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Title: FIBRONECTIN INFLUENCES THE RATE OF ASSEMBLY AND STRUCTURAL CHARACTERISTICS OF THE FIBRIN MATRIX AND A MAP OF LYSINE PEGYLATION SITES IN FIBRONECTIN
Creator: Ramanathan, Anand
Date: 2015, 2015-07
Description: Fibronectin serves multiple roles during tissue formation and wound healing, functioning through interactions with cells and extracellular...
Show moreFibronectin serves multiple roles during tissue formation and wound healing, functioning through interactions with cells and extracellular molecules. The overall objective of my research was to investigate fibronectin biochemistry on responses associated with wound healing. My approach was to engineer relevant in vitro models highlighting fibronectin functionality in tissues and link this work to more complex wound healing systems. My research goals were accomplished through the following three specific aims: (1) Determine the role of fibronectin on the kinetics of formation and structure of a fibrin-fibronectin matrix, (2) Determine the effect of protease on the activity of fibronectin in decellularized extracellular matrices and (3) Map the sites of polyethylene glycol conjugation or PEGylation to lysine residues in fibronectin. Aim 1: I demonstrated that fibronectin increased the initial rate of fibrin matrix formation and altered the fibrin matrix structure. These findings are novel because they link results from light absorbance studies to microcopy analyses and demonstrate the influence of fibronectin on fibrin matrix structural characteristics. Aim 2: I demonstrated a link between fibronectin proteolysis and reduced cell adhesion in decellularized extracellular matrices. This study demonstrates the susceptibility of fibronectin to proteolysis in the extracellular matrix and the resulting loss of matrix functionality, placing weight on bioengineering strategies to stabilize fibronectin against proteolysis. Aim 3: I examined proteolytic fragments of native and PEGylated fibronectin to map fibronectin lysine residues that are conjugated PEG. From four key chymotryptic fragments that span fibronectin and are recognized by specific monoclonal antibodies, I provide a map of lysine PEGylation sites for fibronectin. Moreover, I show that lysine PEGylation of fibronectin occurs asymmetrically on the dimer arms. Knowledge of the lysine PEGylation sites can be used to plan future experiments for investigating fibronectin biochemical interactions in complex in vitro and in vivo models. In accomplishing these specific aims, I identified key biomolecular mechanisms involving fibronectin and created relevant in vitro models to study these interactions. The work detailed in this thesis lays the foundation for future experiments to investigate fibronectin functionality and develop therapeutic strategies targeting fibronectin biochemistry in tissue development.
Ph.D. in Chemical Engineering, July 2015
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Title: MULTIPHASE CFD MODELING AND SIMULATION OF GAS-SOLID FLOW SYSTEMS INCLUDING CO2 CAPTURE PROCESSES
Creator: Ghadirian Hoseinabadi, Emad
Date: 2016, 2016-05
Description: Carbon capture and sequestration (CCS) is one of the key technologies needed to reduce the carbon dioxide (CO2) emission and its effects on...
Show moreCarbon capture and sequestration (CCS) is one of the key technologies needed to reduce the carbon dioxide (CO2) emission and its effects on climate change. The goal of this study is to develop an advanced design and scale-up tool for a regenerable solid sorbent carbon capture process using computational fluid dynamics (CFD). In this study, a systematic methodology was established, starting from investigating the properties of the sorbent and its reaction kinetics, to developing models to design, evaluate, troubleshoot, and scale-up of the reactors that are needed to deploy this technology for an advanced power plant (i.e., integrated gasification combined cycles [IGCC]). To develop a realistic CFD model, the effect of formation of clusters in the system was studied using an energy minimization multi-scale (EMMS) approach and was shown to calculate the fluidized bed expansion with high accuracy. The effect of compaction of particles was also investigated and a model capable of simulating independent experimental data for the angle of repose was presented. In addition, this dissertation provides detailed investigations of a magnesium oxide (MgO)-based sorbent and its performance for CO2 capture from a syngas stream including the development of shrinking core models (SCM). Initially, the regenerator fluidized bed reactor at elevated temperature and pressure was simulated and several case studies were performed. Furthermore, a three-dimensional (3D) CFD simulation of a full-loop circulating fluidized bed was provided based on the developed constitutive relations and coupling them with two-fluid model equations. In order to reduce the computational time, a CFD simulation in a two-dimensional (2D) domain including heterogeneous regeneration and carbonation reactions based on the shrinking core model was performed that can be used for parametric studies and optimization of the CO2 sorption and desorption processes in a circulating fluidized bed (CFB) reactor. In addition, a coupled CFD-PBE (population balance equation) model based on the FCMOM (finite size domain complete set of trial functions method of moments) approach was developed and was shown to have broad application in reaction engineering and reactor design where the poly-disperse nature of the phases has a strong effect on the hydrodynamics of the system such as coal gasifiers. Finally, the base case design for CFB reactors incorporated in the CO2 capture process using techno-economic analysis was developed and the operating and capital costs of the unit were demonstrated. It was shown that capturing CO2 in an IGCC power plant by pre-combustion technology is economically viable and can compete with other available technologies.
Ph.D. in Chemical Engineering, May 2016
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Title: CARBON DIOXIDE CAPTURE USING SOLID SORBENTS IN A FLUIDIZED BED WITH REDUCED PRESSURE REGENERATION IN A DOWNER
Creator: Kongkitisupchai, Sunti
Date: 2012-11-11, 2012-12
Description: The most commonly used commercial technology for post-combustion CO2 capture for existing power plants is the amine solvent scrubber. However,...
