Doctor of Philosophy, The Ohio State University, 2014, English

My dissertation traces and analyzes the identifications with science that emerge in the rhetorical tradition of the multimodal exhibition of scientific objects, concepts, processes, and practices in the museum context. I demonstrate how multimodal exhibits in science centers have embedded implicit instruction in scientific method and its value; these identifications with science are further reinforced and complicated by wider cultural expectations and ambitions for science and science centers, and how those expectations and ambitions come to be realized in the built spaces of the science centers enclosing the exhibits themselves. I argue that the display of science exhibits within the context of science centers' built spaces reproduces a rhetorical tradition that encourages visitors to respond according to sense-making conventions that are historic in origins, and which privilege a “folk epistemology of common sense empiricism.” The compelling characterization of science as a process conducted through careful observation and inference was separated from the dominant definition of science when experimental science displaced analytical science and its practice moved from private homes and museums to university laboratories. In the twentieth century, through their reproduction of exhibits' “naked eye science,” museums—both natural history and the emerging institution of the science center—preserved the now-outdated theory of knowledge-making with objects. As cultural expectations and ideas about science changed during the twentieth century, the needs of local communities hosting science centers changed, and science center institutions and buildings were adapted to address new educational, economic and civic demands. While exhibits' sense-making functions remained based on the assumption that science is done through careful observation of past events, new architectures and built spaces enclosing those exhibits realized celebratory functions for their surrounding communi (open full item for complete abstract)

Committee: H. Lewis Ulman (Advisor); Elizabeth Weiser (Committee Member); Jonathan Buehl (Committee Member) Subjects: Epistemology; Multimedia Communications; Museum Studies; Rhetoric

Doctor of Philosophy, University of Akron, 2013, Polymer Science

A series of densely branched comb polystyrenes with well-defined architectural details were prepared by living anionic polymerization via the “grafting-through” approach. A new, general method was developed for the synthesis of well-defined, comb polystyrenes with controlled, variable amounts and types of branch end functionalities (C8F17, OH or COOH), by combining living anionic polymerization and thiol-end “click” chemistry. Characterization by NMR, SEC, and MALDI-TOF mass spectrometry established their chemical structures and chain-end functionalities, which indicated precisely defined comb polystyrenes with controlled degrees of functionalization. Surface segregation in blends of well-defined comb and linear polystyrenes was investigated by neutron reflectivity (NR) and Static Time-of-Flight Secondary Ion Mass Spectrometry (STOF-SIMS) measurements. The results indicate strong enrichment of combs at the blend surface. In contrast to previously reported examples of blends of long-branched and linear chains, a thermal annealing process is not necessary for achieving significant surface segregation in these comb/linear blends. It is found that architecture details of the comb component have a strong impact on the bulk miscibility with the linear component in a blend and therefore also on its surface segregation. A self-consistent field theory by Wu and Fredrickson is able to describe the surface segregation behavior in the comb/linear blends reasonably well after accounting for a surface attraction for the ends higher than anticipated by the theory. Measurements of the surface segregation, as well as macroscopic hydrophobicity in blends containing branch end-functionalized comb polystyrenes, show that comb molecules with 25% branch chain ends functionalized with hydrophobic or hydrophilic groups still enrich the surface, though the contact angle of a blend depends on whether the functionalities themselves reside right at the surface, or are buried beneath the outer (open full item for complete abstract)

Committee: Mark D. Foster Dr. (Advisor); Jutta Luettmer-Strathmann Dr. (Committee Member); Roderic P. Quirk Dr. (Committee Member); Chrys Wesdemiotis Dr. (Committee Member) Subjects: Materials Science; Polymer Chemistry; Polymers

Master of Science in Engineering, Youngstown State University, 2024, Department of Civil/Environmental and Chemical Engineering

A longitudinal study in corrosion was performed on tensile-elongation dog-bones, created using 3D-printed stainless steel. The effects of exposure to an acidic environment were investigated regarding mass-loss, tensile and yield strength, modulus of elasticity, profilometry of pits and defects, and microscopy of fracture-sites. The SS316L specimens were manufactured using different print-directions, specifically overlapping unidirectional or rotated bidirectional for each layer by an additive manufacturing unit, the Mazak VC-500/5X AM HWD. The novel aspect of this research is focusing on the differences that the path the hot-wire, direct energy deposition, print-head has on its corrosion characteristics, as opposed to only focusing on the printing-parameters. The goal was to determine what printing-directions and methods were best for resisting corrosion. The research outlines the process of preparing samples for controlled weight-loss in HCl as well as the methods used to measure the mechanical properties. This allows for the results to be repeated if desired. Upon thoroughly reviewing the data and drawing connections where applicable, it was determined within the test samples that unidirectional print-directions yielded better mass-loss and mechanical attributes than bidirectional printing. It was found that some print directions, namely 90°, which is perpendicular to the printing door, performed notably better than other directions such as 0° or 45°.

