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Three-Dimensional Microstructure-Based Models For Fatigue Crack Nucleation And Fatigue Crack Branching In High Strength Al Alloys, Lin Yang

Theses and Dissertations--Chemical and Materials Engineering

This study is concerned with using numerical three-dimensional microstructure-based models to quantify the multi-site fatigue crack initiation behaviors by simulating the effects of pores in a cast aluminum alloy, and to analyze the mechanism of fatigue crack branching in thick aluminum alloy plates. It has been recently recognized the three-dimensional effects of pores on fatigue crack initiation, which provide opportunity to quantitatively identify the fatigue weak-link density and strength distribution in aluminum alloy. The stress and strain fields around a micro-pore in an A713 aluminum alloy (an elasto-plastic media) under cyclic loading were quantified as a function of pore position …

Lnvestigation Of The Critical Role Of Polymeric Binders For Silicon Negative Electrodes In Lithium-Lon Batteries, Jiagang Xu

Theses and Dissertations--Chemical and Materials Engineering

Silicon is capable of delivering a high theoretical specific capacity of 3579 mAh g^-1, which is about 10 times higher than that of the state-of-the-art graphite-based negative electrodes for lithium-ion batteries (LIBs). However, the poor cycle life of silicon electrodes, caused by the large volumetric strain during cycling, limits the commercialization of silicon electrodes. As one of the essential components, the polymeric binder is critical to the performance and durability of lithium-ion batteries as it keeps the integrity of electrodes, maintains conductive path and must be stable in the electrolyte. The guideline for binder selection of silicon electrodes …

First-Principles Studies Of Structure-Property Relationships: Enabling Design Of Functional Materials, Qunfei Zhou

Theses and Dissertations--Chemical and Materials Engineering

First-principles calculations based on quantum mechanics have been proved to be powerful for accurately regenerating experimental results, uncovering underlying myths of experimental phenomena, and accelerating the design of innovative materials. This work has been motivated by the demand to design next-generation thermionic emitting cathodes and techniques to allow for synthesis of photo-responsive polymers on complex surfaces with controlled thickness and patterns. For Os-coated tungsten thermionic dispenser cathodes, we used first-principles methods to explore the bulk and surface properties of W-Os alloys in order to explain the previously observed experimental phenomena that thermionic emission varies significantly with W-Os alloy composition. Meanwhile, …

Understanding Dna Condensation By Low Generation (G0/G1) And Zwitterionic G4 Pamam Dendrimers, Min An

Theses and Dissertations--Chemistry

Cationic polymers have shown potential as gene delivery vectors due to their ability to condense DNA and protect it from cellular and restriction nucleases. Dendrimers are hyperbranched macromolecules with precisely defined molecular weights and highly symmetric branches stemming from a central core. The nanosize, tunable surface chemistries and ease of surface functionalization has made dendrimers an attractive alternative to conventional linear polymers for DNA delivery applications. The commercially available, cationic dendrimer poly(amidoamine) or PAMAM is the most widely studied dendrimer for use as a gene delivery vector. The aim of this dissertation is to provide an increased understanding of the …

Design, Synthesis And Physicochemical Analysis Of Ruthenium(Ii) Polypyridyl Complexes For Application In Phototherapy And Nucleic Acid Sensing, Erin Melissa Wachter

Theses and Dissertations--Chemistry

Current chemotherapeutics exhibit debilitating side effects as a result of their toxicity to healthy tissues. Reducing these side effects by developing chemotherapeutics with selectivity for cancer cells is an active area of research. Phototherapy is one promising modality for selective treatment, where drug molecules are “turned on” when irradiated with light, reducing damage to healthy tissues by spatially restricting the areas exposed to irradiation. A second approach to improve selectivity is to exploit the differences in cancerous versus healthy cells, such as increased metabolism and/or upregulation of cell surface receptors. Ruthenium(II) polypyridyl complexes are candidates for phototherapy due to their …