Show moreThe most commonly used commercial technology for post-combustion CO2 capture for existing power plants is the amine solvent scrubber. However, the energy consumption for capturing CO2 from flue gases using amine solvent technology is 15 to 30% of the power plant due to the use of steam in solvent regeneration. Hence there is a need to develop more efficient methods of removing CO2. The objective of this thesis research is to demonstrate the design of a complete loop system of dry solid sorbent technology, which consumes less energy, as an alternative CO2 capturing technology. The design of a complete riser-sorber and downer-regenerator loop system for a dry solid sorbent technology is developed using the recently developed kinetic theory based multiphase computational fluid dynamics (CFD). The complete dry solid sorbent loop system comprises of an atmospheric fluidized bed riser-sorber and a reduced pressure downer-regenerator. The proposed dry solid sorbent used in this thesis research is a dry sodium carbonate sorbent recently developed at RTI and earlier by Gidaspow and Onischak. The dry solid sorbents capture CO2 and water vapor from flue gases through chemical sorption in the sorber-riser. The captured CO2 is released from the solid sorbent along with water vapor in the reduced pressure regenerator-downer where the solid sorbent regeneration occurred. The complete dry solid sorbent loop system demonstrates the possibility of solving three main technical challenges, which are the handling of large volumetric flow rate of the flue gases, the required operating power, and the quantity of CO2 sorption. xvii A new proposed pressure-equilibrium based sorption rate model for the dry sodium carbonate sorbents is used in the simulations. The simulations of both fluidized riser-sorber and downer-regenerator were done using commercial CFD code; Fluent. The energy efficiency of the proposed dry solid sorbent loop system was studied using thermodynamic availability analysis for both an individual vessel and for the overall process for evaluating the minimum energy requirement for CO2 separation. A T-s diagram of inlet and outlet streams for both the riser-sorber and the downer-regenerator are included in the thermodynamics analysis. The results from multiphase CFD simulations showed that the heat liberated during CO2 sorption in the riser-sorber can be nearly fully recovered in form of sensible heat in the solid sorbent. The captured heat in the solid sorbents is used as the energy for CO2 desorption in the sorbent regeneration process inside the reduced pressure downerregenerator. Hence, the only parasitic power loss will be the energy needed for sorbent circulation, air-lock rotary valves, and vacuum fan. The drastic energy saving is possible due to the high solid circulation rate between sorber-riser and downer-regenerator. Additionally, the simulation results showed that the core-annular regime flow pattern in the riser-sorber can be almost completely eliminated by using multiple jet inlets and increasing solid sorbent particle size, from 75 microns manufactured by RTI to 500 micron sorbent particles. Furthermore, the large sorbent particle size allows better solid settling in the downer. The simulations also showed that a core-annular flow pattern occurred inside the downer-regenerator. However, there is no negative effect of having a core-annular regime inside the downer-regenerator.
PH.D in Chemical Engineering, December 2012
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Title: CHAIN BY CHAIN MONTE CARLO SIMULATIONS FOR POLYMERIZATION PROCESSES
Creator: Demirel, Derya
Date: 2016, 2016-05
Description: Predicting chain microstructure became an important task for polymer scientists. Polydisperse nature of polymer molecules makes it an...
Show morePredicting chain microstructure became an important task for polymer scientists. Polydisperse nature of polymer molecules makes it an interesting research area. In this work, a new method, called “Chain-by-Chain Monte Carlo Method” (CBCMC), is presented for simulating chain microstructures one-by-one or chain-by-chain. To the best of our knowledge, it is a new approach for the simulation of chain microstructures. It is a hybrid deterministic-stochastic method that uses the best of two worlds by obtaining information on the mean-field background environment as concentrations of polymer populations and small molecules (only) from the deterministic solver and using it in the stochastic part of the algorithm. Deterministic solver can employ any method that provides this data and in this work uses method of moments. With this information, stochastic part of the algorithm employs kinetic Monte Carlo algorithm to simulate chains one-by-one. The computational load of simulating the whole ensemble is eliminated by getting the mean-field background information from deterministic solvers as concentrations of polymer populations and small molecules at certain time intervals. CBC-MC is suited for chemistries, or situations in which the chain architecture develops slowly with respect to the background environment such as controlled reversible-deactivation radical polymerizations. This method is applied to two case studies for synthesis of linear gradient copolymers. First case study is a styrene/ methyl methacrylate copolymerization by nitroxide-mediated polymerization with forced gradient techniques and the second one is the synthesis of methyl methacrylate/ methyl acrylate hyberbolic gradient copolymerization by atom-transfer radical polymerization again with forced gradient techniques. Gradient distribution of chain properties is analyzed in all cases since it is relatively more challenging and interesting. Chain properties such as number average chain length, weight average chain length, polydispersity index, cumulative and instanteneous copolymer compositions, full molecular weight distributions and sequence length distributions are obtained and compared to results from method of moments and kinetic Monte Carlo methods for di↵erent sample sizes. Results were in good agreement with wellestablished method of moments and kinetic Monte Carlo methods. Importance of simulating chain microstructure rather than average properties is made clear. Simulation times were reduced by at least a factor of six compared to kinetic Monte Carlo method. Results confirm that if applicable, full information regarding the microstructure of chains can be obtained using this method with reduced simulation times and smaller sample sizes. This method is also applied to non-linear copolymerization of acrylamide/N,N-methylenebis(acrylamide) (AM/BisAM) leading to gelation. The e↵ect of a gradient distribution of pendant double bonds along the primary chains on the simulated portion of gel molecules is investigated with the aim of detecting the macro-heterogeinities. Five cases are studied with di↵erent feeding policies but same total number of comonomers introduced to each of them. Primary chain results are compared with MOM for cumulative and instantaneous BisAM compositions, crosslink and PDB densities and found to be in excellent agreement. Further investigations are done on primary chain microsturctures to better understand multiple phenomena going on in these systems such as the age distribution of crosslinking points and PDBs, density of crosslinking points and PDBs in monomer bins along the primary chains and average segment lengths. It has been found that a gradient in PDB distribution along the primary chains can introduce heterogeneities into the gel molecules in surface-bound type polymerizations where primary chains within gels are aligned in the same direction but these heterogeneities seem to be disappearing in bulk polymerizations where the chain alignments are random.
Ph.D. in Chemical Engineering, May 2016
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Title: ELECTROCHEMICAL AND THERMAL BEHAVIOR OF ENERGY STORAGE AND CONVERSION SYSTEMS: LITHIUM ION BATTERIES AND PEM FUEL CELLS
Creator: Ha, Seonbaek
Date: 2015, 2015-05
Description: In this dissertation, three major topics in electrochemical energy storage and conversion systems are discussed. Lithium-ion batteries as...
