Doctor of Philosophy, The Ohio State University, 2015, Physics

In this thesis, we improve several aspects of the standard model of relativistic heavy-ion collisions. We include a pre-equilibrium dynamical stage and study it in the strong and weak coupling limits. We stress the importance of this stage on the later hydrodynamic evolution as well as on the mean transverse momenta, transverse momentum distributions and anisotropic flow coefficients of directly emitted hadrons. In order to properly address the bulk viscosity, we update the hydrodynamic equations within the boost-invariant viscous hydrodynamic simulation program VISH2+1 to a more complete set of equations that includes non-linear terms related to the shear stress tensor and bulk pressure. The importance of each non-linear term is discussed. With the understanding that the effects of tunable parameters in the heavy-ion simulation model on physical observables are entangled, we optimize them simultaneously. We perform such optimizations for Pb + Pb collisions at the Large Hadron Collider (LHC) for both Monte Carlo Kharzeev-Levin-Nardi (MC-KLN) and Monte Carlo Glauber (MC-Glb) initial-state models. In a first stage we test the parameter optimization routine with zero bulk viscosity and without the hadronic after-burner. This sets the baseline for subsequent searches including the hadronic after-burner and a non-zero bulk viscosity. We report the preferred parameter ranges and compare them across different initial-state models, with and without pre-equilibrium dynamics. The parameter space for the runs with hadronic after-burner is further explored within a Bayesian approach. Using a Markov Chain Monte Carlo routine we determine the posterior probability distribution of each parameter and assign quantitative uncertainty ranges to them.

Committee: Ulrich Heinz (Advisor); Michael Lisa (Committee Member); Robert Perry (Committee Member); Junko Shigemitsu (Committee Member) Subjects: Nuclear Physics; Physics; Theoretical Physics

Doctor of Philosophy, University of Akron, 0, Mechanical Engineering

Elastohydrodynamic lubrication (EHL) theory has been used to model the lubrication state of antifriction machine elements, where initial viscosity and pressure viscosity coefficients are essential parameters in film thickness modeling. Since the pressures of lubricants in the contact zone can be very high, it is important to know the rheological properties of lubricants in these pressure and temperature regimes. The characteristics of viscosity behavior as a function of pressure are also essential for a universal definition of the pressure viscosity coefficient in order to estimate film thickness in an EHL regime. In this study, viscosities and pressure-viscosity coefficients of ten commercial engine and gear oils and seventeen laboratory-produced oil/polymer viscosity modifiers (VM) additives are measured up to 1.3 GPa at 40, 75 and 100 °C. For the first time, a sharp increase in the viscosity and piezoviscous factor is observed in both mineral-based and synthetic-based oils with different VMs. Analysis of the experimental results indicates that sharp increase in viscosity observed in these experiments are believed to arise from physical changes in the VMs, that is liquid-solid phase transition. Evidence is offered that polymer properties such as molecular weight, concentration and structure influence the onset of the phase transitions. A modified Yasutomi model, which normally describes the pressure dependence of the viscosity of lubricants very well, fails to predict the viscosity of the specimens above the onset of sharp increase in viscosity. A design of experiment (DOE) analysis using Design-Expert software indicates that pressure and temperature are the most critical parameters in the viscosity variation. Tribological tests demonstrate that wear in the contact, zone occurs at temperatures and stresses that coincides with the VM phase transitions in both commercial and laboratory synthesized oil/VMs. Tribological results also indicate that the onset of the (open full item for complete abstract)

Committee: Gary Doll (Advisor); Paul Shiller (Committee Member); Greg Morscher (Committee Member); Matthew Becker (Committee Member); Ryan Evans (Committee Member) Subjects: Energy; Engineering; Mechanical Engineering; Physics; Polymer Chemistry; Polymers

Doctor of Philosophy (PhD), Ohio University, 2011, Physics and Astronomy (Arts and Sciences)

