Advanced oxidation of organic pollutants with TiO2 photocatalysts is limited due to the wide bandgap of TiO2, 3.2 eV, which requires ultraviolet (UV) radiation. When nanosized TiO2 is modified by carbon doping, charge recombination is inhibited and the bandgap is narrowed, allowing for efficient photodegradation under visible light. Here, we propose a flame spray pyrolysis (FSP) technique to create TiO2. The facile process of FSP has been successful in preparing highly crystalline TiO2 nanoparticles. Using the same procedure to deposit TiO2 onto biochar, the photocatalyst was doped by the carbonaceous material. The morphology, crystalline and electronic structure of the FSP TiO2 and TiO2-decorated biochar (TiO2-BC) were characterized by SEM, XRD, TGA, DLS, and diffuse reflectance UV-vis spectroscopy. Photocatalytic performance of TiO2 and TiO2-BC was investigated for model organic contaminants in an aqueous solution under UV and visible light, which will be compared to that of Degussa P25 TiO2 as a control.

Commercially important hydrogenation reactions make use of precious noble metal catalysts which are becoming increasingly scarce, and the search for capable alternative catalysts prevails. Transition metal carbides of group IV-VI metals show similar catalytic behavior to platinum and are $103/kg lower in price than the precious metal catalysts. Tungsten carbide, studied in this work, can form in different stoichiometries and phase compositions depending upon synthesis methods. Synthesis of high surface area tungsten carbide with control over its phase composition remains a challenge currently. In this work, the novel isothermal synthesis method of tungsten carbide (WC, W2C) in a CH4/H2 carburization atmosphere with synthesis temperature and presence or absence of a silica support in the catalyst precursor (WO3) as process variables was investigated. The amounts of CO and H2O formed during synthesis corresponded to the amount of oxygen in the WO3 precursor. The catalysts were further characterized by X-ray diffraction to determine phase composition and crystallite size, by scanning electron microscopy to determine morphology, and by CO chemisorption to determine metallic surface area. X-ray diffraction analysis indicated the carbide catalysts to contain W2C, WC, and metallic W phases. The use of a silica-supported precursor favored the formation of a nearly phase pure, high surface area W2C rich catalyst whereas high synthesis temperature and absence of silica precursor favored formation of a low surface area WC rich catalyst. Further, the catalysts were tested for steady state activity at a W/F (weight catalyst/toluene feed rate) of 0.20-0.30 h-1, addition of H2 to a total pressure of 21 bar absolute and 250 °C, and the effect of phase composition and surface area on the activity was studied. This work resulted in the successful synthesis of 4 tungsten carbide catalysts with varying phase compositions and surface areas and correlation of their compositions and surface areas with their corresponding toluene hydrogenation activities.

<p dir="ltr">Regulation of complex biological processes aims to achieve goals essential for an organism's survival or to exhibit specific phenotypes in response to stimuli. This regulation can occur at several levels, such as cellular metabolism, signaling pathways, gene transcription, mRNA translation into proteins, and post-translational modifications. Systems biology approaches can facilitate integrating mechanistic knowledge and high-throughput omics data to develop quantitative models that can help improve our understanding of regulations at various levels. However, computational modeling of biological processes is challenging due to the vast details of various processes with unknown mechanisms. The cybernetic modeling approach accounts for unknown control mechanisms by defining a biological goal that the system aims to optimize and subsequently mathematically formulates the cybernetic goal.</p><p dir="ltr">This thesis aims to develop a mathematical framework that integrates a cybernetic model with novel information-theoretic methods to study the inflammatory response in mammalian macrophage cells. The inflammatory response of the body is a protective mechanism that fights off infecting pathogens by inducing the production of immune signaling proteins called cytokines and chemokines, as well as specific lipids known as eicosanoids. However, excessive levels of cytokines and eicosanoids may result in chronic inflammatory diseases such as hyper-inflammation syndrome, COVID-19, and asthma. Only a few studies have focused on quantitative modeling of the role of lipid metabolism in inflammation. One key lipid is Arachidonic acid (AA), which during inflammation, gets converted into inflammatory lipids called eicosanoids. Previous models utilize Michaelis-Menten kinetics or assume the linear form and can, at best, include control at the gene expression level only. The distinguishing feature of a cybernetic model is that by defining a cybernetic objective, it can account for control at multiple levels, including transcriptional, translational, and post-translational modifications.