Show moreIn this dissertation, three major topics in electrochemical energy storage and conversion systems are discussed. Lithium-ion batteries as electrochemical energy storage and catalyst support in proton exchange membrane (PEM) fuel cells as an electrochemical energy conversion system has been investigated. Most work was done to understand the mechanism of an electrochemical reaction and performance degradation in both systems. After that, it was essential to overcome the technical challenges. The thermal stability of lithium-ion cells has been characterized by a novel cathode and anode material with an electrolyte. For electrochemical energy storage, LiFePO4 as a cathode material in a lithium-ion battery has been investigated by various electrochemical techniques. Generally, the electrode consists of an active material, polymer binder, and conducting agents. The electrode material compositions can affect the electrochemical performance by changing the ratio of carbon content to binder or active material content. The LiFePO4 electrodes were optimized by several factors; electronic conductivity, over voltage during discharge, area specific impedance, hybrid pulse power, and energy density. Silicon is a promising material as a novel anode material in lithium-ion batteries. The importance of selecting a polymer binder among various binders has been addressed by the experiments. The additive in the electrolyte also affects the interfacial property between the solid active material and the electrolyte. The effect of fluoroethylene carbonate (FEC) additive was investigated by electrochemical and physical characterization. The thermal stability of the silicon anode was studied by varying the FEC concentration. Metal oxide, as a non-carbon catalyst support in the PEM fuel cell, was chosen and developed to replace the carbon support for better electrochemical durability. The electronic conductivity; Brunauer, Emmett and Teller (BET) surface area; stability in acid media; and the electrochemical stability of fabricated Zr-doped In2O3 were evaluated.
Ph.D. in Chemical Engineering, May 2015
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Title: CLONING AND CHARACTERIZATION OF HOTSPOT II EXON EDITED DYSTROPHIN RODS
Creator: Kuruba, Balaganesh
Date: 2014, 2014-05
Description: Duchenne muscular dystrophy, DMD, is an X–link recessive disorder with an incidence of 1 in 3500 male births worldwide. This fatal condition...
Show moreDuchenne muscular dystrophy, DMD, is an X–link recessive disorder with an incidence of 1 in 3500 male births worldwide. This fatal condition has no effective treatment, but due to its high incidence and severity, several strategies are the subject of on-going clinical trials including gene therapy (delivery of replacement genes via viral vector systems) and exon skipping (administration of therapeutic compounds to mask certain exons and so repair the defective gene). Both of these approaches result in the production of modified dystrophin proteins with deletions in the central rod region. It is unknown how such edits will affect protein structure, although it has been shown that the nature of the edit is related to clinical severity. DMD defects are non-randomly distributed along the gene, being clustered in two regions: the so-called hotspot region I (Exons 11 – 22) and the hotspot region II (Exons 45 – 55). We are producing alternative exon skipped proteins in the hotspot II region and are characterizing them with respect to biophysical and biochemical stability by thermal denaturation and proteinase challenge studies in order to determine which of these potential edits are most similar to native, undamaged dystrophin.
M.S. in Cell and Molecular Biology, May 2014
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Title: ELECTROCHEMICAL, TRANSPORT AND THERMAL INVESTIGATION OF NOVEL ELECTROLYTES AND ELECTRODES FOR LITHIUM-ION AND MAGNESIUM-ION BATTERIES
Creator: Benmayza, Aadil
Date: 2014, 2014-12
Description: Energy conversion and energy storage are becoming indispensable in today’s society due to the increased demand for immobile and mobile power....
Show moreEnergy conversion and energy storage are becoming indispensable in today’s society due to the increased demand for immobile and mobile power. Cathode material is considered as the only source of energy in the electrochemical cell for secondary battery and thus the quantity of energy of the battery is largely determined by the type of the cathode’s chemistry and its amount used as well. Electrolyte has also a significant impact on the electrochemical performance of the battery. Its properties such as ionic conductivity and transference number play a substantial role in the transport of energy between the cathode and the anode. Moreover, the electrolyte can also limit the accessibility of the active charged ions into the active material through the formation of a Solid Electrolyte Interface (SEI). In addition to the importance of energy, safety is another critical element in the determination of the battery’s quality. Cathode material and non-aqueous electrolyte are two major dimensions of the safety in the design of secondary battery. For instance, in the presence of heat (due to thermal, mechanical, or electrical abuse), the electrolyte can ignite fire if the cathode material releases the oxygen. Therefore, the cathode materials and electrolytes are both central factors in the determination of battery energy and safety. Nowadays, lithium-ion batteries are widely used as power source in many applications; however, their maximum energy density (400Wh/Kg) is not sufficient enough to meet the demands of high power applications such as electric vehicles owing to the limited driving range caused by current lithium-ion batteries. Furthermore, safety concerns have been raised after several incidents have been reported recently. Therefore, improving the safety of lithium-ion battery systems through the formulation of non-flammable electrolytes and synthesizing stable electrodes are highly required for high thermal stability. In contrast, fulfilling the long driving range requires other battery systems that provide higher energy density. The large energy density of Mg metal (3832 mAh/cm3) opens a new horizon toward future potential energy storage system, which is a very promising candidate to overcome the long driving range issue and thus needs to be investigated for its potential use as rechargeable battery. In this present thesis, thermal stability of lithium-ion cells is examined through the use of Fluoro Ethylene Carbonate (FEC) as non-flammable co-solvent with Ethylene Carbonate (EC) on lithium-nickel-cobalt-aluminum-oxide cathode (LiNi0.8Co0.15Al0.05O2). This cathode chemistry was deliberately chosen because of its low thermal stability due to the oxidation of Ni+3 to Ni+4 upon charging. Additionally, optimization of the cathode composition (active material, conducting agent, binder) was examined for high energy and power. Lithium iron phosphate (LiFePO4) was chosen for this study because of its high thermal stability against the liberation of oxygen. Electrolytic properties of a magnesium organohaloaluminate electrolyte were investigated in order to understand their role and effect on the magnesium deposition process. Electrochemical and thermal study of bismuth material as a potential negative electrode for magnesium-ion cell under the use of magnesium organohaloaluminate electrolyte was also performed. Moreover, a thermal modeling was performed through the use of Isothermal-Micro-Calorimeter (IMC) technique to identify the sources of heat released during the magnesiation and demagnesiation of bismuth electrode.
