Chemical Engineering Masters Theses Collection

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  • Publication
    Catalytic Fast Pyrolysis of Biomass in a Bubbling Fluidized Bed Reactor with Gallium Promoted Zsm-5 Catalyst
    (2012) Shi, Jian
    The huge energy demand of our society is causing fossil fuel resources to diminish rapidly. Therefore, it is critical to search for alternative energy resources. Biomass is currently both abundant and inexpensive. Biofuels (fuels produced from biomass) have the potential to replace fossil fuels if a cost effective process can be develop to convert biomass into fuels. Catalytic fast pyrolysis is a technology that can convert biomass into gasoline ranged aromatics in a single step. By heating biomass quickly to an intermediate temperature, biomass will thermally decompose into small molecules which can fit into zeolite catalyst pores. Inside the catalyst pores, these small molecules undergo a series of reactions where aromatics are formed along with olefins, CO, CO2, CH4 and water. Gallium promoted ZSM-5 catalyst has been shown to promote small alkanes aromatization, thus it has the potential to increase aromatic yield in catalytic fast pyrolysis process. The focus of the thesis is to study the behavior of catalyst fast pyrolysis of biomass over Gallium promoted catalyst, and explore various ways to utilize the gas phase olefins to increase the aromatic yield. [CG1] The effect of reaction parameters (temperature, weight hourly space velocity, and fluidized gas velocity) on catalytic fast pyrolysis of biomass with Ga/ZSM-5 were studied in a fluidized bed reactor using pine saw dust as the biomass feed. The product distribution and hydrocarbon selectivity are shown to be a strong function of temperature and weight hourly space velocity. Compared to ZSM-5 catalyst at the same reaction conditions, Ga/ZMS-5 has been shown to increase the aromatic yield by 40%. Olefins can be recycled back to the CFP fluidized bed reactor to further increase the aromatic yield. The olefin co-feeding with pine saw dust experiments indicates that co-feeding with propylene can increase the aromatic yield, however, co-feeding with ethylene will cause a decrease in aromatic yield. In both co-feeding experiments, an increase in the amount of coke formed was also observed. Besides a simple olefin recycle, another possible way to utilize these olefins, while avoiding the high cost to separate them from other gas phase products (CO, CO2 and CH4),is adding a secondary alkylation unit after the fluidized bed reactor. The alkylation unit could provide a way to produce additional ethylbenzene after the main CFP process. Three zeolite catalysts (ZSM-5, Y-zeolite and Beta zeolite) were tested in the alkylation unit, and ZSM-5 catalyst shows the highest activity and selectivity in the alkylation of benzene and ethylene.
  • Publication
    Molecular-Beam Mass-Spectrometric Analyses of Hydrocarbon Flames
    (2008) Gon, Saugata
    Laminar flat flame combustion has been studied with molecular-beam mass-spectrometry (MBMS) for a fuel-rich cyclohexane (Ф = 2.003) flame, a fuel-lean toluene (Ф = 0.895), and a fuel-rich toluene (Ф = 1.497) flame. Different hydrocarbon species in these flames were identified, and their mole fraction profiles were measured. The information can be used to propose reaction mechanisms for the different hydrocarbon flames. One MBMS apparatus located at Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory was used to identify and measure the mole-fraction profiles of different species in these flames. The MBMS apparatus located at University of Massachusetts Amherst was used to measure the temperature profile of the cyclohexane flame. The temperature profile of two different fuel-rich toluene flames (Ф= 2.02 , Ф = 3.94) and a fuel-lean (Ф=0.452) methane flame were also measured with the UMass apparatus.
