Doctor of Philosophy, Case Western Reserve University, 2024, Physics

Semiconductor devices have become an inherent part of our life and are being used in broad range of technologies such as telecommunication, health, lighting, computers and so on. The development of new materials can be accelerated by predictive first-principles calculations of their properties. On the other hand, even with the accumulated scientific knowledge, certain cost, performance and stability issues still persist. In this dissertation, we apply many-body perturbation theory, namely density functional theory (DFT) and quasiparticle self-consistent GW method (QSGW ), to investigate various materials to advance our knowledge in order to eliminate these persisting problems. After providing the theoretical background, we introduce a cut-and-paste scheme to improve the cost-efficiency of the computationally expensive QSGW calculations. In the essence of this scheme, the self-energy is calculated in the vicinity of the defect which requires a rather minimal unit cell. Simultaneously, the defect structure is calculated in a large supercell at the DFT level. As the final step of the scheme, the two results are “merged” to obtain the electronic band structure in the GW -level accuracy. This way, a point defect can be calculated at the GW -level in a supercell large enough to approximate the dilute limit without losing accuracy. The efficiency of this scheme is showcased for a well known antisite defect AsGa in GaAs crystal. Then, we investigate the optical properties of ZnGeN2 in comparison to well-studied GaN and draw attention to the similarities between these materials in terms of their exciton properties and dielectric function. To investigate the mechanism behind the excitons, we decompose the dielectric function into individual band-to-band optical transitions and argue the relation between these contributions and the energy band differences between the relevant conduction and valence bands. Finally, we investigate a II-IV-N2/III-N alloy, namely MgSiN2-GaN as a candi (open full item for complete abstract)

Committee: Walter Lambrecht (Advisor); Shulei Zhang (Committee Member); Kathleen Kash (Committee Member); Roger French (Committee Member) Subjects: Condensed Matter Physics

Doctor of Philosophy, Case Western Reserve University, 2024, Management

In a world grappling with energy poverty, Africa, especially sub-Saharan Africa, faces profound challenges marked by extreme disparities in energy access. Study 1 advocates for the integration of environmental, social, and governance (ESG) principles as a linchpin for alleviating energy poverty by enhancing reliability and affordability and catalyzing low greenhouse gas (GHG) emissions. It emphasizes the urgent need for a shared language among diverse stakeholders to pursue sustainable energy solutions. Study 2 introduces "coopetition" as a groundbreaking strategy across 54 African nations, combining cooperation and competition to drive energy access while reducing greenhouse gas emissions. Challenging prevailing assumptions about the direct influence of financial development through official development assistance and foreign direct investment, the study highlights the pivotal role of transparent regulations and risk mitigation in fostering sustainable energy solutions. Study 3 further explores the interplay of coopetition and climate policy, introducing a model encompassing the Sustainable Development Index, GDP Growth Rate, and Corruption Perception Index. Coopetition emerges as an independent variable, moderated by climate policy, revealing a nuanced understanding of collaborative efforts' impact on energy poverty and emissions. The tripartite exploration underscores the call for a harmonious symphony of ESG principles, coopetition strategies, and tailored collaborations to illuminate the path toward a sustainable and equitable energy future for Africa.

Committee: Christopher Laszlo (Advisor) Subjects: Climate Change; Energy; Environmental Justice; Environmental Law; Environmental Management; Management

MDES, University of Cincinnati, 2023, Design, Architecture, Art and Planning: Design

