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<p>Pollution problems have drawn worldwide awareness and become significantly important now. Particulate matter (PM) emission is one of the key pollution issues. Particulate matter has a significant impact on the environment and human health, especially particle sizes that range below 10μm. Researches continuously work an improvement of fine particulate matter collections emitted from all kinds of sources, such as automobiles, industrial combustion, etc. Governments in many countries are planning to regulate the PM emission from the existing PM_10 (particle diameter<10μm) to new limits PM_2.5 (particle diameter<2.5μm) within the next few years. For this reason, present PM control system needs to be improved.</p><p>The objective of this work is to develop a dust flow separator type electrostatic precipitator (DFS-ESP) for the effective control of fine particulate matter emission from natural gas combustions. The characteristic of PM emitted from natural gas combustion is studied, and the performance of a DFS-ESP is evaluated by experiments and numerical predictions.</p><p>An experiment was conducted for natural gas combustion exhaust flow rates from 2.5 to 9 Nm^3/h, ESP applied voltages from 0 to 30kV, and gas temperature from 80 to 160°C. A series of particle measurements were conducted at upstream, downstream and middle of the DFS-ESP system by an optical particle counter for particle mass density, and by condensation nucleate particle counter for particle size distributions and particle number density. Particle sampled from the natural gas combustion system was also analyzed by an environmental scanning electron microscope (ESEM) technique. Flow velocity profile and pressure drop of the DFS-ESP were measured by a Pitot tube and diaphragm type pressure transducer, respectively.</p><p>The experimental results show that the particle size emitted from natural gas combustion ranges from 17 to 300nm in diameter, and the volume density is approximately from 5 x 10^8 #pt/m^3 to 5 x 10^9 #pt/m^3 depending on the combustion conditions. The dust flow separator can concentrate 90% of fine particles in 1 to 3% of the gas flow and divert it from the main flow to the ESP section where the particles can be removed. In terms of overall particle collection efficiency, the DFS-ESP system can remove up to 90% of the particles based on the number density. The pressure drop across the DFS-ESP is observed to be lower than lPa for the present range of flow rate, which is within acceptable limits for industrial applications.</p> / Thesis / Master of Applied Science (MASc)

<p> Pollution problems have drawn worldwide awareness and become significantly important now. Particulate matter (PM) emission is one of the key pollution issues. Particulate matter has a significant impact on the environment and human health, especially particle sizes that range below lOJJ.m. Researches continuously work an improvement of fine particulate matter collections emitted from all kinds of sources, such as automobiles, industrial combustion, etc. Governments in many countries are planning to regulate the PM emission from the existing PM10 (particle diameter<10μm) to new limits PM2.5 (particle diameter<2.5μm) within the next few years. For this reason, present PM control system needs to be improved. </p> <p> The objective of this work is to develop a dust flow separator type electrostatic precipitator (DFS-ESP) for the effective control of fine particulate matter emission from natural gas combustions. The characteristic of PM emitted from natural gas combustion is studied, and the performance of a DFS-ESP is evaluated by experiments and numerical predictions. </p> <p> An experiment was conducted for natural gas combustion exhaust flow rates from 2.5 to 9 Nm^3/h, ESP applied voltages from 0 to 30kV, and gas temperature from 80 to 160°C. A series of particle measurements were conducted at upstream, downstream and middle of the DFS-ESP system by an optical particle counter for particle mass density, and by condensation nucleate particle counter for particle size distributions and particle number density. Particle sampled from the natural gas combustion system was also analyzed by an environmental scanning electron microscope (ESEM) technique. Flow velocity profile and pressure drop of the DFS-ESP were measured by a Pitot tube and diaphragm type pressure transducer, respectively. </p> <p> The experimental results show that the particle size emitted from natural gas combustion ranges from 17 to 300nm in diameter, and the volume density is approximately from 5 x 10^8 #pt/m^3 to 5 x 109 #pt/m^3 depending on the combustion conditions. The dust flow separator can concentrate 90% of fine particles in 1 to 3% of the gas flow and divert it from the main flow to the ESP section where the particles can be removed. In terms of overall particle collection efficiency, the DFS-ESP system can remove up to 90% of the particles based on the number density. The pressure drop across the DFS-ESP is observed to be lower than lPa for the present range of flow rate, which is within acceptable limits for industrial applications. </p> / Thesis / Master of Applied Science (MASc)

