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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 …

Ultrasound-Driven Fabrication Of Nanosized High-Entropy Materials For Heterogeneous Catalysis, Francis Uchenna Okejiri

Doctoral Dissertations

High-entropy materials (HEMs) have emerged as a new class of multi-principal-element materials with great technological prospects. As a unique class of concentrated solid-solution materials, HEMs, formed on the premise of incorporating five or more principal elements into a single crystalline phase, provide an excellent opportunity to access superior catalytic materials ‘hiding’ in the unexplored central regions of a multicomponent phase space of higher orders.

However, the fabrication of HEMs is energy-intensive, typically requiring extreme temperatures and/or pressures under which agglomeration of particles occurs with a commensurate decrease in surface area. For most catalytic applications, non-agglomerated particles with high surface areas …

Exploring Novel Anti-Obesity Strategies: Nutritional And Pharmacological Interventions To Induce Browning And Brown Adipogenesis, Haley Beth Overby

Doctoral Dissertations

Obesity is a global pandemic and its comorbidities are the top causes of preventable death in America. Brown and inducible beige fat can significantly contribute to energy expenditure, possibly leading to weight loss, and is considered a novel approach to combat obesity. Browning of white adipocytes can be achieved using cold exposure, β [beta]-adrenergic receptor (β-AR) and peroxisome proliferator-activated receptor gamma (PPAR [gamma]) agonists, and some nutritional and pharmaceutical agents. Trans-resveratrol (Res) and indomethacin (Indo) have shown promising abilities to promote browning. Res has been shown to induce browning in vitro and in vivo; however, its rapid metabolism and poor …

Observation Of Baryon Number Violation Via Cold Neutron Sources, Matthew Frost

Doctoral Dissertations

The observation of neutron/anti-neutron transformation would directly, and for the first time, demonstrate that there are processes that violate baryon number, thus revealing the fundamental mechanism of the origin of our universe. Prior experiments that would show the existence of such transformations are inconclusive thus far, providing only lower limits for the transformation rate. New experiments utilizing cold neutrons at spallation sources such as the European Spallation Source (ESS) provide a means by which to search for these higher energy scale phenomena beyond that which can be achieved with a collider. An experiment with the opportunity to contribute to the …

Nanobrazing Of Inconel 718 And Ti-6al-4v, Denzel Bridges

Doctoral Dissertations

For high temperature brazing applications, several design considerations must be evaluated including metallurgical compatibility, mechanical stability, wettability, and many others. One of the obstacles to high temperature brazing is minimizing the melting temperature of the brazing material without sacrificing high operating temperature. Traditionally, this is accomplished by adding melting point depressants such as boron and silicon. However, the addition of boron and silicon exposes the base material to the formation of brittle boride and silicide intermetallic phases and/or low melting eutectic phases. Nanomaterials experience size-dependent melting point depression without the use of melting point depressants via the Gibbs-Thomson effect. Until …

Synthesis And Application Of Oil-Soluble Polymer Brush-Grafted Silica Nanoparticles As Lubricant Additives For Friction And Wear Reduction, Bryan Thomas Seymour

Doctoral Dissertations

Although inorganic and metallic nanoparticles are potentially effective oil lubricant additives for friction and wear reduction, their high tendency to undergo aggregation and precipitation in base oils has been an obstacle for real-world applications. This dissertation research aims to develop oil-soluble, polymer brush-grafted nanoparticles (hairy NPs) for use as additives for base oils such as polyalphaolefin (PAO). Well-defined hairy NPs were synthesized by surface-initiated reversible addition-fragmentation chain transfer polymerization from chain transfer agent-functionalized, 23 nm silica NPs, and their lubrication properties were investigated in PAO by high-contact-stress ball-on-flat reciprocating sliding tribological tests.The effects of alkyl pendant groups of poly(alkyl methacrylate) …

Mössbauer Spectroscopy Of Iron Oxide Nanoparticles: Materials For Biomedical Applications, Hien-Yoong Hah

Doctoral Dissertations

Nanoparticles of Fe₃O₄ (magnetite) and gamma-Fe₂O₃ (maghemite) have been studied by Mössbauer spectroscopy. These nanoparticles have applications as contrast agents for Magnetic Resonance Imaging. At room temperature, they are superparamagnetic and the magnetic hyperfine fields were averaged to zero. The spectra of Fe₃O₄ were composed of two lines corresponding to two crystal sites, identified from their isomer shifts as Fe³⁺ on the tetrahedral A site and Fe^2.5+ (mixed Fe²⁺ and Fe³⁺) on the octahedral B site. The relative intensity of the two lines shows that the …

Crafting Nanostructured Neural Interfaces With Hydrogel Particles, Emily Ann Morin