Environmental concerns continue to increase daily, leaving many wondering what they might do to minimize their impact on the planet. As a result, it is critical to educate the general public, particularly secondary school students, about embracing more sustainable practices. As these students will become our society's future designers and consumers, it is crucial to equip them with the necessary tools and knowledge to foster a more responsible future for our environment and climate. This starts with smart, responsible design. As the Ellen MacArthur Foundation says, “Waste and pollution does not exist by accident, it is the result of design decisions” (2021). To adequately equip our future decision-makers, it is crucial to educate them on the importance of Circular Design (CD), a way of designing products that fit into the Circular Economy (CE). The CE is an environmentally sustainable “system of closed loops, where nothing becomes waste, and everything has value” (Foundation, 2021). However, CD is rarely integrated into the curricula of public schools, with sustainable education predominantly offered within Montessori environments or at the university level. This usually means that public school students are left out of this important equation. There is little evidence to support that CD is currently widely taught in many schooling environments. This research study aims to understand how we might best educate Gen Z public school students on the foundations of CD. Additionally, it seeks to determine whether an elevated level of content regarding CD can influence these students to become more conscientious about their role in the world and how they can apply these practices to their daily lives. Through three phases of applied research methods, this study explores how we might dress this gap. The first phase relies on a literature review to create CD learning tools for students and teachers, which were then refined with Montessori educators in (open full item for complete abstract)

Committee: Brooke Brandewie M.S. (Committee Member); Ashley Kubley M.F.A. (Committee Chair) Subjects: Environmental Education

Doctor of Philosophy (PhD), Ohio University, 2023, Instructional Technology (Education)

This study sought to provide an examination of the instructional design strategies used in an entrepreneurship clinic (EC) and determine their influence on the post-graduation outcomes of its alumni. The conceptual lens for the study comprised Merrill's (2002) first principles of instruction and Lent et al.'s (1994) social cognitive career theory (SCCT). Merrill's first principles provided a standardized set of instructional principles to examine the instructional strategies used within clinic and the SCCT examined the influence of these strategies on building the necessary competencies for participants to pursue entrepreneurship after graduation. The case for this study was the EC organized by the Kwame Nkrumah University of Science and Technology (KNUST). This case is bounded geographically on the KNUST campus in Ghana. This case is situated contextually in the larger issue of graduate unemployment and how entrepreneurship education and training can be used to address it. Data sources for the study were interviews and documents (Patton, 2015). The data was analyzed a priori through the lenses of Merrill's (2002) first principles of instruction and Lent et al.'s (1994) SCCT constructs--self-efficacy beliefs, outcome expectations, and personal goals. Also, the data was analyzed inductively to discover emergent patterns, categories, and themes to arrive at the findings (Patton, 2015). There were three key takeaways from the study. The first is the importance of an entrepreneurship ecosystem to fill the gaps in entrepreneurship knowledge. The second is the temporal nature of entrepreneurship education and the importance of life-long learning. The third is the personality of the participant is important in pursuing entrepreneurship. The study has implication for scholarship in that it extends research by identifying the possibility of building self-efficacy through observation of role-models or mentors. An implication for practice is to provide a (open full item for complete abstract)

Committee: Arthur Hughes (Committee Member); David Moore (Committee Chair); Dwan Robinson (Committee Member); Greg Kessler (Committee Member) Subjects: Education; Education Policy; Educational Technology; Educational Theory; Entrepreneurship; Instructional Design

Master of Arts, The Ohio State University, 2022, Bioethics

This project is a critique of the concept of consensus and its relation to secular moral reasoning. Proponents of public deliberation argue that achieving consensus is crucial to informing moral norms in secular pluralist societies. Without a transcendental basis for morality, ascribing authority to moral norms requires a process of deliberation. Many bioethicists are concerned with formulating ways to ensure discourse is tolerant, non-coercive, mutually respectful, and grounded in intersubjective understanding. The problem is that secular discourse is fraught with varying conceptions of human rights, ethical principles, and what constitutes a morally authoritative consensus. Bioethicists acknowledge the tyranny of the majority problem, but secularism lacks a sufficient rationale to identify when a majority is wrong. Since competing visions of the good comprise bioethics and consensus does not necessarily indicate moral truth, moral uncertainty is the logical result of secular pluralism. Some moral scientists argue that science can inform moral norms, but a careful reading of their work suggests that what is being espoused is moral nihilism. From determinism to deep pragmatism, many scientists are inadvertently supporting a view of reality that obliterates the possibility of values. In secular pluralist societies, consensus is required to establish basic norms, but no account of consensus can indicate when moral truth is known. Consensus is necessary to fulfill the visions of moral scientists, but such scientists implicitly endorse nihilism. What secularists are discovering – by their own reasoning – is that moral truth is elusive, science cannot inform human values, and bioethical dilemmas are incapable of being resolved. The conclusion to this project offers an Engelhardtian solution. Not only is the principle of permission the only viable basis for secular pluralism – the principle coincides with moral scientists' own account of human nature.

