The objective of this research is to create biodegradable mats with tunable characteristics such as fiber diameter and surface area. The drug delivery mats enable spatially controlled delivery of disease-specific therapeutics. Using a large electric potential to draw fibers from a solution flowing at a specific rate, the polymer fibers reach a grounded target several inches away. The biodegradable polymer used in this study was poly(lactic acid-co-glycolic acid) (PLGA). PLGA solutions ranging from 0.5 to 27 wt.% were prepared by dissolving the block copolymer in a solvent mixture containing tetrahydrofuran (THF) and dimethylformamide (DMF) at a 3:1 weight ratio. They were then electrospun at needle-to-target distances of 7, 14, and 18 cm and rates ranging from 0.8 to 4 mL/h. The range of voltage used was between 8 – 15 kV, which was based on the observation of the formation of a Taylor cone, largely affected by on the environment and weather (e.g., temperature and humidity in the lab). A 27 wt.% PLGA solution, electrospun at 1 mL/h at a voltage of 11.25 kV and needle-to-target distance of 14 cm produced uniform fibers with an average fiber diameter of 0.985 m. All other parameters outside the range given created beaded fibers. In addition, solution rheology was performed on some of the PLGA solution to measure viscosity, which is directly correlated to the fiber diameter of the electrospun mats. Observing the impact of solvent on fiber spinning and fiber diameter brings about many positive results in developing fully characterized and well-understood fibrous mats for drug delivery. The nanoscale fibers will be used as drug delivery mats and, therefore, the biodegradation kinetics of the polymers will be studied. Next, parameters of the polymers as well as the polymeric mats will be correlated to the degradation-mediated release of small molecule therapeutics (e.g., peptides, drugs, etc.) such that time-resolved dosing profiles can be created.

The current methods of drug delivery prove to have inefficiencies as far as drug administration to the target site. Due to adverse factors that the drug faces within the body, it can be broken down before the therapeutic can be applied. Polymeric micelles have shown promising results in the face of these circumstances, by being able to self-assemble into a core-shell structure to better house the medicine as it travels through blood stream upon intravenous injection. The triblock copolymer, PEG-PPG-PEG, uses it hydrophilic and hydrophobic components to form a spherical micelle at a nanoscale size allowing it cross barriers with greater ease and prolong dissociation. The resulting size of the micelle is measured by the use of a dynamic light scattering machine. Stability factors, such as, thermodynamic and kinetic stability, also aid in the formation of micelles, but are generally effected in drug delivery process by factors such as salt concentration and pH. Both these factors can cause a lack of stability resulting in aggregation of the micelles; therefore, their affects need to be prolonged in order to have sufficient drug delivery.

The engineering of microbial cell factories capable of synthesizing industrially relevant chemical building blocks is an attractive alternative to conventional petrochemical-based production methods. This work focuses on the novel and enhanced biosynthesis of phenol, catechol, and muconic acid (MA). Although the complete biosynthesis from glucose has been previously demonstrated for all three compounds, established production routes suffer from notable inherent limitations. Here, multiple pathways to the same three products were engineered, each incorporating unique enzyme chemistries and/or stemming from different endogenous precursors. In the case of phenol, two novel pathways were constructed and comparatively evaluated, with titers reaching as high as 377 ± 14 mg/L at a glucose yield of 35.7 ± 0.8 mg/g. In the case of catechol, three novel pathways were engineered with titers reaching 100 ± 2 mg/L. Finally, in the case of MA, four novel pathways were engineered with maximal titers reaching 819 ± 44 mg/L at a glucose yield of 40.9 ± 2.2 mg/g. Furthermore, the unique flexibility with respect to engineering multiple pathways to the same product arises in part because these compounds are common intermediates in aromatic degradation pathways. Expanding on the novel pathway engineering efforts, a synthetic ‘metabolic funnel’ was subsequently constructed for phenol and MA, wherein multiple pathways were expressed in parallel to maximize carbon flux toward the final product. Using this novel ‘funneling’ strategy, maximal phenol and MA titers exceeding 0.5 and 3 g/L, respectively, were achieved, representing the highest achievable production metrics products reported to date.

A comprehensive and systematic investigation on the diffusion and phase behaviors of nanoparticles and macromolecules in two component liquid-liquid systems via Molecule Dynamic (MD) simulations is presented in this dissertation.