  • Publication
    Synthesis and Adsorption Studies of the MIcro-Mesoporous Material Sba-15
    (2007) You, Eunyoung
    Over the past decades, there have been worldwide efforts to synthesize new types of ordered porous materials for catalysis, separations, etc. Among those, mesoporous material with microporous walls are promising in a sense that while mesopores act as channels for the reactant transport with little diffusion limitation, micropores in the wall act as active sites for reactions or storage of the molecules. In this study, we focused on the SBA-15 material, which is a highly ordered mesoporous silica material with micropores present in the wall. We have studied the synthesis of the material by manipulating various factors that are known to have influence on the porous characteristic of the material. We have aimed our studies particularly on the micropores present in the material. Unlike zeolite materials, which have regular, well characterized pore structures, micropores in the SBA-15 are not ordered, thus may have a very broad pore size distribution. We have synthesized sets of mesoporous silica materials that have characteristics similar to those reported in the literature. Using microwave heating, we were able to synthesize the target material within a short period of time, about 10 to 12-fold reduction of the conventionally known synthesis time. The synthesized materials were initially characterized using XRD and SEM. Adsorption studies were then undertaken on the materials to determine the surface area and pore structure. The interpretation of micropores has heretofore been problematic and the models are ambiguous. Relatively simply ordered, 1-dimensional channel type, zeolite materials were also studied; MTW, MTT, TON, ATS, VET frameworks. Adsorption isotherms of these materials were obtained and simple empirical models were developed to determine the pore size distribution. Further, a sequential adsorption technique, using n-nonane as a preadsorbate, was used to evaluate the realistic external surface areas of zeolite materials and mesopore surface areas of micro-mesoporous materials. Applying this technique to “multidimensional pore system” will provide another way to obtain the realistic surface area and mesopore size distribution.
  • Publication
    Self-nucleated Crystallization of a Branched Polypropylene
    (2011) Alotaibi, Dhwaihi
    Long chain branched polypropylene (LCBPP) crystallizes rapidly and with high nucleation density. The origin of this fast crystallization process is not well understood. It has been attributed to its complicated molecular architecture. In this research, we explore isothermal crystallization of LCBPP, 5%LCBPP and linear polypropylene (LPP) through rheological, thermal, microscopy and optical measurements at different experimental temperatures. The time resolved mechanical spectroscopy technique was used to predict the liquid-to-solid transition (gel point) at different crystallization temperatures (supercooling rates) in order to understand the structure during the crystallization process. The crystallization process of LCBPP was completed in time scale less than that of 5%LCBPP and LPP at different supercooling rates. This has been observed in all crystallization experiments using DSC, SALS and Rheometery. LCBPP exhibit stiff behavior at gel point compared to 5%LCBPP and LPP which imply that the small spherulites observed under polarized microscopy are stiff. Understanding of the rheological behavior during crystallization process will help to develop polymer with different processing conditions and applications.
  • Publication
    Patterned Well-Ordered Mesoporous Silica Films for Device Fabrication
    (2009) Crosby, Todd A
    Developing effective methods of generating thin metal oxide films are important for sensing and separations applications. An obstacle to device fabrication is controlling the size and spatial orientation of domain level pores while retaining the ability to generate arbitrary device level patterns. Well-ordered hexagonally packed cylindrical pores were created by taking advantage of block copolymer self-assembly followed by selective condensation of silica precursors using supercritical carbon dioxide as the solvent. It was possible to control the pore size by choosing PEO-PPO-PEO (Pluronic® series) triblock copolymers of differing molecular weights. These processes were then incorporated with conventional lithographic techniques to generate patterns on the device scale. The first route involves replacement of the organic acid catalyst with a photoacid generator that restricts acid formation by masking pre-determined regions then exposing to UV light. The second route is similar except that addition of a cross-linking agent limits acid diffusion while reversing the tone of the final pattern. The third route avoids acid diffusion altogether and generates the pattern through reactive ion etching through a sacrificial photoresist. A completely different fourth route was taken and nanoimprint lithography was used to generate sub-micron patterns with alternate block copolymers. The feasibility of the preliminary devices generated in this thesis has been examined through particle diffusion experiments. Samples were soaked in a fluorescent dye then exposed to multiple sizes of gold nanoparticles. Fluorescence quenching was then monitored to determine pore accessibility.
