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Experimental Study Of Viscoelastic Fluid-Structure Interactions, Anita Anup Dey

Doctoral Dissertations

It is well known that when a flexible or flexibly-mounted structure is placed perpendicular to a Newtonian fluid flow, it can oscillate due to the shedding of vortices at high Reynolds numbers. Unlike Newtonian fluids, viscoelastic fluid flow can become unstable even at infinitesimal Reynolds numbers due to a purely elastic flow instability occurring at large Weissenberg numbers. This thesis focuses on exploring the mechanisms of viscoelastic fluid-structure interactions (VFSI) through experimental investigations on several different combinations of flexible and flexibly-mounted circular cylinders, micro and macro-scale cantilevered beams and viscoelastic fluids such as wormlike micelle solutions and polymer solutions. VFSI …

Encapsulation And Stabilization Of Biomacromolecules, Whitney Blocher Blocher Mctigue

Doctoral Dissertations

Recent work in the area of protein encapsulation has turned away from traditional methods of sequestration toward gentler, purely aqueous techniques. Among them, complex coacervation has become a topic of discussion. Complex coacervation is an all-aqueous liquid-liquid phase separation phenomenon dominated by electrostatic interactions and entropic gains. The use of coacervates as protein encapsulants has garnered much attention, but there has been little headway in determining a set of design rules. We considered coacervation between two oppositely-charged polypeptides and a biomacromolecule cargo to investigate the effects of changing aspects of the coacervating polymers and/or various solution parameters. We characterized the …

Micro-Physiological Models To Mimic Mucosal Barrier Complexity Of The Human Intestine In Vitro, Abhinav Sharma

Doctoral Dissertations

The mucosal barrier in the intestine is vital to maintain selective absorption of nutrients while protecting internal tissues and maintaining symbiotic relationship with luminal microbiota. This bio-barrier consists of a cellular epithelial barrier and an acellular mucus barrier. Secreted mucus regulates barrier function via in situ biochemical and biophysical interaction with luminal content that continually evolves during digestion and absorption. Increasing evidence suggests that a mucus barrier is indispensable to maintain homeostasis in the gastrointestinal tract. However, the importance of mucus barrier is largely underrated for in vitro mucosal tissue modeling. The major gap is the lack of experimental material …

Rational Design Of Non-Noble Metal Intermetallic Compounds With Tunable Surface And Catalytic Chemistry Via Combined Computational And Experimental Method, Yuanjun Song

Doctoral Dissertations

This study focuses upon understanding and rationally tuning the surface reactivity towards C, H, and O of non-noble metal intermetallic compounds (IMCs) catalysts in olefin production and hydrocarbons reforming reactions. In these reactions, different degrees of surface reactivity towards C, H, and O are required to achieve high activity and selectivity as well as stability. A combined computational and experimental method was performed to build this understanding how to rationally design catalysts. Investigations based on quantum chemical calculations indicate surface reactivity towards C, H, and O is a function of element size of constituent elements as well as bulk and …

Enhanced Kinetics And Modeling Of Pan-Based Carbon Felt Anodes In Vanadium Redox Flow Batteries, Michael Cyrus Daugherty

Doctoral Dissertations

All-vanadium redox flow batteries (VRFBs) are a promising technology for grid-level energy storage, however, there are still several limitations in the forms of durability, efficiency, and overall costs, which are barriers to its commercial viability. With both bulk electrolyte flowing through its porous matrix and species flux at the solid-electrolyte interface, electrodes are the component of VRFB systems which host electrochemical reactions and facilitate contact between the liquid phase electrolyte and the electronically conductive solid phase. While the more limiting electrode in VRFB systems is dependent on the material, for polyacrylonitrile (PAN)-based carbon felts, the anode constitutes a larger portion …

Rapid Design, Construction, And Validation Of Synthetic Metabolic Pathways In A Modular Escherichia Coli (Chassis) Cell, Jong-Won Lee

Doctoral Dissertations

Current strain development has been hindered by the vast biochemical space in nature. The concept of modular cell design has been invented to enable rapid and predictable construction of multiple optimal production strains for efficient production of a large variety of biochemicals with minimal experimental effort. While modular cell design principles have been successfully validated in some cases, its development is still limited by the small library of the production modules demonstrated.