Towards Catalytic Oxidative Depolymerization Of Lignin, Justin K. Mobley

Theses and Dissertations--Chemistry

Lignin is one of the most abundant and underutilized biopolymers on earth. Primarily composed on three monolignol units (sinapyl, coniferyl, and p-coumaryl alcohol), lignin is formed through a radical pathway resulting in an assortment of linkages, of which the β-O-4 linkage is the most prevalent (up to 60% in some hardwood species). In planta, lignin plays an important role in water transport and in protecting plants from chemical and biological attack. Traditional attempts to depolymerize lignin have focused on the cleavage of β-O-4 linkages via thermal or reductive routes. However these pathways lead to low-value, unstable product mixtures. Moreover, …

The Development Of Colorimetric Assays To Determine The Identity And Frequency Of Specific Nucleobases In Dna Oligomers, Elizabeth Marie Thomas

Theses and Dissertations--Chemistry

Colorimetric methods combined with color-changing chemical probes are widely used as simple yet effective tools for identifying and quantifying a wide variety of molecules in solution. For nucleic acids (DNA and RNA), perhaps the most commonly used colorimetric probe is potassium permanganate, which can be used to identify single-stranded pyrimidines (thymine and cytosine) in polymers. Unfortunately, permanganate is not an effective probe for identifying purines (adenine and guanine), especially in the presence of the more reactive pyrimidines. Therefore, robust methods for discriminating between the purines remain elusive, thereby creating a barrier toward developing more complex colorimetric applications. In this dissertation, …

Using Conventional And In Situ Transmission Electron Microscopy Techniques To Understand Nanoscale Crystallography, Bethany M. Hudak

Theses and Dissertations--Chemistry

Transmission electron microscopy (TEM) is a powerful tool for studying solidstate crystalline systems. With the advances in aberration correction, monochromation, and in situ capabilities, these microscopes are now more useful for addressing fundamental materials chemistry problems than ever before. This dissertation will illustrate the ways in which I have been using high-resolution imaging and in situ heating in the TEM during my Ph.D. research to investigate unique solid state chemistry questions.

This dissertation will focus on four unique crystal systems: thermoelectric skutterudite crystals, vapor-liquid-solid (VLS) grown nanowires, and hafnium dioxide nanorods. Although these systems are very different from one another, …

Implementation Of Hiv Drug Resistance Testing In Kenya, Horacio Duarte, Ingrid Beck, James Munyao, Molly Levine, Catherine Kiptinness, Bhavna Chohan, Samah Sakr, Michael Chung, Lisa Frenkel

Internal Medicine, East Africa

Background: Testing for HIV drug resistance prior to antiretroviral therapy (ART) is standard of care in the United States but is rarely performed in Africa due to its high cost. The prevalence of HIV drug resistance is increasing in resource-limited settings (RLS). An affordable and feasible strategy is needed in RLS to identify individuals with drug resistance and prescribe effective ART. Our group developed a low-cost oligonucleotide ligation assay (OLA) that detects mutations conferring resistance. Little data exists on implementing HIV drug resistance testing in RLS. Here, we describe the implementation of OLA in one laboratory in Kenya and discuss …

A Framing Analysis Of The News Coverage Of Science, Sam Babin

Graduate Research Theses & Dissertations

This study investigated how the field of science is framed by the United States news media. One full year's (i.e., 2014) worth of science news from four newspapers (i.e., two prestige newspapers, The New York Times and The Washington Post, and two high-circulation newspapers, The Philadelphia Inquirer and the Minneapolis Star Tribune) was gathered and content analyzed in an attempt to determine the distribution of positive, negative, and neutral/ambiguous science news and to compare these distributions in different types of newspapers. Results of a content analysis of 425 (N=425) science news articles indicated that there were no statistically significant differences …

A Matter Of Size : Examining Representation And Responsiveness In State Legislatures And City Councils, Benjamin Bingle

Graduate Research Theses & Dissertations

Representation and legislative responsiveness are vital components of a functional democracy. In representative democracies legislators are elected to stand for, and act on behalf of, the citizenry. Although fundamental to the effectiveness of America's political system, both representation and responsiveness can be influenced by external factors such as legislature and constituency size. What follows is an exploration of representation and responsiveness in American states and cities through the lens of legislature and constituency size. All 50 states are included in the analyses as well as cities with populations of at least 100,000 people as of the 2010 decennial census. In …

A Qualitative Exploration Of Masculinity Among Community College Males, Marianne Fontes