</p><p dir="ltr">The following paragraphs address a specific research problem, outline the approaches to investigate it, and summarize the key findings.</p><p dir="ltr">First, we studied the cellular response to inflammatory stimuli that produce eicosanoids—prostanoids (PRs) and leukotrienes (LTs)—and signaling molecules—cytokines and chemokines—by macrophages. A few studies suggest that targeting eicosanoid metabolism could be a promising new approach to regulating cytokine storm in COVID-19 infection. We developed a cybernetic model combined with novel information-theoretic approaches to study the integrated system of eicosanoids and cytokines. Our cybernetic model formulates a cybernetic goal, which requires the causal relationship between the eicosanoid and cytokine secretion processes; however, this causal relationship is unknown due to insufficient mechanistic information. We developed novel information-theoretic approaches (discussed later in detail) to understand the causality between eicosanoids and cytokines. The causality result from information theory suggests that Arachidonic acid (AA) may be the cause for initiating the secretion of cytokine TNF. The model captured the data for all experimental conditions, including control, treatment with Adenosine triphosphate (ATP), (3-deoxy-d-manno-octulosonic acid) 2-lipid A (Kdo2-Lipid A, abbreviated as KLA), and a combined treatment of ATP and KLA in mouse bone marrow-derived macrophages (BMDM). The model explains the dynamics of metabolites for all experimental conditions, validating the hypothesis. It also enhanced our understanding of enzyme dynamics by predicting their profiles. The results indicated that the dominant metabolites are PGD2 (a PR) and LTB4 (an LT), aligning with their corresponding known prominent biological roles during inflammation. Based on the causality and cybernetic model result and using heuristic arguments, we also infer that AA overproduction can lead to increased secretion of cytokines/chemokines. Consequently, a potential clinical implication of this study is that modulating eicosanoid levels could lower TNFα expression, suggesting eicosanoids could be a viable strategy for managing hyperinflammation.</p><p dir="ltr">Second, we studied the dynamics of the anti-inflammatory lipid mediators from eicosapentaenoic acid (EPA) metabolism, which can be beneficial in reducing the severity of diseases such as cancer and cardiovascular effects and promoting visual and neurological development. This study employed a cybernetic model to study the enzyme competition between AA and EPA metabolism in murine macrophages. The cybernetic model adequately captured the experimental data for control non-supplemented and EPA-supplemented conditions in RAW 264.7 macrophages. The cybernetic variables provide insights into the competition between AA and EPA for the COX enzyme. Predictions from our model suggest that the system undergoes a switch from a predominantly pro-inflammatory state in control to an anti-inflammatory state with EPA supplementation. A potential application of this study is utilizing the model estimation of the ratio of concentrations required for the switch to occur as 2.2, which aligns with the experimental observations and falls within the recommended range of 1-5 needed to promote anti-inflammatory response.</p><p dir="ltr">Third, we focused on predicting novel causal connections between AA and cytokines using time series analysis as mechanistic information connecting AA and cytokines is unknown. In this work, we developed Time delay Renyi Symbolic Transfer Entropy (TDRSTE), a novel model-free information-theoretic metric. We computed it from high-throughput omics datasets for bivariate non-stationary time series to quantify causal time delays. The TDRSTE method adequately estimated time delay for the synthetic dataset, captured causality for the real-world biological dataset of the AA metabolic network with a prediction accuracy of 80.6%, where it correctly identified 25 out of 31 connections, and detected novel connections between non-stationary lipidomics and transcriptomics profiles for eicosanoids and cytokines, respectively. The results indicate that AA may initiate the secretion of cytokines like TNFα, IL1α, IL18, and IL10. Conversely, cytokines such as IL6 and IL1β may have an early causal impact on AA. These findings suggest a potential causal link between AA and cytokines, paving the way for further exploration with more extensive experimental data in future investigations.