Committee: Matthew Vest (Advisor); Ryan Nash (Committee Member); Ashley Fernandes (Committee Member) Subjects: Ethics; Philosophy; Philosophy of Science

MDES, University of Cincinnati, 2022, Design, Architecture, Art and Planning: Design

The excessive presence of technology in everyday life has challenged the usability of products for the older adult population. This population's feelings of frustration, uselessness, and lack of independence had been caused by the lack of accessibility components in technology, impacting their quality of life and psychological well-being. In addition, the rapid growth of smart applications and the lack of inclusion for older adults in the design development have enhanced the absence of engagement. Therefore, they have created complications that directly affect the quality of services they are receiving. This project focuses on the interaction between older adults and smart applications, specifically in health-related services, and draws attention to the lack of accessibility design for older populations. It uses exploratory research and participatory design methods to ideate possible interventions to improve older adults' health applications' experience, interaction, and usability. The design outcome of this project is a series of design principles for interface designers that strive to be a valuable tool to encourage the readers to reflect and improve accessibility features for older adults in smart applications. In addition, these principles seek to be easily readable and immediately applicable to interface design processes.

Committee: Renee Seward M.G.D. (Committee Member); Claudia Rebola Ph.D. (Committee Member) Subjects: Design

Doctor of Philosophy, University of Toledo, 2021, Physics

This dissertation is a systematic computational investigation of transition metal nitrides in M4N structure and in two alloy systems of Ti1-xScxN and Ti1-xYxN (0 ≤ x ≤ 1). Transition metal nitrides constitute a class of materials which have been broadly applied in the industry of hard coatings and cuttings. Our objective is to expand the currently existing database of these materials by exploring their structural, mechanical, magnetic, electronic, and thermodynamic properties, stability and hardness using the state-of-the-art first principles computational approach. Chapters 4 and 6 contain the main results and are summarized as follows. 1. We performed first-principles calculations with density functional theory on 28 metal rich cubic binary M4N structures. We provided a high through-put database of mechanical, electronic, magnetic, and structural properties for these compounds. We observed three compounds with Vickers hardness around or above 20 GPa, such as Re4N, Tc4N, and Mn4N (Chapter 4). We also identified 25 M4N compounds as mechanically stable while the remaining 3 (V4N, Nb4N, and Pt4N) as unstable. 2. We showed the relationship between the hardness and stability of these compounds and the density of states. We also calculated the magnetic properties of five magnetic compounds and exhibited that the consideration of electronic spin-polarization is very important in accurately calculating ground state energy and hence mechanical properties of these transition metal nitrides. 3. We also studied the phase stability, mechanical and electronic properties of two ceramic quasi-binary systems, Ti1-xScxN and Ti1-xYxN using density functional theory, cluster expansions and Monte Carlo simulations. We predicted strong exothermic mixing of TiN and ScN due to cationic similarity with the formation of 4 novel intermetallic compounds TiScN2, TiSc8N9, TiSc9N10, and Ti3Sc2N5 in the Ti1-xScxN system having hardness as high as 27.3 GPa. The phase diagram of Ti1-xScxN sys (open full item for complete abstract)

Committee: Sanjay Khare Dr. (Committee Chair); Jacques Amar Dr. (Committee Member); Richard Irving Dr. (Committee Member); Aniruddha Ray Dr. (Committee Member); Anju Gupta Dr. (Committee Member) Subjects: Physics