  • Publication
    Computer simulation of an ethylene plant
    (1976) Weinstein, Charles David
  • Publication
    Asymmetric Large Area Model Biomembranes
    (2020-05) Liu, Paige
    All biological cell membranes maintain an electric transmembrane potential of around 100 mV, due in part to an asymmetric distribution of charged phospholipids across the membrane. This asymmetry is crucial to cell health and physiological processes such as intracell signaling, receptor-mediated endocytosis, and membrane protein conformation and function as well as active processes involving flippase and floppase proteins. Despite the biological significance, there are limited studies linking the consequences of lipid asymmetry to critical membrane properties and processes involving ion channels. One reason for this is the scarcity of reliable methods to create artificial membrane systems that incorporate both transverse lipid asymmetry and ion channels. Experimental artificial membrane systems incorporate essential cell membrane structures, namely the phospholipid bilayer, in a controllable manner where specific properties and processes can be isolated and examined in an environment much simpler than living systems. It is of particular interest to study asymmetry in transverse lipid composition across the phospholipid bilayer on such a system to probe the effects of the lipid composition and asymmetric arrangement of these lipids on the physicochemical properties of the membrane. By doing so, an understanding of how membrane asymmetry dictates membrane properties and in turn impacts cellular processes will be achieved. The primary goal of this thesis is to develop a platform for fabricating and characterizing compositionally controlled planar, free-standing, asymmetric membranes. This asymmetry was qualitatively demonstrated using a fluorescence quenching assay, and it has been quantified using a combination of anionic and zwitterionic lipids in concert with a patch-clamp amplifier system. Initial measurements of a transmembrane potential on a partially asymmetric bilayer were found to be between 10 and 25 mV. Increasing membrane charge asymmetry increases the offset voltage, as expected, and also modifies the stiffness of the membrane. These initial successes demonstrate a viable pathway to fabricate and quantitatively characterize asymmetric bilayers that can be extended to accommodate more complex membrane processes in the future.
  • Publication
    Effect of Chemotherapeutic Treatment Schedule on a Tissue Transport Model
    (2014) Ganz, Dan E
    Current chemotherapeutic treatment schedule prediction methods rely heavily on PK/PD-based models and overlook the important contribution of tissue-level transport and binding. Tissue-level transport and binding phenomena are essential to understanding drug delivery and efficacy in tumors. Drugs with desirable PK/PD properties often fail in vivo due to poor tissue-level transport. We developed an in silico method to predict the effect of treatment schedule on efficacy that couples PK/PD with tissue-level transport. Treatment schedules were implemented on theoretical drugs with different PK/PD and transport properties. For each drug with a given clearance rate, diffusivity, and binding, treatment schedules consisting of one to 20 doses were simulated. Results show that at binding constants around one, high diffusivities, and high clearance rates, implementation of a treatment schedule becomes more significant. At low clearance rates, regardless of tissue-level transport and binding, one dose was predicted to be most efficacious. Tissue Drug Exposure (TDE) was shown to be to a crucial factor for treatment schedule efficacy. Efficacy was improved by increasing TDE. Implementation of a treatment schedule with more doses than one curbed the effect of poor retention with drugs. This model investigates the effect of treatment schedule on a tissue transport model and shows implementation of a proper dosing regimen is crucial to maximize TDE and chemotherapeutic efficacy.