A detailed quantitative comparison between the results of shear viscosities from the Chapman-Enskog and Relaxation Time methods is performed for the following test cases with specified elastic differential cross sections between interacting hadrons: 1. The non-relativistic, relativistic and ultra-relativistic hard sphere gas with angle and energy independent differential cross section sigma = a^2/4, where $a$ is the hard sphere radius, 2. The Maxwell gas with sigma (g,Theta)= mGamma(Theta)/2g, where $m$ is the mass of the heat bath particles, Gamma(Theta) is an arbitrary function of Theta, and $g$ is the relative velocity, 3. Chiral pions for which the $t-$averaged cross section sigma = s/(64pi^2 f_pi^4) × (1+1/3 × cos^2 Theta), where $s$ and $t$ are the usual Mandelstam variables and $f_pi$ is the pion-decay constant, and 4. Massive pions for which the differential elastic cross section is taken from experiments. Quantitative results of the comparative study conducted revealed that * the extent of agreement (or disagreement) depends very sensitively on the energy dependence of the differential cross sections employed, stressing the need to combine all available experimental knowledge concerning differential cross sections for low mass hadrons and to supplement it with theoretical guidance for the as yet unknown cross sections so that the temperature dependent shear viscosity to entropy ratio can be established for use in viscous hydordynamics. * The result found for the ultra-relativistic hard sphere gas for which the shear viscosity eta_s = 1.2676~k_BT~c^{-1} /(pi a^2) offers the opportunity to validate ultra-relativistic quantum molecular dynamical (URQMD) codes that employ Green-Kubo techniques. * shear viscosity receives only small contributions from number changing inelastic processes. The dependence of the bulk viscosity on the adiabatic speed of sound is studied in depth highlighting why only hadrons in the intermediate relat (open full item for complete abstract)

Committee: Madappa Prakash Dr. (Advisor); Charlotte Elster Dr. (Committee Member); Justin Frantz Dr. (Committee Member); Alexander Neiman Dr. (Committee Member); Jeffrey Rack Dr. (Committee Member) Subjects: Physics

Master of Science, Miami University, 2025, Mechanical and Manufacturing Engineering

Reduced order modeling (ROM) methods, such as those based upon Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD), offer data-based turbulence modeling with potential applications for flow control. While these models are often cheaper than numerical approaches, their results require validation with source data. Within the literature, the metrics and standards used to validate these models are often inconsistent. Chabot (2014) produced a data-driven framework for validating these ROMs that used surrogate Markov models (SMMs) to compare how the system dynamics evolved rather than how any single metric evolved. These SMMs were constructed by clustering the flow data into different states of suitably similar flow fields, and the Markov model then mapped how likely each state was to transition into another. While this method was successful, there persisted an amount of uncertainty in how the outlier states within this clustering scheme were determined. Additionally, the study only examined the application of this procedure to POD-Galerkin ROMs. This study aims to tie the outlier state determination directly to the models' parent data. The study will also apply this procedure to ROMs generated from DMD to investigate how this framework's effectiveness carries over to different classes of ROMs.

Committee: Edgar Caraballo (Advisor); Andrew Sommers (Committee Member); Mehdi Zanjani (Committee Member) Subjects: Aerospace Engineering; Fluid Dynamics; Mathematics; Mechanical Engineering; Statistics

Master of Science, The Ohio State University, 1917, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1965, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Arts, The Ohio State University, 1924, Graduate School

Committee: Not Provided (Other) Subjects:

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

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2023, Photochemical Sciences

