Chemical Engineering Commons^™

Methods Of Cellular Integration And Techniques For Improving Encapsulated Cell Viability For The Purpose Of Developing Living Materials And Cell Based Bio-Sensing Materials, Travis J. Savage

Chemical and Biological Engineering ETDs

Living materials offer the potential for detection-reporter systems based on living cells that are genetically tailored to sense target analytes with high levels of specificity and accuracy. A biotic or living material would allow the development of simple, hand held devices that could be utilized for many applications including industrial process monitoring, environmental remediation, military and defense applications and drug delivery. Many living materials have been developed and characterized but they still lack heightened and prolonged encapsulated cell viability necessary to make the material a candidate for widespread use. One particular material offers several advantages to increase yeast cell viability …

Fabrication And Characterization Of Synthetic Substrates For Use In Rigidity Cell Culture Studies Of Valvular Interstitial Cells For Aortic Valve Tissue Engineering, Alexander T. Leonard

Chemical and Biological Engineering ETDs

More than 100,000 Americans each year undergo aortic valve (AV) replacement due to valve failure. An AV can become diseased, impairing the proper function of the valve. Common treatments for a defective valve are either replacement with a decellularized biologic or a synthetic valve. These treatments options are limited by short functional lifetime and thrombogenic surfaces. Tissue engineered heart valve will have the ability to integrate with the surrounding tissue as well as to repair and remodel. However, a greater understanding of valve cell biology is required to induce analogous tissue formation. A diseased valve is associated with stiffening of …

Novel Routes For Synthesis Of Pd Nanoparticles And Faceted Zno Supports For Heterogeneous Catalysts, Patrick David Burton

Chemical and Biological Engineering ETDs

Alcohol steam reforming is a promising source of hydrogen as fuel, and could be improved by the use of an optimal catalyst. The methanol steam reforming reaction, CH3OH+H2O --> 3H2+CO2 frequently conducted by means of a Cu/ZnO catalyst. Unfortunately, this catalyst deactivates quickly and is pyrophoric. Pd catalysts are much more stable, but reactions using these catalyst follow the decomposition pathway, CH3OH --> 2H2+CO. PdZn alloys can achieve the desired selectivity, and have been noted to form under reaction conditions from Pd/ZnO heterogeneous catalysts. In the present work, careful synthesis techniques of specific support and nanoparticle surfaces have been developed …

Polymerization In Emulsion Microdroplet Reactors, Nick J. Carroll

Chemical and Biological Engineering ETDs

The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic …

Development Of Novel Bio/Nano Interfaces For Materials Science And Biomedical Applications, Carlee Ashley

Chemical and Biological Engineering ETDs

Virus-like particles (VLPs) of MS2 bacteriophage possess a variety of characteristics that enable their use in biomedical and materials science applications. MS2 VLPs are perfectly monodisperse and possess a highly regular periodic structure. Their protein capsids can be modified in precise locations via chemical conjugation or genetic display of peptides, and their interior volumes can be readily loaded with a variety of non-genomic materials by taking advantage of their ability to self-assemble in the presence of RNA and RNA-modified cargos. Using peptides identified by filamentous phage display, I have demonstrated the utility of MS2 VLPs as targeted nanocarriers capable of …

Selective Epitaxial Growth Techniques To Integrate High-Quality Germanium On Silicon, Darin Leonhardt

Chemical and Biological Engineering ETDs

High-quality Ge-on-Si heterostructures have been actively pursued for many advanced applications, including near-infrared photodetectors, high-mobility field effect transistors, and virtual substrates for integrating III-V multijunction solar cells. However, growing epitaxial Ge on Si poses many engineering challenges, ranging from lattice mismatch, to thermal expansion coefficient mismatch, to non-planar morphological evolution. The lattice mismatch between Ge and Si often leads to a high density of threading dislocations. These dislocations, if not reduced, propagate through the subsequently grown GaAs layer, deteriorating its quality. To overcome these engineering challenges, we have developed three different approaches based on molecular beam epitaxy to significantly reduce, …