Graduate Research Theses & Dissertations

The purposes of this grounded theory study were to explore how traditional-aged community college males experience masculinity and to examine how they engage with community college support systems. Eleven diverse participants engaged in three interviews each in which they were asked to reflect on their definitions of masculinity as well as their activities on and off campus. Open, axial, and selective coding methods were employed, and a new theory emerged. The new theory suggests that the participants' hesitation to make concrete educational decisions is related to their resistance to manhood. Findings implicate the need to engage faculty in the support …

A Study Of Boundary Spanning : Pastors' Perceptions Of Their Role As Boundary Spanners In The Elca, Rachel Carrie Berry

Graduate Research Theses & Dissertations

This project examined pastors' roles as boundary spanners regarding information received from the synodical expression in the Evangelical Lutheran Church in America (ELCA). Twenty-six pastors from the Northern Illinois Synod of the ELCA were interviewed and transcriptions were analyzed using the constant comparative method of inductive analysis. Two research questions were posed to explore boundary spanning from a pastor's perspective. The results echoed the literature on boundary spanning responsibilities and challenges, expanding the boundary spanning research field into the realm of religious organizations and leadership. Implications of this research and further areas of study are provided.

Analysis Of An Integrated Readout Layer For Use In A Highly Granular Analog Hadron Calorimeter, Heath J. Lefevre

Graduate Research Theses & Dissertations

Analysis of an Integrated Readout Layer for use in a Highly Granular Analog Hadron Calorimeter The International Linear Collider requires high granularity calorimetry to reach the performance benchmarks necessary for the physics it intends to measure. The leading option for achieving this granularity in the hadron calorimeter are 3 cm x 3 cm scintillator tiles mated to Silicon Photomultipliers. This thesis reviews the design, assembly and performance of an integrated readout layer (IRL) in the form of a 9x11 scintillator megatile directly coupled to silicon photomultipliers (SiPM). The IRL performance in terms of response and efficiency and optical crosstalk is …

Analysis Of Metal Cutting Process Using Abrasive Water Jet, Saumil Patel

Graduate Research Theses & Dissertations

Abrasive water jet (AWJ) cutting is one of the most developing technologies for metal cutting process. It is superior in processing very difficult to cut material which are highly sensitive to temperature variation compared to other machining processes. Although cutting capability in terms of surface roughness, depth of jet penetration and kerf quality are the major obstructions limiting its pertinence, more study is required to understand the cutting process and cutting mechanism, and to optimize cutting performance. This research is to conduct comparative study of effecting parameters such as abrasive mass flow rate, standoff distance of nozzle from workpiece, water …

Assessing The Compatibility Of Filth Fly Pesticides With Filth Fly Biological Control Parasitoids Through Toxicological And Behavioral Assays, Edwin R. Burgess Iv

Graduate Research Theses & Dissertations

Filth flies are a significant pest at animal production facilities, leading to economic losses that include reductions in animal weight and milk production. Pesticides and biological control organisms are two important components of Integrated Pest Management (IPM) programs against filth flies. Biological control against filth flies frequently involves augmentative releases of pupal parasitoids. The compatibility of pesticides and the parasitoids Spalangia endius Walker and Urolepis rufipes Ashmead was examined using one of the most common filth flies, the house fly, Musca domestica L. The specific goals were to 1) assess the effects of the active ingredients of several house fly …

Automatic Machine Learning-Guided Methods For 3d Synapse Quantification In Confocal Neuron Images, Jonathan William Sanders

Graduate Research Theses & Dissertations

This thesis explores computational methods for automatically detecting and quantifying synapses in complex 3D neuronal images. The resulting approach is a novel combination of traditional image processing, machine learning algorithms, and multi-channel comparison methods designed to overcome the unique challenges posed by these images. The methods investigated combine the strengths of each of these components in order to produce an overall method that is capable of fully detecting the synapses in large 3D confocal neuron images with minimal interaction. Human annotation of 3D neuron images remains prohibitively difficult and subjective, and computational analysis tools are highly desirable in the expanding …

Behavioral And Chemical Ecology Of A Male-Produced Substrate-Borne Pheromone In Urolepis Rufipes, Tyler Wittman

