Engineering Commons^™

Characterization Of Lignin Structural Variability And The Associated Application In Genome Wide Association Studies, Nathan D. Bryant

Doctoral Dissertations

Poplar (Populus sp.) is a promising biofuel feedstock due to advantageous features such as fast growth, the ability to grow on marginal land, and relatively low lignin content. However, there is tremendous variability associated with the composition of biomass. Understanding this variability, especially in lignin, is crucial to developing and implementing financially viable, integrated biorefineries. Although lignin is typically described as being comprised of three primary monolignols (syringyl, guaiacyl, p-hydroxyphenyl), it is a highly irregular biopolymer that can incorporate non-canonical monolignols. It is also connected by a variety of interunit linkages, adding to its complexity. Secondary cell wall …

Understanding Lignin’S Fast Pyrolysis Through Examination Of The Thermolysis Mechanisms Of Model Oligomers, Ross Wesley Houston

Doctoral Dissertations

The lignocellulosic biorefinery is a visionary concept that endeavors to provide an alternative to fossil-based refineries by producing biobased fungible fuels and specialty chemicals almost exclusively derived currently from petroleum refineries. This vision of the lignocellulosic biorefinery can only be realized if all fractions of lignocellulosic biomass are efficiently deconstructed and valorized to generate a diverse portfolio of products to sustain it against market vicissitudes. Of the three main structural constituents of lignocellulosic biomass (i.e., cellulose, hemicellulose, and lignin), lignin is underutilized despite being the most abundant renewable source of aromatic platform chemicals, representing a growing 250 billion dollar market. …

Evaluation Of Biomass As Bio-Additive In 3d Printing, Shuyang Zhang

Doctoral Dissertations

The petrol-based polymer has been widely applied in current daily life. The end-of-life of polymeric products has drawn environmental concerns. One of the solutions to such issues is to use bio-renewable materials to replace or reduce the use of petrol-based materials. Lignocellulosic materials are one of the potential candidates. Along with the features of 3D printing and the unique properties of biomass, 3D-printed biomass-based materials could be promising in preparing sustainable alternatives.

In this dissertation, lignin and other biomass were applied to various 3D printing techniques for sustainable composites. Stereolithography (SLA) was first used, and the kraft softwood lignin was …

Xanthan Gum Isolation Alternative Via Ultrafiltration, Anna Beth Malone, Jeffrey Greer, Lareesa Thomas, Lucy Moore

Chancellor’s Honors Program Projects

No abstract provided.

Analysis Of Physicochemical Properties And Terrestrial Dynamics Of Mechanically Formed Micro-Nano Scaled Particles From Agricultural Plastic Mulches, Anton Friedrich Astner

Doctoral Dissertations

Release of microplastics (MPs) and nanoplastics (NPs) into agricultural fields is of great concern due to their reported ecotoxicity to organisms that provide beneficial service to the soil such as earthworms, and the potential ability of MPs and NPs to enter the food chain. Most fundamental studies of the fate and transport of plastic particulates in terrestrial environments employ idealized MP materials as models, such as monodisperse polystyrene spheres. In contrast, plastics that reside in agricultural soils consist of polydisperse fragments resulting from degraded films employed in agriculture. There exists a need for more representative materials in fundamental studies of …

Confinement And Interface Effects In Self Assembly Of Functional Block Copolymers, Jonathan P. Coote

Doctoral Dissertations

Functional block copolymers are of increasing interest for their ability to combine the functional properties of one polymer, such as a polymer electrolyte or semiconductor, with the mechanical properties of another polymer. Balancing properties in this way can be challenging, however, due to the complex relationship between self-assembled morphology and resulting properties. Interface effects in particular, whether due to confinement within a self-assembled domain or at macroscopic boundary, are poorly understood in such functional block copolymers. This dissertation consists of two main thrusts, each investigating confinement or interfacial effects in a different functional block copolymer system. The first thrust focuses …

Functional Bottlebrush Polymer Additives For Thin Films And Coatings, Travis S. Laws

Doctoral Dissertations

Bottlebrush polymers are a class of highly branched polymers consisting of polymeric side chains that are densely grafted to a linear backbone. Their highly branched architecture results in surface enrichment across a broad range of materials. The goal of my research has been centered around the design of functional bottlebrush polymers and their use as surface active additives in blend films and coatings.