Synthesis And Characterization Of Tethered Poly(N-Isopropylacrylamide) For Quantitative Cell Adhesion Studies, Phanindhar J. Shivapooja

Chemical and Biological Engineering ETDs

Environmentally responsive (or smart') polymers represent a new approach for controlling biofouling release. Poly(N-isopropylacrylamide) (PNIPAAm) is a thermo responsive polymer that can potentially be used to control biofouling, as it exhibits a change in its relative hydrophobicity above and below its lower critical solution temperature (LCST ~ 32\uf0b0C). This thesis reports on grafted PNIPAAm brushes, synthesized using a relatively simple and rapid method which allows atom transfer radical polymerization (ATRP) in presence of air. In this study the structure, purity and thermally responsive behavior of grafted brushes have been characterized using X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy, Fourier …

Ionic Self-Assembly Of Porphyrin Micro-Nano Structures For Solar Hydrogen Evolution, Yongming Tian

Chemical and Biological Engineering ETDs

This research project develops self-assembled porphyrin micro-nano structures and their metal nanocomposites for efficient solar H2 evolution. The project is composed of three inter-related tasks. The first task is to develop the synthetic methods for preparing the binary porphyrin micro-nano structures by ionic self-assembly under various aqueous solution conditions. Although the porphyrin molecules have been widely studied in artificial photosynthesis, the porphyrin monomers absorb light in a limited range of the solar spectrum and are unstable in solution. In using ionic selfassembly of two oppositely charged porphyrin molecules, we successfully synthesized the more robust micro/nano clover-like structures to replace the …

Sintering Of Metal Nanoparticles On Model Substrates, Levi R. Houk

Chemical and Biological Engineering ETDs

The sintering of precious metal catalysts is an important problem for the automotive and chemical process industry. As these precious metal catalysts sinter, the metal nanoparticles grow, which in return causes a loss in the overall surface area from loss of the number of available reaction sites. At high temperatures, sintering as a thermally activated process occurs more rapidly and the energetics of the sample changes. In automotive catalysis, for the catalytic converter, the exhaust gases from automobiles contain carbon monoxide, nitrogen oxide compounds, and other hydrogen compounds, which are detrimental to the atmosphere, and a catalyst is required to …

Model Electrode Structures For Studies Of Electrocatalyst Degradation, Ronald Goeke

Chemical and Biological Engineering ETDs

Proton exchange membrane fuel cells (PEMFCs) are being extensively studied as power sources because of their technological advantages such as high energy efficiency, high energy and power densities, environmental friendliness, low noise, rapid refueling, and fuel flexibility. The most effective catalyst in these systems consists of nanoparticles of Pt or Pt-based alloys on carbon supports. Understanding the role of the nanoparticle size and structure on the catalytic activity and degradation is needed to optimize the fuel cell performance and reduce the noble metal loading. Electrocatalyst degradation is believed to occur by four mechanisms; particle sintering (Ostwald ripening and migration and …

The Sintering And Stability Of Catalytic Nano-Particles, Andrew Delariva

Chemical and Biological Engineering ETDs

Studies were performed on three different catalysts in order to determine their stability and sintering behavior. Pd deposited on a flat single crystal substrate made of Al2O3 was characterized to determine if the mechanism of Ostwald ripening was solely dominated by vapor phase transport of metal atoms. The atoms emitted could be determined by the rate of evaporation and an attempt was then made in order to relate the rates of emission to sintering (instability of nanoparticles). It was found that the rates of emission did not fully reflect vapor phase transport (direct evaporation). The particle-support interaction was increasing the …

Long-Term Desorption Behavior Of Uranium And Neptunium In Heterogeneous Volcanic Tuff Materials, Dean Cynthia