Committee: Holly Martin PhD (Advisor); Pedro Cortes PhD (Committee Member); Bharat Yelamanchi PhD (Committee Member) Subjects: Chemical Engineering; Chemistry; Engineering; Experiments; Materials Science

Master of Science, University of Akron, 2024, Computer Science

Within this study, Random Forest regression models were employed to predict the viscosity of ionic liquids (ILs) using an expanded dataset generated from the cheminformatics software RDKit. The initial dataset comprised over 22,000 experimental observations for 2,068 different ILs. This dataset was meticulously filtered to remove data points with high uncertainty or inconsistencies, ensuring the reliability of the training data. Feature extraction was performed using RDKit, significantly expanding the dataset from 4 initial features to 126 features, including various molecular descriptors such as molecular weights, charges, and structural characteristics. To mitigate the high dimensionality and improve model performance, Principal Component Analysis (PCA) was used to reduce the feature space while retaining 95% of the variance. Feature selection techniques, including SelectKBest, Recursive Feature Elimination (RFE), and a novel Bayesian Feature Selection (BFS), were utilized to refine the feature set further by identifying and removing redundant and less informative features. Hyperparameter tuning via Bayesian optimization was also performed, which systematically explored the hyperparameter space to identify the optimal settings for the Random Forest model. This is then followed with a rigorous cross validation process, involving 10-fold cross-validation, which confirm the model's generalizability and robustness. The model development involves autonomous creation and testing of numerous models with varying features and hyperparameter subsets. Machine learning methods were applied to efficiently predict viscosities and establish accurate structure-property relationships. The resulting predictions showed an average R² value of 0.96 for the training set and 0.76 for the test set, indicating robust predictive performance for viscosity. Overall, this study demonstrates the effectiveness of combining advanced data preprocessing, feature engineering, and machine learning (open full item for complete abstract)

Committee: En Cheng (Advisor); Fardin Khabaz (Committee Member); Zhong-Hui Duan (Committee Member) Subjects: Computer Science; Materials Science

Master of Science (MS), Bowling Green State University, 2023, Geology

Concrete production is the third largest energy consumer in the world and the calcination process used to produce Portland Cement is responsible for 7% of global CO2 emissions; hence, there is great interest in developing methods to decrease the amount of Portland Cement used in concrete. One such method is the use of supplementary cementitious materials (SCM). In a recent study, Bernard (2023) evaluated the use of dolomite aggregate of various sizes and replacement quantities on the compressive strength of mortar samples made without SCMs and with limestone SCM. The results showed that mortar made with dolomite SCM had a greater compressive strength after 1 day of curing than samples without SCM or with limestone SCM. Other researchers have also reported concretes with dolomite SCM have higher compressive strengths at shorter curing times and have suggested that the formation hydrotalcite may be the cause. The objective of this study is to determine if hydrotalcite formed in the dolomite SRM mortar samples in sufficient manner to cause the early strengthening. The mortar samples were analyzed using a Scanning Electron Microscope with an Energy Dispersive Spectrometer (SEM-EDS) and by powder x-ray diffraction (XRD). The results of the SEM-EDS analysis confirmed the presence of hydrotalcite grains within dolomite reaction rims. However, the amount of hydrotalcite in the mortar samples was too low for detection by XRD analysis. As such, the direct impact of hydrotalcite formation on early strengthening of the dolomite SCM mortar cubes is questionable. Prior studies that reported significant hydrotalcite formation in dolomite SCM concretes were cured at higher temperatures and for longer durations than the mortar samples analyzed in this study.

Committee: John Farver Ph.D. (Committee Chair); Yuning Fu Ph.D. (Committee Member); Kurt Panter Ph.D. (Committee Member) Subjects: Earth; Geochemistry; Geology; Materials Science; Mineralogy

Master of Science (MS), Bowling Green State University, 2023, Physics

Colloidal semiconductor nanocrystals (NCs) have been utilized to great effect in optoelectronic applications in the last half-century due to their favorable optical and electronic properties. However, these materials suffer significant performance decline as optical or electrical excitation power increases. The culprit of this decline is the Auger recombination of multiple excitons that produces excess heat from the NC energy. This process poses a significant obstacle to NC performance in photodetectors, X-ray scintillators, lasers, and high-brightness LEDs. A new NC structure, semiconductor quantum shells (QSs) are an emerging NC morphology that solve this problem by providing one of the slowest rates of Auger decay for colloidal NCs yet. These NCs are synthesized in a series of time-dependent injections that layer the desired materials in successive shells. Early iterations of these NCs were still limited by a high rate of surface-trap recombination. Alloying the outer CdS layer with ZnS to produce a CdS-CdSe-CdS-ZnS QS has proven to reduce surface carrier decay. The resulting QSs have photoluminescence quantum yields as high as 90%, and biexciton emission quantum yields as high as 79%. These characteristics make QSs favorable for high-excitation applications when compared to other low-dimensional semiconductors.