Ph.D. in Chemical Engineering, December 2014
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Title: MATHEMATICAL MODELING AND ANALYSIS OF WASTEWATER TREATMENT PROCESSES
Creator: Raju Ganesan, Arun Kumar
Date: 2013-04-25, 2013-05
Description: The activated sludge process is the most commonly used biological waste water treatment system. Mathematical modeling of this process is...
Show moreThe activated sludge process is the most commonly used biological waste water treatment system. Mathematical modeling of this process is important for improving its treatment efficiency and thus the quality of the effluent released into the receiving water body. These models can help the operator predict the performance of the plant to take cost-effective and timely remedial actions that would ensure consistent treatment efficiency and meeting discharge requirements. However, due to the highly complex and non-linear characteristics of this biological system, mathematical modeling of this treatment process has remained a challenge. The first part of this study is to build fundamental grey-box models to predict the raw influent quality and the preliminary effluent of the plant for any given day using historical data. The thesis is an attempt to model the various waste water treatment processes and validate the model with the historical data available for the Stickney Water Reclamation Plant, Chicago. This model has been further used to analyze the plant on both dry and wet weather conditions. Wastewater treatment processes utilize approximately 3% of the energy consumption in the US. A detailed study of the aeration required for the activated sludge tanks has been performed. The plant has been operated at a far higher aeration compared to the minimum required aeration which has increased the operating costs tremendously. A description of cost reduction by minimizing aeration usage without compromising on the discharge limits has been provided. Finally, storms are one of the biggest challenges faced by the operators in treatment plants. Dynamic simulations of storms have been described using the model to understand and control storm events in a more robust manner.
M.S. in Chemical Engineering, May 2013
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Title: STUDY OF PARALLEL AUTOCATALYTIC REACTIONS IN COUPLED REACTORS
Creator: Hegishte, Swapnil R.
Date: 2012-04-29, 2012-05
Description: The inherent nonlinearity in cubic autocatalytic system has been the reason for its study in various combinations. Parallel cubic...
Show moreThe inherent nonlinearity in cubic autocatalytic system has been the reason for its study in various combinations. Parallel cubic autocatalytic reactions are analogous to the simultaneous consumption of multiple substrates by the same autocatalytic species. Steady state analysis reveals that there can be up to five steady states possible and two of them are always unstable. Individual parameter effect on steady state structure leads to identification of an isola, mushroom and other exotic patterns on equilibrium plot. Stability analysis leads to developing an operating diagram, which also explains the oscillatory behavior with the study of Hopf bifurcation. Concept of coupled isothermal continuous stirred tank reactors enriches the complexity of the system and the steady state behavior. The two reactors are identical in terms of the feed concentrations and the reactor space time. The coupled reactor system can have maximum twenty five steady states at very low interaction rate (R → 0), nine out of which may be stable. The steady state analysis portrays the patterns for transition in number of steady states as R is varied. Appearance of an additional Hopf point confirms the effect of complexity of coupled reactors configuration on stability structure of the system. Numerical simulations exhibit the rich steady state behavior in coupled reactors. Dynamic study for single reactor confirms the possibility of chaos in multistable parameter space. The coupled reactor dynamics focuses on the limit cycle interactions and emergence of chaos due to an added complexity.
M.S. in Chemical Engineering, May 2012
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Title: ELECTROCHEMICAL CONTINUOUS AND AB INITIO DFT MODELING OF ELECTRODE REACTIONS IN PEM FUEL CELLS, AND LI-ION AND MAGNESIUM BATTERIES
Creator: Ramanathan, Mayandi
Date: 2013, 2013-07
Description: Electrochemical energy conversion and storage systems are set to play a major role in the scheme of providing clean and renewable energy to...
Show moreElectrochemical energy conversion and storage systems are set to play a major role in the scheme of providing clean and renewable energy to the growing energy demands, both in the nearby and long-term future. PEM fuel cells are the widely tested energy conversion devices with hydrogen as fuel and air as oxidant. Li-ion batteries are commercialized for short and medium range energy demands. But for fulfilling the long range energy demands, research in some new technologies such as Li-air, Magnesium and Sodium batteries are in progress. Magnesium batteries have huge potential to be a high energy density battery suitable for long range electric vehicles and electrical grid energy storage. In PEM fuel cells, Oxygen reduction reaction is the performance limiting factor due to the sluggish reaction kinetics and expensive, but relatively stable Pt catalyst. In the present study, combined DFT modeling and experimental annealing procedure is being employed to improve the ORR activity of Pd by alloying with transition metal elements such as Ni, Cu and Fe. In Li-ion battery, LiFePO4 is the widely commercialized cathode material, but it suffers its limitation of possessing poor electronic conductivity, which affects the cell performance at high discharge rates. A simple isothermal, one-dimensional John Newman Li-ion battery model is being employed to study the effects of changes in LiFePO4, carbon and binder composition towards changes in electrode porosity, electrical conductivity and cell capacity. With the help of modeling results, an optimum composition zone is located for optimizing the high rate performance. In Magnesium batteries, a modified isothermal, one-dimensional John Newman battery model was employed to study the characteristics of the Mg intercalation reactions, predict the performance of the Bi anode electrode and also understand the underlying phenomena and properties that dictate the characteristics of the Mg intercalation in Bi electrode.
PH.D in Chemical Engineering, July 2013
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Title: CHARACTERIZATION OF DROSOPHILA MELANOGASTER FONDUE MUTANTS
Creator: Bajzek, Clara
Date: 2013, 2013-12
Description: Efficient clotting is essential to invertebrates with open circulatory systems. Like blood clotting in vertebrates, coagulation is important...