Chemical and Biological Engineering ETDs

Uranium and neptunium desorption were studied in long-term laboratory experiments using four well-characterized volcanic tuff cores collected from southeast of Yucca Mountain, Nevada. The objectives of the experiments were to 1. Demonstrate a methodology aimed at characterizing distributions of sorption parameters (attributes of multiple sorption sites) that can be applied to moderately-sorbing species in heterogeneous systems to provide more realistic reactive transport parameters and a more realistic approach to modeling transport in heterogeneous systems. 2. Focus on uranium and neptunium because of their high solubility, relatively weak sorption, and high contributions to predicted dose in Yucca Mountain performance assessments. Also, …

Atomic-Level Investigation Of Surface Processes Governing Sige Wetting Layer Formation Using Stm/Sts, Kyle J. Solis

Chemical and Biological Engineering ETDs

Upon sub-monolayer Ge deposition on the 2xn reconstructed SiGe alloy wetting layer at room temperature, the predominant adspecies observed are so-called addimer chain structures (ADCSs). Polarity-switching scanning tunneling microscopy (STM) is used to study ADCSs, as they only appear in empty-state images. ADCSs are dilute structures comprising type-C addimers that reside in neighboring troughs and extend along all equivalent < 130> directions of the surface, giving rise to a zigzagged morphology. ADCSs exhibit localized movements, wherein their rearrangements are strongly coupled with the structure of the underlying substrate dimers. At elevated temperatures, ADCSs are observed to transition to compact epitaxial segments of …

Bioadhesion To Model Thermally Responsive Surfaces, Brett J. Andrzejewski

Chemical and Biological Engineering ETDs

This dissertation focuses on the characterization of two surfaces: mixed self-assembled monolayers (SAMs) of hexa(ethylene glycol) and alkyl thiolates (mixed SAM) and poly(N-isopropylacrylamide) (PNIPAAm). The synthesis of hexa(ethylene gylcol) alkyl thiol (C11EG6OH) is presented along with the mass spectrometry and nuclear magnetic resonance results. The mixed SAM surface was confirmed to be thermally responsive by contact angle goniometry, 35° at 28 °C and 55° at 40 °C. In addition, the mixed SAM surfaces were confirmed to be thermally responsive for various aqueous mediums by tensiometry. Factors such as oxygen, age, and surface mole fraction and how they affect the thermal …

Unraveling The Intricacies Of Spatial Organization Of The Erbb Receptors And Downstream Signaling Pathways, Michelle Costa

Chemical and Biological Engineering ETDs

Faced with the complexity of diseases such as cancer which has 1012 mutations, altering gene expression, and disrupting regulatory networks, there has been a paradigm shift in the biological sciences and what has emerged is a much more quantitative field of biology. Mathematical modeling can aid in biological discovery with the development of predictive models that provide future direction for experimentalist. In this work, I have contributed to the development of novel computational approaches which explore mechanisms of receptor aggregation and predict the effects of downstream signaling. The coupled spatial non-spatial simulation algorithm, CSNSA is a tool that I took …

Reactivity Study Of Platinum Nanoparticles And Nanowires Inside The Channels Of Mesoporous Silica, Marcus R. Smith

Chemical and Biological Engineering ETDs

Pt metal nanowires and nanoparticles were prepared using mesoporous silica as the template. Mesoporous silica with straight 1-dimensional, tortuous 1-dimensional and 3-dimensional channels was used. The experimental techniques included CO oxidation, Chemisorption, XRD, and STEM. CO oxidation and chemisorption provided the data to calculate the intrinsic reactivity, known as turn over frequency (TOF). Powder XRD was used to measure line broadening. The FWHM of the XRD line broadening was used with the Scherrer formula to determine Pt metal crystallite size. STEM images permitted for the measurement of the particle diameters, and the determination of morphology.

Two commercially available reference samples …

Infrared Diode Laser Absorption Spectroscopy Measurement Of Gas Phase Radicals In C₄F Discharges For Plasma Model Validation, Karla Waters

Chemical and Biological Engineering ETDs

The etching characteristics of oxide and photoresist thin films in C₄F₈ discharges in an inductively coupled GEC Reference cell have been determined. Infrared diode laser absorption spectroscopy (IR-DLAS) measured absolute concentrations of CF_x radicals in C₄F₈ discharges and correlated their behavior to the oxide etch process. Additionally, Langmuir probe and OES data were collected to aid in characterizing the plasma and the oxide/photoresist etch processes.