  • Publication
    Noncovalent Functionalization of Latex Particles using High Molecular Weight Surfactant for High-Performance Coatings
    (2019-05) Zheng, Lei
    The expected outcome of this project is to develop a general strategy to functionalize dispersions, by noncovalent adsorption of HMW surfactants, ultimately for applications such as hydrophobic coatings with high hiding power and hardness, improved mechanical properties via pigment-latex interactions, improved substrate adhesion or improved freeze-thaw stability. So far, we have produced poly (methyl methacrylate-co-butyl acrylate) latexes in the presence of HMW surfactants via emulsion polymerization and demonstrated stronger adsorption of HMW surfactants on particle surface than sodium dodecyl sulfate (SDS). In addition, we have developed surfactant-free latexes, poly (methyl methacrylate-co-butyl acrylate-co-methacrylic acid), as models for post functionalization with high molecular weight surfactants. The successful transfer of surfactants onto particle surface from liquid crystals was indicated by the increase in zeta potential and confirmed via chemical shifts variation in 1H NMR spectra. Additionally, the HMW surfactants were used for dispersing hydrophobic inorganic particles, such as hydrophobic carbon black, in aqueous phase, providing an indication of the general applicability and versatility of our approach.
  • Publication
    Electrospinning Nanofibers from Chitosan-Hyaluronic Acid Complex Coacervates
    (2019-05) Sun, Juanfeng
    Electrospun nanofibers have been used for many applications, but a reliance on organic solvents limits their use in biomedical fields. In this study, we successfully electrospun nanofibers from aqueous chitosan-hyaluronic acid complex coacervates. We studied how solvent’ properties affected the average nanofiber diameter by using pure water as a solvent versus ethanol-water solutions. Experimentally, we investigated the effect of electrospinning apparatus parameters, such as how the applied voltage affected fiber formation and morphology. The smallest average nanofiber diameter was determined to be around 115 ± 30 nm when 3 wt% ethanol coacervate samples were electrospun using the applied voltage of 24 kV. Linear viscoelastic measurements were used to study the rheological characterization of complex coacervate with different salt concentrations and cosolvents (e.g., ethanol weight percent). Chitosan-hyaluronic acid nanofibers hold potential in biomedical applications such as wound dressing, tissue engineering, would healing scaffolds.
  • Publication
    Modeling the Thermodynamics and Dynamics of Fluids Confined in Three-Dimensionally Ordered Mesoporous (3DOm) Carbon Materials
    (2016-05) Desouza, Anish Julius
    Porous materials have application in adsorption based processes due to their high internal surface area and tailorable pore size. They find uses in fields such as catalysis, separation, biotechnology, and microelectronics. Fluids confined in such materials exhibit interesting behavior in regards to the condensation and evaporation mechanisms. Understanding study the behavior of fluids confined in these porous materials is necessary for the efficient design of these materials. The adsorption/desorption isotherm provides valuable information about the effect of network features like pore connectivity and pore size distribution on fluid behavior during pore condensation and evaporation. Such insight can be useful in the characterization of these porous materials. Three dimensionally ordered mesoporous (3DOm) carbon is a porous material that has recently emerged and is of interest. These porous structures are obtained from templating colloidal crystals formed from lysine-silica nanoparticles. The resulting structure consist of spherical pores connected to each other by windows. Due to the use of silica nanoparticles a range of tunable pore sizes can be obtained. These structures have high degree of order. They find applications in the synthesis of zeolites due to their highly controllable pore size. Hence a study of the adsorption properties of these structures is of importance. Molecular modeling has proved effective in the study of porous materials. The development of the density functional theory (DFT) and the dynamic mean field theory (DMFT) has led to great advances in the study of the behavior of confined fluids. The DFT enables the study of the adsorption desorption hysteresis phenomena of confined fluids. The DMFT describes the density profile versus time for a step change in relative pressure on the isotherm. These theories have been applied in the past to two dimensional model pore networks to investigate the mechanisms of adsorption and desorption. In this research project we aim to apply the same to various model 3DOm carbon pore networks. Studying the density distributions in these networks can help understand the thermodynamics of fluid adsorption and desorption in these structures. The results could be useful in understanding the effect of pore structure features like pore size and windows on adsorption and desorption. Also the effect of disorder in the pore network as well as effect of variation in pore size on fluid behavior can be studied. Study of the dynamics of adsorption gives an insight into the nucleation mechanisms that govern the condensation of fluid in the pore. These results could prove useful in the characterization of these porous structures.