MFA, Kent State University, 2021, College of Communication and Information / School of Visual Communication Design

As society evolves, technology also evolves to meet the wants and needs of changing cultures. Since the turn of the 21st century, social networking has dominated the world of technology and has radically influenced how we communicate as humans. With new technological shifts in social networking comes many advancements on both an individual and societal level. At the same time, however, these shifts present many ethical dilemmas such as the collection of personal data, the exploitation of our psychological vulnerability, or the promotion of addictive habits and behaviors. What are the driving factors that keep us immersed in our virtual lives and what keeps us coming back for more? How do these social networks affect our behaviors? Our ability to be constructive individuals? Our perceptions of ourselves and others? These are some of the considerations this paper investigates. Designers play an important role in the creation and application of technology. Thus, it is imperative for designers to consider how their design decisions affect the sustainable health and well-being of people. Are designers responsible for the design decisions they make? What resources are available to help guide them in making ethical design decisions? The goal of this thesis is to explore the relationships between media, audiences, and society as well as to reevaluate, through data analysis, the effects and implications of ethical design principles and practices to help designers better understand their role when it comes to ethics and technology.

Committee: Jessica Barness (Advisor); Aoife Mooney (Committee Member); Ken Visocky-O'Grady (Committee Member) Subjects: Communication; Design; Education; Ethics; Psychology; Technology

Doctor of Philosophy, University of Akron, 2021, Engineering

Lean Management Systems (LMS) and Continuous Improvement (CI) program deployments are increasingly becoming an important strategy for many organizations for gaining competitive advantage. Such deployments promise success to organizations of any nature and size. Significant resources in the form of employee time, external consultants and training programs are spent on LMS/CI deployments by a vast number of companies every year. Yet despite the long history and evolution of CI methodology, ease of concepts and application, high amount of time and resources spent and furthermore proliferation of such deployments - the adoption and ultimately the success of such programs is highly variable. While many research papers and companies claim to have realized hundreds of millions in economic benefits from Lean deployments, just as many report to not even recover the cost of deployment. Researchers conclude that a complete systems approach to successfully deploy Lean methodology for long-term sustained gains is not widely understood or practiced. For this reason, in this research I present the design work of a new way to approach Lean/CI deployment methodology utilizing first-principles. The need for the new approach to deploying Lean/CI was engendered due to a mandate from the Senior Leadership Team (SLT) at the organization. The SLT desired a holistic approach that would align better to Company's Lean principles (first principles), show financial impact and bring about behavioral cultural change. This research presents the new approach - from First-Principles for the methodology, design criterion from SLT, to the design of the methodology, and then the application of the methodology to different businesses in the company. In essence, the research shows how any organization can build its own LMS utilizing first- principles to fit their own needs rather than copy pasting fragmented components offered by expensive consultants or snippets from literature – neither of w (open full item for complete abstract)

Committee: Shengyong Wang (Advisor); Asoke Dey (Committee Member); Xiaosheng Gao (Committee Member); Ping Yi (Committee Member); Chen Ling (Committee Member) Subjects: Banking; Engineering; Industrial Engineering; Management; Mechanical Engineering; Systems Design; Systems Science

Doctor of Philosophy (PhD), Ohio University, 2020, Instructional Technology (Education)

With the continuing growth of online education in the United States (US) and across the world, the value of quality design and multimedia instruction is critical. The benefits gained from multimedia instruction depends on how well the design of the multimedia instructional materials align with the human cognitive learning process, and this is where the multimedia learning principles come into play. Mayer's (2001, 2009) multimedia learning principles posit that people learn better when words and images are combined instead of words only. Most of the experiments conducted focused on concise, narrated animations and computer-based as well as paper-based lessons lasting few minutes in studying the effect of individual principles on learning. Empirical studies that specifically evaluates the strengths, weaknesses or possible improvement of the principles are limited or lacking. These principles and their guidelines, like other design theories are not in a state of perfection and still has room for improvement (Reigeluth & Frick, 1999). In this study, the multimedia learning principles for optimizing generative processing was used to design an instance of an online lesson for teaching informational content (cyberbullying). To contribute to the expansion of the knowledge base of the multimedia learning principles and its application, the researcher employed Reigeluth's and Frick's (1999) formative research methodology. The commitment of the researcher was to search for how the guidelines for the application of the multimedia learning principles can be improved, in areas where the goal of the design theory was not achieved based on learner feedback. The findings showed that the use of multimedia assets that allowed learners varying degrees of interactivity in the lesson was both effective and appealing. Other features that worked or were liked by learners include content accuracy and relevance and overall lesson sequence, among others. Learners felt distracted and di (open full item for complete abstract)