A central composite design of experiment was employed. The factors were source power, chuck bias power, and total pressure. The source power varied from 200 to 500 W, …

Activation Of Precipitated Iron Fischer-Tropsch Catalysts, Mehul D. Shroff

Chemical and Biological Engineering ETDs

The Fischer-Tropsch Synthesis (FTS) is an important step in the manufacture of synthetic fuels from coal. The use of iron catalysts for FTS, though desirable from the standpoint of process economy, is hampered by problems relating to catalyst attrition and carbon buildup. In addition, from a research perspective, there has been a long-standing controversy in the literature with regard to the nature of the active phase.

The effect of activation and reaction treatments on the resulting phase transformations in a commercial, precipitated and spray-dried, Fe₂O₃ - CuO - K₂O Fischer-Tropsch catalyst have been studied. Different …

X-Ray Induced Electron Emission, Charles A. Aeby

Chemical and Biological Engineering ETDs

An experimental technique has been developed and successfully used in the measurement of X-Ray induced electron emission from a variety of materials including a group of significance to satellite applications. A database has been established which extends measure emission characteristics to an order of magnitude lower energies than previously available.

Separations Of Dilute Solutions By The Smooth Deposit Approach Of The In-Situ Indirect Freezing Process, Jeng-Hung Lue

Chemical and Biological Engineering ETDs

The main objective of the present study is to demonstrate experimentally the feasibility of applying the smooth deposit ap­proach of the in-situ indirect freezing process to the separations of both dilute organic mixtures and aqueous mixtures. The in-situ indirect freezing process with in-situ washing and melting opera­tions was first introduced by C. Y. Cheng and S. W. Cheng [1].

Assessment Of Corrosion And Scaling In A Low Temperature Geothermal System, David Bruce Orrell

Chemical and Biological Engineering ETDs

The feasibility of a low temperature geothermal system to be located in the area immediately surrounding Albuquerque, New Mexico, was assessed with respect to corrosion and scaling. Theories of corrosion and scaling were explored and an extensive literature survey was performed to predict trends and apply design criteria and guidelines regarding corrosion and scaling from other geothermal environments to the proposed geothermal installation in Albuquerque. A recirculating corrosion test loop was built, and fifteen metals were tested for general corrosion resistance in seawater at 190° F and 3 ft/sec flow velocity. Results show this test procedure to be viable and …

Deep Penetration Of Electrons Into Homogeneous Media By The Method Of Condensed Collisions, Joseph Francis Janni

Chemical and Biological Engineering ETDs

The objective of this dissertation was to develop an accurate and efficient alternative to presently available methods of calculating the steady state penetration of electrons deep into homogeneous materials. A thorough solution must include scalar fluxes, net currents, angular distributions, and differential energy spectra. This research has successfully developed the method of condensed collisions, which provides an alternative to methods now in use for the solution of the electron transport problem. The condensed collsion method is general, but has been applied specifically to deep penetration electron transport to demonstrate its utility. The present aplication was for electrons having incident energies …

Mass Transfer At The Edge Of A Rotating Disk, Jeffrey Malcolm Cohen

Chemical and Biological Engineering ETDs

A different approach to the problem of mass transfer to a rotating disk, employing less restrictive assumptions, has been undertaken to quantify the phenomenon of mass transfer at the disk's edge. Experimental work in support of theor­etical conjectures was performed as part of this work.