Show moreEfficient clotting is essential to invertebrates with open circulatory systems. Like blood clotting in vertebrates, coagulation is important to stop bleeding and prevent bacteria from entering at the wound site of invertebrates. Multiple Drosophila clotting factors have been identified and work has started to study the effects of a few in vitro and more importantly in vivo. Here we characterize the fondue clotting factor mutants. Effects are seen in vitro for fon RNAi knock downs, hypmorph mutants, and null mutants we generated by excising a Minos element. However, with the current in vivo assay, no coagulation phenotype is observed. We developed a new quick and easy in vivo assay, called the capillary assay, to measure how much wounded larvae bleed. Although findings from this assay showed strong results for hmlf03374 mutants, fon mutants still showed no in vivo phenotype with this assay. This reinforces the idea of redundant hemostatic mechanisms in Drosophila larvae. In addition to coagulation phenotypes, fon mutants are pupal lethal and have an elongated pupal shape. Driving the expression of fondue-GFP fusion construct showed that fondue is expressed in a stripped pattern along the body of the larvae. The similarity of this pattern to the expression pattern of tiggrin, a protein involved in muscle attachment, led to the discovery that some clotting factors, including fondue, act in muscle attachment in Drosophila.
M.S. in Biology, December 2013
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Title: INTERACTIONS BETWEEN NANOFLUIDS AND A SOLID SUBSTRATE: ROLE OF pH AND NANOFLUID PARTICLE CONCENTRATION ON THE THREE-PHASE CONTACT ANGLE
Creator: Horiuchi, Hiroki
Date: 2013, 2013-12
Description: We investigate the effect of pH on the interactions between a silica slurry and a silica wafer substrate (TEOS) made by the chemical vapor...
Show moreWe investigate the effect of pH on the interactions between a silica slurry and a silica wafer substrate (TEOS) made by the chemical vapor deposition of tetraethylorthosilicate gas in order to understand the optimization of the Chemical Mechanical Polishing (CMP) process and develop a high-performance silica slurry. The nature of the interactions is probed by the solid-liquid interfacial energy and the electrostatic surface potential at the solid surface. An overview of the CMP process is discussed in Chapter 1. Conventional techniques used to measure the electrostatic potential at the solid/liquid interface, such as the streaming potential and potentiometric titration method, are reviewed. Although there are many techniques for measuring the surface potential of powders, such as potentiometric titration and zeta potential measurement, there is no well-established technique for measuring the surface potential of the silica wafer. Therefore, in this research, we developed a methodology to determine the surface potential and surface charge density of a silica wafer substrate in contact with a slurry. We developed a novel method for calculating the surface potential and surface charge density using the experimental data of the three-phase contact angle in conjunction with the Young- Lippmann and the Poisson-Boltzmann equations. The surface chemistry of silica is discussed in Chapter 2 to elucidate the origin of the surface charge due to the ionization of the silanol groups on a silica wafer. Since the silica wafer is always in contact with the aqueous solution during the CMP process, we specifically focus on the behavior of silica in aqueous solutions. xvi In Chapters 3 and 4, the three-phase contact angle (TPCA) on silica is measured as a function of the pH by the goniometric technique. The surface potential and surface charge density at the silica/water surface are calculated by a model based on the Young- Lippmann equation in conjunction with the Gouy-Chapman model for the electric double layer. In measurements of the TPCA on silica, two distinct regions are identified with a boundary at pH 9.5—showing a dominance of the surface ionization of silanol groups below pH 9.5 and a dominance of the dissolution of silica into the aqueous solution above pH 9.5. Since the surface chemistry changes above pH 9.5, the model is applied to solutions below pH 9.5 (ionization dominant) for the calculation of the surface potential and surface charge density at the silica/aqueous interface. In order to evaluate the model, a galvanic mica cell was made of a mica sheet and the surface potential was measured directly at the mica/water interface. The model results are validated by the experimental data from the literature, as well as the results obtained by the potentiometric titration method and the electro-kinetic measurements. The interactions between the nanofluid and solid surface are explored in Chapter 5. Measurements of three-phase contact angle of the nanofluid on a silica substrate show that the contact angle decreases as the volume fraction increases due to the formation of particle layers on the solid surface. We conclude that it is driven by the depletion attractions between the nanoparticles and a solid surface. In the calculations, the energy (based on Young’s equation) and the structural energy of silica particles (based on statistical mechanics---Henderson’s equation) are in good agreement, indicating that the formation of the nanoparticle layering occurs near the solid surface, as expected. We reference the measurement of the forces between two mica surfaces by Israelachvili and xvii Pashley (1983 and 1984) to calculate the interaction energy against the distance between the two surfaces; we found that the strong repulsive force (hydration force) at a short distance (less than 2 nm) gives rise to enough energy to change the three-phase contact angle. In addition, the calculated inter-particle energy due to the hydration force (by using a statistical mechanics approach, see Trokhymchuck et al. 2001) shows that the hydration force can dramatically increase the inter-particle energy in the case of a volume fraction of water that is from 40 to 45%. The inter-particle energy corresponds to the energy change of 3-5⁰ in the three-phase contact angle, which is same as that found in our experimental data obtained from the contact angle measurements. Finally, we conclude that the hydration force between the silica particles on the solid surface plays an important role in altering the interfacial energy between a solid and liquid.
PH.D in Chemical Engineering, December 2013
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Title: UNEQUAL GRANULAR TEMPERATURE THEORY FOR MOTION OF RED BLOOD CELLS AND PLATELETS
Creator: Aralaguppe Deepak Chandra, Vishak Chandra
Date: 2015, 2015-07
Description: Blood is a multiphase mixture of liquid plasma and solid blood cells. The primary objective of this thesis is to numerically model the motion...
Show moreBlood is a multiphase mixture of liquid plasma and solid blood cells. The primary objective of this thesis is to numerically model the motion of red blood cells and platelets in blood vessels using kinetic theory based multiphase flow transport phenomena. Many experimental observations over the years have concluded that the concentration of platelets and red blood cells vary across the radius of the blood vessel. It has been shown that shear drives the platelets towards the wall, while the red blood cells move towards the center of the blood vessel. Other studies have observed that the platelet adhesion at the walls of the vessel is strongly dependent on the wall shear rate and the concentration of red blood cells. Platelet adhesion to the walls of the vessel has been explained by various shear induced diffusion models over the past few years. The diffusion models are heavily dependent on empirical relations which do not fully explain the phenomena behind the migration. In this study we postulate the dependence of red blood cell concentration on the migration of platelets using kinetic theory. The experimentally measured motion of platelets to the wall and red blood cells to the center is explained by unequal granular temperature kinetic theory. The migration of platelets in the presence of red blood cells is caused by the high granular pressure produced by the random oscillations of the red blood cells and the dissipation of platelet random energy at the walls. At the wall the shear has the highest value. This produces a high granular pressure and temperature which drive the red blood cells towards the center. An analytical solution for the platelet concentration was derived.