Committee: Greg Kessler PhD (Committee Chair); Krisanna Machtmes PhD (Committee Member); Alan Wu PhD (Committee Member); Jesse Strycker PhD (Committee Member); Danielle Dani PhD (Other) Subjects: Education; Educational Technology; Instructional Design

Master of Arts, University of Akron, 2020, Communication

This study explored if law schools are applying Kent and Taylor's principles of dialogic communication to Instagram. A content analysis was performed on 167 individual posts from 10 law schools. Posts were coded for whether or not they met each principle of dialogic communication, and the audience. Engagement between Instagram users was measured by followers, likes, and comments. It was found that law schools are employing Instagram in a dialogic way but that improvements could be made. This study presents a point of reference for other higher education institutions or law schools to consider when utilizing Instagram as a recruitment tool in their communication efforts.

Committee: Heather Walter PhD (Advisor); Amber Ferris PhD (Committee Member); Rhiannon Kallis PhD (Committee Member) Subjects: Communication

Doctor of Philosophy, The Ohio State University, 2019, Materials Science and Engineering

Novel two dimensional (2D) materials have been receiving increasing attention due to various exotic properties such as massless fermions, versatile gap engineering, topological edge states and superconductivity. With that, they are currently becoming one of the most import families of quantum materials and feature very high potential to be the basis for a manifold of disruptive technologies within the realm of functional materials. Density Functional Theory (DFT) has been playing an essential role in understanding their fundamental properties and discovering new candidate materials for a wide range of applications. Here, we used DFT to study the structural, electronic, optical and transport properties of a large variety of novel 2D and layered materials. After a high-level overview, we will first discuss structural defects in hydrogen and methyl terminated germanene. There, we will show why random twisting, which is a rotation between neighboring layers, is limited to small angles in germananes and results in turbostratic disorder, which is confirmed by electron diffraction. Twisting has recently been shown to have surprising results on band structures and transport properties, which is rationalized by our results for charge redistribution between Ge atoms and terminating hydrogen atoms in a turbostratically twisted structure. Band structures are also affected by point defects such as vacancies or residual intercalation atoms from the synthesis process, especially in the form of deep level defect states in the band gap, which are validated by cathodoluminescene and surface photovoltage spectroscopy, for which we discuss the role of DFT in analyzing experimental spectra. Such an approach can also be applied to the analysis of experimental Raman spectra of lattice vibrations, as we demonstrate for the example of CrI3, the first reported single layer 2D magnetic semiconductor. In the effort of seeking electric field tuning of band gaps in semiconductors, we propose and (open full item for complete abstract)

Committee: Wolfgang Windl (Advisor); Joseph Heremans (Committee Member); Joshua Goldberger (Committee Member) Subjects: Materials Science

Doctor of Philosophy, The Ohio State University, 2019, Materials Science and Engineering