To correlate and be able to tune the photophysical properties of molecular scale chromophores with the mechanical properties of the macroscale supramolecular polymer such as viscosity, modulus etc. is a complex phenomenon. To tune these properties, we utilize dynamical coordination bonds such as Metal-Ligand interactions. In this work, we present how we can use the photophysical properties specifically probing excited state arising from these tunable dynamical interactions to probe the mechanical properties of the macroenvironment real time in-situ. Utilizing this approach, we were able to detect the viscosity of supramolecular polymeric assembly by probing emission lifetime from triplet electronic state of [Cu(diptmp)2]2+. However, this correlation is not quantitatively ubiquitous in every polymeric host. We probed the reversibility of the polymeric assembly by swelling and deswelling the polymer assembly which is attributed to micro-viscosity. The photophysical changes were of significant magnitude to be able to detect even small reversible changes during swelling and deswelling the polymer. Furthermore, worked on synthesizing a bio-based polymer and made a composite material with multiple ligand moieties. We present how these moieties interact with the polymeric environment and quantify them through their affinity to different metals. The photophysical changes in emission of a bio-based Cu-curcumin polymeric composite material upon applying stress to the composite material has been discussed. We also present to show whether we can induce the photophysical changes in NIR emission of a water soluble [Cr(ddpd)3]3+ complex termed as molecular ruby exhibiting upon subjecting it to thin supramolecular films with increasing modulus and looked at its stress-response.

Committee: Alexis D. Ostrowski Ph.D. (Committee Chair); Francisco Cabanillas Ph.D. (Other); Joseph C. Furgal Ph.D. (Committee Member); Alexander N. Tarnovsky Ph.D. (Committee Member) Subjects: Chemistry; Inorganic Chemistry; Physical Chemistry

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

Cells are highly ordered, structurally complex systems with billions of years of evolution. There are great endeavors in understanding how biological components and biomolecular processes shape the diverse living systems today. Recent progress in cellular biology pointed out the key role of coacervates in numerous extracellular and intracellular activities, including stress response, gene regulation, signaling, extracellular load-bearing matrix, and underwater adhesion. Inspired by nature, material scientists utilize synthetic coacervates for various applications, including underwater adhesives and therapeutic protein delivery. Growing evidence has verified biological coacervates are driven by collective interactions, which offer coacervates remarkable robustness in highly diverse living systems. Currently, coacervate-forming synthetic materials are mainly induced by electrostatic interaction, which shows instability in complex environmental conditions. Here, a new library of coacervate-forming polyesteramides driven by hydrophobic interactions and stabilized by bridged hydrogen bonding is presented. The polyesteramides are prepared by ring-opening polymerization, which provides controllability in molecular structure, end group functionality, and molecular weight. These polyesteramide coacervates demonstrate low viscosity, low interfacial energy, and the capability to form multilayered structures analog to biological coacervates. The phase behavior and physical properties can be controlled by varying chemical structures and the temperature. This study provides a stepping stone to developing biomimetic synthetic coacervates for understanding cellular activities and designing advanced coacervate-based materials.

Committee: Abraham Joy (Advisor); Mesfin Tsige (Committee Member); Chunming Liu (Committee Member); Ali Dhinojwala (Committee Member); Adam Smith (Committee Member) Subjects: Polymers

PhD, University of Cincinnati, 2021, Pharmacy: Pharmaceutical Sciences

Many sulfate-free and amino acid-based surfactant systems for personal care formulations do not respond to salt thickening with sodium chloride as readily as traditional sulfate-based formulations. This thesis focuses on alternative thickening mechanisms for a model amino acid-based surfactant, sodium lauroyl sarcosinate (SLSar). Rheology, diffusing wave spectroscopy, potentiometric titration, cross-polarized microscopy, zeta potential and cryo-TEM were used to obtain zero-shear viscosity and analyze the structure-rheology relationship. We focused on using pH adjustment as the main thickening mechanism while incorporating various types of additives. There were three main additives that we studied: zwitterionic surfactant, cationic ions/surfactant and nonionic cosurfactants. For the model formulation investigated here, thickening through partial neutralization of the titrable surfactant by lowering pH and the addition of nonionic surfactants to control the micelle breakage kinetics were most successful in providing robust thickening mechanisms. Chapter 3-6 were submitted for publication. The content of this dissertation is based on the following publications: 1.