</p><p dir="ltr">This thesis develops a theoretical framework that integrates the cybernetic modeling technique with novel information-theoretic approaches to study the inflammatory response in mouse macrophages. As described in previous paragraphs, the success of the cybernetic framework in capturing the dynamic behavior of multiple processes serves to validate the idea that regulation is driven toward achieving cellular goals. The cybernetic framework can be applied to better understand the mechanisms underlying the normal and diseased states and to predict the behavior of the system given a perturbation.</p>

Development of biomass feedstocks with desirable traits for cost-effective conversion is one of the main focus areas in biofuels research. As suggested by techno-economic analyses, the success of a lignocellulose-based biorefinery largely relies on the utilization of lignin to generate value-added products, i.e. fuels and chemicals. The fate of lignin and its structural/compositional changes during pretreatment have received increasing attention; however, the effect of genetic modification on the fractionation, depolymerization and catalytic upgrading of lignin from genetically engineered plants is not well understood. This study aims to fractionate and characterize the lignin streams from a wild-type and two genetically engineered switchgrass (Panicum virgatum) species (low lignin content with high S/G ratio and high lignin content) using three different pretreatment methods, i.e. dilute sulfuric acid, ammonia hydroxide, and aqueous ionic liquid (cholinium lysinate). The structural and compositional features and impact of lignin modification on lignin-carbohydrate complex characteristics and the deconstruction of cell-wall compounds were investigated. Moreover, a potential way to upgrade low molecular weight lignin to lipids by Rhodococcus opacus was evaluated. Results from this study provide a better understanding of how lignin engineering of switchgrass influences lignin fractionation and upgrading during conversion processes based on different pretreatment technologies.

Over the last two centuries, the discovery and application of catalysts has had a substantial impact on how and what chemicals are produced.Given their broad significance, our group has focused on developing new catalyst systems that are recoverable and reusable, in an attempt to reduce concomitant costs. Our efforts have centered on constructing a recyclable chiral heterogeneous catalyst capable of effecting asymmetric hydrogenations of olefins with high stereoselectivity. A class of phosphinoimidazoline ligands, developed by researchers at Boehringer-Ingelheim, known as BIPI ligands, have proven efficacious in the asymmetric reduction of alkenes. However, these chiral ligands are homogeneous and coordinated to precious metals, rendering them irrecoverable and expensive. To address these issues, our group has derivatized the BIPI ligand-metal complex and immobilized it to the surface of graphene oxide as well as polystyrene. Their efficacy and recyclability toward the asymmetric hydrogenation of a functionalized olefin have been evaluated. Another facet of our work has included developing a cost effective synthetic process to artemisinin, the gold standard drug in the treatment of malaria.As a natural product, artemisinin’s worldwide supply remains highly unpredictable, contributing to great price volatility.Combining the benefits of catalysis and the advantages of continuous flow chemistry, our research has sought to develop an economical approach to convert a biosynthetic precursor, artemisinic acid, to artemisinin in three chemical transformations. High-throughput experimentation allowed us to screen a prodigious number of catalysts and identify those effective in the asymmetric hydrogenation artemisinic acid to dihydroartemisinic acid, the first step in the transformation. This screening directed us to an inexpensive, heterogeneous ruthenium catalyst. The second step of the process includes the photooxygenation of dihydroartemisinic acid, which involves photochemically generated singlet oxygen. We have evaluated a commercially available heterogeneous photocatalyst packed in a transparent bed, surrounded by light emitting diodes in the continuous photooxygenation of dihydroartemisinic acid to dihydroartemisinic acid hydroperoxide. The third and final step, an acid induced hock cleavage, initiates an intricate cascading reaction that installs an endoperoxide bridge to deliver artemisinin. Our process afforded a 57% yield from dihydroartemisinic acid to artemisinin.

