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Articles 1 - 14 of 14
Full-Text Articles in Engineering
Multi-Scale Characterization And Engineering Of Taxus Suspension Cultures, Sarah A. Wilson
Multi-Scale Characterization And Engineering Of Taxus Suspension Cultures, Sarah A. Wilson
Doctoral Dissertations
Plants produce a diversity of natural products that have commercial applications as flavorings, fragrances, pesticides and pharmaceuticals. These compounds are often the result of specialized metabolic pathways that are unique to plant systems, and have complex structures that make chemical synthesis routes infeasible. This necessitates exploitation of biological production routes. This thesis work presents a multi-scale characterization and engineering approach to understand and manipulate plant cell cultures on the extracellular (culture) and intracellular (metabolic pathway) levels. Studies focus on the commercially relevant suspension culture system Taxus, a medicinal plant species used for production of the FDA-approved anticancer drug paclitaxel. …
Modeling The Self-Assembly Of Ordered Nanoporous Materials, Szu-Chia Chien
Modeling The Self-Assembly Of Ordered Nanoporous Materials, Szu-Chia Chien
Doctoral Dissertations
Porous materials are of great importance in many fields due to their wide applications. An ongoing theme in this area is the tailoring of materials for specific applications. With a better understanding of the formation mechanisms, tailoring and controlling the pore structure may be achieved. The objective of this research is acquiring further understanding of the fundamental physics that govern the formation of these materials using molecular simulations. We are aiming to unravel the assembly process of silica porous materials using a semi-rigid silica tetrahedral model. This model together with reaction ensemble Monte Carlo simulations allows us to study the …
Investigation Of Hydration Induced Structural Rearrangements Of Poly(Lactic Acid), Omkar Vidyadhar Vyavahare
Investigation Of Hydration Induced Structural Rearrangements Of Poly(Lactic Acid), Omkar Vidyadhar Vyavahare
Doctoral Dissertations
A comprehensive analysis of microstructural changes associated with hydration of Poly(lactic acid) (PLA) and their effect on the macroscopic properties has been provided. Although water absorbed in PLA is extremely small (~0.5% by weight or 1 water molecule per 30 PLA monomer units), we found significant increase in the kinetics of physical aging and crystallization in the presence of water. The fact that water has such a strong effect on PLA structure is attributed to the polar nature of water, strong intermolecular interactions present in PLA and their changes in the hydrated state. Using vibrational spectroscopy, features associated with bound …
Synthesis And Biological Applications Of Heavy-Metal-Free Semiconductor Nanocrystals, Ying Qi
Synthesis And Biological Applications Of Heavy-Metal-Free Semiconductor Nanocrystals, Ying Qi
Doctoral Dissertations
Semiconductor nanocrystals, also called quantum dots (QDs), are an interesting class of materials exhibiting size-tunable optical properties. QDs are attractive for a variety of applications, such as biological sensing and imaging, high color definition display technologies, and photovoltaics. The most widely studied QDs are compound semiconductors of the type CdX and PbX (with X= S, Se, and Te). The absorption and fluorescence emission wavelengths of these QDs span the visible and near infrared (NIR) regions of the electromagnetic spectrum. However, the highly toxic heavy metals Cd and Pb contained in these materials are problematic for their widespread use in commercial …
Mimicking The Arterial Microenvironment With Peg-Pc To Investigate The Roles Of Physicochemical Stimuli In Smc Phenotype And Behavior, William G. Herrick
Mimicking The Arterial Microenvironment With Peg-Pc To Investigate The Roles Of Physicochemical Stimuli In Smc Phenotype And Behavior, William G. Herrick
Doctoral Dissertations
The goal of this dissertation was to parse the roles of physical, mechanical and chemical cues in the phenotype plasticity of smooth muscle cells (SMCs) in atherosclerosis. We first developed and characterized a novel synthetic hydrogel with desirable traits for studying mechanotransduction in vitro. This hydrogel, PEG-PC, is a co-polymer of poly(ethylene glycol) and phosphorylcholine with an incredible range of Young’s moduli (~1 kPa - 9 MPa) that enables reproduction of nearly any tissue stiffness, exceptional optical and anti-fouling properties, and support for covalent attachment of extracellular matrix (ECM) proteins. To our knowledge, this combination of mechanical range, low …
