Doctor of Philosophy, The Ohio State University, 2018, Chemistry

The studies in this thesis utilize theoretical approaches to investigate the dynamics involved in the photodissociation of small anionic systems in which nonadiabatic interactions result in charge transfer during the dissociation process. The aim of these studies is to gain insights into the nature of the electronic states involved in the dissociation and to understand the role of intramolecular motions and the energy distributions among the various degrees of freedom. In this thesis, the dynamics of the photodissociation of XCN- (X = I or Br) following electronic excitations to states that dissociate to X- + CN and X* + CN- have been investigated. Based on previous quantum dynamics studies of the photodissociation of ICN-, the two electronic states are accessed by visible or ultraviolet excitation and are found to be coupled, leading to the observation of both photoproducts in the dissociation process. Due to the small energy difference between the two asymptotic channels (roughly 0.14 eV for ICN- and -0.05 eV for BrCN-), a nonadiabatic interaction similar to that observed in ICN- plays an important role in the dynamics involving BrCN-. The dissociation processes in BrCN- are studied using a similar quantum dynamics approach that was applied in the studies of ICN-. The calculations are performed on diabatic models of the potentials developed for the two relevant excited states. The calculated branching ratios indicate that the nonadiabatic effects are more pronounced in BrCN- than in ICN-. The energy distribution among the various degrees of freedom is also found to have a large influence on the branching ratios of the photoproducts. The solvation of ICN- by argon atoms interestingly leads to the experimental observation of a small fraction of recombination products following the excitation of clusters as small as ICN-(Ar) or ICN-(Ar)2 in the visible or ultraviolet region, respectively. Argon solvation is therefore expected to alter the interactions between g (open full item for complete abstract)

Committee: Anne B. McCoy (Advisor); Claudia Turro (Committee Chair); Vicki Wysocki (Committee Member); Cosmin S. Roman (Committee Member) Subjects: Chemistry; Physical Chemistry

Doctor of Philosophy, University of Akron, 2024, Polymer Engineering

Reciprocating compressors are critical components for the natural gas energy infrastructure throughout the world. Proper lubrication of PTFE and PEEK based packings and piston rings (seals) in the compressor cylinder is necessary to prevent leaks of methane to the environment and allow efficient, reliable, and extended operation of the compressor. Cylinder lubrication is poorly understood and commonly cited as the reason for premature seal failures while being a major annual expense for compressor station operators. An industry priority is to reduce the amount of lubricant injected into the compressor cylinder. The lubricant is carried away by the process gas and collects in pipelines or other downstream equipment. To better understand the tribological aspects and physical phenomena of compressor cylinder lubrication, the effect of high pressure methane on the surface tension of common lubricants and sealing materials was investigated. Methane gas pressure exhibited an inverse relationship with liquid lubricant surface tension through a pendant drop test. Methane pressure also increased the contact angles of sessile drops of lubricants on the solid surfaces. Nitrogen pressure exhibited the same trends but to a lesser extent than methane. Analysis using the Owens, Wendt, Rabel and Kaelble calculation method revealed that as methane pressure increased, the surface free energy of the seal materials decreased. These results further revealed that increased gas pressure decreased the wettability of lubricants on the materials. PTFE based materials decreased much more than PEEK based materials. Spontaneous adsorption of the pressurized gases on the surface of the lubricant drops and sealing materials was determined to be the underlying cause of the reductions of surface energy. This new understanding is significant because it better explains the observed lubrication phenomena and may be able to guide the industry toward optimized lubrication, more efficient se (open full item for complete abstract)

Committee: Kevin Cavicchi (Advisor); Weinan Xu (Committee Chair); Christopher DellaCorte (Committee Member); Fardin Tayebeh Khabaz (Committee Member); Sadhan Jana (Committee Member) Subjects: Energy; Engineering; Materials Science; Mechanical Engineering