<p> Increasingly stringent legislation governing the emissions of diesel engine particulate matter (DPM) has required the development of technological improvements to diesel engines, fuels and exhaust treatments. A main focus of diesel particulate matter abatement is on exhaust after treatment, that consists of the removal of particulate matter from the exhaust gas after it exits the engine. This is currently accomplished with regenerative diesel particulate traps that are effective at removing DPM, but are costly and introduce a significant pressure drop in the exhaust flow.</p> <p> The objective of this study was to evaluate the potential of a novel particulate removal system consisting of a particulate flow separator combined with electrostatic precipitators (ESPs). Previous application of this system to natural gas emissions resulted in collection efficiencies larger than 90% with negligible pressure drop.</p> <p> The ESPs used in the proposed flow separator-ESP were characterized and have collection efficiencies of up to 99% at the flow rates studied. The flow separator-ESP was characterized with a straight inlet section and an expanding inlet section. The collection efficiency of the flow separator-ESP configured with the expanding inlet section was up to 60% for a flow rate of 2.5 kg/hr, that corresponded to laminar flow with Reynolds number of 1100. Collection efficiencies on the order of 20% were obtained for exhaust flow rates of 3.75 kg/hr (Re = 1500) and 5.0 kg/hr (Re = 2100) for both inlet configurations, and 2.5 kg/hr with the straight inlet. The effectiveness of the current design is limited by exhaust flow rate.</p> <p> The diesel exhaust gas was sampled using a partial flow dilution tunnel developed specifically for this study. The dilution ratio for this system can be estimated to within ±10% using volumetric flow measurements. It was found that changes in the dilution and sampling velocity ratios for diesel exhaust have some effect on measured particulate matter mass concentrations.</p> / Thesis / Master of Applied Science (MASc)

The electrostatic self-assembly (ESA) method presents an effective application in the field of biosensing due to the uniform nanoscale structure. In previous research, a single mode fiber (SMF) sensor system had been investigated for the thin-film measurement due to the high fringe visibility. However, compared with a SMF sensor system, a multimode fiber (MMF) sensor system is lower-cost and has larger sensing area (the fiber core), providing the potential for higher sensing efficiency. In this thesis, a multimode fiber-optic sensor has been developed based on extrinsic Fabry-Perot interferometry (EFPI) for the measurement of optical thickness in self-assembled thin film layers as well as for the immunosensing test. The sensor was fabricated by connecting a multimode fiber (MMF) and a silica wafer. A Fabry-Perot cavity was formed by the reflections from the two interfaces of the wafer. The negatively charged silica wafer could be used as the substrate for the thin film immobilization scheme. The sensor is incorporated into the white-light interferometric system. By monitoring the optical cavity length increment, the self-assembled thin film thickness was measured; the immunoreaction between immunoglobulin G (IgG) and anti-IgG was investigated. / Master of Science

Heterogeneous reactions between gas-phase oxidants and particulate-phase organic compounds impact many important atmospheric chemical processes. For example, little is known about the reaction dynamics of gaseous oxidants with organic compounds found in the atmosphere. The first step of the reaction between gaseous ozone and solid pentacene was investigated using Reflection Absorption Infrared Spectroscopy (RAIRS). Ozone was found to add to pentacene non-selectively and form a range of products after heavy ozone exposure. The rate limiting step had an activation energy of 17 kJ/mol, which is consistent with the findings of previous ozone oxidation studies for the cleavage of a carbon-carbon double bond. Unfortunately the products could not be used to distinguish between probable reaction mechanisms. Hydroxyl radicals (•OH) play a major role processing atmospheric hydrocarbons. Due to their short lifetimes, not much is known about the dynamics of the first steps of •OH reactions. To investigate these reactions, a rotational state-selector was constructed to filter a molecular beam of •OH for reaction dynamics investigations with organic surfaces. The rotational state-selector was designed to leverage the linear Stark effect to pass only suitable molecules in a particular rotational state and block the flow of any other atoms, molecules and ions in a molecular beam. The state-selector was validated and used to positively deflect molecular beams of methyl iodide and D₂O via the linear Stark effect. Future studies with the rotational state-selector will investigate the initial steps of •OH reactions with solid organic compounds. / Master of Science