For the aim of production of poly(ethylene terephthalate), PET based flame retardant composites / boron based flame retardant additives, 3.5 mole hydrated zinc borate and boron phosphate were synthesized. Zinc borate was synthesized with the reaction of boric acid and zinc oxide in both laboratory and pilot scale reactors. Effects of reaction parameters on kinetics of reaction and final product particle size were evaluated. Boron phosphate was synthesized via dry, wet and microwave methods. In addition to the synthesized flame retardant additives, several non-halogenated flame retardant additives, which were commercially available, were also used. Composites were prepared using twin screw extruder and molded by injection molding, followed by characterization in terms of flame retardancy behavior, mechanical and thermal properties, and morphologies. Based on the results of first stage experiments, aiming to determine effective additives, different amounts and combinations of triphenyl phosphate, triphenyl phosphine oxide, zinc borate and microwave produced boron phosphate were chosen and used in PET matrix. Flame retardancy of the composites were determined by conducting horizontal burning rate and limiting oxygen index (LOI) tests. Smoke emissions during fire were also measured. According to the LOI test results, LOI of neat PET was determined as 21%, and with the addition of 5% boron phosphate and 5% triphenyl phosphate together, LOI was increased up to 36%. The smoke density analysis results implied that, boron phosphate was a successful smoke suppressant for PET matrix. In addition to flammability properties, tensile and impact properties of the composites were also improved with flame retardant additives and expecially with the addition of triphenyl phosphate.

In dieser Arbeit wird die partielle Autoxidation von Cyclohexan zu Cyclohexanol und Cyclohexanon mit Luftsauerstoff in einem Kapillarrohrreaktor untersucht. Gegenüber dem konventionellen Verfahren wurde die Temperatur auf 180-250°C und der Druck auf 20-80 bar angehoben. Auf diese Weise konnte eine Steigerung der Raum-Zeit-Ausbeute um etwa den Faktor 200 (von 25 kg/m³*h auf ca. 6000 kg/m³*h) erreicht werden. Die Umsätze sind dabei denen der industriellen Anlage vergleichbar. Die Selektivität der partiellen Oxidation zu den Wertprodukten cyclohexanol, Cyclohexanon und Cyclohexylhydroperoxid liegt im Kapillarrohrreaktor mit 80-90 % etwas unter den in der industriellen Anlage erreichbaren Selektivität von ca. 90-95 %. Die Reaktion im Kapillarrohrreaktor wurde auch aus sicherheitstechnischer Perspektive untersucht. Cyclohexan ist in die Explosionsgruppe IIA eingeordnet. Um das System in konservativer Weise zu betrachten, wurde als Stoffsystem Ethen (Referenzgas der Explosionsgruppe IIB) im Gemisch mit Sauerstoff bzw. Lachgas ausgewählt. Es wurde ein Versuchsaufbau konstruiert, mit dem ex möglich war stabile Detonationen zu erzeugen, diese in die Mikrostruktur einzuleiten und deren Ausbreitung und ggf. Austritt aus der Mikrostruktur zu beobachten. Im Versuchsprogramm wurde der Anfangsdruck im Bereich von 0,1 bis 10 bar und der Rohrdruchmesser der eingesetzten Kapillarrohr im Bereich von 0,13 - 1 mm variiert. Es zeigt sich, dass sich stabile Detonationen von stöchiometrischen Ethen/Sauerstoff-Gemischen bei einem Anfangsdruck von 1 bar abs gerade noch durch eine Kapillare mit einem Innendurchmesser von 0,13 mm ausbreiten können. Es wurde aus den Messdaten und theoretischen Betrachtungen eine Kennzahl für die Bewertung von Mikrostrukturierten Bauteilen entwickelt und diskutiert: der maximale sichere Rohrdurchmesser. / In this thesis a process is described for the uncatalyzed selective oxidation of cyclohexane with air at high-p, T-conditions in a micro capillary reactor. At 533 K a spacetime-yield of about 6000 kg/(m3 ? h) is reached, which corresponds to a size of 2 m x 2 m x 2 m(8 m3) of the microstructured reactor assuming a capacity of 100000 t/a compared to 500 m3 total reactor volume realized with a cascade of bubble columns of each about 100 m3. Unfortunately, selectivity drops at this temperature below 80 % which is significantly lower than the selectivity in the conventional process. With the help of the Hatta number, mass transfer limitations can be excluded for the micro capillary reactor, whereas the bubble column reactor is weakly limited by the gas/liquid mass transfer of the molecular oxygen. Thus, process intensification by enhancing mass transfer using a microstructured reactor for cyclohexane oxidation with air is quite low. Furthermore a method and its corresponding results are presented for the determination of maximum safe capillary diameters, which may be used to describe the extended range of safe operation conditions for gas phase oxidation reactions in microstructured reactor devices. Sections of stainless steel micro capillaries of different inner diameters are mounted between a primary and a secondary chamber. An explosion is ignited in the primary chamber, where also a deflagration to detonation transition occurs. The propagation of the detonation through the stainless steel micro capillaries is monitored by pressure transducers located between the sections of the micro capillaries. This setup is used in order to determine explosion velocities inside the capillaries, maximum safe initial pressures and corresponding maximum safe capillary diameters. Initial investigations are performed with an ideal stoichiometric mixture necessary for complete combustion of ethene with oxygen respectively ethene and nitrous oxide at room temperature. The measured maximum safe capillary diameters obey an indirect proportionality to the initial pressures. The maximum safe capillary diameter can be estimated on the basis of the lambda/3-rule.