Committee: Mikhail Zamkov Ph.D. (Committee Chair); Marco Nardone Ph.D. (Committee Member); Alexey Zayak Ph.D. (Committee Member) Subjects: Materials Science; Physical Chemistry; Physics

Doctor of Philosophy, University of Toledo, 2023, Physics

Current manufacturing techniques allow for mass production of high-efficiency cadmium telluride (CdTe) photovoltaic (PV) modules at a low cost per watts. The robust nature of the materials and the high optical absorption coefficient with a suitable band gap for optimal photon power conversion made CdTe more attractive. Today's CdTe solar cells hold a record efficiency of 22.1%. However, the CdTe device efficiency is below the theoretical limits due to the recombination of photo-generated carriers in front/back interfaces and in the bulk of the absorber. Such recombination reduces the open circuit voltage (Voc) of the devices. Understanding the role of the different defects and defects complexes formed during absorber preparation and after post-deposition treatments is necessary to minimize carrier recombination. Also, using the front/back buffer layers for proper band alignment at interfaces are needed to reduce interfacial recombination. This dissertation focuses on materials engineering and control to minimize carrier recombination and hence improve devices performance. We fabricated high-quality CdTe absorbers with a new approach to CdTe deposition using a high vacuum close space sublimation (CSS) system. Reorganization of the defect complexes associated with Cu ion migration during light soaking of CdSe/CdTe devices is studied. A minority carrier lifetime of 656.5 ns is reported with a high-quality CdTe absorber and passivated back surface with a back buffer layer of copper aluminum oxides (CuxAlOy), resulting in ~ 860 mV Voc and ~ 17.5 % device efficiency. A problem with low-doped magnesium zinc oxide (MZO) as a front emitter layer in CdSe/CdTe devices has been resolved by increasing the doping density of MZO films with high vacuum annealing. To minimize front interfacial recombination, a new wide bandgap front emitter layer of indium gallium oxide (InxGa1-x)2O3 (IGO) has been introduced to tune the bandgap and conduction band offset (CBO) with absorber at th (open full item for complete abstract)

Committee: Michael Heben Dr. (Advisor); Michael Heben Dr. (Committee Chair); Alvin Compaan Dr. (Committee Member); Randy Ellingson Dr. (Committee Member); Richard Irving Dr. (Committee Member); Yanfa Yan Dr. (Committee Member) Subjects: Physics

Bachelor of Science (BS), Ohio University, 2019, Chemistry

As methacrylate-based polymers have numerous applications in biomedical materials, electrolytes, and nanotechnology, a systematic understanding of the molecular conformation under various preparation methods is important for exploring these applications and many others. Using the surface sensitive techniques of sum frequency generation spectroscopy, atomic force microscopy and goniometry, this work aims to study the effects of polymer structure, solvent, and heating time on the morphology and molecular conformation of methacrylate-based polymer thin films. The solvent choice not only affects the morphology of the thin films bases on the Young-Dupre equation, but also the molecular conformation, as shown in SFG data. The heating time affects the morphology and the molecular conformation of the PTFs.