Committee: Gerald Kasting Ph.D. (Committee Chair); Kavssery Ananthapadmanabhan ENG.SC.D. (Committee Member); Peter Koenig Ph.D. (Committee Member); Harshita Kumari Ph.D. (Committee Member); Michael Weaver Ph.D. (Committee Member) Subjects: Chemical Engineering; Pharmaceuticals

Master of Science, The Ohio State University, 2021, Animal Sciences

Mastitis is a key challenge for the dairy industry. Defined as inflammation of the mammary gland, mastitis is most commonly caused by a bacterial intramammary infection (IMI). A large proportion of dairy heifers have an IMI prior to calving and beginning their first lactation. An infection during this time is expected to be deleterious to the growth and development of the mammary gland (quarter), diminishing future milk production and producer profitability. The objectives of these works were to describe the effects an IMI has on primigravid heifer mammary secretions, determine if prepartum administration of an internal teat sealant (ITS) in heifers reduced the odds of IMI at calving, and determine if administration of ITS earlier (75 vs 35 days prepartum) differentially affected the odds of IMI at calving. A total of 270 heifers were utilized. Aseptic secretion samples were obtained from one quarter of every heifer at 75 days prepartum and another quarter of every heifer at 35 days prepartum. Immediately following sampling, the designated quarter was administered ITS. The other 2 quarters of every heifer were not interfered with prior to calving. After calving, each quarter of every heifer was sampled. Both prepartum secretion as well as colostrum samples were bacterially cultured to determine quarter infection status and the somatic cell count (SCC) was enumerated. Prepartum secretion samples were scored based on viscosity as thick or thin. At 75 days prepartum, 26% of quarters had an IMI, and 28% were infected at 35 days prepartum. Uninfected secretion samples were 133.2 (95% confidence interval (CI): 16.8 - > 999.9) times more likely to be thick compared to samples infected with a major pathogen, and 14.3 (95% CI: 8.5 - 24.1) times more likely to be thick compared to samples infected with non-aureus staphylococci (NAS). Secretion SCC was elevated when an IMI was present within the quarter; quarters with an IMI caused b (open full item for complete abstract)

Committee: Benjamin Enger (Advisor); Jessica Pempek (Committee Member); Craig Zimmerly (Committee Member) Subjects: Animal Sciences

Doctor of Philosophy, The Ohio State University, 2021, Food Science and Technology

Texture of food plays a determining role in food liking. Foods with textures perceived as negative are often avoided more than positively-connotated textures are sought out signifying negativity bias. The first objective of the present research was to quantitatively determine whether consumers' food choices are motivated more by avoiding disliked food textures or seeking out liked food textures. An adaptive choice-based conjoint analysis survey was created to ascertain which food textures drive consumer choice behavior. In total, 30 attributes within 8 overall texture categories were assessed by 54 adults. Hierarchical Bayes estimation calculated utility scores (part-worths) for each of the 30 attributes and importance scores for the 8 categories. The survey also retrieved information regarding whether any of these 30 attributes were “unacceptable” or “must-have” textures. The results of a one-way analysis of variance (ANOVA) indicated that the most important texture categories were mouthfeel, particulate, and bite resistance signaling that these categories were driving consumers' choice and that attributes within the groups were most relevant in decision-making. Across all participants, 137 attributes were identified as unacceptable. The distribution of unacceptable attributes across textural categories was uneven (χ2= 321.73; p<0.001) with most unacceptables falling within the first, second, and third most important categories for each participant. No must-have attributes were selected in the survey, indicating participants place less weight on positive textures. This conjoint survey was further utilized in Objective 2 to assess the selectivity (pickiness) of children toward food textures. Three children populations aged 10-15 were sampled: neurotypical non-picky, neurotypical picky with food texture, and children with autism spectrum disorder (ASD) who are picky with food texture. Three metrics were assessed to quantify selectivity. The first was the number of un (open full item for complete abstract)