Doctor of Philosophy, University of Akron, 2024, Mechanical Engineering

Processing-related defects such as porosity, residual stress, and surface roughness are the primary impediments to the widespread adoption of additive manufacturing in high-performance aerospace structures, primarily in applications where fatigue is an area of concern. Strengthening the surface through an emerging surface treatment approach has the potential to mitigate these defects and subsequently improve the surface quality, as well as increase the fatigue strength of the additively manufactured components. The core objective of this research work was to employ a severe surface plastic deformation (SSPD) process to improve the surface and fatigue properties of additively manufactured Ti-6Al-4V alloys with a particular emphasis on directed energy deposition (DED) re-paired and fully produced electron beam powder bed fusion (EB-PBF), via combination of laser heating (LA) and ultrasonic nanocrystal surface modification (UNSM). Laser heating plus ultrasonic nanocrystal surface modification is an innovative mechanical sur-face treatment tool, and it has been demonstrated as an interesting laser-based mechanical surface treatment technology to induce thicker deformation layer on the surface using low energy input, impact load, low amplitude, and high ultrasonic frequency, leading to enhancement of the microstructure features, surface strength, and resultant mechanical properties of metallic materials. Physical and mechanical characteristics changes in target materials were investigated using optical (OM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), profilometry, and a hardness tester. The results revealed that the proper thermal and impact energies of the applied surface treatment was effective in inducing higher plasticity flow and promoted greater surface grain refinement. Strengthening of metallic alloys through grain refinement is evidenced by achieving maximum strength, a phenomenon referred to as the Hall-Perch principle. In particular, the s (open full item for complete abstract)

Committee: Gregory Morscher (Advisor); Yalin Dong (Committee Member); Jun Ye (Committee Member); Wieslaw Binienda (Committee Member); Manigandan Kannan (Committee Member) Subjects: Aerospace Materials; Materials Science; Mechanical Engineering

MS, University of Cincinnati, 2023, Engineering and Applied Science: Civil Engineering

Precast concrete sandwich panels (PCSPs) are widely used in construction for several reasons, one of the more important reasons is the thermal performance since it implements an insulation layer sandwiched between two layers of concrete, which improves the thermal resistance of the wall assembly considering that most of energy loss in buildings is through the exterior walls. Concrete can be an ideal material for energy saving, due to its thermal mass which acts as a thermal battery for the building, absorbing energy during the day and releasing it at night. Many energy codes recognize the benefits of thermal mass and require less insulation for mass walls. Many designs can be applied to the exterior layer of PCSPs mainly for esthetics. These designs can also influence the thermal lag by increasing or decreasing the time expected to absorb or release the heat. The proposed research is aimed to investigate the effect of the architectural patterns on the exterior layer of the precast concrete sandwich panel on the thermal lag in terms of absorbing, storing, and releasing heat energy.

Committee: Anton Harfmann M.Arch. (Committee Chair); Jeffrey Kastner Ph.D. (Committee Member); Pravin Bhiwapurkar Ph.D. (Committee Member) Subjects: Civil Engineering

Doctor of Philosophy, Case Western Reserve University, 2023, Chemical Engineering

The work of my Ph.D. thesis focuses on understanding the physical and electrochemical properties of deep eutectic solvents (DESs) and concentrated hydrogen bonded electrolytes (CoHBEs) through experiments concerning their use as electrolytes for redox flow batteries. My work aims to provide a fundamental understanding of how DES components govern bulk properties and double-layer structure with the ultimate goal of leveraging the gained knowledge to design new electrolytes for flow battery applications. Thesis Goals ● Bulk liquid properties: To determine how molecular structure and composition of DES components affect bulk macroscopic properties such as density, viscosity, and conductivity. ● Electrode-electrolyte interface: To develop a physical model of the voltage-dependent ion accumulation in DESs and CoHBES near the electrode and to identify surface species during the course of a redox reaction. ● Redox active organics: To study redox active organics as potential candidates for redox material in a CoHBE-based flow batteries. Chapter 3: In Chapter 3, we investigate the differential capacitance of choline chloride (ChCl) and ethylene glycol (EG) as a function of potential and composition using electrochemical impedance spectroscopy (EIS) on glassy carbon, Au, and Pt electrodes. We compared these results to glyceline (ChCl:glycerol, 1:2). The capacitance-potential curves on glassy carbon were best explained by the modified Gouy-Chapman model. We observe a dampened U-shape similar to dilute electrolytes. However, the presence of significant ionic and hydrogen bonding interactions in these electrolytes introduced ambiguity regarding the point of zero charge, where the capacitance weakly depended on potential. When using Au electrodes, we observe an increase in capacitance due to desolvation and specific adsorption of Cl ions. Conversely, with Pt electrodes, we observe increased capacitance with decreasing Cl concentrations. These results indicate that deep e (open full item for complete abstract)