  • Publication
    Metabolic Modeling of Secondary Metabolism in Plant Systems
    (2014-05) Leone, Lisa M
    In the first part of this research, we constructed a Genome scale Metabolic Model (GEM) of Taxus cuspidata, a medicinal plant used to produce paclitaxel (Taxol®). The construction of the T. cuspidata GEM was predicated on recent acquisition of a transcriptome of T. cuspidata metabolism under methyl jasmonate (MJ) elicited conditions (when paclitaxel is produced) and unelicited conditions (when paclitaxel is not produced). Construction of the draft model, in which transcriptomic data from elicited and unelicited conditions were included, utilized tools including the ModelSEED developed by Argonne National Laboratory. Although a model was successfully created and gapfilled by ModelSEED using their software, we were not able to reproduce their results using COBRA, a widely accepted FBA software package. Further work needs to be done to figure out how to run ModelSEED models on commonly available software. In the second part of this research, we modeled the MJ elicited/defense response phenotype in Arabidopsis thaliana. Previously published models of A. thaliana were tested for suitability in modeling the MJ elicited phenotype using publicly available computation tools. MJ elicited and unelicited datasets were compared to ascertain differences in metabolism between these two phenotypes. The MJ elicited and unelicited datasets were significantly different in many respects, including the expression levels of many genes associated with secondary metabolism. However, it was found that the expression of genes related to growth and central metabolism were not generally significantly different for the MJ+ and MJ- datasets, the pathways associated with secondary metabolism were incomplete and could not be modeled, and FBA methods did not show the difference in growth that was expected. These results suggest that behavior associated with the MJ+ phenotype such as slow growth and secondary metabolite production may be controlled by factors not easily modeled with transcriptome data alone. Additional research was performed in the area of cryosectioning and immunostaining of fixed Taxus aggregates. Protocols developed for this work can be found in Appendix B.
  • Publication
    Engineering Escherichia coli Nissle 1917 to Enable Functional Genomic Interrogation using CRISPR Interference
    (2024-02) Moore, James M
    Improving the ability for probiotic bacteria to adhere to the intestinal wall and form biofilms is critical to promoting a healthful gut environment in patients suffering from inflammatory bowel diseases (IBDs). One probiotic bacterium, Escherichia coli Nissle 1917 (EcN), has been identified as a safe treatment for patients with IBDs but is not able to colonize all treated individuals even with repeated daily doses. In order to enhance its persistence and probiotic capacity, a greater understanding of the relationship between genetics and the potential for bacteria to adhere to surfaces and form biofilms is required. Toward this end, here a CRISPR-based screen was chosen to explore the underlying functional genomics of EcN because of its exceptional ability to select gene targets with high specificity reducing the number of off-target effects. A strain of EcN was designed to contain a CRISPR interference (CRISPRi) genetic system that can be easily programmed to selectively repress genes. This platform strain would allow for later assays that could uncover the relationship of repression of certain genes with biofilm formation. The CRISPRi system consists of a catalytically dead Cas protein, Lb-dCas12a that is genomically integrated along with a plasmid expressing the guide RNA and was designed here to enable genome-wide CRISPRi screening. The insertions of eYFP into the recA, lacZ, and mutS sites of EcN was carried out using λ-Red recombineering, and its inducible expression was assayed by flow cytometry. For genome-wide CRISPRi screening in EcN, the current design is predicted to be able to target 95.6% of EcN’s annotated genes. Hopefully, this strain will be used in a future CRISPRi screen to bring a more resolved understanding to the genetic controls for biofilm formation in Escherichia coli Nissle 1917.
