Supported metal oxides are an important class of heterogeneous catalysts active for many selective oxidation reactions including alkane oxidative dehydrogenation. Attempts to develop fundamental structure-function relationships for supported metal oxide catalysts for alkane oxidative dehydrogenation have been challenging, with many conflicting reports in literature. This has been in part due...
It is pertinent now more than ever that we find sustainable alternatives to produce chemicals. For decades, scientists and engineers have turned to biological systems to help meet societal needs in energy, medicine, materials, and moreespecially when chemical synthesis is untenable. Often, biologically-produced small molecules are insufficient for production at...
Nanostructured semiconductors exhibit promising optoelectronic properties, such as high photoluminescence quantum yield and efficient charge separation, making them attractive materials for applications including photovoltaics, LEDs, and lasers. These superior properties are often due to improved crystallinity and reduced charge separation distance compared to bulk semiconductors. As a result, it is...
Biology is entering the exciting world of big data. Modern high-throughput experimental techniques often produce large datasets that aim to capture complex relationships often found in biological systems. While these larger data sets contain vast amounts of useful information, the answers are often locked behind a wall of numbers. As...
Composites of metal nanoparticles encapsulated by metal-organic frameworks (NP@MOFs) have recently emerged as intriguing heterogeneous catalysts for regioselective reactions. Sharing qualities of both zeolites and enzymes, these catalysts employ the pore system of a MOF to direct reactant access to the surface of nanoparticles. This dissertation seeks to better understand...
The phase-field crystal (PFC) model is an exciting new method for simulating crystalline materials with atomic resolution over diffusional time scales. Unfortunately, applications of the model have been severely limited by the requirement that novel free energies must be constructed for each new material of interest. This thesis describes three...
Gene regulatory networks contain multiple components including microRNAs (miRNAs) that coordinate regulation of genes to produce higher level cell functions. miRNAs are small non-coding RNA molecules that modulate gene expression post-transcriptionally by binding to short target motifs on mRNA transcripts to down-regulate target genes. Because miRNA regulation of genes is...
Oxidation processes play an integral role in many industries, but questions still remain regarding the mechanisms of carbon-hydrogen bond activation and oxidation in free-radical and catalyzed processes. Microkinetic modeling is a powerful tool capable of examining oxidation processes at the mechanistic level to gain understanding and guide catalyst applications. This...
Pressure swing adsorption (PSA) is a promising technology for carbon capture and sequestration (CCS). However, while there has been much interest in PSA process development, the choice of adsorbent for the separation is just as important as the process configuration. Therefore, it is important to develop PSA processes in conjunction...
The use of biomass as a feedstock for fuels and chemicals has been a long-standing challenge and opportunity for the chemical and basic materials industries. In order to unlock the value of biomass, it is necessary to first deconstruct its structural polymers, cellulose, hemicellulose, and lignin, into low molecular weight...
Mixed oxides including SiO2', 'and supported oxides on SiO2', 'comprise the majority of', 'heterogeneous catalysts employed in the chemical industry. SiO2', '-Al2O3', 'and microporous,', 'crystalline variants called zeolites have been used widely since the 1960s in petroleum', 'processing, commodity chemical production, and fine chemical synthesis [1]. SiO2', 'supported', 'TiOx catalysts...
The ability to efficiently sense and respond to molecular signals is crucial for any organism's survival. Sensitive, specific and timely, microbial sensing systems provide an excellent starting point for the engineering of single-celled organisms to detect new molecules of human interest. Towards this goal, our lab pursues the engineering of...
Computational models greatly benefit metabolic engineering efforts by helping to elucidate experimental observations and predict engineering targets for improved cellular performance. Additionally, supplementing experimental efforts with computational modeling can reduce the loss of time and resources in the lab by narrowing down testing conditions. In optimal cases, computational models can...
The rational and deliberate assembly of functional materials from nanoscale building blocks requires a fundamental understanding of interactions between individual components as well as their collective behavior. This thesis investigates the hierarchical organization of nanoparticles using DNA into well-defined three-dimensional materials on the micrometer and millimeter length scales. This assembly...
Metabolic engineering of microorganisms to produce useful compounds from renewable substrates is a promising means for sustainable, on-demand production of chemicals. However, efforts to design and engineer microbial cell factories are constrained by costly and slow “build” times in which each genetic variation requires re-engineering a new strain for each...
Lewis acids are an important class of catalysts for chemical synthesis and manufacturing. Tris-(pentafluorophenyl)borane (FAB) catalyst has been discovered as an excellent Lewis acid catalyst for a great variety of reactions in organic and organometallic chemistry, particularly for alkoxylation reactions which is relevant to the industrial production of polyether alcohols....