The goals of this thesis are i) to establish a framework for rapid design, construction, and validation of production modules to explore a large space of molecules (e.g., …

Local Structure And Dynamic Studies Of Mixed Ch4-Co2 Gas Hydrates Via Computational Simulation And Neutron Scattering, Bernadette Rita Cladek

Doctoral Dissertations

Permeated throughout the ocean floor and arctic permafrost, natural gas hydrates contain an estimated 3000 trillion cubic meters, over three times that of traditional shale deposits, of CH₄ that is accessible for extraction. Gas hydrates are a crystal structure in which water molecules form a cage network, the host, through hydrogen bonds while trapping a guest molecule such as CH₄ in the cavities. These compounds form naturally where the appropriate low temperature and high pressure conditions occur. A promising and tested method of methane recovery is through exchange with CO₂, which energetically takes place of the …

Approaches To Studying Bacterial Biofilms In The Bioeconomy With Nanofabrication Techniques And Engineered Platforms., Michelle Caroline Halsted

Doctoral Dissertations

Studies that estimate more than 90% of bacteria subsist in a biofilm state to survive environmental stressors. These biofilms persist on man-made and natural surfaces, and examples of the rich biofilm diversity extends from the roots of bioenergy crops to electroactive biofilms in bioelectrochemical reactors. Efforts to optimize microbial systems in the bioeconomy will benefit from an improved fundamental understanding of bacterial biofilms. An understanding of these microbial systems shows promise to increase crop yields with precision agriculture (e.g. biosynthetic fertilizer, microbial pesticides, and soil remediation) and increase commodity production yields in bioreactors. Yet conventional laboratory methods investigate these micron-scale …

Multiscale Simulations Of Polymeric Electrolytes For Electrochemical Devices, Xubo Luo

Doctoral Dissertations

Polymeric electrolytes are polymers containing the ionic moieties used for ion conduction in electrochemical devices. The strategic design of these materials requires the in-depth understanding of the relation between the molecular structure and the properties. This dissertation reports on computational simulations for two types of materials: hydrated anion exchange membranes (AEMs) for fuel cells and the polymerized ionic liquids (PolyILs). Various chemical structures were covered for systematic investigations.

For AEMs, the ion conducting channels or domains are essential for the efficient ion transport, and thus the morphology of the hydrated membrane is worthy of study. Dissipative particle dynamics simulations were …

Manufacturing Of Carbon-Based Hybrid Nanocomposites With Engineered Functionalities Via Laser Ablation Synthesis In Solution (Lasis) Techniques, Erick Leonardo Ribeiro

Doctoral Dissertations

Carbon-based composite materials have long been fabricated and extensively used in our daily lives. In the past decades, with rapid development of nanotechnology, these class of material have gained even more attention owing to their outstanding properties which directly results in their prospects to revolutionize technological development in many fields, ranging from medicine to electronics. Nevertheless, for certain applications, including electrochemical energy storage/conversion devices, the chemically inert nature of these materials creates obstacles and thus requires their coupling with other active species. This thesis explores the use of Laser Ablation Synthesis in Solution (LASiS) in tailoring promising strategies and pathways …

Nano- And Micro-Structured Temperature-Sensitive Hydrogels For Rapidly Responsive Devices, Qi Lu

Doctoral Dissertations

This thesis aims to extend the understanding and explore the application of temperature-responsive hydrogel systems by integrating microelectromechanical systems (MEMS). Stimuli-responsive hydrogel systems are immensely investigated and applied in numerous fields, and interfacing with micro- and nano-fabrication techniques will open up more possibilities. In Chapter 2, the first biologically relevant, in vitro cell stretching device based on hydrogel surface instability was developed. This dynamic platform is constructed by embedding micro-heater devices under temperature-responsive surface-attached hydrogels. The fast and regional temperature change actuates the stretching and relaxation of the seeded human artery smooth muscle cell (HASMC) via controllable surface creasing instability. …

Sequence Control Of Complex Coacervation, Li-Wei Chang

Doctoral Dissertations

Complex coacervation is a liquid-liquid phase separation driven by the complexation of oppositely charged polyelectrolytes. The resulting coacervate phase has been used for many applications, such as underwater adhesives, drug delivery, food and personal care products. There also has been increasing interest in coacervate-like droplets occurring in biological systems. The majority of these “membraneless organelles” involve a combination of intrinsically-disordered proteins and RNA, and phase separate due to long-range charge effects and short-range hydrophobic effects. While evolution has optimized the self-assembly of these types of biological polymers, our ability to design such materials remains limited, in part because the relevant …