The interface of biphasic liquid systems has attracted great attention because it offers a simple, flexible, and highly reproducible template for the assembly of a variety of nanoscale objects. However, certain important fundamental issues at the interface have not been fully explored, especially when the size of the object is comparable with the liquid molecules. In the first MD simulation system, the diffusion and self-assembly of nanoparticles with different size, shape and surface composition were studied in an oil/water system. It has been found that a highly symmetrical nanoparticle with uniform surface (e.g. buckyball) can lead to a better-defined solvation shell which makes the “effective radius” of the nanoparticle larger than its own radius, and thus, lead to slower transport (diffusion) of the nanoparticles across the oil-water interface. Poly(N-isopropylacrylamide) (PNIPAM) is a thermoresponsive polymer with a Lower Critical Solution Temperature (LCST) of 32°C in pure water. It is one of the most widely studied stimulus-responsive polymers which can be fabricated into various forms of smart materials. However, current understanding about the diffusive and phase behaviors of PNIPAM in ionic liquids/water system is very limited. Therefore, two biphasic water-ionic liquids (ILs) systems were created to investigate the interfacial behavior of PNIPAM in such unique liquid-liquid interface. It was found the phase preference of PNIPAM below/above its LCST is dependent on the nature of ionic liquids. This potentially allows us to manipulate the interfacial behavior of macromolecules by tuning the properties of ionic liquids and minimizing the need for expensive polymer functionalization. In addition, to seek a more comprehensive understanding of the effects of ionic liquids on the phase behavior of PNIPAM, PNIPAM was studied in two miscible ionic liquids/water systems. The thermodynamic origin causes the reduction of LCST of PNIPAM in imidazolium based ionic liquids/water system was found. Energy analysis, hydrogen boding calculation and detailed structural quantification were presented in this study to support the conclusions.

This is a two-part thesis assessing the long-term reliability of photovoltaic modules.

Part 1: Manufacturing dependent reliability - Adapting FMECA for quality control in PV module manufacturing

This part is aimed at introducing a statistical tool in quality assessments in PV module manufacturing. Developed jointly by ASU-PRL and Clean Energy Associates, this work adapts the Failure Mode Effect and Criticality Analysis (FMECA, IEC 60812) to quantify the impact of failure modes observed at the time of manufacturing. The method was developed through analysis of nearly 9000 modules at the pre-shipment evaluation stage in module manufacturing facilities across south east Asia. Numerous projects were analyzed to generate RPN (Risk Priority Number) scores for projects. In this manner, it was possibly to quantitatively assess the risk being carried the project at the time of shipment of modules. The objective of this work was to develop a benchmarking system that would allow for accurate quantitative estimations of risk mitigation and project bankability.

Part 2: Climate dependent reliability - Activation energy determination for climate specific degradation modes

This work attempts to model the parameter (Isc or Rs) degradation rate of modules as a function of the climatic parameters (i.e. temperature, relative humidity and ultraviolet radiation) at the site. The objective of this work was to look beyond the power degradation rate and model based on the performance parameter directly affected by the degradation mode under investigation (encapsulant browning or IMS degradation of solder bonds). Different physical models were tested and validated through comparing the activation energy obtained for each degradation mode. It was concluded that, for the degradation of the solder bonds within the module, the Pecks equation (function of temperature and relative humidity) modelled with Rs increase was the best fit; the activation energy ranging from 0.4 – 0.7 eV based on the climate type. For encapsulant browning, the Modified Arrhenius equation (function of temperature and UV) seemed to be the best fit presently, yielding an activation energy of 0.3 eV. The work was concluded by suggesting possible modifications to the models based on degradation pathways unaccounted for in the present work.

A new class of layered materials called the transition metal trichalcogenides (TMTCs) exhibit strong anisotropic properties due to their quasi-1D nature. These 2D materials are composed of chain-like structures which are weakly bound to form planar sheets with highly directional properties. The vibrational properties of three materials from the TMTC family, specifically TiS3, ZrS3, and HfS3, are relatively unknown and studies performed in this work elucidates the origin of their Raman characteristics. The crystals were synthesized through chemical vapor transport prior to mechanical exfoliation onto Si/SiO¬2 substrates. XRD, AFM, and Raman spectroscopy were used to determine the crystallinity, thickness, and chemical signature of the exfoliated crystals. Vibrational modes and anisotropic polarization are investigated through density functional theory calculations and angle-resolved Raman spectroscopy. Particular Raman modes are explored in order to correlate select peaks to the b-axis crystalline direction. Mode III vibrations for TiS3, ZrS3, and HfS3 are shared between each material and serves as a unique identifier of the crystalline orientation in MX3 materials. Similar angle-resolved Raman studies were conducted on the novel Nb0.5Ti0.5S3 alloy material grown through chemical vapor transport. Results show that the anisotropy direction is more difficult to determine due to the randomization of quasi-1D chains caused by defects that are common in 2D alloys. This work provides a fundamental understanding of the vibrational properties of various TMTC materials which is needed to realize applications in direction dependent polarization and linear dichroism.

Water recovery from impaired sources, such as reclaimed wastewater, brackish groundwater, and ocean water, is imperative as freshwater resources are under great pressure. Complete reuse of urine wastewater is also necessary to sustain life on space exploration missions of greater than one year’s duration. Currently, the Water Recovery System (WRS) used on the National Aeronautics and Space Administration (NASA) shuttles recovers only 70% of generated wastewater.1 Current osmotic processes show high capability to increase water recovery from wastewater. However, commercial reverse osmosis (RO) membranes rapidly degrade when exposed to pretreated urine-containing wastewater. Also, non-ionic small molecules substances (i.e., urea) are very poorly rejected by commercial RO membranes.