MoS2 is a ubiquitous catalyst for hydrogenation and hydrogenolysis reactions for hydrotreating of petroleum sources for the removal of sulfur and nitrogen containing compounds. Through exploration of this activity, structural models for MoS2 as a series of stacked S-Mo-S platelets held together by Van der Waals forces has been developed....
Supported metal oxides are an important class of catalysts for chemical synthesis and manufacturing, particularly for selective oxidation reactions. This dissertation seeks to understand broad relationships among families of silica-supported Group 4 and 5 metal oxide catalysts for the synthesis of epoxides with hydrogen peroxide (H2O2) and to further extend...
Graphene and graphene oxide (GO), a highly oxidized form of graphene, are materials with incredibly interesting chemical and mechanical properties. These materials have high surface areas and electrical properties that can be tuned by reducing the amount of oxygenates on the surface. They have already demonstrated their importance in the...
Individuals commonly engage in collaborative behavior to more easily produce works of high societal impact. The effect of many individual characteristics such as age or gender on the effectiveness of a team is still unclear. Gender is especially pertinent because many professional settings are still far from gender parity, despite...
There is a need for alternative biomanufacturing solutions to produce novel medicines and help solve long-standing issues regarding difficult-to-treat diseases. Cell-free protein synthesis (CFPS) provides scientists with a new paradigm for producing proteins with an unprecedented freedom and control over the biomolecular machinery involved. In this document, I describe my...
The Escherichia coli ribosome is a 2.4 MDa molecular machine that consists of a large subunit and a small subunit, and is the key catalyst in gene expression, responsible for synthesizing proteins from amino acids in a sequence-defined fashion with impressive speed and accuracy. Expanding the repertoire of ribosome substrates...
Granular solids consisting of various particle sizes exhibit the tendency to de-mix, or segregate, when caused to shear by external forces such as gravity. This well-known phenomenon is of special practical interest to many industries involved in the handling and transportation of bulk solids, where segregation can lead to adverse...
Growing concerns associated with global warming and the depletion of oil reserves have motivated significant research in support of sustainable polymers systems. In this thesis, biobased and biodegradable polymer blends and nanocomposites were created using a novel processing method, solid-state shear pulverization (SSSP). This process utilizes a modified twin-screw extruder...
The adoption of surfactant replacement therapy (SRT) for the treatment of neonatal respiratory distress syndrome (nRDS) is one of the main contributors to the dramatic decline in infant mortality rates observed in the 1980s. Despite the significant efficacy of animal-derived surfactant preparations, there are still some concerns associated with their...
To increase the butanol titers and selectivity in <em>Clostridium acetobutylicum</em> we replaced the promoter of the alcohol/aldehyde dehydrogenase (<em>aad</em>) gene with the phosphotranbutyrylase (<em>ptb</em>) promoter and combined this with CoAT downregulation to minimize acetone production. This led to early production of high alcohol (butanol plus ethanol) titers and overall solvent...
Granular materials exhibit a wide variety of fascinating physical properties that can be observed both in nature and industry. The goal of this work is to better understand the flow, mixing, and segregation of granular materials in a prototypical system, the rotating tumbler, using numerical modeling, specifically, the Discrete Element...
Nature has been evolving innovative solutions to complex design challenges for billions of years, the success of which is evidenced by the myriad of life-sustaining systems that operate with unparalleled simplicity, efficiency, and durability. Biomimetic researchers derive inspiration from principles underlying natural phenomena to solve design challenges. This work is...
T-cell activation is an essential step of the immune response, yet the cellular and molecular events underlying this complex process are not fully understood. Significantly, a comparative genome-scale transcriptional analysis of two T-cell subsets and the natural-mixed CD3+ population remains unexplored. Using microarrays, we investigated the temporal global transcriptional profile...
Improving cancer treatments are saving the lives of many young women, however these treatments often lead to premature infertility. The in vitro development of ovarian follicles would provide reproductive options to these women by supporting immature follicle growth following ovarian tissue cryobanking. In addition, the system provides a platform to...
The genetic information in DNA is transcribed to mRNA and then translated to proteins, which form the building blocks of life. Translation, or protein synthesis, is hence a central cellular process. Decades of experimentation have elucidated a vast wealth of molecular information about discrete translation steps, but the sheer complexity...
Tissue engineering offers a promising approach for the replacement of diseased or injured tissues, and is based upon the premise that cells can be induced to form new tissues when presented with the appropriate set of environmental cues. Polymer scaffolds play a central role in most tissue engineering strategies by...