Committee: Christopher Simons (Advisor) Subjects: Food Science

Master of Arts, Miami University, 2020, Speech Pathology and Audiology

Purpose: This study parameterized the texture of heated baby foods to increase clinical knowledge of the use of these purees in patients with oropharyngeal dysphagia. The data from this study was combined with previously acquired data to construct a statistical model describing the effect of significant independent variables on the resultant IDDSI level. Methods: A two-team, regimented heating and IDDSI protocol was applied to 62 regionally-available baby food purees across three brands (Beechnut, Gerber, and Earth's Best). The resultant data was combined with data from room temperature and cooled trials to construct a mixed-effects ANCOVA model controlling for the unwanted extraneous effects. Results: The heated samples exhibited a lower average IDDSI level than other serving temperatures. The significant independent variables from the ANCOVA model included brand, manufacturer-labeled stage, serving temperature, and whether the product contained meat. The relationships between these variables and the IDDSI levels differed from brand to brand. Conclusions: Clinicians and caregivers need to understand the effect that serving temperature and constituent ingredients have on the texture of baby food purees. They also need to consider and test foods on an individual basis as there is lack of evidence for generalizable trends between brands.

Committee: Donna Scarborough (Advisor); Michael Bailey-Van Kuren (Committee Member); Susan Brehm (Committee Member) Subjects: Food Science; Speech Therapy

Master of Science in Polymer Engineering, University of Akron, 2020, Polymer Engineering

In the recent years, thermoset powder coating has been overgrowing as a clean and environmentally friendly technology to respond increasing demands of environmental legislation and global regulatory attention for reducing Volatile Organic Compounds (VOC) in the coatings industry. It uses 100% solid components formulation including resins, pigments, fillers, curing agents, and other additives. Resins usually determine the properties of the coating such as abrasion resistance, corrosion protection, adhesion, and weatherability. Based on the resin or binder used in the powder coating, there are two coating systems: thermoplastic and thermoset. UV-powder coating was developed to achieve low-temperature thermoset curing. Incorporation of both powder curing and UV technologies provides rapid cure at lower temperatures which is suitable for heat-sensitive substrates like wood or plastic. In the UV-powder coating, the melt flow process is separated from the curing. When the coating applied on the substrate, it will be heated to the melt; then, cured by the UV light. Since the melt temperature is lower than usual, conventional cosmetic problems such as orange-peel effect and poor leveling are minimized in the UV-powder coating. In the present study a UV-curable bismaleimide methacrylated polyimide (BMI-PI-MA) was synthesized and fully characterized. BMIs are classified as thermoset polyimides (PI) with two maleimide end groups. These resins can do either thermal or UV curing. BMIs have high Tg, high thermal stability, high chemical resistance, and excellent mechanical properties. Synthesized BMI-PI-MA was mixed and formulated at different contents with a commercially available resin, UVECOAT, to study the application of UV powder coating. Resulted blends have shown the formation of polymer networks at the molten state and under UV light. Properties of UV cured films were investigated by thermomechanical analysis (TMA), differential scanning calorimetry (DSC), and dynam (open full item for complete abstract)

Committee: Mark D. Soucek PhD (Advisor); Kevin A. Cavicchi PhD (Committee Member); Thein Kyu PhD (Committee Member) Subjects: Chemical Engineering; Engineering; Polymer Chemistry; Polymers

MS, University of Cincinnati, 2019, Engineering and Applied Science: Mechanical Engineering

This thesis focuses on experimental investigation and subsequent regime mapping of the aperiodic bubbling from submerged capillary orifices through quiescent adiabatic liquids with varying viscosities. A high-speed and high-resolution digital camera is used to capture formation, departure, and coalescence of air bubbles in static liquids. Water and five glycerol-water mixture with 36%, 48%, 65%, 77%, and 87% glycerol by volume are used to alter dynamic viscosity while keeping density and surface tension nearly the same. Five stainless steel orifices with diameter- 0.8 mm, 1 mm, 1.4 mm, 1.8 mm and 2.4 mm are used to vent compressed air through the liquids with air Reynolds number ranging from 100 to 1800. With increase in the flow rate, bubble frequency increases and beyond a critical value wake effect of the preceding bubble affects the formation and departure of trailing bubble. Due to this wake effect trailing bubble rises faster and coalesces with the leading bubble. In this flow regime fluid dynamics is conducive to coupling. With further increase in the flow rate, wake effect grows in strength and facilitates coalescence of two already coalesced bubbles. This regime is called quadrupling regime. For water, a tripling regime is also observed for orifice diameters 1 and 1.8 mm, where a single trailing bubble coalesces with a coupled bubble. Effect of viscosity on aperiodic bubbling is investigated using different glycerol-water solutions. Mathematical analysis of experimental data shows that Capillary number is an appropriate physical parameter for the characterization of different bubbling regimes. Effect of orifice diameter is also studied and for smaller orifice diameters, bubbles are seen to coalesce closer to orifices and coalescence takes place at larger Capillary numbers. For quadrupling, a high value of Ca is obtained for the smallest orifice and this is almost thrice the value for the largest orifice. A correlation between Capillary Number and non (open full item for complete abstract)