In this study, an innovative composite membrane that integrates water-selective molecular sieve particles into a liquid-barrier chemically resistant polymer film is synthetized. This plan manipulates distinctive aspects of the two materials used to create the membranes: (1) the innate permeation and selectivity of the molecular sieves, and (2) the decay-resistant, versatile, and mechanical strength of the liquid-barrier polymer support matrix.

To synthesize the membrane, Linde Type A (LTA) zeolite particles are anchored to the porous substrate, producing a single layer of zeolite particles capable of transporting water through the membrane. Thereafter, coating the chemically resistant latex polymer filled the space between zeolites. Finally, excess polymer was etched from the surface to expose the zeolites to the feed solution. The completed membranes were tested in reverse osmosis mode with deionized water, sodium chloride, and rhodamine solutions to determine the suitability for water recovery.

The main distinguishing characteristics of the new membrane design compared with current composite membrane include: (1) the use of an impermeable polymer broadens the range of chemical resistant polymers that can be used as the polymer matrix; (2) the use of zeolite particles with specific pore size insures the high rejection of the neutral molecules since water is transported through the zeolite rather than the polymer; (3) the use of latex dispersions, environmentally friendly water based-solutions, as the polymer matrix shares the qualities of low volatile organic compound, low cost, and non- toxicity.

Gene delivery is a broadly applicable tool that has applications in gene therapy, production of therapeutic proteins, and as a study tool to understand biological pathways. However, for successful gene delivery, the gene and its carrier must bypass or traverse a number of formidable obstacles before successfully entering the cell’s nucleus where the host cell’s machinery can be utilized to express a protein encoded by the gene of interest. The vast majority of work in the gene delivery field focuses on overcoming these barriers by creative synthesis of nanoparticle delivery vehicles or conjugation of targeting moieties to the nucleic acid or delivery vehicle, but little work focuses on modifying the target cell’s behavior to make it more amenable to transfection.

In this work, a number of kinase enzymes have been identified by inhibition to be targets for enhancing polymer-mediated transgene expression (chapter 2), including the lead target which appears to affect intracellular trafficking of delivered nucleic acid cargo. The subsequent sections (chapters 3 and 4) of this work focus on targeting epigenetic modifying enzymes to enhance polymer-mediated transgene expression, and a number of candidate enzymes have been identified. Some mechanistic evaluation of these targets have been carried out and discussion of ongoing experiments and future directions to better understand the mechanistic descriptions behind the phenomena are discussed. The overall goal is to enhance non-viral (polymer-mediated) transgene expression by modulating cellular behavior for general gene delivery applications.

Silicone compounds have a very low surface energy due to highly flexible Si-O-Si backbone and large number of –CH3 groups, but these compounds are extremely hydrophobic and thus have limited applications in aqueous formulations. Modification of such silicone compounds by grafting hydrophilic chains provides a wide range of silicone products called "Silicone Surfactants". Silicone surfactants are surface active agents which get adsorbed at the air-water interface thereby, reducing the interfacial tension. Some of the larger applications of silicone surfactant are in the manufacture of plastic foams, in personal care products and as spreading and wetting agents (Hill, R.M, 2002).

In this thesis, a series of silicone surfactant graft copolymers were synthesized via hydrosilylation reaction. Poly(ethylene glycol) (PEG) of different chain length was grafted to a hydrophobic Poly(methylhydrosiloxane) (PMHS) backbone to improve the final hydrophilicity. Also, a positively charged quaternary ammonium salt (allyltriethylammonium bromide) was grafted to the PMHS backbone. The objective of this thesis was to synthesize polymers in predefined ratios of the above mentioned side groups and utilize these polymers to-

1) Study the effect of PEG chain length and its composition on the hydrophilicity of the polymer.

2) Study the effect of PEG: ammonium salt ratio on the surface tension of aqueous systems.

Analysis of FT-IR and 1H NMR spectra of the polymers confirmed the predicted structure. The absence of characteristic Si-H absorbance peak at 2160 cm-1 in FT-IR spectra indicates consumption of silane groups along the polymer backbone. The actual moles of the side chain grafted on the backbone are calculated by 1H NMR peak integration. The results of contact angle studies indicated an increase in hydrophilicity with an increase in the composition of PEG in molecule. A 2*2 factorial DOE analysis reported that the fraction of Si-H bonds converted to PEG grafts was the critical factor towards increasing the hydrophilicity (p value of 0.015). Surface tension studies report that the air-water interfacial tension of the synthesized polymers is between 28mN/m – 45mN/m. The amount of Si-H was concluded to be the deciding factor in lowering the surface tension.