M.S. in Chemical Engineering, July 2015
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Title: ELECTROCHEMICAL AND TERMAL MECHANISTIC STUDY OF BEYOND LITHIUM ION SYSTEMS: LITHIUM SULFUR AND LITHIUM OXYGEN CELLS
Creator: Seo, Jeongwook
Date: 2016, 2016-05
Description: Electrochemical and Thermal Mechanistic Study of Lithium Sulfur Cell. The thermal behavior of Li/S cells was studied using IMC in terms of...
Show moreElectrochemical and Thermal Mechanistic Study of Lithium Sulfur Cell. The thermal behavior of Li/S cells was studied using IMC in terms of reversible and irreversible heat generation. The heat generation profile was compared with the voltage profile during discharge of the cell and it was found that the trend of heat generation rate shows excellent correlation with the evolution of reaction voltage, which demonstrates that the IMC technique can be used as an useful tool to study the elementary reactions of the Li/S cell. A simple heat generation model provides reasonable agreement with the measured trends in the heat release. The resistive heat evolution that is calculated by over voltage has the largest portion of total cell heat generation (85%) after the IMC heat evolution model analysis. The qualitative agreement between the aforementioned experimental results and heat generation model yields a comprehensive picture of the elementary reaction steps in Li/S cell. The increase of cell conductivity can be expected to bring about low heat evolution during cell cycling by reducing resistive heat. Doped Sulfur as a conductive cathode is a good suggestion to improve cell heat behavior. Furthermore, better cell cycle capability is expected by using lithium metal oxide cathode composites. The thermal behavior of three cathode materials for lithium/sulfur (Li/S) cell, namely - sulfur, sulfur-LiFePO4 (S-LFP) composite and sulfur-LiV3O8 (S-LVO) composite were comparatively studied using Isothermal Micro-Calorimetry (IMC) at various rates of discharge current. A continuum model was used to calculate the reversible entropic heat and irreversible resistive heat generated over the discharge process and the model data was compared to the experimental data to elucidate these contributions to the overall heat generated. The S-LVO composite cathode was found to show the least heat generation during discharge. Further, Accelerating Rate Calorimetry (ARC) was used to study the thermal safety of these three cells. The cell with the S-LVO composite cathode was found to have the highest onset temperature for thermal runaway and also the lowest maximum self-heat rate. The combination of high capacity, long cycle life and thermal stability makes the S-LVO composite cathode a very promising material for Li/S cells Oxygen Reduction Reaction Studies using Rotating Ring Disk Electrode for Li-Air battery. The oxygen reduction reaction (ORR) studies in aqueous electrolytes have reported the following reaction mechanisms: (i) four electron reaction, (ii) two electron reaction and (iii) one electron chemical reaction. On the other hand, the aprotic ORR literature has no reports of four electrons and two electrons transfer reaction. The kinetics of ORR on the cathode was carried out using rotating ring disk electrode (RRDE) technique. The first step of ORR which produces the superoxide radical was investigated on glassy carbon (GC) disk in 0.1 M tetrabutylammonium bis-(trifluoromethane)imide (TBATFSI)/dimethoxyethane (DME). One-electron reduction to the superoxide radical was founded in the linear sweep voltammetry (LSV) analysis. Further, ORR to produce LiO2 and Li2O2 was carried in bis(trifluoromethane)sulfonimide-lithium(LITFSI)/DME on porous carbon coated glassy carbon electrode disk. The reaction kinetic rate on the porous carbon was calculated using the Li-O2 ORR mechanism model. The kinetic rate was compared with the kinetic rate of glassy carbon electrode. The non-aqueous system has several advantages compared to the aqueous system such as high operation voltage and non-reactive electrolyte with Li+. However this system has some critical problems such as low solubility of Li2O2 and High charge over potential. One attempted solution for these disadvantages of the non-aqueous system was to carry out water addition into the solvent which was expected to produce highly soluble LiOH with lower overpotential. Small amount of Water, 0.5 wt% added into 0.1 M LiTFSI/DME and 1 wt% added in the 0.2 M TBATFSI/DME electrolyte, showed great electrochemical performance with lower onset potential and overvoltage. The kinetics of ORR study for the non-aqueous and aqueous hybrid system was carried out using RRDE technique. Koutecky-Levich plot and Tafel slope analysis indicated two electron transfer reaction on the hydrated 0.1 M LiTFSI/DME. This hydrated system can be expected to double energy storage by two electron transfer ORR for Li-O2 Cell.
Ph.D. in Chemical Engineeering, May 2016
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Title: INVENTORY CREEP PHENOMENON IN PROCESS SCHEDULING
Creator: Aleissa, Yazeed Muqbel
Date: 2016, 2016-05
Description: This work discuss the inventory creep phenomenon that occurs in production processes. Most production process use inventory to store their...
Show moreThis work discuss the inventory creep phenomenon that occurs in production processes. Most production process use inventory to store their products for max- imizing profit. When planning and scheduling control methods were applied, these processes encountered this phenomenon at the end of the controlled horizon. We applied the economic model protective control on a production process example and demonstrate the effect the inventory creep in open-loop and closed-loop solutions. An approach is developed to negate this problem by implementing a novel terminal constraints that showed a promising results in the overall performance of the process.
M.S. in Chemical Engineering, May 2016
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Title: CLONING, EXPRESSION, PURIFICATION AND STRUCTURE DETERMINATION OF PEANUT ALLERGEN ARA H 5
Creator: Wang, Yang
Date: 2012-11-21, 2012-12
Description: In our study, the peanut allergen Ara h 5 was cloned from raw peanut mRNA. The cDNA of the gene was then introduced into different expression...
