Polyurethane (PU) is an important commodity polymer with a broad range of applications. Increasing regulations on isocyanates have prompted investigations into alternative routes to PU. Cyclic carbonate aminolysis leading to polyhydroxyurethane (PHU) is a promising alternative. This dissertation describes the first fundamental investigation of the synthesis and properties of segmented,...
Advancements in nanotechnology have led to the production of devices with components with sub-100 nm size scales. Studies have investigated how properties of polymers change when confined to nanoscale dimensions. However, stiffness-confinement studies have reported increases, decreases, and invariance with confinement for different polymer/substrate pairs, making it difficult to obtain...
The genetic code, a set of rules by which mRNA codons are translated into the twenty standard amino acids used in protein synthesis, was once thought to be immutable. As we expanded our understanding of molecular biology more variations in this genetic code have been found across the animal kingdom....
Free radical polymerization has a wide range of applications and continues to attract research interest as the demand for tailored specialty polymers grows. Sequence distribution, tacticity and composition of copolymers play a key role in understanding the reaction kinetics and the properties of the polymers 1. One of the chief...
Phase separation in segmented polymers provides distinct challenges in regard to their chemical reaction kinetics and characterization. Well studied, it has been shown that structure, phase separation and non-covalent interactions are key factors in the design of elastomeric polyurethanes. Specifically, this dissertation is focused on two areas: the synthesis of...
Autoxidation is a primary route by which lubricants in working conditions undergo degradation. Degraded lubricants, if not replaced periodically, contribute to increased wear and product failure. Experimental studies of lubricant degradation have yielded useful results but have left important questions unanswered. While many computational studies of degradation have been carried...
The use of processes based on microorganisms to produce fuels, monomers, and pharmaceuticals from renewable feedstocks is increasing today due to their environmental and economic advantages over petrochemical-based processes. In order to unlock the full potential of microorganisms to produce a sustainable industry centered on biosynthesis, an improved understanding of...
Modeling and simulation at different scales were used to study mass transport, residence times and selective oxidation in nanostructured membranes. First, analytical equations of the possible mass transport mechanisms inside the pores were used to determine that diffusion dominates over convection under the conditions of interest for selective oxidation: 700...
Spontaneous regeneration in the adult mammalian central nervous system is rare, minimal, and generally does not lead to substantial functional recovery. Tissue engineering strategies to promote nerve regeneration aim to provide an environment that is physically and chemically engineered to enhance tissue formation. Strategic design of this environment is crucial...
The study of granular matter is both scientifically intriguing and industrially important, yet it presents several unique characteristics and challenges. The discrete nature of granular materials often precludes the use of the continuum descriptions that are so commonly used for fluids, so alternative methods must be developed. Particles interact via...
The emergence of antimicrobial resistance and the growing concern to produce new drugs have influenced an increase in the amount of research directed towards the engineering of novel polyketides. The polyketide carbon backbone is synthesized by a set of enzymes known as polyketide synthases (PKSs). These catalyze the formation of...
Nature often uses reaction-diffusion(RD) as a means of making structures and materials of unique properties or morphologies on scales from macro- (e.g., stripes in zebras, tigers, and seashells, and formations in trees, agates, and rocks) to microscopic (e.g., cellular growth, chemotaxis and biological waves). However, reaction-diffusion phenomena have not yet...
Structural dynamics in three polymer blend systems, differing largely with respect to morphology, have been investigated. The first system, composed of two immiscible homopolymers, exhibits a microstructure of micron-sized droplets dispersed in a matrix phase. We have examined small-angle x-ray scattering (SAXS) as a new approach for conducting in situ...
Little is known about the transcriptional events underlying megakaryocytic (Mk) differentiation from hematopoietic stem cells. We sought to identify genes and pathways not previously associated with megakaryopoiesis and to evaluate the CHRF-288-11 (CHRF) megakaryoblastic cell line as a model system for investigating megakaryopoiesis.
Using DNA microarrays, Q-RT-PCR, and protein-level assays,...
Megakaryocytic cells (Mks) are derived from hematopoietic stem cells (HSCs) and give rise to platelets. Ex vivo culture of HSCs under conditions that promote Mk differentiation has been proposed as a method for producing Mks and platelets for cell therapies. Mk maturation involves the development of polyploid cells via endomitosis,...
The physics of granular materials is one of the big questions in science. Granular materials serve as a prototype of collective systems far from equilibrium and fundamental questions remain. At the same time, an understanding of granular materials has tremendous practical importance. Among practical problems, granular mixing and its interplay...
The hematopoietic stem cell (HSC) niche is the site where HSCs reside in vivo. The HSC niche is formed by supporting cells that provide structure and appropriate environmental cues for HSCs. In this study, three components of the HSC niche were evaluated for their influence on HSC expansion ex vivo:...
Using a novel DNA-microarray hybridization protocol, the diffusion distance during static microarray hybridization was estimated for Cy3- and Cy5-labeled cDNA probes as 3.8 and 2.6 mm, respectively, despite having almost identical molecular masses. Continuous mixing during microarray hybridization resulted in a 15-20% increase in signal intensity over arrays hybridized statically....
Two subjects are the focus of this dissertation: Au/TiO2 catalyst used for oxidation of CO at low temperature and siloxane nanocages, a novel material (~2nm) recently developed in our group
While bulk gold is chemically inert, gold supported as nanoparticles is remarkably active for the oxidation of carbon monoxide at...
The task of designing porous materials for use in specific applications requires a detailed understanding of the adsorption process and how adsorption is affected by material properties. Applications of interest include maximizing gravimetric or volumetric adsorption capacity for hydrogen and carbon dioxide and increasing the selectivity for carbon dioxide in...