Development And Characterization Of Robust And Cost-Effective Catalysts For Selective Biomass Upgrading To Fuels And Chemicals By Deoxydehydration, Bryan E. Sharkey

Doctoral Dissertations

The use of biomass-derived ligno-cellulose as a possible alternative source of fuels and chemicals to fossil-based hydrocarbons, however, biomass offers many challenges based on processing and its high oxygen content. One promising upgrading route is deoxydehydration, a reaction which combines a deoxygenation by a sacrificial reductant and dehydration in a single step to selectively convert vicinal diols into an olefin. This reaction is highly selective when using homogeneous oxo-rhenium catalysts, which can easily undergo the necessary changes in coordination and oxidation state, however the high cost of rhenium and difficulty of homogeneous catalyst recovery make these catalysts untenable for large …

Elucidating Mechanisms Of Metastasis With Implantable Biomaterial Niches, Ryan Adam Carpenter

Doctoral Dissertations

Metastasis is the leading cause of cancer related deaths, yet it remains the most poorly understood aspect of tumor biology. This can be attributed to the lack of relevant experimental models that can recapitulate the complex and lengthy progression of metastatic relapse observed in patients. Mouse models have been widely used to study cancer, however they are critically limited to study metastasis. Most models generate aggressive metastases in the lung without the use of unique cell lines or specialized injection techniques. This limits the ability to study disseminated tumor cells (DTCs) in other relevant metastasis prone tissues. Prolonged observation of …

Kinetics Of The Crystal-Melt Phase Transformation In Semicrystalline Polymers, Kiran Subramaniam Iyer

Doctoral Dissertations

The assembly of long-chain polymers into an ordered state is a process that has puzzled polymer scientists for several decades. A process that is largely controlled by the strength of intermolecular attractions in small molecular systems, this crystallization in the case of polymers is controlled by a competition between the aforementioned force of attraction between monomers and the formidable conformational entropy of polymer chains. Any factor that affects this conformational entropy, whether that is an equilibrium thermodynamic factor or a kinetic factor, has the ability to control polymer crystallization. In this thesis, we focus on understanding the underlying kinetic processes …

Characterizing Non-Linear Structural, Mechanical, And Volumetric Properties Of Aliphatic And Aromatic Thermosets, Brendan Robert Ondra

Doctoral Dissertations

A unifying theme throughout this dissertation employs advanced experimental mechanics, including the design and development of new instruments, testing techniques, and analysis strategies. Chapter 1 covers the design and development of a new instrument for polymer and composite characterization. More specifically, a bi-fluidic, confining-fluid, pressurizable dilatometer (referred to herein as the BFCF-PVT). Whereas both classical and contemporary confining-fluid type pressurizable dilatometers utilize a bellows and / or piston system along with a Linear Variable Displacement Transducer to apply pressure and track volume changes, the BFCF-PVT that was designed and built utilizes a fluid-fluid interface (composed of two immiscible fluids that …

The Effect Of Oxygen On Properties Of Zirconium Metal, Jie Zhao

Doctoral Dissertations

The influence of oxygen on the thermophysical properties of zirconium has been investigated using MSL-EML (Material Science Laboratory Electromagnetic Levitator) on ISS (International Space Station) in collaboration with NASA (National Aeronautics and Space Administration), ESA (European Space Agency), and DLR (German Aerospace Center). Zirconium samples with different oxygen concentrations was subjected to multiple melt cycles during which the thermophysical properties, such as density, viscosity and surface tension, have been measured at various undercooled and superheated temperatures. Also, there are melt cycles for verifying the solidification mechanism. Similar samples were found to show anomalous nucleation of the solid for certain ranges …

Metabolic Modeling Of Multispecies Microbial Biofilms, Poonam Phalak

Doctoral Dissertations

Biofilms are ubiquitous in medical, environmental, and engineered microbial systems. The majority of naturally occurring microbes grow as mixed species biofilms. These complicated biofilm consortia are comprised of many cell phenotypes with complex interactions and self-organized into three-dimensional structures. Approximately 2% of the US population suffers from non-healing chronic wounds infected by a combination of commensal and pathogenic bacteria whereas about 500,000 cases of Clostridium difficile infections (CDI) are reported annually. These polymicrobial infections are often resilient to antibiotic treatment due to the nutrient-rich environments and species interactions that promote community stability and robustness. This thesis focusses on developing metabolic …