Assembly And Deformation Of Amphiphilic Copolymers And Networks At Fluid Interfaces, Jinhye Bae
Assembly And Deformation Of Amphiphilic Copolymers And Networks At Fluid Interfaces, Jinhye Bae
Doctoral Dissertations
Surface tension generally plays a negligible role on macroscopic scales, but it is often the dominant force on nanometer to micrometer length-scales. The efforts of this dissertation are mainly focused on understanding the role that surface tension plays on sub-millimeter scale objects, especially on soft material systems, and how to utilize this phenomenon to assemble and deform objects. This dissertation addresses several phenomena of nano-and micron-sized objects at fluid interfaces. For nano-scale objects, amphiphilic block copolymer chains were used to explore interfacial behaviors due to their enhanced stability, mechanical properties, and tunability compared to other interfacially active materials such as …
Experimental And Modeling Studies On The Formulation Of Stable Lipid Nanoparticle Dispersions, Yihui Yang
Experimental And Modeling Studies On The Formulation Of Stable Lipid Nanoparticle Dispersions, Yihui Yang
Doctoral Dissertations
This thesis presents both experimental and modeling studies on the formulation of stable lipid nanoparticle dispersions. A population balance equation (PBE) model was developed for prediction of the average polymorph content and aggregate size distribution to better understand the undesirable SLN aggregation behavior. Experimental and modeling studies showed that the polymorphic transformation was the rate determining step for my system, SLNs with smaller initial size distributions aggregated more rapidly, and aggregates contained particles with both alpha and beta crystals. Next the effect of different liquid carrier oils on the crystallization and aggregation behavior of tristearin NLC dispersions was investigated. I …
Bicontinuous Materials From Telechelic Macromonomers Using Thiol-Ene Chemistry, Catherine Nancy Walker
Bicontinuous Materials From Telechelic Macromonomers Using Thiol-Ene Chemistry, Catherine Nancy Walker
Doctoral Dissertations
Bicontinuous structures are beneficial to many applications from health and medicine to energy and the environment. Although these materials can be used for many applications, current strategies yield bicontinuous structures only under highly specific processing conditions. Development of a versatile platform to reliably obtain bicontinuous morphologies will be broadly beneficial. This work presents two platforms that can be used to produce bicontinuous morphologies using a simple Mitsunobu/thiol-ene strategy. This platform allows for the incorporation of a variety of polymer chemistries to yield well-defined polymer networks or multiblock copolymers (MBCs). It also allows for the systematic investigation of factors affecting the …
Transport Limitations In Zeolites And Biomass Pyrolysis, Andrew Robert Teixeira
Transport Limitations In Zeolites And Biomass Pyrolysis, Andrew Robert Teixeira
Doctoral Dissertations
Biomass pyrolysis has been widely explored for its potential to generate a sustainable chemical source capable of producing synthetic fuels and chemicals. Lignocellulosic biomass is the carbon rich, inedible fraction of wood that is comprised of long oxygenated biopolymers, primarily cellulose, hemicellulose and the highly aromatic lignin. High temperature thermal conversion of biomass to bio-oil (pyrolysis oil) occurs on the order of milliseconds and converts long chain biopolymers to a carbon-rich liquid crude. The chemistry of biomass pyrolysis is greatly complicated by significant heat and mass transport challenges. The complex fluid dynamics of the reactive liquid intermediate are examined in …
On The Ordering, Microstructure And Hole Transport Correlations In Semi-Crystalline Poly(3-Hexylthiophene), Xiaobo Shen
On The Ordering, Microstructure And Hole Transport Correlations In Semi-Crystalline Poly(3-Hexylthiophene), Xiaobo Shen
Doctoral Dissertations