Committee: Katherine Cimatu (Advisor) Subjects: Chemistry

Doctor of Philosophy, University of Akron, 2018, Polymer Science

Fossil energy from coal, gas, and oil-based fuel stocks remains a vital cornerstone of the global energy infrastructure while contributing over half of annual CO2 emissions. Rising global CO2 concentrations and aberrant trends in climate have sparked recent scrutiny of the energy industry sustainability. Carbon capture, utilization, and storage (CCUS) at the site of power plants has been proposed as a strategy for mitigating atmospheric CO2. This dissertation covers simulated and experimental models designed to address key problems in both the fundamental science and applied engineering of amine-functionalized silica sorbents for carbon capture from few molecule DFT (density functional theory) calculation to kilogram-scale technology validation. DFT was used to emulate small molecule and polymeric amines with good agreement in four successive series of models. (i) The concept of CO2 adsorption strength on secondary amines was investigated which revealed lone amine sites produce weakly adsorbed species while dense amine pairs yield strongly adsorbed species. (ii) Mixed amine types are common in blended or polymeric amine systems and convolute data interpretation. The hydrogen bonding ability of ammonium carbamate pairs demonstrated significant dependence on amine type and local hydrogen bond partners. (iii) Fixation of amines onto substrates is a ubiquitous strategy for preparing CO2 sorbents. The effect of geometric constraint imposed by immobilization was investigated for simulated propylamine pairs. Binding energy was linearly dependent on the alignment of ammonium carbamate. FTIR features were categorized into four groups. (iv) Selective formation of carbamic acid was studied by modeling reactants, intermediates, transition states (TS), and products of the amine-CO2 reaction on simulated diamine substrates. It was shown that significant reduction in TS activation energy occurred by Grotthus-like proton hopping. Coal-fire power plant CO2 capture was experime (open full item for complete abstract)

Committee: Steven Chuang (Advisor); Mesfin Tsige (Committee Chair); Tianbo Liu (Committee Member); Stephen Cheng (Committee Member); David Perry (Committee Member) Subjects: Chemical Engineering; Chemistry; Materials Science; Physical Chemistry; Polymers

Master of Arts in English, Cleveland State University, 2017, College of Liberal Arts and Social Sciences

In the early part of the twentieth century, the Modernist literary movement was moving into what was arguably its peak, and authors we would now unquestioningly consider part of the Western literary canon were creating some of their greatest works. Coinciding with the more mainstream Modernist movement, there emerged a unique sub- genre of fiction on the pages of magazines with titles like Weird Tales and Astounding Stories. While modernist writers; including Marcel Proust, Virginia Woolf, Ernest Hemingway, D.H. Lawrence, James Joyce, Ezra Pound, William Faulkner, and T.S. Elliot – among others – were achieving acclaim for their works; in the small corner of unique weird fiction there was one eccentric, bookish writer who rose above his own peers: Howard Phillips Lovecraft. I would argue that within the works of Lovecraft there are glimpses of modernism. Lovecraft was aware of and wrote with an understanding of the concerns of the more mainstream literature of the Modernists, and he situated his narratives and stories within a modernist framework that reflected this. Most importantly, it is the way in which Lovecraft used science and religion, and blended myth with material culture, that Lovecraft most reflects modernist leanings. It's important to make the distinction that he is not part and parcel a Modernist, but he was influenced by, interacted with, and showed modernist tendencies. There is a subtlety to the argument being made here in that Lovecraft was not Joyce, he was not Elliot, he was most definitely not Hemingway, and his fiction was by no means what we would consider traditionally modernist. In 2005 he received inclusion in the Library of America series and, although this isn't an indicator or guarantee of inclusion in a large canon, the argument that he in no way had a discourse, awareness, or did not contribute to what would be more properly termed `Modernist' warrants consideration when properly situating Lovecraft within early-twentieth century lite (open full item for complete abstract)

Committee: James Marino Ph.D. (Committee Chair); Adam Sonstegard Ph.D. (Committee Member); Julie Burrell Ph.D. (Committee Member) Subjects: American Literature; Literature; Modern Literature

Doctor of Philosophy, University of Akron, 2017, Polymer Engineering

ABSTRACT Efficiently and economically harnessing the solar energy via solar cell devices is one of promising solutions to address the global energy crisis. This thesis mainly focuses on a novel family of photoactive layer materials, namely organic-inorganic lead halide perovskite hybrids, and their corresponding solar cell devices, due to their potential for achieving outstanding power conversion efficiency and low-cost processibility. Specifically, the main research themes of this thesis are to achieve high performance perovskite hybrid solar cells through optimizing device structures, developing novel functional perovskite materials, and elucidating the underlying physics and mechanisms for guiding us to construct high performance solution-processed perovskite hybrid solar cells. This dissertation contains four parts and 10 chapters. In PART I, a broaden overview on both solar cell device and material is given, which specifically reviews the importance of solar energy and solar cells, comparison between previous-generation solar cells and perovskite hybrid solar cells, history of perovskite hybrid materials for solar cell application in Chapter 1 and describes the theoretical background of solar cell devices and material used for fabrication of solar cells in Chapter 2. PART II mainly includes the detailed projects on solar cell device engineering. Firstly, in Chapter 3, we employ a highly electrical conductive, polyethylene oxide (PEO)-doped poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as the hole extraction layer (HEL) for the planar heterojunction (PHJ) perovskite hybrid solar cells (pero-HSCs). The dramatically enhanced electrical conductivity of the PEO-doped PEDOT:PSS HEL provides an efficient pathway for the hole extraction, transport, and collection from the perovskite active layer to the anode. As a result, a significantly enhanced short-circuit current (JSC) of 23.42 mA cm-2, a slightly enlarged open-circuit voltage (VOC) of 0 (open full item for complete abstract)