Committee: Burcu Gurkan (Advisor); Clemens Burda (Committee Member); Robert Warburton (Committee Member); Robert Savinell (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy (PhD), Ohio University, 2023, Chemical Engineering (Engineering and Technology)

Internal corrosion of transmission tubulars is a huge concern in the oil and gas industry. Corrosion inhibitors (CIs) are often considered the first step in mitigating internal corrosion due to their high efficiency and cost-effectiveness. Yet, predicting the efficiency of corrosion inhibitors, developed and tested in a laboratory environment, in operating field conditions is very challenging. In addition, the presence of corrosion residues or corrosion products on the internal surface of tubular steels can significantly affect the inhibition performance of organic corrosion inhibitors. This aspect is only rarely considered when characterizing the performance of corrosion inhibitors. Therefore, understanding their effects on corrosion inhibition is of great benefit in applying corrosion inhibitors to tackle internal corrosion issues, particularly in aging pipelines. This work mainly focuses on evaluating the corrosion inhibition and revealing the inhibition mechanisms in the absence and presence of various corrosion residues or products, commonly found in oil and gas production. The first half of this work (Chapter 5 and 6) presents a methodology for the characterization of corrosion inhibitors and proposes several innovations to an inhibition prediction model, originally based on the work of Dominguez, et al.. An inhibitor model compound, i.e., tetradecyl phosphate ester (PE-C14), was synthesized in-house and characterized to obtain necessary parameter values required as inputs for the inhibition model. The updated inhibition model could predict steady state and transient corrosion inhibition behaviors with good accuracy. The second half of the presented work (Chapter 7, 8, and 9) focuses on the effects of corrosion residue (Fe3C) and products (FeCO3 and FeS) on corrosion inhibition and advances the understanding of the associated inhibition mechanisms. The galvanic effect caused by residual Fe3C on corrosion rate and inhibition efficiency was quantitatively (open full item for complete abstract)

Committee: Marc Singer (Advisor); Srdjan Nesic (Committee Member); David Young (Committee Member); Sumit Sharma (Committee Member); Katherine Cimatu (Committee Member); Katherine Fornash (Committee Member) Subjects: Chemical Engineering; Engineering; Materials Science

Master of Science, The Ohio State University, 2023, Environmental Science

Biophysical modeling has experienced significant advancements over time, transitioning from physics-based approaches to regression modeling and now embracing machine learning techniques alongside vast quantities of environmental data. However, a growing concern in data-driven models is the lack of physical consistency and transparency, leading to the emergence of a field known as hybrid machine learning. In this abstract, we present two studies that leverage the availability of cost-effective in-situ remote sensing systems to address data limitations in surface energy modeling. The first study focuses on developing simple machine learning models to improve model transparency and physical consistency by accurately estimating soil heat flux—a vital component of the energy balance. To achieve this, we utilized two variables, namely radiometric surface temperature (LST) and the normalized difference vegetation index (NDVI), which could capture upwards of 85% of the variability in soil heat flux at half-hourly resolution across four agricultural systems. The performance of these models surpassed that of existing semi-empirical models, while significantly reducing the costs associated with measuring soil heat flux. In the second study, we demonstrate the application of simple machine learning for parameter estimation, serving as a precursor to physical modeling. Specifically, we validated the Surface Temperature Initiated Closure (STIC) model simultaneously over four crop systems in Ames, Iowa. Through this implementation, we discovered that simple machine learning estimation can replace model inputs without introducing additional biases. Furthermore, leveraging the parametric estimations of energy conductance provided by STIC, the study identified variations in stomatal response and drought resilience among the four crop systems. Integrating machine learning and remote sensing techniques shows promise in improving our understanding and predictive capabilities in surface (open full item for complete abstract)

Committee: Darren Drewry (Advisor); John Fulton (Committee Member); Christopher Stewart (Committee Member) Subjects: Agriculture; Biophysics; Environmental Science; Remote Sensing