  • Publication
    Experimentally and Computationally Analyzing Interstitial Flow After Spinal Cord Injury
    (2024-02) Kwon, Hoi
    Approximately 17,000 people sustain a spinal cord injury (SCI) in the U.S. each year, and over a quarter million Americans currently live with paralysis due to SCI. Injury severity and functional deficits due to SCI correlate with the extent of fluid accumulation (i.e., edema) occurring immediately after injury. Previous studies showed fluid pressure around the injured spinal cord (supraspinal) remains elevated for at least three days and contributes to a phase of tissue damage known as secondary injury. While neural cells will more directly interface with fluid within the spinal cord (interstitial), it is currently unknown how SCI affects interstitial fluid pressure and if interstitial forces also contribute to secondary injury. In this project, I will use a combination of in silico and in vivo models to address these questions. Understanding the contributions of fluid forces and flows after SCI may enable strategies to limit tissue damage and functional deficits after SCI.
  • Publication
    Optimizing Channel Formation in PEG Maleimide Hydrogels
    (2023-09) Kannadasan, Bakthavachalam
    Blood vessels including the arteries, veins, and capillaries are a critical and indispensable component of various organisms. Some studies estimate that if all the blood vessels present in our body are arranged in line, they would amount to a total length of approximately 60,000 miles. This distance is enough to circle the world two and a half times! In addition to being all pervasive, blood vessels perform certain key functions such as delivery of oxygen and nutrients to various tissues in the body. They also assist in the spread of diseases such as cancer. Therefore, it is important to study vessels from the point of view of tissue engineering applications. In this study, I have adapted the design of an open-source 3D printed device to create channels in Poly (ethylene glycol) Maleimide (PEG-Mal) hydrogels using the subtractive technique. The PEG-Mal hydrogels can be formed in various formulations to mimic the biophysical and biochemical properties of various tissues such as bone marrow, brain, and lung. These channels created within hydrogels can be easily perfused with physiologically relevant flow rates found in blood vessels and capillaries. Additionally, I have also optimized the hydrogel formulations to improve channel reproducibility. It was found that the number of arms of PEG-Mal contributed the most to channel reproducibility with higher success rates of channel formation in 8-arm gels when compared to 4-arm gels. Therefore, this project delineates the formation of simple in vitro channels in hydrogels which combines properties of the tissue specific extracellular matrix with hemodynamics. It is expected that such a system will find potential use in various tissue engineering and disease modeling studies.
  • Publication
    Machine Learning Modeling of Polymer Coating Formulations: Benchmark of Feature Representation Schemes
    (2023-09) Evbarunegbe, Nelson I
    Polymer coatings offer a wide range of benefits across various industries, playing a crucial role in product protection and extension of shelf life. However, formulating them can be a non-trivial task given the multitude of variables and factors involved in the production process, rendering it a complex, high-dimensional problem. To tackle this problem, machine learning (ML) has emerged as a promising tool, showing considerable potential in enhancing various polymer and chemistry-based applications, particularly those dealing with high dimensional complexities. Our research aims to develop a physics-guided ML approach to facilitate the formulations of polymer coatings. As the first step, this project focuses on finding machine-readable feature representation techniques most suitable for encoding formulation ingredients. Utilizing two polymer-informatics datasets, one encompassing a large set of 700,000 common homopolymers including epoxies and polyurethanes as coating base materials while the other a relatively small set of 1000 data points of epoxy-diluent formulations, four featurization schemes to represent polymer coating molecules were benchmarked. They include the molecular access system, the extended connectivity fingerprint, molecular graph-based chemical graph network, and graph convolutional network (MG-GCN) embeddings. These representation schemes were used with ensemble models to predict molecular properties including topological surface area and viscosity. The results show that the combination of MG-GCN and ensemble models such as the extreme boosting machine and random forest models achieved the best overall performance, with coefficient of determination (r2) values of 0.74 in topological surface area and 0.84 in viscosity, which compare favorably with existing techniques. These results lay the foundation for using ML with physical modeling to expedite the development of polymer coating formulations.