Titanium alloys containing β stabilizers such as Mo, Nb and Ta are highly desirable for biomedical implants applications due to their low elastic modulus and excellent corrosion and fatigue resistance. To find the relation between β-Ti alloy compositions and their properties, a set of Ti-based diffusion multiples were made to generate composition libraries/gradients within the Ti-Mo-Nb-Ta-Zr system. Various experimental and analytical tools are applied to the diffusion multiples to extract the composition dependence of diffusion and mechanical properties. Diffusion is one of the fundamental processes in nature. A fast and easy-to-use simulation tool can help researchers understand and optimize diffusion processes in materials. A new Python-coded algorithm was developed to perform diffusion simulation in a fast and robust way. The core mechanism in this algorithm includes dynamic meshing and moving boundary structure. The diffusion simulation algorithm was combined with forward simulation analysis (FSA) to efficiently extract diffusion coefficients from experimental diffusion profiles. These diffusion simulation and analysis tools are coded and packaged as “pydiffusion”, a free open-source Python library that was deposited into the GitHub software sharing platform along with a description of its usage in a publication in the Journal of Open Research Software. Three Ti-Mo-Nb-Ta-Zr diffusion multiples were annealed at 800 ℃, 1000 ℃ and 1200 ℃, respectively to perform interdiffusion experiments. Electron probe micro-analysis (EPMA) was employed to collect diffusion profile data of various binary systems within three diffusion multiple samples. FSA was then applied to extract interdiffusion and impurity diffusion coefficients of seven Ti-X and Zr-X (X=Mo, Nb, Ta) binary systems. The new experimental results provide the most systematic and reliable data for the bcc phase of these seven binary systems. Through FSA calculation, the extracted interdiffusion coeffici (open full item for complete abstract)

Committee: Ji-Cheng Zhao Dr. (Advisor); Stephen Niezgoda Dr. (Committee Member); Vicky Doan-Nguyen Dr. (Committee Member); Patrick Woodward Dr. (Committee Member) Subjects: Materials Science

Master of Fine Arts, The Ohio State University, 2019, Art

This paper provides commentary on my process for creating my MFA thesis show, Transluminal, a work of expanded animation. I have deconstructed the principles of animation and interwoven accounts of intimate personal experiences to explore how Transluminal breaks away from our traditional expectation of the animation form and into the material world. In Transluminal, I abstract the human body and physiological processes to create tactile sculptures that provide an immersive sensory experience for the viewer, allowing moments of intimacy, discovery, and humor. Through active viewership and the spirit of play, the work is in a constant state of becoming that reflects our own bodies' material condition and illuminates the tension between our desire for and lack of control over this constant metamorphosis.

Committee: Kenneth Rinaldo (Advisor); Alison Crocetta (Committee Member); Amy Youngs (Committee Member); Deborah Scott (Committee Member) Subjects: Fine Arts

Bachelor of Arts, Ashland University, 2018, Communication Arts

This study began in response to two areas in higher education that are threatened: civil discourse and core curricula. For the past several years, university campuses have been met with a number of violent or disruptive protests against guest speakers with simply different viewpoints. Students, and even adults, sought to prevent speakers from delivering their lectures. Rather than defeating opposing arguments with reason and open discourse, there are those who do not wish to let opposing arguments see the light of day. This study references three specific events that ended in disruption and chaos in 2017; Charles Murray's invitation to speak at Middlebury College, Gavin McInnes' at New York University, and Xavier Becerra's at Whittier College. A number of notable American higher education institutions have adopted an “open curriculum” to meet their general education standards; notably Brown University, Amherst College, and Hamilton College. An open curriculum essentially means the respective university has no general education requirements for their students. Students, therefore, are able to choose from among hundreds of courses to meet the required amount of credits that satisfy a complete general education. Typically, they receive a type of professional academic guidance at these universities, but the choice of what to take is ultimately up to them. When this study began, it was easy to say core curricula and civil discourse were threatened. This study, however, first required a foundation for core curricula and civil discourse to be analyzed. The foundational question asked, what is the value of a liberal arts education? In order to discover the answer to this question, this study looks at the writings and time periods of Thomas Jefferson and Cardinal John Henry Newman. These men, 100 years apart, witnessed significant shifts in history and governments. Jefferson was involved with the founding of a nation, a nation governed by its people which (open full item for complete abstract)