Doctor of Philosophy, University of Akron, 2022, Polymer Science

Contact between polymers and ice occurs in several scenarios and presents opportunities for many technological applications. These applications mainly fall into one of two categories where it is desired to (i) decrease the adhesion of ice to a surface or (ii) increase static friction between a surface and ice and snow. The adhesion strength σs of ice on a polymer film of thickness $h$ and shear modulus μ has been shown to be σs ∝ (Waμ/h)1/2. Tuning the material properties of the polymer (h and μ) is common to achieve low ice adhesion strength, but the thermodynamic work of adhesion term Wa is largely ignored. This term depends on both the surface properties of the polymer and ice, as well as the interfacial properties between the polymer and ice. In comparison to that of other systems (e.g., polymer and glass), this term is complex due to the surface premelting of ice. In this work, we use surface-sensitive sum frequency generation (SFG) and infrared (ATR-FTIR) spectroscopy to understand how the molecular structure of ice dictates both the thermodynamic work of adhesion and the adhesion strength between polymers and ice. In the first study, we link a transition in the thermodynamic work of adhesion between polydimethylsiloxane (PDMS) and ice to a surface premelting transition of ice. We then use SFG to show that this transition is due solely to the ice surface. We then examine how this transition in the surface energy of ice affects the adhesion strength of ice to PDMS. In the second study, we use SFG and ATR-FTIR to show that non-frozen water at the interface of ice and polyelectrolyte brushes (below the freezing temperature of water) is correlated to the ice adhesion strength. In the third study, we characterize the microstructure of ice accrued at environmental conditions relevant to aircraft and examine its influence on the ice adhesion strength to aerospace materials. To increase friction on snow, mimicking the surface roughness of polar bear paw pads h (open full item for complete abstract)

Committee: Ali Dhinojwala (Advisor); Hunter King (Committee Chair); Peter Niewiarowski (Committee Member); Mark Foster (Committee Member); Mesfin Tsige (Committee Member) Subjects: Aerospace Materials; Animal Sciences; Biophysics; Materials Science; Physics; Polymers

Doctor of Philosophy, The Ohio State University, 2022, Mathematics

We explore lattice point counting and the method of stationary phase through the lens of questions about the number of lattice points on and near surfaces with vanishing curvature. Our focus is on spheres arising from the Heisenberg groups. In particular, we prove an upper bound on the number of points on and near large dilates of the unit spheres generated by the anisotropic Heisenberg norms for α ≥ 2. We accomplish this through a transformative process that takes a number theory question about counting lattice points and translates it into that of an analytical estimation of measure. This process relies on truncating and scaling the n-dimensional integer lattice to produce a fractal-like set. By introducing a measure on this resulting set and using elementary Fourier analysis, the counting problem is transformed into one of bounding an energy integral. This process uses principles of fractal geometry and oscillatory integrals. Primary challenges that arise are the presence of vanishing curvature and uneven dilations. Following a discussion and formal estimate of the curvature of the Heisenberg spheres, we utilize the method of stationary phase to compute a bound on the Fourier transform of their surface measures. Our work is inspired by that of Iosevich and Taylor (2011) and Garg, Nevo, and Taylor (2015). We present an extension of the main result in the former to surfaces with vanishing curvature. Furthermore, we utilize the techniques developed here to estimate the number of lattice points in the intersection of two such surfaces. Additionally, we present a mini-course on the basics of stationary phase—a quick-start guide to stationary phase in practice. This includes a discussion of the formulation of oscillatory integrals and their solutions with a focus on the impact of geometric properties (e.g. curvature) on the estimates for the decay of the Fourier transform. It further serves as a supplement to [Shakarchi and Stein, Functional Analysis: Chapter (open full item for complete abstract)

Committee: Krystal Taylor (Advisor); Rodica Costin (Committee Member); Barbara Keyfitz (Committee Member) Subjects: Mathematics

Master of Science in Materials Science and Engineering (MSMSE), Wright State University, 2021, Materials Science and Engineering

Methylammonium lead triiodide (MAPbI3) has garnered attention due to their high solar cell efficiencies and low cost to manufacture, but commercialization is not yet possible owing to poor environmental stability. Thus, researchers seek ways which optimize the performance of the MAPbI3 solar cell by modifying the architecture and through interfacial engineering of the charge transport layers. Difficulties in understanding these devices arise from ion migration, charge separation and recombination, and metastable, thermally active precessions of the methylammonium (MA) moiety in the lead iodide framework. In this work, focus is given to the perovskite and an adsorbed monolayer, 2,3,4,5,6-pentafluorothiophenol (C6F5SH), which has demonstrated to increase environmental stability and solar cell efficiency when placed at the perovskite/hole transport layer interface. Utilizing a first principles approach, the interface of MAPbI3 and C6F5SH is explored using various metastable methylammonium orientations to understand the relative stability, electronic properties, bandgap, and infer impact on solar cell performance.