  • Publication
    Chromatographic Dynamic Chemisorption
    (2022-05) Thakkar, Shreya
    Reaction rates of catalytic cycles over supported metal catalysts are normalized by the exposed metal atoms on the catalyst surface, reported as site time yields which provide a rigorous standard to compare distinct metal surfaces. Defined as the fraction of exposed metal surface atoms to the total number of metal atoms, it is important to measure the dispersion of supported metal catalysts to report standardized rates for kinetic investigations. Multiple characterization techniques such as electron microscopy, spectroscopy and chemisorption are exploited for catalyst dispersion measurements. While effective, electron microscopy and spectroscopy are not readily accessible due to cost and maintenance requirements. Commercial instruments therefore typically rely on chemisorption measurements, but can be cost prohibitive nonetheless, hindering the ability of catalysis research to report rigorous measures of activity. Thus, a dispersion measurement technique based on gas chromatograph (GC) ubiquitous in catalysis research is proposed, based on the principle of dynamic carbon monoxide (CO) chemisorption, where number of exposed metal surface atoms are estimated based on the amount of adsorbed CO. In this technique, the supported metal catalyst is packed into a liner, and inserted in the temperature-controlled inlet of the GC. The catalyst is pre-treated, purged with inert gas, and pulses of known amount of CO are passed through it via an automated sequence. The CO chemically adsorbs on the supported metal catalyst and the unadsorbed CO is detected by the flame ionization detector/methanizer on the GC. The amount of CO adsorbed is estimated by the difference between the amount of CO pulsed and detected, translated to estimate the number of exposed metal surface atoms using a stoichiometry factor. Dispersion measurements for several group VIII metal catalysts were conducted using this technique to demonstrate its applicability across a range of weight loadings and support identities. An agreement between catalyst dispersion measured using this technique and commercially available instruments indicated the reliability of this technique. The amount of dispersed metal as low as 0.02 mg could be estimated by this technique.
  • Publication
    Engineering and Evaluation of Reconstituted HDL Nanoparticles to Target Tumor-Associated Macrophages.
    (2022-05) Menon, Aishwarya
    Conventional cancer therapies such as chemotherapy and radiation often lead to severe side effects since they are unable to specifically target the tumor. Additionally, they do not guarantee the prevention of metastasis or recurrence. Recent developments on small-molecule inhibitors, such as kinase inhibitors that target cellular pathways characteristically upregulated in cancer cells, show promise. However, significant challenges such as tolerance and mutations causing drug resistance need to be overcome. Immunotherapy, wherein the host's immune system is leveraged to recognize and target cancer cells, is a better alternative that shows reduced toxicity. Macrophages are an attractive target for immunotherapy seeing as they constitute 50% of the infiltrating leukocytes in the tumor microenvironment. Their plastic nature allows them to be modulated from pro-tumor to anti-tumor phenotype. Although, it does not work for everyone, necessitating a need to monitor response to medication at earlier time points. In this thesis, I have designed an HDL mimicking nanoparticle system to target tumor associated M2 macrophages through the SRB1 receptor. The nanoparticle was optimized for better stability, better loading of the targeting peptide, and the drug as well. It was used to deliver a CSF1R inhibitor drug to successfully repolarize pro-tumor M2 macrophages to anti-tumor M1 phenotype. In addition to that, it was also used to deliver an Arginase-responsive probe that only fluoresces when engulfed by arginase-producing M2 macrophages, differentiating them from arginase non-producing M1 phenotype. Through this study, the SRB1 receptor was successfully targeted to effectively deliver small molecules. This can be used to target and modulate tumor-associated macrophages.