In the first chapter, we examine the segregation behavior of polystyrene bottlebrushes that are blended with linear polystyrene. We systematically vary the lengths of the bottlebrush backbone (Nb), side-chain (Nsc), and the linear matrix (Nm) in order …

A Rapid And Ultra-Sensitive Biosensing Platform Based On Tunable Dielectrophoresis For Robust Poc Applications, Yu Jiang

Doctoral Dissertations

With the ongoing pandemic, there have been increasing concerns recently regarding major public health issues such as abuse of organophosphorus compounds, pathogenic bacterial infections, and biosecurity in agricultural production. Biosensors have long been considered a kernel technology for next-generation diagnostic solutions to improve food safety and public health. Significant amounts of effort have been devoted to inventing novel sensing mechanisms, modifying their designs, improving their performance, and extending their application scopes. However, the reliability and selectivity of most biosensors still have much to be desired, which holds back the development and commercialization of biosensors, especially for on-site and point-of-care (POC) …

Elucidating Mammalian Cellular Responses To The Uptake Of Nanoparticles (Nps), Pathogens, And Lipoproteins: Similarities And Differences, Monireh Asoudeh

Doctoral Dissertations

Soft poly-ethylene-glycol (PEG)-based soft nanoparticles (NPs) including cylindrical (CNPs) micelles, spherical (SNPs) micelles, and lipid bilayer vesicles (LNPs) are thought to be treated as foreign objects by mammalian phagocytes. If this hypothesis is true, NPs should trigger a proinflammatory, autophagic phenotype that is similar to the one seen when macrophages phagocytose pathogens or when macrophage surface expressed proteins bind pathogen surface factors such as lipopolysaccharide (LPS). Here, we show that macrophage responses to the above NPs are almost completely unique from those triggered by group A streptococcus (GAS) pathogens (JRS4 cells) and LPS. Instead, macrophages treat these soft NPs more …

Crowd Control: Regulating The Spatial Organization Of Biopolymers And Gene Expression By Macromolecular Crowding, Gaurav Chauhan

Doctoral Dissertations

The intracellular environment is crowded with macromolecules that can occupy a significant fraction of the cellular volume. This can give rise to attractive depletion interactions that impact the conformations and interactions of biopolymers, as well as their interactions with confining surfaces. We used computer simulations to study the effects of crowding on biologically-inspired models of polymers. We showed that crowding can lead to attractive interactions between two flexible ring polymers, and we further characterized the adsorption of both flexible and semiflexible polymers onto confining surfaces. These results indicate that crowding-induced depletion interactions could play a role in the spatial organization …

Biomass Conversion To Bio-Derived Materials And Their Applications, Luna Liang

Doctoral Dissertations

Nowadays, fossil fuels still serve as the primary global energy resource. Replacing fossil fuels with renewable sources of energy and developing efficient energy storage technology is an urgent problem to solve. Lignocellulosic biomass has been investigated as a promising alternative for the production of biofuels, chemicals, and materials. In this dissertation, we studied the thermochemical biomass conversion strategies via different pretreatments strategies (e.g. dilute acid, ethanol, tetrahydrofuran, gamma-valerolactone) and genetic modification to overcome the biomass recalcitrance and achieve efficient conversion process. The biomass component structure of lignin and cellulose after thermal treatments were characterized and analyzed.

To further explore the …

Electrode Development Of Water Electrolyzer Cells For Low-Cost And High-Efficiency Hydrogen Production, Shule Yu

Doctoral Dissertations

A worldwide increase in energy demand and a latent crisis in the fossil fuel supply have spurred broad research in the renewable energy. Currently, most renewable energy resources (e.g., hydro, wind, solar, tide) face supply challenges as they are known to be intermittent, unstable, and locally shackled, which calls for urgent development in energy storage and conversion. Hydrogen is regarded as an ideal energy carrier with its advantages (e.g., high energy density, environmentally friendliness, and low weight). In practice, the proton exchange membrane electrolyzer cell (PEMEC) is considered to be one of the optimal hydrogen production and energy storage devices …

Oligodimethylsiloxanes With Charged Chain Ends: Synthesis, Characterization, And Properties, Tianyu Li

Doctoral Dissertations

Charged polymers have been intensively studied because of their scientific and industrial importance. In certain cases, a single charged group in the chain end can alter the structure and properties of a polymer dramatically. On the other hand, oligomers, which are different from both discrete small molecules and higher molecular weight polymers, have become an emergent class of materials. There are several charged chain-end functionalized oligomers reported, but this area has been largely unexplored. The work described in this dissertation is aimed at using well-characterized end-group functionalized oligodimethylsiloxane (oDMS) as model materials to understand the effects of charged end groups …

Interactions Between Soft Nanoparticles And Mammalian Cells, Mitchell Raith

Doctoral Dissertations

Nanoparticles have been of interest to the pharmaceutical industry since the 1980s. The first FDA approved nanoparticle-based therapies included liposomal anesthesia agents. Since then, the amount of FDA-approved nanoparticle therapies remains low. This is because nanoparticle-patient interactions can be very complex and are not well understood. Complicating factors also include increasing obesity rates among the patient population and many small animal pre-clinical trials are completed with healthy, lean animals. The biochemical differences between lean and obese patients prevents early studies from accurately predicting nanoparticle clinical behaviors. Many nanoparticles fail in trails. In this thesis, I aimed to uncover how nanoparticles …