Committee: Howard Walters Ph.D. (Advisor); Michael Poliakoff Ph.D. (Committee Member); Christopher Burkett Ph.D. (Committee Member) Subjects: Education History; Education Philosophy; Education Policy

Master of Science (MS), Bowling Green State University, 2018, Physics

ZnO is an abundant wide band gap semiconductor with promising applications in optoelectronic technologies. Electronic and optical properties of this material depend critically on the physics of various defects which are very common in ZnO. Controlling those defects is the key to the development of ZnO-based applications, which is still a challenging process. This master thesis work is primarily concerned in studying the pristine ZnO and its native oxygen point defects. The objective is to study, investigate, measure and correlate the electronic, vibrational and thermal properties of the pristine ZnO and its native oxygen point defects, along with drawing necessary inferences for creating substantial theories. Further, the mode of study is the first-principles calculations performed with density functional theory, implemented in the VASP code using the GGA-PBE and LDA+U as functionals. A short discussion of these calculations will be given. At last, we perform a comparative study with these functionals in their application to compute the electronic, vibrational and thermal properties of the pristine ZnO and its native oxygen point defects.

Committee: Alexey Zayak (Advisor); Alexey Zayak (Committee Chair); Lewis Fulcher (Committee Member); Marco Nardone (Committee Member) Subjects: Physics

Doctor of Philosophy, Case Western Reserve University, 2018, Communication Sciences

Purpose: Although most children with speech sound disorders are able to remediate their errors, some individuals have errors that persist into late childhood and even adulthood. These individuals are considered to have residual speech sound errors (RSSEs), and they are at risk for social, academic, and employment difficulties. Most individuals with RSSEs have participated in years of traditional speech therapy with little success. Visual biofeedback provides an alternative method of treatment that may be what finally allows these individuals to remediate their errors. This study utilized Opti-Speech, a visual biofeedback software that uses electromagnetic articulography to create a threedimensional rendering of the tongue that moves in real time with the participant's own tongue, for the remediation of RSSEs. Method: This single subject multiple baseline design included 18 participants (11 males and 7 females) who ranged from 8 -22 years of age. Speech sounds addressed in treatment included "r", "s", "sh", "ch", and "l". Participants attended an average of three baseline sessions and ten treatment sessions that utilized Opti-Speech visual biofeedback, and returned for a two-month follow-up. Results: Perceptual measures were based on generalization to untreated words. Eleven of the 18 participants were able to make clinically significant improvements for their target sound by their final treatment session, and 11 of 16 participants who returned for follow19 up measures had made clinically significant improvement on their target sound. When final session perceptual ratings were compared to follow-up, eight of the nine participants who presented with clinically significant improvement for their target sound were able to maintain their progress or presented with significantly improved speech sound skills. However, generalization was not seen at the sentence level. When considered as a group, clinically significant improvements were seen overal (open full item for complete abstract)

Committee: Jennell Vick Ph.D. (Committee Chair); Barbara Lewis Ph.D. (Committee Member); Elizabeth Short Ph.D. (Committee Member); Gregory Lee Ph.D. (Committee Member); Parrill Fey Ph.D. (Committee Member) Subjects: Speech Therapy

Doctor of Philosophy, Case Western Reserve University, 2017, Chemical Engineering

Everyone has probably had the experience of feeling shocked when touching a doorknob after walking across a carpet. This is one of the many examples of electrostatic charging on surfaces. Electrostatic charging, or contact electrification, is a well-known phenomenon in various instances. However, the charging mechanism remains poorly understood. This thesis will elucidate the scientific basis of contact charging on quartz (0001) and sapphire (0001) surfaces with first principle electronic calculations, supported by experimental results. Both experiments and simulations show consistent charging direction and magnitude results, demonstrating the possibility to address electrostatic charging on surfaces of more complicated structures. Electrostatic discharge can happen as a result of charge buildup on surfaces, leading to the gas breakdown. Inadvertent gas breakdown can be harmful, such as damage to microelectronic components. Intentional gas breakdown can be utilized to generate plasma. With high reactivity at relative low temperature, plasma is able to dissociate thermodynamically stable molecules near room temperature, such as carbon dioxide and methane. In this work, we modulate power, volume, flow rate, pressure, voltage, discharge gap distance, and the simultaneous use of catalysts on conversion processes to control plasma reactions. Our combined experimental and multiscale simulation techniques provide a guidance to optimize plasma conversion processes.