  • Publication
    Metabolic Modeling of Cystic Fibrosis Airway Microbiota from Patient Samples
    (2021-09) Vyas, Arsh
    Cystic Fibrosis (CF) is a genetic disorder, found with higher prevalence in the Caucasian population, affecting > 30,000 individuals in the United States and > 70,000 worldwide. Due to the astoundingly high rate of mortality among CF patients being attributed to respiratory failure brought on by chronic bacterial infections and subsequent airway inflammation, there has been a lot of focus on systematically analyzing CF lung airway communities. While it is observed traditionally that Pseudomonas aeruginosa is the most threatening and persistent CF colonizer due to high antibiotic resistance, recent studies have elicited the roles of other pathogens and it has been widely accepted the CF lung airway consists of a complex codependent community of bacteria, viruses, and fungi. To elucidate the interplay among the members of this community, within the constraint of lung uptake regime, I developed a community metabolic network model comprising of >380 metabolites obtained after modeling 39 most abundant bacterial genera across 279 sputum specimens collected from 79 individuals over 10 years from a study by LiPuma et. al. by 16S rRNA gene sequencing, accounting for >89% of reads across samples. The community metabolic model was contrasted with the 16S relative abundance data through standard data mining techniques employed for the analysis of multidimensional data. I further attempted to quantitatively analyze and elucidate the correlations among patient lung function, disease progression, community diversity, microbial compositions, and metabolic capabilities by standard classical hypothesis testing methods. Comparison through linear dimensionality reduction (PCA) of the 16S data and the model data revealed slightly higher variance explained by the model, indicating presence of relatively smaller number of metabolite-based than the 16S-based polymicrobial communities. A deeper analysis elucidated both the phenomena, consolidation of compositionally different communities due to metabolic closeness, as well as splitting of other communities into metabolically distinct clusters due to minor changes in composition and increase in diversity. Clustering of 16S-based relative abundance data and the model data revealed that the rare Burkholderia infections are metabolically distinct from other CF communities, and are heavily dominated by this genus. It was also reiterated that Achromobacter infections are highly resilient to treatment. Linear regression analysis between lung function and microbiota diversity revealed no strong correlation across the population, however, diversity was found to first increase and then subsequently decrease drastically with disease severity.
  • Publication
    Synthesis of Functionalized Acrylic Nanoparticles as a Precursor to Bifunctional Colloids
    (2021-09) Tillinghast, Guinevere E
    Water-borne coatings have increased in popularity due to the recent environmental regulations being placed on coating formulation. The most readily available coatings without volatile organic compounds are thermoplastic polymer dispersions that rely on interdiffusion to form a film. These dispersions are reliant on toxic crosslinking chemistries to achieve adequate coating mechanical properties, but still have significantly inferior properties when compared with current thermosetting industrial coatings that contain volatile organic compounds. As a result, waterborne coatings made with conventional emulsion polymers cannot be considered for high-performance coatings. Polyurethane dispersions have been developed that can meet these demands, but require several lengthy coating applications and are therefore incredibly costly. A water-based acrylic emulsion polymer coating that could self-stratify and apply multiple crosslinkable layers simultaneously, has the potential to revolutionize current coating formulations. Recent advances in anisotropic polymer colloid synthesis offer a potential pathway to make such a high-performance coating. Incorporating unique functionality into each of the lobes of a bilobal particle would enable the formation of a new class of water-based, self-stratifying, high-performance, acrylic coatings. The primary goal of this thesis was to show proof of concept for a bilobal platform that could be used to form water-based self-stratifying coatings. The approach was adapted from recent advances in pigment-associating emulsion polymers used to improve coating pigment dispersion. Butyl acrylate and methyl methacrylate seed particles ~90 nm in size were formed and subsequently used to synthesize preliminary ~130 nm acrylic bilobal particles, within the target size range of water based coating dispersions. Control over the seed particle glass transition temperature, size, and morphology, and synthesis of promising preliminary bilobal particles was demonstrated; this was accomplished using a systematic analysis of various reaction conditions, namely, pre-emulsification, reaction duration, and the concentrations of the monomers. Expanding upon the chemical versatility would enable these particles to be used in a wide variety of applications, but this thesis represents a promising start for the bilobal platform within the coating industry.