Surface Driven Flows : Liquid Bridges, Drops And Marangoni Propulsion, Samrat Sur

Doctoral Dissertations

Molecules sitting at a free liquid surface against vacuum or gas have weaker binding than molecules in the bulk. The missing (negative) binding energy can therefore be viewed as a positive energy added to the surface itself. Since a larger area of the surface contains larger surface energy, external forces must perform positive work against internal surface forces to increase the total area of the surface. Mathematically, the internal surface forces are represented by surface tension, defined as the normal force per unit of length. One common manifestation of surface tension is the difference in pressure it causes across a …

Engineered Nanoparticles For Site-Specific Bioorthogonal Catalysis: Imaging And Therapy, Riddha Das

Doctoral Dissertations

Bioorthogonal catalysis offers a strategy for chemical transformations complementary to bioprocesses and has proven to be a powerful tool in biochemistry and medical sciences. Transition metal catalysts (TMCs) have emerged as a powerful tool to execute selective chemical transformations, however, lack of biocompatibility and stability limits their use in biological applications. Incorporation of TMCs into nanoparticle monolayers provides a versatile strategy for the generation of bioorthogonal nanocatalysts known as “nanozymes”. We have fabricated a family of nanozymes using gold nanoparticles (AuNPs) as scaffolds featuring diverse chemical functional groups for controlled localization of nanozymes in biological environments, providing unique strategies for …

Catalytic Utilization Of Carbon Dioxide As Renewable Feedstock For Production Of Chemicals And Fuels, Abbas Alaa Jawad

Doctoral Dissertations

"The utilization of CO₂ as a renewable feedstock for producing commodity chemicals and fuels is an interesting challenge to explore new concepts and opportunities in catalysis and industrial chemistry. This sustainable approach not only leads to production of useful chemicals, but also has the potential to mitigate anthropogenic CO₂ emissions to the atmosphere. CO₂ itself is a sustainable and inexhaustibly available carbon source, however, it is inextricably linked to its inherent inertness. It is a thermodynamically stable molecule (ΔG_f = -394.01 kJ.mol^-1) with high oxidation state, hence, reactions of CO₂ must be combined …

Studies On The Stability Of Plasma Proteins And Their Fragments, Paul Praveen Nakka

Doctoral Dissertations

“The stability of a protein-based biological drug is an important concern during processing, storage or patient administration. There are various forces which contribute to the stabilizing of proteins. Both hydrogen bonds and hydrophobic interactions play an important role in protein stability. Improper folding or misfolding of proteins leads to aggregation, which is a major problem found in the bioprocessing industry. The objectives of this research are: 1) to determine the effect of environmental factors such as pH, temperature, additives or salts, and cosolvents on the stability human serum albumin (HAS), which is the most abundant protein in plasma, 2) to …

Integrated Approach To Investigate The Wellbore Integrity Under Downhole Conditions, Weicheng Zhang

Doctoral Dissertations

“The integrity of the cement sheath is the key part to maintain zonal isolation and prevent the inter-zonal communication. Loads arising from multiple stages of wellbore life span may induce various modes of cement failure within the cement (disking and radial cracks) and at the cement-casing and the cement-formation interfaces (debonding fractures). This research utilizes the integrated laboratory and numerical approach to investigate the cement hardening process, to predict the cement failure under various loading conditions. An innovative experimental setup is established to measure the cement pore pressure variation during the hardening process under downhole conditions, and a staged 3D …

Experimental And Modeling Studies Using Packed Bed Reactors: Liquid Phase Ethylene Production By Hydrogenation Of Acetylene, Humayun Shariff

Doctoral Dissertations

"Gas-phase catalytic hydrogenation of acetylene to produce ethylene, commonly practiced in industries, has green oil formation, which leads to catalyst deactivation and sometimes reactor runaway risks due to high exothermicity. To overcome these issues as well as to increase the selectivity and conversion, liquid-phase hydrogenation of acetylene was investigated in packed bed reactors (PBR) using a commercial catalyst. The reactor performance of two-phase flow PBRs was assessed experimentally complemented by a validated mathematical model at different scales.