This dissertation focused on the potential use of highly charged nanoparticles to stabilize dispersions of weakly charged microparticles. The experimental components of the project centered on a model colloidal system containing silica microparticles at the isoelectric point where the suspensions are unstable and prone to flocculation. The stability of the silica suspensions was studied in the presence of highly charged nanoparticles. Initial experiments used polystyrene latex with either sulfate or amidine surface groups. Effective zeta potentials were measured with nanoparticle concentrations ranging from 0.001% to 0.5% vol. Adsorption levels were determined through direct SEM imaging of the silica microparticles, showing that the nanoparticles directly adsorbed to the microparticles (amidine more than sulfate), producing relatively large effective zeta potentials. However, stability experiments showed that the latex nanoparticles did not stabilize the silica but merely provided a reduction in overall flocculation rate. It was concluded that the zeta potential was an insufficient predictor of stability as there was still sufficient patchiness on the surface to allow for the silica surfaces to aggregate. Experiments using zirconia and alumina nanoparticles did achieve effective stabilization; both types stabilized the silica suspensions for longer than the observation period of approximately 15 hours. Stability was observed at concentrations of 10^-4% to 1.0% (zirconia) and 10^-2% vol. (alumina). These particles adsorbed directly to the microparticles (confirmed via SEM) and produced increasing effective zeta potentials with increasing nanoparticle concentrations. The adsorption resulted in significant electrostatic repulsion that was determined to be effectively irreversible using colloidal probe AFM. The improved stabilizing ability was attributed to the increased van der Waals attraction between the oxide nanoparticles (compared to polystyrene). Finally, an unexpected result of the CP-AFM force measurements showed that the repulsive forces between a nanoparticle-coated particle and plate lacked the normal dependence on the radius of the probe as predicted by the Derjaguin approximation. The forces observed in nanoparticle suspensions were virtually identical for 5 µm and 30 µm probes. Based on calculations of the shear rate in the gap, it was theorized that this phenomenon may have resulted from the shearing of adsorbed particles from the surfaces, which leads to similar interaction geometries for the two probe sizes. / Ph. D.

Anionic polymerization and controlled radical polymerization enabled the synthesis of novel block copolymers with non-covalent interactions (electrostatic interaction and/or hydrogen bonding) to examine the relationships between mesoscale phenomenon and macroscopic physical properties. Non-covalent interactions offer extra intra- and inter-molecular interactions to achieve stimuli-responsive materials in various applications, such as artificial muscles, thermoplastic elastomers, and reversible biomacromolecule binding. The relationship between non-covalent interaction promoted mesoscale phenomenon (such as morphology) and consequent macroscopic physical properties is the key to optimize material design and improve end-use performance for emerging applications. Pendant hydrogen bonding in ABA block copolymers promoted microphase separation and delayed the order-disorder transition, resulting in tunable morphologies (through composition changes) and extended rubbery plateaus. Reversible addition-fragmentation chain transfer (RAFT) polymerization afforded a facile synthesis of ABA triblock copolymers with hydrogen bonding (urea sites) and electrostatic interactions (pyridinium groups). Pyridine groups facilitated hydrogen bonding through a preorganization effect, leading to highly ordered, long-range lamellar morphology and a significant increase of flow temperature (Tf) 80 °C above the hard block Tg. After quaternization of pyridine groups, electrostatic interaction, as a second physical crosslinking mechanism, disrupted ordered lamellar morphology and decreased Tf. Yet, extra physical crosslinking from electrostatic interactions pertained ordered hydrogen bonding at high temperature and exhibited improved stress-relaxation properties. Both conventional free radical polymerization and RAFT polymerization generated a library of poly(ionic liquid) (PIL) homopolymers with imidazolium groups as bond charge moieties. A long chain alkyl spacer between imidazolium groups and the polymer backbones ensured a low glass transition temperature (Tg), which is beneficial to ion conductivity. Four different counter anions enabled readily tunable Tgs all below room temperature and showed promising ion conductivities as high as 2.45 × 10⁻⁵ S/cm at 30 °C. For the first time, the influence of counter anions on radical polymerization kinetics was observed and investigated thoroughly using in situ FTIR, NMR diffusometry, and simulation. Monomer diffusion and aggregation barely contributed to the kinetic differences, and the Marcus theory was applied to explain the polymerization kinetic differences which showed promising simulation results. RAFT polymerization readily prepared AB diblock, ABA triblock and (AB)3 3-arm diblock copolymers using the ionic liquid (IL) monomers discussed above and deuterated/hydrogenated styrene. We demonstrated the first example of in situ morphology studies during an actuation process, and counter anions with varied electrostatic interactions showed different mesoscale mechanisms, which accounted for macroscopic actuation. The long chain alkyl spacer between imidazolium groups and polymer backbones decoupled ion dynamics and structural relaxation. For the first time, composition changes of block copolymers achieved tunable viscoelastic properties without altering ion conductivity, which provided an ideal example for actuation materials, solid electrolytes, and ion exchange membranes. / Ph. D. / My research focuses on the synthesis of novel soft materials with a special interest in responsive polymers. The incorporation of responsive chemistry, such as hydrogen bonding and ionic interactions, enables soft materials with complex responsive behavior were achieved. Polymers with ion pairs promise great potential as solid-state electrolytes (which transfer ions to generate current) to eliminate potential fire hazard in batteries, which has been an arising concern for modern cellphone and electric car industry. The introduction of strong dipoles into polymers allows the fabrication of actuators, which convert electric signals to physical movement. Under applied voltage, polymers bend within seconds while holding physical loads. Actuator studies in polymers paves the way towards artificial muscles as well as soft robotics. Temperature responsive hydrogen bonding in polymers offers drastically different viscoelastic properties at different temperature and serves as the key mechanism in holt-melt adhesives, controlled drug release, and high performance materials.