Graduate Research Theses & Dissertations

Use of chemical signals for sexual communication is found in a large proportion of insects. Pheromones may also act as honest signals of the sender's health and resources. Most research has focused on female-produced pheromones used for attracting mates over large distances or on the role pheromones play in species and mate recognition. Little work has been done exploring male produced pheromones, and how pheromones may be involved in mate assessment. Here I show that females of the parasitic wasp Urolepis rufipes discriminate for some aspects of male quality through the male's substrate-borne pheromones. In two-choice trials females spent more …

Benefits And Emotions Present In Offline And Online Communities : A Taxonomic Analysis, Maureen J. Wieland

Graduate Research Theses & Dissertations

This interpretive qualitative study was established to explore the differences and similarities between the benefits gained through online and offline community membership as well as the emotions that are commonly present during conversations between community members. Through an online survey, responses were collected in order to create a typology of benefits as well as emotions discussed within each type of community (either offline of online). The researchers discovered a variety of differences as well as similarities that expand the current research on the field of communication community scholarship.

Beyond Adat : Transwomen Boldly And Innovatively Navigating Their Communities In Central Java, Indonesia, Laurence Anthonie Tumpag

Graduate Research Theses & Dissertations

The purpose of the following thesis was to investigate how transwomen (otherwise known locally as waria) of Indonesia, navigate their gender identities within their specific locales in central Java. Particularly, I focus how my respondents do this within Yogyakarta, which I define as a cultural hub where local custom and law known as adat predominates and two other field sites located in the periphery of Yogyakarta. Due to the importance of local culture in the general central Javanese region, I hypothesized adat serves to help create space and belonging for my transwomen respondents within each locale. While previous research has …

"All That Weight Is Gonna Crush Your Chest" : Examining The Relationship Between Mentoring, Academic Success, And Self-Efficacy In Latino Male Community College Students, Sadya Khan

Graduate Research Theses & Dissertations

The purpose of this study was to explore the relationship between mentoring, academic success, and self-efficacy for Latino male students at a community college. Additionally, the study explored the significance of mentor matching with respect to race/ethnicity upon academic success and self-efficacy. The study used a quantitative approach to assess the predictive power of mentoring on the academic success of Latino male students, defined by GPA, as well as academic self-efficacy beliefs. The sample consisted of 123 Latino male students from a community college in Illinois. The College Student Mentoring Scale (CSMS) and the SELF-A scales were adapted into a …

"Anonymous" And Frame Construction In Social Media, Justin Yates

Graduate Research Theses & Dissertations

Social movement organizations operate and communicate using new mediums, such as the use of social media. Anonymous is a non-hierarchical online activist group with unidentified members that engages in exploiting technology toward politically motivated goals. This study examined how a group without formal structure or identifiable members frames its activities as "righteous." Specifically, this study examined the rhetoric of a non-hierarchical online activist group with unidentified members and how it frames its activities as just. This study explored the challenges in maintaining and creating righteous rhetoric for a group with online, non-hierarchical, and unidentified members. Using social movement framing theory …

21st Century Assessment : An Examination Of The Relationship Among Computer-Adaptive Homework, Self-Regulation Strategies And Student Scores On Computer-Adaptive Assessment, Darla Bennett-Smailis

Graduate Research Theses & Dissertations

This study investigated the relationship between fifth grade students' computer-adaptive assessment performance (TAP) scores when a computer-adaptive eLearning platform was assigned for homework along with a self-regulated learning (SRL) treatment intervention. The adaptive learning theoretical model and the TAP conceptual framework supported the rationale for the utilization of the digital computer-adaptive systems of learning and assessing. In addition, the study examined the predictive ability of the Measures Strategy Learning Questionnaire (MSLQ) a self-reporting survey on MAP assessment performance scores. The theory of SRL provided the foundation for the strategies implemented in this study. The participants consisted of three fifth-grade classes …

A 5200 Year Record Of Precipitation Changes In West-Central Guatemala Inferred From Lacustrine Carbonate-Based Stable Isotopes, Jacob Ryan Feller

Graduate Research Theses & Dissertations

Guatemala is a drought-sensitive country that experiences varying amounts of precipitation in response to Atlantic and Pacific Ocean influences. A 5.5 m, finely-laminated sediment core from Lake San Francisco in the Huehuetenango province was collected in order to reconstruct precipitation changes over the last ~5,200 years at a decadal-scale resolution. An age-depth model was developed based on 7 radiocarbon ages of charcoal as well as ²¹⁰Pb dating of surface sediments. Authigenic calcite preserved in the sediment record provides an archive of lake-water isotopic variability in response to climate driven changes in hydrologic balance. Modern surface water isotope data taken from …