Accelerated Catalyst Diffusion In Chemically Amplified Resists, Christopher M. Bottoms

Doctoral Dissertations

Quantitative reaction-diffusion models are critical for the development of high-resolution lithographic processes based on chemically amplified resists (CARs). CARs consist of a glassy polymer resin with a photoacid generator. Patterns are formed through a coupled reaction-diffusion process. It is known that reaction kinetics is controlled by the slow diffusion of acid-anion pairs (catalysts), and catalyst diffusion lengths partly control the pattern resolution and uniformity. However, it is difficult to quantify the diffusivity during reaction, let alone examine the roles of polymer-ion and ion-ion interactions on catalyst mobility, using direct measurements. This work presents a concerted experimental and computational effort to …

Improving The Biocompatibility Of The Bio-Inorganic Interface For Enhanced Photosystem I-Based Biophotovoltaic Device Performance, Alexandra H. Teodor

Doctoral Dissertations

The world’s energy demands are projected to increase by nearly 50% by the year 2040, and consumption of carbon-based fuels continues to release greenhouse gases such as carbon dioxide and methane into the atmosphere. This has been causally linked with climate change and increased extreme weather events, which has been further linked to adverse health outcomes and negative effects on biodiversity, food security, and increased disease transmission. Clearly, there is a need for a sustainable, carbon-free, and cost-effective method of energy production to meet growing energy production demands. The sun irradiates Earth’s surface annually with ~80,000 terawatts (TW), making solar …

Defining Interactions Between Deformable Dna Origami And Lipid Bilayers Through Molecular Dynamics Simulation, Zachary A. Loyd

Chancellor’s Honors Program Projects

No abstract provided.

Structural Stability Of Thermosets During Material Extrusion Additive Manufacturing, Stian K. Romberg

Doctoral Dissertations

Over the past decade, the scale of polymer additive manufacturing has been revolutionized with machines that print massive thermoplastic parts with greater geometric complexity than can be achieved by traditional manufacturing methods. However, the heat required to print thermoplastics consumes energy and induces thermal gradients that can reduce manufacturing flexibility and final mechanical properties. With the ability to be extruded at room temperature and excellent compatibility with fibers and fillers, thermoset resins show promise to decrease the energy consumption, expand the manufacturing flexibility, and broaden the material palette offered by large-scale polymer additive manufacturing. However, structural instability in the uncured …

Purification Of I-129 From Spent Pwr Fuel, Sydney B. Whitaker, Kaitlyn Pierson, Kaylie Richard, Samantha Cahill

Chancellor’s Honors Program Projects

No abstract provided.

Characterization Techniques And Cation Exchange Membrane For Non-Aqueous Redox Flow Battery, Kun Lou

Doctoral Dissertations

The motivation of this work comes from one of the major problems of emerging non-aqueous flow battery (NAFB) that a separator or membrane which facilitates conductivity and blocks redox species crossover does not exist. Although many aspects of principles can be mirrored from mature fuel cell and aqueous flow battery, it is found that some well-defined membrane properties in aqueous systems such as swelling, transport and interactions are different in non-aqueous solvents to some extent. However, the approach of this work does follow the way perfluorosulfonate ion exchange membrane (PFSA) facilitated development of fuel cell and aqueous flow battery in …

Thermochemical And Continuum Modeling To Understand The Chemical Composition Of Pwr Fuel Crud, Jason T. Rizk

Doctoral Dissertations

Computational modeling of Chalk River Undesirable Deposits (CRUD) allows for the prediction of associated phenomena that impact nuclear power plant performance, reliability, and safety. It also provides insight into the physical mechanisms by which CRUD forms and affects plant performance. A major concern in pressurized water reactors (PWRs) is Axial Offset Anomaly (AOA) which is caused by CRUD’s proficiency at trapping boron within the reactor core. The ability to predict AOA and other phenomena requires a detailed explanation of the chemical composition of CRUD. By pairing computational models that can simulate the structure and species trapping with detailed thermochemical models, …

Experimental And Computational Study Of Determining Mass Transport Parameters In Vanadium Redox Flow Batteries, Tugrul Y. Ertugrul

Doctoral Dissertations

Vanadium redox flow batteries are a promising large-scale energy storage technology, but a number of challenges must be overcome for commercial implementation. At the cell level, mass transport contributes significantly to performance losses, limiting VRFB performance. Therefore, understanding mass transport mechanisms in the electrode is a critical step to mitigating such losses and optimizing VRFBs.