Show moreIn our study, the peanut allergen Ara h 5 was cloned from raw peanut mRNA. The cDNA of the gene was then introduced into different expression vectors for protein expression in different E.coli strains. Recombinant protein expression was very successful with useful amounts of soluble protein produced. Fast protein liquid chromatography was used to purify the recombinant Ara h 5. High purity protein was subjected to crystallization screen and good quality crystals were harvested. Several crystallographic data sets were collected at a synchrotron X-ray beam line. The three-dimensional structure of the peanut profilin Ara h 5 was determined to 1.10Å resolution. The purified protein and the purification methods can be used in future research on the protein’s allergenecity, cross-reactivity and allergy immunotherapies. The high resolution structure was compared with the structures of homologous allergens and the putative epitopes was displayed on the allergen structure to evaluate their possible legitimacies. In the future, the Ara h 5 structure could be very valuable in studies of allergenecity and in the design of future immunotherapies.
PH.D in Biology, December 2012
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Title: THERMO-RESPONSIVE HYDROGELS FOR INTRAVITREAL INJECTION AND BIOMOLECULE RELEASE
Creator: Drapala, Pawel
Date: 2011-04-20, 2011-05
Description: In this dissertation, we develop an injectable polymer system to enable localized and prolonged release of therapeutic biomolecules for...
Show moreIn this dissertation, we develop an injectable polymer system to enable localized and prolonged release of therapeutic biomolecules for improved treatment of Age-Related Macular Degeneration (AMD). Thermo-responsive hydrogels derived from N-isopropylacrylamide (NIPAAm) and cross-linked with poly(ethylene glycol) (PEG) poly(L-Lactic acid) (PLLA) copolymer were synthesized via free-radical polymerization. These materials were investigated for (a) phase change behavior, (b) in-vitro degradation, (c) capacity for controlled drug delivery, and (d) biocompatibility. The volume-phase transition temperature (VPTT) of the PNIPAAm-co-PEG- b-PLLA hydrogels was adjusted using hydrophilic and hydrophobic moieties so that it is ca. 33 C. These hydrogels did not initially show evidence of degradation at 37 C due to physical cross-links of collapsed PNIPAAm. Only after addition of glutathione chain transfer agents (CTA)s to the precursor did the collapsed hydrogels become fully soluble at at 37 C. CTAs signi cantly a ected the release kinetics of biomolecules; addition of 1.0 mg/mL glutathione to 3 mM cross-linker accelerated hydrogel degradation, resulting in 100 % release in less than 2 days. This work also explored the e ect of PEGylation in order to tether biomolecules to the polymer matrix. It was demonstrated that non-site-speci c PEGylation can postpone the burst release of solutes (up to 10 days in hydrogels with 0.5 mg/mL glutathione). Cell viability assays showed that at least two 20-minute bu er extraction steps were needed to remove cytotoxic elements from the hydrogels. Clinically-used therapeutic biomolecules Lucentis® and Avastin® were demonstrated to be both stable and bioactive after release form PNIPAAm-co-PEG-b-PLLA hydrogels. The thermo-responsive hydrogels presented here o er a promising platform for the localized delivery of proteins such as recombinant antibodies.
Ph.D. in Chemical and Biological Engineering, May 2011
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Title: MODELING GLUCOSE-INSULIN DYNAMICS AND AUTOMATED BLOOD GLUCOSE REGULATION IN PATIENTS WITH TYPE 1 DIABETES
Creator: Oruklu, Meriyan
Date: 2012-11-06, 2012-12
Description: Estimation of future glucose concentrations is a crucial task for diabetes management. Predicted glucose values can be used for early...
Show moreEstimation of future glucose concentrations is a crucial task for diabetes management. Predicted glucose values can be used for early hypoglycemic/hyperglycemic alarms or for adjustment of insulin amount/rate. In the first part of this thesis, reliable subject-specific glucose concentration prediction models are developed using a patient’s continuous glucose monitoring (CGM) data. CGM technologies provide glucose readings at a high frequency and consequently detailed insight into a patient’s glucose variation. Time-series analyses are utilized to develop low-order linear models from a patient’s own CGM data. Glucose prediction models are integrated with recursive identification and change detection methods, which enable dynamical adaptation of the model to inter-/intra-subject variability and glycemic disturbances. Two separate patient data sets collected under hospitalized (disturbance-free) and normal daily life conditions are used to validate the univariate glucose prediction algorithm developed. Prediction performance is evaluated in terms of prediction error metrics and Clarke error grid analysis (CG-EGA). The long-term complications of diabetes can be reduced by controlling the blood glucose concentrations within normoglycemic limits. In the second part of this thesis, the subject-specific modeling algorithm developed in part one is integrated with a control algorithm for closing the glucose regulation loop for patients with type 1 diabetes. An adaptive control algorithm is developed to keep a patient’s glucose concentrations within normoglycemic range and dynamically respond to glycemic challenges with automated subcutaneous insulin infusion. A model-based control strategy is used to calculate the required insulin infusion rate, while the model parameters are recursively identified at each sampling step. The closed-loop algorithm is designed for the subcutaneous route for both glucose sensing and insulin delivery. xii It accounts for the slow insulin absorption from the adipose tissue and the time-delay between blood and subcutaneous glucose concentrations. The performance of the control algorithm developed is demonstrated on two simulated patient populations to provide effective blood glucose regulation in response to multiple meal challenges with a simultaneous challenge on a patient’s insulin sensitivity. Physical activity and emotional stimuli such as stress are known to have a significant effect on a patient’s whole-body fuel metabolism. In the third part of this thesis, the univariate time-series models developed from recent glucose concentration history are extended to include additional information on a patient’s physical and emotional condition. Physiological measurements from a multi-sensor body monitor are used to supplement a patient’s CGM data and develop multivariate glucose prediction models. The prediction performance of the multivariate algorithm developed is evaluated on data collected from patients with type 2 diabetes, and a real life implementation of the algorithm is demonstrated for early (i.e., 30 min in advance) hypoglycemia detection. Finally, the control algorithm developed in part two is extended to utilize the glucose profiles predicted by the multivariate patient model. The multivariate closedloop algorithm is tested with two clinical experiments performed on a patient with type 1 diabetes during a high intensity exercise followed by a carbohydrate-rich meal challenge. The algorithm acquires the patient’s CGM and armband (body monitor) data every 10 min, and accordingly calculates the required basal insulin infusion rate. Insulin is administered in a fully automated manner without any food or activity announcements (e.g., no information on meal/exercise size or time). None of the algorithms developed in this thesis require any patient specific tailoring or prior experimental data before implementation. They are also designed to function in a fully automated manner and do not require any disturbance announcexiii ments or manual inputs. Therefore, they are good candidates for installation on a portable ambulatory device used in a patient’s home environment for his/her diabetes management.