Committee: Daniel Lacks (Advisor); R. Mohan Sankaran (Committee Member); Heidi Martin (Committee Member); Hatsuo Ishida (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, University of Toledo, 2017, Physics

This dissertation is a computational exploration of transition metal nitrides, a group of materials that have myriad applications in the hard coatings industry. We aim to explore their structural, mechanical, electronic and thermodynamic properties and their solid solutions, discovering trends and correlations of their bonding nature and cause of superior stability and hardness. Here are the major work and results: 1. We performed first-principles calculations with density functional theory on six cubic structural prototypes, zincblende, rocksalt, cesium-chloride, NbO, fluorite and pyrite. We observed a few compounds with Vickers hardness higher than 20 GPa, such as rocksalt-structure ScN, TiN, cesium-chloride-structure VN, NbO-structure CrN, MoN, WN, and pyrite-structure MnN2, PtN2. (Chapter 4, Chapter 5 and Chapter 6) 2. We established an anti-correlation between metallic compounds' total electronic density of states at the Fermi energy level, an indicator of metallicity and their shear-related mechanical properties, such as elastic constant C44, shear modulus, Pugh's ratio and Vickers hardness. (Chapter 4, Chapter 5 and Chapter 6) 3. Beyond single-cation phases, we further studied the phase equilibria of three ceramic quasibinary systems, Ti1-xZrxN, Ti1-xHfxN and Zr1-xHfxN. We analyzed the asymmetry of composition-dependent formation energy curves through two energetically partially canceling processes. We concluded that the absence of experimental observations of phase separation, as predicted by our calculations in Ti1-xZrxN and Ti1-xHfxN is probably due to a combined effect of insufficient undercooling, inadequate atomic diffusivity, and the initial energy barrier for chemical exchange with constrained lattices. (Chapter 8) 4. We also showed that mixing nitrides of same group transition metals does not lead to hardness increase from an electronic origin, but through solution hardening mechanism, a plastic phenomenon difficult to catch with first-pr (open full item for complete abstract)

Committee: Sanjay Khare (Committee Chair); Jacques Amar (Committee Member); Nikolas Podraza (Committee Member); Bo Gao (Committee Member); Daniel Georgiev (Committee Member) Subjects: Physics

Doctor of Philosophy (PhD), Ohio University, 2017, Mathematics (Arts and Sciences)

The field of Selection Principles in Mathematics is in some sense the study of diagonalization processes. It has its roots in a few basic selection principles that arose from the study of problems in analysis, dimension theory, topology, and set theory. These "classical" selection principles were formally defined by M. Scheepers in 1996, but they go back to classical works of F. Rothberger, W. Hurewicz, and K. Menger. Since then, new selection principles and new types of covers have been introduced and studied in relation to the classical selection principles. We consider the relationship between gamma-sets, which are spaces satisfying a specific classical selection principle, and a newer selection principle (A, B_∞) that was introduced by B. Tsaban in 2007. First, we survey known results of gamma-sets due to F. Galvin and A.W. Miller and prove which results hold for the (A, B_∞) selection principle. Then, we establish filter characterizations for these selection principles to prove new properties and positively answer a question asked by B. Tsaban. Afterward, we prove several results about a concrete construction of a gamma-set on the Cantor space due to T. Orenshtein and B. Tsaban. Lastly, we revisit our properties to formulate some open questions raised by our work.

Committee: Todd Eisworth (Advisor); Vladimir Uspenskiy (Committee Member); Sergio Lopez (Committee Member); Phillip Ehrlich (Committee Member) Subjects: Mathematics