Doctoral Dissertations

Central nervous system neural device functionality hinges on effective communication with surrounding neurons. This depends on both the permissiveness of the device material to promote neuron integration and the ability of the device to avoid a chronic inflammatory response. Here, a facile approach has been developed exploring the multiple functionalities of hydrogel particles to provide cues to impart neural integration for such materials. Three distinct, yet interconnected tasks were undertaken: investigating hydrogel particle-modified substrate neuron integration and central nervous system inflammatory response, investigating guided hydrogel particle adsorption, and investigating hydrogel particles as local reservoirs for counteracting adverse effects from oxidative …

Elucidating The Effects Of Metabolic State On Nanoparticle Distribution In Mice And In Vitro Uptake, Kevin James Quigley

Doctoral Dissertations

Since almost 70% of the U.S. population over 20 years old is overweight and 30% is obese, with much of the western world following suit, many patients that will potentially be administered circulating nanoparticles designed to localize to tumors and avoid non-target areas will have significant amounts of white adipose tissue (WAT), enlarged livers, and additional metabolic complications such as type 2 diabetes. However, studies on nanoparticle biodistribution and efficacy take place almost without exception in lean rodents with healthy metabolic states. In this work, I determined the biodistribution of model nanoparticles – neutral filomicelles and polystyrene spheres both carrying …

Symbiotic Plasmonic Nanomaterials: Synthesis And Properties, Abhinav Malasi

Doctoral Dissertations

Metal particles of the dimensions of the order of 1 to 100's of nanometers show unique properties that are not clearly evident in their bulk state. These nanoparticles are highly reactive and sensitive to the changes in the vicinity of the particle surface and hence find applications in the field of sensing of chemical and biological agents, catalysis, energy harvesting, data storage and many more. By synthesizing bimetallic nanoparticles, a single nanoparticle can show multifunctional characteristics. The focus of this thesis is to detail the synthesis and understand the properties of bimetallic nanomaterial systems that show interesting optical, chemical, and …

Polymer Additives Effects On Structure And Dynamics, Adam Eugene Imel

Doctoral Dissertations

This dissertation presents work that expands the understanding of the effect additives have on the structure and dynamics of a polymer matrix. Polymer additives are molecules, nanoparticles or fibers that are added to a polymer to modify the properties of the host polymer. Due to the vast amount of additives available, our studies were limited to C₆₀ (C60), soft polystyrene nanoparticles, and poly(ethylene oxide).

The first part of this project examined the influence that C₆₀ nanoparticles have on the assembly of polyacrylonitrile using small angle and wide-angle x-ray scattering techniques and viscometry. The addition of C₆₀ (C60) …

Processing, Structure, And Properties Of Nanoparticle Reinforced Nonwoven Sandwich Composites, Josh Griffith Fogle

Doctoral Dissertations

Shockwaves produced from ballistic impacts and improvised explosive devices are capable of causing severe internal trauma to soldiers. Current antiballistic materials give adequate protection to soldiers from high velocity impacts, however they are insufficient at absorbing and dissipating shockwave energy generated by these impacts and explosive blasts. The goal of this research was to develop shockwave absorbing protective materials which can be used as liners in conjunction with current antiballistic materials by reinforcing thermoplastic polyurethane nonwovens with high modulus nanoparticles

To determine the appropriate TPU for the application, a series of TPUs of shore hardness ranging from 60D to 85A …

Green Manufacturing Of Nanoparticles For Biomedical Applications, Sijia Yi

Doctoral Dissertations

The vast majority of nanomaterials are chemically synthesized, a costly process, that is environmentally risky, and the produced nanoparticles are potentially toxic to patients. Nature-based nanomaterials, however, are proving to be much more biocompatible with lower environmental toxicity. Even though a variety of natural nanomaterials have been designed, fabrication technologies for the desired natural nanoparticles with reproducible quality, high productivity and low cost remain a challenge. My objective has been to establish strategies for the isolation, purification and characterization of nanoparticles using a production system based on green tea and fungus (Arthrobotrys oligospora) and also to develop new …

Label-Free Mapping Of Near-Field Transport Properties Of Micro/Nano-Fluidic Phenomena Using Surface Plasmon Resonance (Spr) Reflectance Imaging, Iltai Kim

Doctoral Dissertations

My doctoral research has focused on the development of surface plasmon resonance (SPR) reflectance imaging technique to detect near-field transport properties such as concentration, temperature, and salinity in micro/nano fluidic phenomena in label-free, real-time, and full-field manner. A label-free visualization technique based on surface plasmon resonance (SPR) reflectance sensing is presented for real-time and full-field mapping of microscale concentration and temperature fields. The key idea is that the SPR reflectance sensitivity varies with the refractive index of the near-wall region of the test mixture fluid. The Fresnel equation, based on Kretschmann’s theory, correlates the SPR reflectance with the refractive index …