+ score according to the American Society of Civil Engineers’ Report Card. There is a critical need for accurately …

Anisotropic Flow And Fiber Orientation Analysis Of Preimpregnated Platelet Molding Compounds, Drew E. Sommer

Open Access Dissertations

Process modeling of prepreg platelet molded composites (PPMC) is of interest for enabling optimized design of PPMC structures. The platelet mesoscale and the part scale are on the same order, which introduces several modeling challenges including the treatment of variability. The fiber length and concentration results in anisotropic rheological behavior during processing. Current commercial flow simulation tools do not include anisotropic constitutive models and utilize second order orientation tensor methods for the fiber orientation which requires significant interpretation to inform a structural model. A flow and fiber orientation model to predict the final orientation state in molded parts should treat …

Study Of The Nano-Structured Materials For Energy Conversion And Storage Devices, Fan Yang

Open Access Dissertations

Two major parts consist of my work in this dissertation which are the study of the materials for fuel cell catalysts and lithium-ion battery cathodes,

In the first part, FeOF is studied as a new generation cathode material due to its high specific capacity. To overcome its weaknesses which are low conductivity and poor cycle life, graphene sheets are introduced into FeOF to form a FeOF/graphene hybrid. It has been found that introducing graphene sheets can greatly improve the reversibility of FeOF and improve the specific capacity and rate performance by increasing its electronic conductivity. The cycle life and columbic …