Committee: Milind Jog Ph.D. (Committee Chair); Je-Hyeong Bahk Ph.D. (Committee Member); Raj Manglik Ph.D. (Committee Member) Subjects: Mechanical Engineering

Master of Science, University of Akron, 2019, Chemical Engineering

The next generation electronic devices are expected to be small in size and of magnified capacity. Denser packaging of the active components is important to miniaturize the electronic devices. Denser packaging is feasible only when heat generated by heat sources is quickly and effectively carried away to the heat sink. Next generation electronic devices with high performance microprocessors and integrated circuits along with diminished volume have led to major heat dissipation issue. Heat dissipation helps to control the temperature of the electronic devices at a desired level. Heat is dissipated to the heat sink from heat generator by the process of thermal conduction. Due to irregularities on the surfaces of the heat generator and heat sink, air is entrapped, and the air gap is formed in the path of thermal conduction. Air gap disturbs the thermal conduction as air is a really poor thermal conductor with a thermal conductivity of 0.026 W/mK at room temperature. Air acts as a thermal barrier preventing the effective heat transfer between the heat source and heat sink. Different kind of thermal interface materials are used to fill up the air gap between the heat generator and the heat sink to improve thermal conduction. Introduction of thermal interface material can significantly increase the performance of electronic device. In a typical power electronic package, a grease is used as thermal interface material. Thermal conductive paste with high thermal conductivity (much greater than air) fills up all the air gaps between the heat generator and the heat sink to improve the thermal conduction. Development of the thermal conductive paste with low thermal resistance, high thermal conductivity and low electric conductivity is challenging and the most important aspect in today's electronic industries. In the current study, we have tried to overcome this challenge by developing a thermally conductive grease with low thermal resistance, high thermal conductivity and low (open full item for complete abstract)

Committee: Jiahua Zhu PhD (Advisor); Rajeev Gupta PhD (Committee Member); Zhenmeng Peng PhD (Committee Member) Subjects: Chemical Engineering; Engineering; Polymers

Master of Arts, Miami University, 2019, Speech Pathology and Audiology

Purpose: This study evaluated characteristics of baby food in order to increase clinical knowledge about pediatric dysphagia. Important characteristics included viscosity, flow rate, cohesion, adhesion, and temperature. Samples were selected from three popular organic and non-organic brands (Gerber, Beechnut, Earth's Best) and included four manufacturing stages and a variety of ingredients (fruits, vegetables, proteins, and blends). Methods: The International Dysphagia Diet Standardization Initiative (IDDSI) and a rheometer was used in order to identify characteristics of baby foods for evaluation. Results: A significant difference was found between the brands and between the nonorganic and organic brands. No logical progression in manufacturing stages was observed; the highest manufacturing stage possessed the lowest IDDSI level. Reduced temperature of samples yielded an overall increase in IDDSI level and all samples demonstrated shear-thinning behaviors when increased force was applied. Conclusions: Findings from the results suggest clear clinical implications including the need for clinicians/caregivers to understand the characteristics of the food presented to the child and how changes in temperature and amount of agitation applied can affect the behavior of the food. Additionally, clinicians/caregivers should know how to implement IDDSI and evaluate foods.