PH.D in Chemical and Biological Engineering, December 2012
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Title: MULTI-AGENT MODELING OF TISSUE GROWTH AND ANGIOGENESIS WITH HIGH PERFORMANCE COMPUTING
Creator: Bayrak, Elif Seyma
Date: 2015, 2015-07
Description: Tissue engineering emerged as a result of the high demand of transplant organ and tissues in spite of low number of donors. Rapid and stable...
Show moreTissue engineering emerged as a result of the high demand of transplant organ and tissues in spite of low number of donors. Rapid and stable vascularization still presents the major challenge for three-dimensional functional tissues. Bone is a highly vascularized tissue. Regeneration of vascularized bone tissue from osteogenic cells in biodegradable scaffolds is strongly affected by the interplay between scaffold properties, chemical cues and precursor cells. The number of variables that contribute to the formation of engineered tissues present a challenging optimization problem that cannot be addressed with the experimentation alone. Complex system such as vascularized tissue growth can benefit from properly developed computational models. Computational models can help us understand interactions between the various parts of the complex systems, imagine all possible outcomes of a specific event, explain reasons and causes and forecast future trajectories. Agent-based modeling (ABM) is a powerful modeling and simulation technique that builds a structure from bottom-up to model and understand systems comprised of autonomous, interacting entities. ABM is a natural choice to model biological system that is comprised of many interacting cells. ABM possesses great advantages including simulating of each individuals behavior, holding their history, allowing them to adapt to dynamic conditions and learn through simple to complex algorithms. One main concern of the modelers is the computational heaviness of ABMs that limits the use of this technique in real time optimization, monitoring and control applications. Discovering the full potential of ABM in biological system with huge population size depend on the computational power available.A multi layer agent based model to simulate vascular bone regeneration in degradable porous hydrogels is developed both for personal computer (PC) environment and high performance computing (HPC) platforms. The personal computer (PC) version of this model is built upon the angiogenesis model that was previously developed by Arsun Artel and Hamidreza Mehdizadeh. This work is focused on development of bone tissue growth layer while considering the interactions and improving the existing layers and uses the parallel processing paradigm for running tissue growth more efficiently and more quickly. This model aims to help investigating and understanding the interactions between soluble factors, scaffolds and cells, and finding the optimal biomaterial structure and soluble cues to maximize vascularization and differentiation to bone tissue.
Ph.D. in Chemical Engineering, July 2015
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Title: MULTIFUNCTIONAL ELECTROCATALYST SUPPORTS AND ELECTROCATALYSTS FOR ELECTROCHEMICAL ENERGY CONVERSION
Creator: Kumar, Amod
Date: 2014, 2014-07
Description: Polymer electrolyte fuel cell (PEFC) technology has several underlying problems (lifetime, reliability and cost) that need to be resolved as a...
Show morePolymer electrolyte fuel cell (PEFC) technology has several underlying problems (lifetime, reliability and cost) that need to be resolved as a prerequisite for large-scale commercialization. Amongst these, the lifetime issue is regarded as critical. From the perspective of durability, the current state-of-the-art electrocatalyst, viz. platinum (Pt) supported on high surface area carbon, suffers substantial degradation during fuel cell operation. A key pathway for electrocatalyst degradation is the corrosion of the carbon support. During fuel cell startup and shutdown in automotive applications, the cathode potential undergoes excursions of up to 1.6 V. At these high potentials, the carbon corrosion reaction is significantly accelerated, leading to irreversible carbon loss at the electrode. The best way to eliminate the issue of support corrosion in PEFCs is to develop alternate corrosion-resistant catalyst supports. This dissertation investigates (i) mixed oxides of silica (SiO2) and ruthenia (RuO2) and (ii) tantalum modified titanium oxide (Ta0.3Ti0.7O2) for use as corrosion-resistant electrocatalyst supports in PEFCs, especially for the automotive sector, using detailed microstructure characterization and electrochemical evaluation, including two carefully chosen accelerated stress tests (startstop cycling to simulate fuel cell vehicle start-up and shut-down, and load cycling to simulate full-load to no-load transitions in the vehicle during operation). RuO2–SiO2 (0.5:0.5) displayed outstanding electrochemical stability upon exposure to rigorous accelerated potential cycling tests that mimic automotive drive cycles. The Pt/RuO2–SiO2 (0.5:0.5) electrocatalyst yielded a mass activity of 50 mA/mgPt and an area specific activity of 156.3 μA/cm2 at 0.9 V vs. RHE when tested in a fuel cell operating at 80 ºC and 75% RH. A 20 wt.% Pt/Ta0.3Ti0.7O2 catalyst was compared in terms of activity and stability against benchmark Pt/C catalysts. The importance of a corrosion resistant support in a PEFC was demonstrated by monitoring performance loss during start-stop cycling and load cycling; while load cycling did not cause a performance drop, the corrosion-resistant nature of the Ta0.3Ti0.7O2 support helped prevent catastrophic fuel cell failure observed in carbon-supported catalysts during start-stop cycling. Corrosion-resistant electrode materials can not only be applied to PEFCs but can also be extended to other electrochemical energy storage and conversion devices such as redox-flow batteries and electrolyzers. The results of this work also indicate suitable strategies for incorporation of other possible dopants (such as Nb, W and Zr) within TiO2, as well as the use of other metal oxides (such as SnO2 and HfO2) as alternative catalyst supports.
Ph.D. in Chemical Engineering, July 2014
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