The selective hydrogenation of acetylene in the liquid phase over a commercial 0.5 wt% Pd/Al₂O₃ catalyst was investigated in a …

Strategies To Improve The Electrochemical Performance Of Lithium-Ion Batteries By Stabilizing The Interface Of Electrode/Electrolyte, Ye Jin

Doctoral Dissertations

”Lithium-ion batteries (LIBs) provide great potential for electric vehicles, and smart grids as future energy-storage devices. However, there are many challenges in the development of the LIB industry, including low energy and power density of electrode materials, poor rate performance, short cycle life of electrode materials, and safety issues caused by the flammability of the conventional organic liquid electrolytes.

In this research, we were committed to using general approach to efficiently and economically synthesize or modify LIB materials by stabilizing the interface between electrode and electrolyte. Atomic layer deposition (ALD) method was used to coat metal oxide thin films on …

Exploring Wellbore And Reservoir Temperature Profiles In Fluid Circulation And Production Operations, Ahmed Qasim Al Saedi

Doctoral Dissertations

"The wellbore heat flow occurs during different well operations resulting from any temperature differences between the wellbore fluid and the adjacent formation. Understanding the direction and mechanism of heat flow whether it is conduction or convection help to represent this heat exchange mathematically. However, the only available factor used to understand the heat flow behavior is the measured wellbore temperature which can be obtained from the direct measurement while drilling or circulation operations, well logging, well test, or from the production operations. Also, the initial geothermal formation temperature resulting from the geothermal gradient will help to understand the undistributed formation …

Factors Impacting The Transport And Enhanced Oil Recovery Potential Of Polymeric Nanogel In Sandstone, Haifeng Ding

Doctoral Dissertations

"Enhanced oil recovery (EOR) using nanometer-sized particles has drawn great attention in the oil industry because of their various advantages brought by size. However, their applications on a field scale are very limited, especially for deformable nanoparticles. The objective of this research is to explore the transport behavior of deformable polymeric nanoparticles (nanogel), the factors impacting these behavior, and their EOR potentials. First, 240 published nanoparticle core flooding experiment data were collected and analyzed about the extent to what the nanoparticles can improve oil recovery. Results show that on the laboratory scale the incremental oil recovery could be as high …

Investigating The Factors Impacting The Success Of Immiscible Carbon Dioxide Injection In Unconventional Shale Reservoirs: An Experimental Study, Sherif M. Fakher

Doctoral Dissertations

"Unconventional shale reservoirs are currently gaining significant interest due to the huge hydrocarbon volumes that they bear. Enhanced oil recovery (EOR) techniques have been suggested to increase recovery from shale reservoirs. One of the most promising EOR methods is gas EOR (GEOR), most notably carbon dioxide (CO₂). Not only can CO₂ increase oil recovery by interacting with the oil and the shale, but it has also been shown to adsorb to the shale rock and thus is effective in both EOR applications and also carbon storage purposes. This research aims to experimentally investigate several of the interactions …

Evaluation Of The Performance Of Different Polymer Gel Systems As An In-Depth Gel Treatment Using Numerical Simulation, Tariq K. Khamees

Doctoral Dissertations

"Oil production from heterogeneous and naturally fractured reservoirs are usually hindered due to the presence of high-permeability streaks and natural fractures networks. Oil production could be more lowered if there is a crossflow from the high- to the low-permeability layers and high mobility ratio. These problems are called conformance problems and the treatment is called conformance improvement technologies (CITs). The aims of CIT is to correct the heterogeneity of the reservoir and to lower the unfavorable mobility ratio. These technologies are leading to the diversion of post-treatment water into the low-permeability layers and to increase the viscosity of the displacing …

Polymeric Nanoparticle As A New Platform For High Removal Of Endotoxins From Biopharmaceutical Solutions, Sidharth Razdan

Doctoral Dissertations

"Presently, approximately one-third of all biopharmaceutical drugs are derived from biological sources like gram-negative bacteria. Gram-negative bacteria like E.coli are much cheaper to cultivate and provide higher biotherapeutic yield compared to mammalian cells. On extracting the useful biotherapeutics from the gram-negative bacterial cells (E.coli), endotoxin present in the bacteria is released in the surrounding media thus contaminating the lifesaving biotherapeutics. Application of the endotoxin-contaminated therapeutics to humans or animals can cause serious health issues like septic shock, tissue injury and ultimately death. Hence, thorough purification of biotherapeutics before parenteral application is necessary. Although there are multiple methods for …