Selectively permeable biological membranes composed of lipophilic barriers inspire the design of biomimetic carrier-mediated membranes for aqueous solute separation. This work imparts selective permeability to lipid-filled pores of silica thin film composite membranes using carrier molecules that reside in the lipophilic self-assemblies. The lipids confined inside the pores of silica are proven to be a more effective barrier than bilayers formed on the porous surface through vesicle fusion, which is critical for quantifying the function of an immobilized carrier. The ability of a lipophilic carrier embedded in the lipid bilayer to reversibly bind the target solute and transport it through the membrane is demonstrated. Through the functionalization of the silica surface with enzymes, enzymatic catalysis and biomimetic separations can be combined on this nanostructured composite platform. The successful development of biomimetic nanocomposite membrane can provide for efficient dilute aqueous solute upgrading or separations using engineered carrier/catalyst/support systems. While the carrier-mediated biomimetic membranes hold great potential, fully understanding of the transport processes in composite synthetic membranes is essential for improve the membrane performance. Electrochemical impedance spectroscopy (EIS) technique is demonstrated to be a useful tool for characterizing the thin film pore accessibility. Furthermore, the effect of lipid bilayer preparation methods on the silica thin film (in the form of pore enveloping, pore filling) on ion transport is explored, as a lipid bilayer with high electrically insulation is essential for detecting activity of proteins or biomimetic carriers in the bilayer. This study provides insights for making better barriers on mesoporous support for carrier-mediated membrane separation process. Porous silica nanoparticles (pSNPs) with pore sizes appropriate for biomolecule loading are potential for encapsulating dsRNA within the pores to achieve effective delivery of dsRNA to insects for RNA interference (RNAi). The mobility of dsRNA in the nanopores of the pSNPs is expected to have a functional effect on delivery of dsRNA to insects. The importance of pores to a mobile dsRNA network is demonstrated by the lack of measurable mobility for both lengths of RNA on nonporous materials. In addition, when the dsRNA could not penetrate the pores, dsRNA mobility is also not measurable at the surface of the particle. Thus, the pores seem to serve as a “sink” in providing a mobile network of dsRNA on the surface of the particle. This work successfully demonstrates the loading of RNA on functionalized pSNPs and identified factors that affects RNA loading and releasing, which provides basis for the delivery of RNA-loaded silica particles in vivo.