A Bioinformatic Study On The Evolution Of Bamboos And Other Graminoid Poales, William P. Wysocki

Graduate Research Theses & Dissertations

For the past decade, next-generation sequencing (NGS) has been used to undertake genomics-scale projects in molecular biology. This method of sequencing involves randomly fragmenting a sample of nucleic acid and randomly generating millions of short reads. The large number of reads moves the assembly and other analyses to be performed by computer algorithms. As well as sequencing full chromosomes, full RNA extracts can be sequenced to determine levels of gene expression and exon boundaries. In this study, NGS is used to examine the evolution of bamboos (Bambusoideae), which are a subfamily of grasses (Poaceae). Bamboos are divided into two main …

A Bird For The Ages : National Concupiscence In The Work Of John Milton, Doug Depalma

Graduate Research Theses & Dissertations

This thesis examines the religious concept of concupiscence in the work of John Milton from Comus to Samson Agonistes with a special focus on Milton's political tracts and histories. I suggest in readings of Comus, Eikonoklastes, and The Ready and Easy Way that we find Milton interacting with concupiscence in a different way as his experiences in the British Commonwealth advanced. In the Comus we find Milton willing to forgive the concupiscent Lady, yet in Eikonoklastes and The Ready and Easy Way, Milton describes the "thralls" that dominate his later prose work in a keenly concupiscent manner such that the …

A Case Study Exploring Saudi Special Education Teachers' Perceptions Toward The Use Of Mobile Technology For Teaching Purposes, Adel Ibrahim Qahmash

Graduate Research Theses & Dissertations

Within the last few decades special education has benefited from the vast revolution of technologies. These technologies have contributed in facilitating cognitive development as well as learning processes for students with disabilities. One of these emerging technologies is the tablet device and its applications. Due to increasing demands to integrate the latest technology into educational settings, previous studies have looked at the potential of adopting tablet devices and their applications as instruction technology tools in special education classrooms. This case study sought to explore male special education teachers' perceptions toward using tablet devices for teaching purposes in Saudi Arabia. The …

A Case Study Examining Perceptions Of Female Saudi University Students Regarding The Use Of Asynchronous Online Discussion Boards, Hanadi M. Bokhari

Graduate Research Theses & Dissertations

This phenomenological case study explored undergraduate Saudi female students' perceptions of using asynchronous online discussion boards (AODB) as a learning tool. In addition, the current study explored factors that helped students learn skills, specifically their language learning. The current study sought to add to knowledge about how asynchronous online discussion forums can benefit undergraduate Saudi female students' development of learning. Data were collected during the Spring 2016 semester through focus group and individual interviews with ten undergraduate students in an online course as well as their narrative reflections and the researcher reflections and notes. Participants were undergraduate Saudi female students …

A Covert War At Sea : Piracy And Political Economy In Malaya, 1824-1874, Scott C. Abel

Graduate Research Theses & Dissertations

Piracy around the Malay Peninsula during the 19th century was extraordinarily prevalent and resulted in the death and loss of liberty for an untold number of people. This essay examines the connections between the piracy of this era and the political economies of the Straits Settlements and the Malay states in the region. Malays pirates often had the support of local rulers who required the goods and slaves brought back by pirates to reinforce their own political and socio-economic positions. The piratical system supported by the rulers was a component of the overall Malay economic system known as kerajaan economics, …

Analysis And Extension Of A Flexible Stochastic Differential Equation Model To Estimate The Amount Of Nanoconjugates Required To Initiate Remission Of Cancer, Nicholas Joseph Skradski

Graduate Research Theses & Dissertations

This thesis examines a definition of reliability that can be applied to targeted nanoconjugate chemotherapy in cancer and also simulates a stochastic differential equation model to attempt to predict the estimated time until remission when using targeted nanoconjugate chemotherapy utilizing a recursive algorithm to attempt to find the dose of nanoconjugates that will result in remission by an expected time T. Areas of research that can be used to obtain model parameter values are cited and values for the dose of nanoconjugates, given as number of nanoconjugates, are predicted for several different model parameters. The model is then extended to …