Intrinsically disordered proteins (IDPs) are an abundant class of proteins and protein regions which rapidly change between multiple structures without an equilibrium position. IDPs exist as a series of conformational ensembles of semi-stable conformations that can be adopted based on a hilly landscape of shallow free energy minima. Disordered sequences share characteristic features differentiating them from globular proteins, including low sequence complexity, low occurrence of hydrophobic residues, high polar and charged residue content, and high flexibility. IDPs are commonly involved in regulation in the cell, and frequently function as, or interact with, hub proteins in protein-protein interaction networks, making them an important class of macromolecules for understanding regulatory and other processes. Given their functional importance, these proteins are widely studied. Many analytical techniques are used, though rapid conformational sampling by IDPs makes it difficult to detect many states with NMR or other techniques. Computational approaches such as molecular dynamics are increasingly used to probe the binding and conformational sampling of these proteins, allowing for observation of factors that cannot be observed with traditional analytical methods such as NMR, such as differing conformational ensembles and the dipoles of individual residues. Here, we studied the role of electrostatic interactions in IDP protein-protein interaction using molecular dynamics simulations performed with the Drude-2019 force field (FF), a polarizable model that allows for more accurate representation of electrostatics, an important factor for highly charged systems like IDPs. For this project, a prototypical protein with disordered regions, p53, was simulated with two protein partners, the nuclear coactivator domain of the CREB binding protein (CBP), and the E3 ubiquitin-protein ligase mouse double minute 2 (MDM2). p53 is widely studied, and the p53 transactivation domain (TAD) is disordered and binds to many structurally diverse partners, making this protein domain a useful model for probing the role of electrostatic interactions formed by IDPs at protein-protein binding interfaces. We found that the Drude-2019 FF allows for simulation of the p53 TAD with Cα chemical shifts comparable to those observed with NMR, supporting that the Drude-2019 FF performs well in simulating IDPs. We observed large relative change in sidechain dipole moments when comparing the p53 TAD alone and when bound to either CBP or MDM2. We observed that aliphatic and aromatic amino acids experienced the largest relative change in sidechain dipole moments, and that there is sensitivity to binding shown in this dipole response. The largest percent changes in sidechain dipole moment were found to localize at and around the binding interface. Understanding the binding interactions of IDPs at a fundamental level, including the role of electrostatic interactions, may help with targeting IDPs or their partners for drug design. / Master of Science in Life Sciences / Many proteins adopt one main structure, and these proteins are called ordered proteins. Intrinsically disordered proteins (IDPs) are an abundant category of proteins which adopt multiple structures, and transition between these different structures is based on factors such as the environment around them, modifications, or interactions with other macromolecules. The flexible structures of IDPs allow them to bind to multiple different partners and to regulate processes in the cell. Since IDPs often regulate processes important to cell function, when these proteins are mutated, misfolded, or otherwise mis-regulated the resulting issues are associated with disease states. IDPs are widely studied with analytical techniques, but because IDPs frequently change shape it can be difficult to observe certain behaviors or certain factors with these techniques. Computational approaches, such as molecular dynamics (MD). MD is the study of molecular motion and interaction, and can allow observation of factors that would be difficult or impossible to observe otherwise, such as the varying structures of IDPs or the dipole moments of specific amino acids within the proteins. For this project we wanted to probe the role of dipole moments, which are charge-based interactions, in the binding of IDPs to protein partners, to better understand how IDPs bind to different partners. We used the p53 protein as an example of IDP binding and simulated it alone and bound to two other proteins, the CREB binding protein (CBP), and the E3 ubiquitin-protein ligase mouse double minute 2 (MDM2). We observed that our simulations were comparable to experiments done with nuclear magnetic resonance spectroscopy, which served to validate that our simulations were realistic. We observed that the dipole moments of the proteins change when simulating the proteins alone and in complex, and that the largest relative changes in dipole are observed for regions of the proteins involved in binding. Probing the role of charge-based interactions in protein-protein binding interactions for IDPs can help us to greater understand these interactions at a more fundamental level and could help with targeting IDPs or their partners for drug design or other problems.