This dissertation focuses on describing the research work done on poly(3-hexylthiophene) (P3HT), which represents one of the most important p-type semi-conducting polymers widely used in the field of organic optoelectronics. P3HT is also identified as a typical semi-crystalline material comprising different phases that would yield distinct impacts on its properties when integrated as an active component in optoelectronic devices. In particular, as the material finds great use as a hole-conductor, the objective of the dissertation is to develop a fundamental and quantitative understanding of the relationship between the semi-crystalline morphology and hole transport properties in P3HT. The first section provides …
Prediction Of Emulsion Drop Size Distributions With Population Balance Equation Models To Enable Emulsified Product Design, Shashank Maindarkar
Prediction Of Emulsion Drop Size Distributions With Population Balance Equation Models To Enable Emulsified Product Design, Shashank Maindarkar
Doctoral Dissertations
Oil-in-water emulsions are ubiquitous dispersed phase systems with diverse applications in consumer products, processed foods, and the pharmaceutical industry. Emulsion formulation variables and process operating conditions both impact the drop size distribution, a key property that influences emulsion rheology, stability, texture, and appearance. A typical emulsified product requires the drop size distribution to be maintained within acceptable limits. Due to a lack of quantitative understanding, emulsified products are currently manufactured by combining a broad knowledge of previous product formulations with empirical scientific experimentation. An alternative to trial-and-error experimentation is to utilize a suitable mathematical model to predict the drop size …
Functional Nanostructures From Nanoparticle Building Blocks, Jimmy Lawrence
Functional Nanostructures From Nanoparticle Building Blocks, Jimmy Lawrence
Doctoral Dissertations
Advances in the synthetic strategies of engineered nanomaterials, multifunctional molecules and polymers have opened pathways for the development of functional nanomaterials having unique optoelectronic, mechanical, and biological properties. By designing the chemistry of surface ligands, the organic interface of nanoparticles, one can further the versatility and utilization of engineered nanomaterials, opening pathways for breakthroughs in sensing, catalysis, and delivery using nanomaterials. This thesis describes the synthesis and characterization of small molecule and polymer ligand functionalized inorganic nanoparticles (e.g., metal, semiconducting). Embedding specific chemical functionality into the ligand periphery of nanoparticles enables the resulting functional nanoparticles to react selectively …
Cell Adhesion Biophysics On Dynamic Polymer Constructs, Andreas Kourouklis
Cell Adhesion Biophysics On Dynamic Polymer Constructs, Andreas Kourouklis
Doctoral Dissertations
The biophysical characteristics of cell adhesion from single protein to cell length scales have primarily been studied using purely elastic substrates. However, natural extracellular matrix (ECM) is viscoelastic and contains mobile components. In this work, we combined chemistry and cell biology tools to design and characterize laterally mobile viscoelastic polymer films that promote receptor-specific cell adhesion. Moreover, we used amphiphilic block copolymers that are end-labeled with RGD peptide ligands to allow for integrin-mediated cell adhesion. The addition of a trace hydrophobic homopolymer in the supported bilayer block-copolymer films is used to tune the lateral mobility of the films. NIH 3T3 …
Layer-By-Layer Antimicrobial N-Halamine Polymer Coatings For Food Contact Materials, Luis J. Bastarrachea Gutierrez
Layer-By-Layer Antimicrobial N-Halamine Polymer Coatings For Food Contact Materials, Luis J. Bastarrachea Gutierrez
Doctoral Dissertations
Cross contamination during food processing represents a risk for public health and financial burden. Surface modification of food contact materials to render them antimicrobial can be effective against such risk. The objective of the present work was to develop antimicrobial coatings with the potential to be applied in a variety of food contact materials. The polymer coatings developed became antimicrobial by incorporation of a type of chlorinated compounds called N-halamines, capable of regenerating their antimicrobial activity. Two layer-by-layer (LbL) assembly surface modification procedures were followed. In the first procedure, bilayers of branched polyethyleneimine (PEI) and poly(acrylic acid) (PAA) were applied …