Committee: Amir A. Farajian Ph.D. (Advisor); Hong Huang Ph.D. (Committee Member); Raghavan Srinivasan Ph.D., P.E. (Committee Member) Subjects: Materials Science

PhD, University of Cincinnati, 2021, Engineering and Applied Science: Aerospace Engineering

In streamlined airplane configurations, additional noise sources can be created from interactions between the jet flow and surfaces on an aircraft's body. During takeoff and landing procedures the ground itself is close enough to already cause jet-surface interference. During these procedures, workers on an aircraft carrier are exposed to such noise radiation and can suffer from varying degrees of hearing loss, providing an impetus from the Navy to study these conditions. To assess this interaction, the presence of a flat plate impinging on a supersonic jet of a low aspect ratio (2:1) rectangular nozzle of equivalent exit diameter of De=20.65mm, is studied from the minor and major axis orientation. The impact of the plate, large enough in length to resemble an aircraft carrier deck relative to the nozzle in scale, is studied at supersonic nozzle pressure ratios (NPRs) of 2.5–4.5. These surface interactions have been studied in large part on cold jets to a certain extent, as these are more easily replicated in a laboratory setting. However more realistic applications involve a heated jet flow, particularly in Navy jet applications. This leads to tested operating conditions produced here of the cold flow temperature ratio (TR=1.0) to a heated jet up to TR=3.0. To investigate this application, acoustic data from near-field and far-field arrays is captured, and combined with visual flow measurements from streamwise particle image velocimetry (PIV) and shadowgraph/Schlieren photography. From PIV data, average velocity and turbulence kinetic energy (TKE) of the flow can be extracted, while shadowgraph provides various density gradients across the flow field. Further processing in the form of proper orthogonal decomposition (POD) can be applied here to extract dominant modes of the jet's movement. Plate offset (h) distances of h/De=?0, 1, 2, and 3 from the nozzle lip are studied to assess trends related to shock cell spacing, potential core length, and shear layer devel (open full item for complete abstract)

Committee: Ephraim Gutmark Ph.D. (Committee Chair); Shaaban Abdallah Ph.D. (Committee Member); Jeffrey Kastner Ph.D. (Committee Member); Mark Turner Sc.D. (Committee Member) Subjects: Aerospace Materials

Doctor of Philosophy, Case Western Reserve University, 2020, Macromolecular Science and Engineering

Epoxy adhesives constitute a large majority of the structural adhesive market. Most of these adhesives are 2-component systems consisting of a bisphenol A based resin and an amine based hardener. Bisphenol A is an endocrine disruptor and a known carcinogen, as well as derived from petroleum which in itself is a finite resource. Due to these disadvantages, BPA has been banned in multiple countries and replacements for BPA based resins are persistently sought. One of the most common amine curing agents used in epoxy adhesives is petroleum derived isophorone diamine (IPDA) which has been found to be toxic and a skin sensitizer. The need for adhesive systems that can replace bisphenol A based resins and petroleum based IPDA has never been more urgent. A family of biobased epoxies derived from diphenolic acid (DGEDP epoxies) were recently synthesized that have an estrogen binding capacity of an order of magnitude less than BPA but similar thermo mechanical properties to the diglycidyl ether of bisphenol A (DGEBA), the most commonly used epoxy resin derived from BPA. This family of resins, differing amongst each other only in ester chain length in terms of structure exhibited excellent potential as suitable replacements to DGEBA. Their curing kinetics with regards to IPDA were studied to determine which resin would be suitable for adhesive applications. Isoconversional analysis indicated that the resins cured via an autocatalytic mechanism and modeling of the curing behavior using the Kamal Sourour model showed that the methyl ester resin (DGEDP-methyl) exhibited unusually high curing rates. This resin was then chosen for further development as the resin component for a biobased adhesive. However, when lap shear samples on aluminum were prepared, DGEDP-methyl when cured with IPDA exhibited extremely brittle behavior failing at very low stresses. A commercially available highly aliphatic biobased epoxy resin (NC-514) derived from cashew nut shell liquid was hypot (open full item for complete abstract)

Committee: Ica Manas-Zloczower Prof. (Committee Chair); Donald Feke Prof. (Committee Member); Gary Wnek Prof. (Committee Member); Rigoberto Advincula Prof. (Committee Member) Subjects: Materials Science; Polymers; Sustainability