Committee: Xiong Gong (Advisor); Matthew Becker (Committee Member); Alamgir Karim (Committee Member); Nicole Zacharia (Committee Chair); Jie Zheng (Committee Member) Subjects: Electrical Engineering; Energy; Nanoscience; Physics; Polymers

Master of Science, University of Akron, 2014, Biology

Natural antimicrobials have great success in the chemical space for the discovery of antimicrobials against resistant microorganisms. Spider silk and silkworm silk are two natural fibers of interest for the development of a variety of biomedical devices, including antimicrobial sutures. Spider silk is mainly known for its remarkable mechanical properties and unique molecular structure. Silk can be considered as a potential biomaterial for the development of surgical sutures and tissue scaffold formations because of its desirable biomedical properties like slow biodegradability, biocompatibility, wound healing, and nerve regeneration. Various studies have investigated antimicrobial properties of spider silk, but the data were either inconclusive or there were methodological issues in the techniques used.To understand whether spider silk actively inhibits the growth of microorganisms or is otherwise naturally resistant to bacteria, two different experiments were performed in this study: i) spot assay (antibacterial test) to examine the presence of any non-diffusible inhibitory agent. contact-inhibition- to examine any bactericidal or bacteriostatic action, and ii) scanning electron microscopy analysis- to investigate whether bacteria adheres to spider silk. Both experiments used dragline silk pulled directly from the major ampullate spigot of the orb-weaving spider Argiope aurantia. Organic extracts of spider silk in spot analysis showed absence of any non-difusible agent. Microbial growth curves obtained from Escherichia coli (gram negative bacteria), Bacillus subtilis (gram positive bacteria) and Pseudomonas aeruginosa (Gram negative bacteria) showed no significant effect on bacterial growth patterns. However, sem showed low adherence of bacteria onto the silk surface in comparison to control tubes for the gram negative bacteria (E. coli and P. aeruginosa). Spider silk did not show any significant resistance of adherence of B. subtilis, a gram positive bacterium (open full item for complete abstract)

Committee: Todd Blackledge Dr. (Advisor); Hazel Barton Dr. (Committee Member); Mathew Shawkey Dr. (Committee Member) Subjects: Biology; Materials Science; Microbiology

Master of Science in Engineering, Youngstown State University, 2012, Department of Mechanical, Industrial and Manufacturing Engineering

Interpenetrating phase composites (IPCs) have unique mechanical and physical proper-ties and thanks to these they could replace traditional single phase materials in numbers of applications. The most common IPCs are ceramic-metallic systems in which a duc-tile metal supports a hard ceramic making it an excellent composite material. Fireline, Inc., from Youngstown, OH manufactures such IPCs using an Al alloy-Al2O3 based ceramic-metallic composite material. This product is fabricated using a Reactive Metal Penetration (RMP) process to form two interconnected networks. Fireline products are used, among others, as refractory materials for handling of high temperature molten metals. A novel route to adding a shape memory metal phase within a ceramic matrix has been proposed. A NiO preform was reacted with Ti to produce an IPC using a plasma arc melting system. This reaction is particularly interesting due to the possible formation of a Ni-Ti metal phase which could exhibit shape memory e¿¿¿¿¿¿¿ects within the ceramic-metal network. Di¿¿¿¿¿¿¿erent ratios of NiO and TiO2 (rutile) were reacted with Ti to investigate if the NiTi phase could be formed. In this thesis, two IPCs, one produced by the TCON RMP process and the other by using plasma arc-melting were investigated. The materials include Al-Fe alloy-Al2O3 and NiO-Ti ceramic-metallic IPCs. Analysis was performed using scanning/transmission electron microscopy (S/TEM), energy dispersive spectroscopy (EDS), focused ion beam (FIB), and X-ray di¿¿¿¿¿¿¿raction (XRD). Observations of these IPCs revealed all present phases within the composite material, obtained orientation relationships, and explored the growth mechanism of the RMP process which still puzzles the scientific community. This information is valuable for developing improved IPC systems with diverse elemental composition for a wide variety of applications.

Committee: Virgil Solomon PhD (Advisor); Matthias Zeller PhD (Committee Member); Timothy Wagner PhD (Committee Member); Hyun Kim PhD (Committee Member) Subjects: Engineering; Materials Science; Mechanical Engineering; Mechanics