In this study, mass transport mechanisms (e.g. convection, diffusion) are investigated in a VRFB test bed using a strip cell architecture, having 1 cm² active area. It is found that diffusion-dominated cells have large current gradients; convection-dominated cells have relatively uniform current distribution from …

Development Of Density-Functional Tight-Binding Methods For Chemical Energy Science, Quan Vuong

Doctoral Dissertations

Density-functional tight-binding (DFTB) method is an approximation to the popular first-principles density functional theory (DFT) method. Recently, DFTB has gained considerable visibility due to its inexpensive computational requirements that confer it the capability of sustaining long-timescale reactive molecular dynamics (MD) simulations while providing an explicit description of electronic structure at all time steps. This capability allows the description of bond formation and breaking processes, as well as charge polarization and charge transfer phenomena, with accuracy and transferability beyond comparable classical reactive force fields. It has thus been employed successfully in the simulation of many complex chemical processes. However, its applications …

Elucidating Mechanisms And Genotypes Underlying Robust Phenotypes In Yarrowia Lipolytica, Caleb M. Walker

Doctoral Dissertations

Robustness is an important phenotype for bioenergy microbes to acquire but is difficult to engineer. Hence, tools for engineering microbial robustness are critical to unlock novel phenotypes for innovative bioprocessing strategies. The oleaginous yeast, Yarrowia lipolytica, is an exceptionally robust microbe that can tolerate stressful environments, assimilate a wide range of substrates, and produce high-value chemicals. In this doctoral dissertation, the impacts of systems biology and metabolic engineering to reveal mechanisms and identify genotypes- underlying robust phenotypes are addressed.

The first approach employs adaptive laboratory engineering to generate a platform strain by which to study superior robust mechanisms. This …

Unraveling The Effects Of Molecular Confinement On The Dynamics Of Polymeric Systems: I. Block Copolymer Architecture Ii. Silica Nanopores, Thomas P. Kinsey

Doctoral Dissertations

In this dissertation, broadband dielectric spectroscopy (BDS) is employed as an experimental tool to probe dipolar relaxations in polymeric systems under two types of molecular confinement. First a series of miktoarm star copolymers are used to explore how branching block copolymer architectures constrain polymer relaxations within self-assembled domains in relation to linear systems. Secondly, the effects of hard spatial confinement on the dynamics of polymer chains and of ions in polymerized ionic liquids (PILs) are studied after infiltration into silica nanochannels. Complementary techniques such as transmission electron microscopy, small angle x-ray scattering, and Raman spectroscopy are used to determine various …

The Controlled Synthesis Of Hydrogen Electrocatalysts For Alkaline Exchange Membrane Fuel Cell And Electrolysis Applications Via Chemical Vapor Deposition, Stefan Thurston Dubard Williams

Doctoral Dissertations

The development of catalysts for the electrochemical processes of hydrogen systems (e.g., fuel cells and electrolyzer systems) continues to be an attractive area of research for renewable energy technologies. One significant challenge has been developing hydrogen catalysts suitable for alkaline environments, mainly due to the sluggish kinetics of hydrogen reactions. In alkaline environments, the kinetics are decreased by two orders of magnitude when compared to acidic environments. Chemical vapor deposition (CVD) is a conventional method used to synthesize these types of catalysts. This effort discusses extending work being done using a modified CVD process known as “Poor Man’s” CVD (PMCVD) …

Engineering Modularity Of Ester Biosynthesis Across Biological Scales, Hyeongmin Seo

Doctoral Dissertations

Metabolic engineering and synthetic biology enable controlled manipulation of whole-cell biocatalysts to produce valuable chemicals from renewable feedstocks in a rapid and efficient manner, helping reduce our reliance on the conventional petroleum-based chemical synthesis. However, strain engineering process is costly and time-consuming that developing economically competitive bioprocess at industrial scale is still challenging. To accelerate the strain engineering process, modular cell engineering has been proposed as an innovative approach that harnesses modularity of metabolism for designing microbial cell factories. It is important to understand biological modularity and to develop design principles for effective implementation of modular cell engineering. In this …

Stretching The Applications Of Biomass: Development Of Lignin Based Thermoplastic Elastomers And Composite Materials, Anthony Stephen Bova

Doctoral Dissertations

Bio-based plastics and composites have seen increased industry adoption in recent years due to growing demand for materials with a low carbon footprint. The use of lignin as a feedstock for polymers has seen growing interest as the concept of an integrated cellulosic biorefinery gains traction and advances the need to use all components of separated biomass for value-added applications. Historically, use of lignin in thermoplastic and elastomeric copolymers and blends has been bottlenecked by the inability to introduce lignin content above 30 weight percent due to difficulties with interfacial adhesion of lignin with other soft segments. Efforts to overcome …

Thorium Dioxide Extraction From Monazite Ore, Katherine Glass

Chancellor’s Honors Program Projects

No abstract provided.

Thorium Dioxide Extraction From Monazite Ore, Jason Pan, Niall Phelan Terry, Katherine Glass, Eli Jenkins, Connor High

Chancellor’s Honors Program Projects

No abstract provided.