PHD, Kent State University, 2018, College of Arts and Sciences / Chemical Physics

Our research uses a dynamic cell to measure azimuthal anchoring energy and disclination line tension in a nematic liquid crystal. The dynamic cell is a cell which has controllable twist angle and cell thickness. By increasing the twist angle to an angle greater than 90 degrees, the cell becomes super twisted. In this state, if the cell thickness is decreased to a critical thickness, the surface anchoring breaks. The azimuthal anchoring energy can be calculated from the twist elastic constant, the twist angle, and the cell thickness. When the anchoring breaks, a disclination line is formed separating regions of opposite handed twist. By balancing the forces due to the disclination line tension and the twist distortion, a stable disclination line can be achieved. We can calculate the line tension of the disclination from the radius of curvature of the disclination line at equilibrium. In order to generate disclination lines more easily, we designed a disclination line nucleation site by photopatterned surface alignment. We found that the line tension increases with the cell thickness. By measuring the line tension with respect to cell thickness and temperature, we investigate the core of the disclination line.

Committee: Hiroshi Yokoyama PhD (Advisor); Peter Palffy-Muhoray PhD (Committee Member); Elizabeth Mann PhD (Committee Member); Antal Jakli PhD (Committee Member); Sam Sprunt PhD (Committee Member) Subjects: Condensed Matter Physics; Physics

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

Geckos are intriguing creatures, adhering to ceilings, to leafs, to glass and cement, all without glue. Instead, their adhesion is dependent on surface interactions between their hierarchical adhesive structure and the contacting substrates. These interactions on the nanoscale have significant macroscale influences. Changing the conditions between substrate and the nanostructures of the gecko adhesive affects the ability of geckos to adhere. Improving our understanding of how these conditions affect the adhesion of the natural gecko system can then inform our synthetic adhesive design efforts. Here, I have investigated how geckos perform on 'soft' substrates and on rough underwater substrates. Taking inspiration from the hierarchical nanostructure of the gecko adhesive, and its interactions with water, hierarchical rough carbon nanotube substrates were used to investigate the roles of roughness and surface chemistry on superhydrophobic stability. The 3D structure of CNTs was further used to investigate the influence of surface interactions on the macroscale thermal conductivity properties.

Committee: Ali Dhinojwala Dr. (Advisor); Yu Zhu Dr. (Committee Chair); Gary Hamed Dr. (Committee Member); Mesfin Tsige Dr. (Committee Member); Peter Niewiarowski Dr. (Committee Member) Subjects: Condensation; Experiments; Nanoscience; Physics; Polymers; Zoology

PhD, University of Cincinnati, 2017, Arts and Sciences: Chemistry

The establishment of a single-ion thermodynamic scale is essential to addressing the ubiquitous specific ion effects observed in the literature. Solvation free energies, enthalpies, and entropies when decomposed to their single-ion components include a contribution from 1) a solvophobic effect to make room for the ion and the establishment of ion/solvent interactions and 2) a distant interfacial potential (e.g., the air/water interface). Since experiment can only access the pair quantities, assumptions made to break the figures into a single-ion scale tend to clump into one of two scales. This thesis makes the case that the two scales reflect 1) (“bulk”) and 1) + 2) (“real”). Both 1) and 2) pose a significant challenge to theoretical characterization. The source of the difficulty for the bulk thermodynamic scale is in the handling of non-electrostatic forces between the ion and solvent. My results indicate that polarization plays an important role in ion/water clusters and in the modeling of energy storage solvents like ethylene and propylene carbonate which are very polarizable molecules. My work also draws attention to the strength of dispersion interactions between anions and water, as well as, the almost fluid-like nature of the excess electron's density in anions. About 20% of the charge is diffused over waters in the first solvation shell. Fortunately these effects are found to be relatively short-ranged (1-2 solvation shells) inviting the possibility of simpler models handling longer-ranged interactions. The real scale on the other hand adds the surface potential experienced by a charge crossing the air/water interface. This is found to be -q0.4 V, where q is the signed ion charge, resolving a century old problem. It is further argued that the surface potential contains two contributions a) across the air/water junction and b) across the local ion/solvent boundary. The latter of these is present even in simulations using periodic boundary conditions (PBC). My (open full item for complete abstract)