Independent control of the surface and bulk properties is advantageous for many applications such as adhesives, release coatings, and antimicrobial films. Traditional methods for achieving independent control typically require multiple processing steps such as wet-on-wet or wet-on-dry coating methods. Independent control over the surface properties can achieved in a single step utilizing the temporal and spatial control inherent to photopolymerization. Specifically, a co-photopolymerization of monomers with different reactivities in the presence of a light gradient is capable of producing a polymer film with a surface chemistry that differs from the bulk chemistry. The light gradient, produced via the concentration of photoinitiator in the formulation, results in a reaction gradient through the film with the higher rates of reaction occurring in the high light intensity regions of the film. The preferentially reacting monomer adds at a greater rate in the high light intensity regions resulting in non-uniform consumption yielding a concentration gradient. Consequently, diffusion of the preferentially reacting monomer from the bulk to the surface of the film and a counter-diffusion of the other monomer from the surface to the bulk of the film occurs from the non-uniform monomer consumption thus producing a film with a concentration gradient through the depth of the film with the preferentially reacting monomer enriching the high light intensity regions. A variety of kinetic differences capable of producing a stratified film will be presented including inherent monomer reactivity, number of functional groups per monomer, oxygen inhibition, thiol-ene chemistry, and Norrish type two initiation. Additionally, parameters that control the degree of stratification, such as methods of varying polymerization rate and the light gradient, will be examined. Changes in surface properties (such as contact angle, surface hardness, adhesion) and bulk properties (such as mechanical properties measured by dynamic mechanical analysis and polymer swelling) are studied as a function of stratification. Finally, a mathematical model which describes and predicts the production of stratified films via photopolymerization is presented. Photopolymerization allows for a facile, single step method of generating stratified films with controllable surface chemistries.

Alternative energy research into hydrogen production via water electrolysis addresses environmental and sustainability concerns associated with fossil fuel use. Renewable-powered electrolyzers are foreseen to produce hydrogen if energy and cost requirements are achieved. Electrocatalysts reduce the energy requirements of operating electrolyzers by lowering the reaction kinetics at the electrodes. Platinum group metals (PGMs) tend to be utilized as electrocatalysts but are not readily available and are expensive. Ni1-xMox alloys, as low-cost and earth-abundant transition metal nanoparticles (NPs), are emerging as promising electrocatalyst candidates to replace expensive PGM catalysts in alkaline media. Pure-phase cubic and hexagonal Ni1-xMox alloy NPs with increasing Mo content (0–11.4%) were synthesized as electrocatalysts for the hydrogen evolution reaction (HER). In general, an increase in HER activity was observed with increasing Mo content. The cubic alloys were found to exhibit significantly higher HER activity in comparison to the hexagonal alloys, attributed to the higher Mo content in the cubic alloys. However, the compositions with similar Mo content still favored the cubic phase for higher activity. To produce a current density of -10 mA/cm2, the cubic and hexagonal alloy NPs require over-potentials ranging from -62 to -177 mV and -162 to -242 mV, respectively. The cubic alloys exhibited over-potentials that rival commercial Pt-based electrocatalysts (-68 to -129 mV at -10 mA/cm2). The cubic Ni0.934Mo0.066 alloy NPs showed the highest alkaline HER activity of the electrocatalysts studied and therefore a patent application was submitted. Bulk Ni–Mo phases have been known as electrocatalysts for the HER for decades, while recently transition metal phosphides (TMPs) have emerged as stable and efficient PGM alternatives. Specifically, Ni2P has demonstrated good HER activity and improved stability for both alkaline and acidic media. However, Ni2P electrocatalysts are a compromise between earth-abundance, performance (lower than Ni–Mo and PGMs) and stability. For the first time Ni–Mo–P electrocatalysts were synthesized with varying atomic ratios of Mo as electrocatalysts for alkaline HER. Specific phases, compositions and morphologies were studied to understand the intrinsic properties of TMPs leading to high HER activity. The Ni1.87Mo0.13P and Ni10.83Mo1.17P5 NPs were shown to be stable for 10 h at –10 mA cm-2 with over-potentials of –96 and –82 mV in alkaline media, respectively. The Ni1.87Mo0.13P and Ni10.83Mo1.17P5 NPs exhibited an improved performance over the synthesized Ni2P sample (–126 mV at –10 mA cm-2), likely a result of the overall phosphorous content and hetero-structured morphologies. A strong correlation between phase dependence and the influence of Mo on HER activity needs to be further investigated. Furthermore, understanding the intrinsic properties of electrocatalysts leading to high water splitting performance and stability can apply electrocatalysts in other research applications, such as photoelectrochemical (PEC) water splitting, water remediation and sustainable chemical processing applications. Contributions to photocatalytic water remediation and electrochemical chlorinated generation to halogenate pyridone-based molecules are reported. Electrochemical techniques were developed and reported herein to aid in understanding electrochemical performance, chemical mechanisms and the stability of electrocatalysts at the electrode-electrolyte interfaces.