Resource recovery is a promising category of polymer recycling where polymeric waste is converted via thermal or chemical means to monomer and chemical feedstocks. Specifically, pyrolysis is an attractive method because of its simplicity and ability to handle a heterogeneous feedstock. Polymer pyrolysis is characterized by a complex free radical...
End-Labeled Free-Solution Electrophoresis, or ELFSE, is an alternative strategy for DNA sequencing that proposes to eliminate the need for a viscous sieving matrix for size-based DNA separation. In this bioconjugate method, a perturbing entity or "drag-tag" is attached to differently sized DNA fragments produced by the Sanger reaction. This drag-tag...
Cells are regulated by a combination of soluble stimuli and adhesive interactions with other cells and the extracellular matrix (ECM). We are developing systems to present ECM and cytokine receptor ligands in a defined manner for applications in hematopoietic stem and progenitor cell (HSPC) culture. We hypothesize that the controlled,...
The de novo design of bio-inspired materials with precisely controlled properties is challenging, but has potential applications in nano-biotechnology. Applications range from nanometer scaled assemblies to three-dimensional scaffolds for tissue engineering. Genetic engineering of protein-based polymers offers distinct advantages over traditionally synthesized polymers, de novo proteins can be produced with...
The growing worldwide threat of antibiotic-resistant pathogens has necessitated a constant search for new classes of antibiotics. Antimicrobial peptides (AMPs) are integral components of innate immunity in virtually every living organism, and, due to their proven efficacy over millions of years of evolution, are considered promising leads for new antibiotic...
Over the past decade and a half, there has been considerable interest in the effect confinement and interfaces have on the properties of glass forming materials. With the emergence of nanotechnology, some glass formers, in particular polymeric glass formers, will be used at increasingly smaller length scales. An understanding of...
Natural tissues can have complex architectures characterized by the organization of multiple cells into structures, such as branching networks of the vascular or nervous systems. This cellular organization arises, in part, from spatial patterns in the expression of soluble factors, which create concentration gradients that direct cellular processes during morphogenesis....
The world's aquatic food webs are currently in crisis due to the cumulative, interacting effects of anthropogenic pressures including non-indigenous species invasions, chemical contamination, overfishing, habitat disruption and global climate change. Efforts to restore or protect the integrity and sustainability of these systems are limited by a lack of knowledge...
The average and local glass transition temperatures (Tgs) and physical aging behavior of various confined polymers were studied in order to gain an understanding of these surface/interface effects and their propagation into the polymer. Using a novel multilayer/fluorescence method, the Tgs of layers at the free surface, substrate-polymer interface, and...
The automobile coating industry is undergoing reformation driven by environmental regulations that demand low content of volatile organic compounds. Traditional solvent-borne acrylic resins
consisting of high molecular weight polymers that are produced at low temperatures (< 80 C) need high levels of organic solvent (70%) to be processed as coatings....
The proper distribution of cellular organelles and protein complexes is important for maintaining cellular organization and function. Transport in eukaryotic cells requires three motor proteins, kinesin, dynein, and myosin, attached to specific cargoes mostly by adaptor proteins. This work focuses on the mechanism of microtubule-dependent organelle transport in vivo.
This...
Separation of DNA molecules by electrophoresis through entangled polymer solutions continues to be an important tool for genetic analysis, especially Sanger-based DNA sequencing. Separations of DNA on microfluidic devices are much more efficient than in capillary electrophoresis (CE) systems, such that the implementation of DNA sequencing onto microchips promises to...
Time-resolved in situ synchrotron x-ray scattering studies of particle orientation in polymer-clay nanocomposites under simple shear and complex flow were performed. Shear flow experiments used an annular cone and plate x-ray shear cell to allow measurement of platelet orientation within the flow-gradient plane.
Intercalated nanocomposites were made by dispersing organically...
Granular matter and living cells represent two extremes of what have come to be regarded as complex systems - systems characterized by a richness in global behavior that is not easily deduced from the interactions of their individual parts, even when those interactions are simple and well understood. On the...
The prediction of multicomponent adsorption equilibria from pure component data alone has been an active research area for over forty years. The Ideal Adsorbed Solution theory (IAS) has been the standard method of doing so, but contains an embedded assumption of Langmuir mixing. This assumption causes its predictions to be...
The recent tightening of permissible NOx release from diesel-powered engines has intensified the search for a catalytic system that can effectively remove NOx under challenging diesel exhaust conditions. Hydrogen-assisted selective catalytic reduction (H2-SCR) using supported palladium catalysts offers significant promise for lean NOx treatment due to its high activity 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...
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...