Committee: Donna Scarborough PhD (Advisor); Michael Bailey Van Kuren PhD (Committee Member); Susan Brehm PhD (Committee Member) Subjects: Speech Therapy

Master of Science in Polymer Engineering, University of Akron, 2019, Polymer Engineering

The flow properties of rubbers have been studied for many decades to understand and predict processing behavior. The addition of reinforcing fillers, such as carbon black, is known to greatly affect the rheology of rubber compounds. The present study seeks to find a correlation between the steady shear viscosity and complex dynamic viscosity of carbon black filled rubbers by evaluating the Cox-Merz rule and an alternative approach originally proposed by Philippoff for dilute polymer solutions, but since applied to amorphous polymers and concentrated suspensions. This was done by measuring the rheological properties of 16 rubbers mixed with two different levels of N660 carbon black using a capillary rheometer and a dynamic oscillatory shear rheometer. The pressure drop, end pressure loss, shear stress, and die swell were measured on the capillary rheometer. Both small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) tests were performed on the dynamic oscillatory shear rheometer. The storage modulus, loss modulus, complex dynamic viscosity, and Fourier transform harmonics were recorded. Generally, the end pressure losses, shear stresses, storage, and loss moduli increased and the die swells decreased with increasing filler loading. Relative torque armonics increased with increasing strain amplitude and filler loading. Lissajou figures, shear stress versus shear rate, at 14% strain amplitude showed a nearly linear response for compounds with 20% volume filler. All other shear stress responses demonstrated significant nonlinearity. The complex torque waveforms at 140% strain amplitude for compounds with 35% volume filler displayed a backwards tilted shape consistent with the expectation for highly filled compounds. The complex torque waveforms at 1000% strain amplitude tended toward a rectangular shape consistent with the one expected for pure polymer. Generally, the nonlinear response of the compounds appeared to be dominated (open full item for complete abstract)

Committee: Avraam Isayev (Advisor); Thein Kyu (Advisor); Erol Sancaktar (Committee Chair) Subjects: Polymers

Master of Science, University of Toledo, 0, Mechanical Engineering

Superhydrophobic surfaces execute self-cleaning, anti-icing, and modifying heat transfer in many technological and industrial applications. In quest of maximizing water repellency, modification of droplet dynamics and subsequent reduction of contact time have been achieved by incorporating macrotexture on the superhydrophobic surfaces. However, the dynamics of low temperature water, and other viscous liquid droplets impacting anti-wetting surfaces with macrotextures is not well explored. In this thesis, we study the effect of viscosity on the bouncing dynamics of liquid droplets impacting macrotextured superamphiphobic surfaces using various glycerol-water mixtures as model liquids at different impacting conditions. Macrotextured surface are made by using an anti-wetting spray coating along with a tinned-copper wire as ridge on the silicon substrate. The complexity of viscous dissipation along the macrotexture and on the superamphiphobic surface is studied experimentally and then a new model is proposed for understanding when the macrotexture can induce maximum repellency of the viscous liquids on the superamphiphobic surfaces. A universal model for predicting minimum impact velocity for splitting is developed considering the droplet viscosity, velocity, volume, and other important parameters along with the surface characteristics and the macrotexture size. This enables engineering of surfaces for repelling droplets of viscous liquids such as freezing rain or inks during inkjet printing. Moreover, we studied the potentiality of superhydrophobic highly porous carbon nanotube (CNT) micropillars coated by the ultrathin, conformal, and low-surface-energy layer of poly (1H,1H,2H,2H-perfluorodecyl acrylate) (pPFDA) surfaces in condensation and freezing conditions (at high humidity). Droplet impact dynamics, condensate characteristics and freezing time delays are investigated on the CNT micropillars with various geometry along with the CNT forest and other commercially ava (open full item for complete abstract)

Committee: Hossein Sojoudi (Committee Chair); Reza Rizvi (Committee Member); Ana C. Alba Rubio (Committee Member) Subjects: Mechanical Engineering