Committee: Thomas Beck Ph.D. (Committee Chair); William Connick Ph.D. (Committee Member); George Stan Ph.D. (Committee Member) Subjects: Physical Chemistry

Doctor of Philosophy, The Ohio State University, 1984, Graduate School

Committee: Not Provided (Other) Subjects: Physics

Doctor of Philosophy, The Ohio State University, 1975, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Master of Science, Miami University, 2015, Computational Science and Engineering

Fluorite is a common mineral in the earth. Rare Earth Elements (REEs) readily incorporate into fluorite during its growth and are found to be sectorally zoned (i.e., having substitutional concentration differences among the nonequivalent sectors). The underlying causes of sectoral zoning (SZ) of REEs in fluorite are not clear. Also, the mechanisms which differentiate REEs in terms of binding at kinks (i.e., intermediate twists in crystal growth steps) at a crystal surface are still unknown. To study SZ, it is important to explore the dynamics of crystal growth during the adsorption of REEs. In this work, studies have been done to find the internal reasons behind the SZ by simulations and computations at both the atomic and sub-atomic levels using electronic structure methods. Atom Clusters have been modeled which represent the fluorite surface including various REEs at kink sites and nonequivalent faces. Simulation results of electronic structure methods provides detailed explanations to understand the sectoral zoning by exploring the surface structure, energetics and internal morphology for REE adsorption at the kink site of fluorite. Results indicate that adsorption energy differences among faces and differing bond orders among REEs are likely to be principle causes of SZ at the adsorption stage.

Committee: James Moller Dr. (Advisor); John Rakovan Dr. (Committee Member); Fazeel Khan Dr. (Committee Member) Subjects: Chemistry; Computer Science; Mechanical Engineering

PHD, Kent State University, 2015, College of Arts and Sciences / Chemical Physics

Disclination lines play a decisive role in determining the equilibrium structures of topologically constrained liquid crystal systems including cholesteric blue phases, twist grain boundary phases and liquid crystal colloids. The extra energy associated with disclinations is key to stabilizing one particular director structure over another, yet our knowledge of disclination energetics is limited as are characterization methods. In this work, we detail our approach which has focused onbuilding versatile one-of-a-kind instruments for studying liquid crystal systems. This work details the development and use of two novel instruments: an automated maskless photoalignment pattern generator (maskless system) and ad ynamic-cell system that allows for the automated mechanical adjustment of the liquid crystal cell thickness, twist angle and temperature. Both instruments were extensively refined and characterized for maximum performance. In addition, both instruments were designed as versatile platformsfor new research. In this work, we used the maskless system to create novel surface alignments and Pancharatnam-phase devices, and we employed the dynamic-cell system for the generation and characterization of reverse-twist-domain defect loops.

Committee: Hiroshi Yokoyama (Advisor); Philip Bos (Committee Member); Antal Jakli (Committee Member); Elizabeth Mann (Committee Member); Michael Tubergen (Committee Member) Subjects: Chemistry; Physical Chemistry; Physics

BS, Kent State University, 2014, College of Arts and Sciences / Department of Chemistry and Biochemistry

Biomaterials must adequately facilitate tissue fixation while maintaining mechanical properties. Surface rigidity and roughness have been shown to modulate soft tissue response. In order to improve soft tissue adhesion on rigid substrates, phase separation of organosilanes was employed to create self-assembled monolayers (SAMs) of tunable wettability by creating nano-size hydrophobic and hydrophilic domains capable of eliciting phenotypic response in skeletal myoblast cells. P-aminophenyltrimethoxysilane (APhMS) and octadecyltrichlorosilane (OTS) was varied in a binary solution in order to achieve SAMs with nanoislands. C2C12 skeletal myoblast cells were seeded onto prepared SAMs in order to investigate changes in cell behavior due to surface interactions. Hydrophilic SAMs were observed to enhance cell spreading, viability, and myotube formation on glass surfaces. Furthermore, 5:5 APhMS: OTS was found to increase myoblast differentiation and anisotropy through cell mechanosensing of nanoislands. Virtual roughness of 5:5 APhMS:OTS was created by nanosized methyl-terminated pillars in an amine-terminated matrix.

Committee: Christopher Malcuit Ph.D. (Advisor); Grant McGimpsey Ph.D. (Committee Member); Edgar Kooijman Ph.D. (Committee Member); Paul Sampson Ph.D. (Committee Member) Subjects: Cellular Biology; Chemistry