In order to include the effect of mass transfer at the edge on mass transfer to the entire disk, the equation of convective diffusion was solved in two dimensions over a region that extended beyond physical projection of active area of the disk. A synthesis of experimental results and theoret­ical considerations was used to specify …

Concentrated Organic Separations By The Cyclic Indirect Freezing Process, Jeffrey Carl Miles

Chemical and Biological Engineering ETDs

This study demonstrates the technical feasibility of purifying concentrated organic solutions by the cyclic indirect freezing process with in-situ washing and in-situ melting operations. The key to a successful purification in the freezing process is a near plug flow displacement of unfrozen liquor from the bed in an in-situ washing operation. To be successful, a freezing step has to be initiated uniformly and a high permeability bed has to be formed uniformly throughout the freezing conduits. In the study, a nucleation technique based on pressure induced supersaturation has been used to accomplish a uniform initiation and a pressure induced freezing …

Ocean Thermal Energy Conversion By Using A Solidification Melting Cycle, Wen Liang Lin

Chemical and Biological Engineering ETDs

An OTEC (Ocean Thermal Energy Conversion) power plant uses warm surface seawater (24° C - 28° C) as a heat source and deep cold seawater (4° C - 7°C) as a heat sink. With this temperature difference, a heat engine which delivers either mechanical or electric power can be con­structed. There are some limitations and problems of evaporators and condensers to be used in a closed Rankine cycle OTEC plant which have seriously limited the applicability of this concept. This study proposed a process using the S/L engine---a heat engine that utilizes a working medium undergoing solidification and melting operations. …

The Fracture Toughness Of Steel-Aluminum Deformation Welds, Charles Ellis Albright Jr

Chemical and Biological Engineering ETDs

A study of the fracture toughness (in this case, Gic) of steel-aluminum deformation welds using a specially developed double cantilever beam fracture toughness specimen is presented. Welds made at 350C were heat treated at 360, 380, 400, 420 and 440 C.

An intermetallic reaction product layer of Fe2Al5 is formed at the steel-aluminum interface with increasing heat treating temperature and time by a process of nucleation and growth of discrete particles. A transition in toughness from a higher average Gic value (6097 N/m) to a very low average Gic value (525 N/m) is observed. The decrease in toughness is accomplished …

An Investigation Into The Transport Properties And Kinetic Parameters Of Single Coal Particles During Devolatilization, Gregory Forrest Roach

Chemical and Biological Engineering ETDs

This study focuses on the devolatilization step that occurs in the process of coal gasification. This is a key economic step for both the Lurgi synthetic natural gas process and the in-situ gasification that are being proposed for New Mexican coals. The findings of this study may be used by industry to improve the design and operation of these processes.

The work presented is an investigation into the transport properties and kinetic parameters that govern the extent of pyrolysis for single particles of subbituminous coal from the San Juan Basin in north-west New Mexico. The unique feature of this work …

Desublimation Of Water Vapor At Low Pressure And Evaporative Freezing Of Seawater, Sun Sea Pao

Chemical and Biological Engineering ETDs

The Vacuum-Freezing Vapor-Desublimation and High Pressure Ice-Melting Process has been developed since 1972. In 1976, Mr. T. C. Chung finished a theoretical study of Low Pressure Water Vapor Desublimation Operation. The writer was a co-worker of Mr. Chung, and had worked with him for the study for four months. The information collected in Mr. Chung's thesis was borrowed and edited as Chapters 1 and 2 in the present thesis. Mr. Chung's theory predicts the rate of water vapor desublimation as a function of the difference between operating temperature and desublimer wall temperature. In the present thesis, experimental rates of desublimation …

A Simple, Inexpensive Spinning-Drop Interfacial Tensiometer, Humoud S. Al-Rabiah

Chemical and Biological Engineering ETDs

A spinning-drop interfacial tensiometer was designed, built, and tested. The device is very simple, inexpensive to build, and easy to operate compared with other spinningdrop tensiometers.

The tensiometer measures the interfacial tension of liquid-liquid or liquid-vapor systems. Interfacial tensions of three systems were measured to test the device: water-heptane, glycerol-heptane, and glycerol-air.

Experimental results agree with literature values within one percent for the glycerol-heptane system. The variations among the values for the liquid-liquid systems at different rotational speeds are within six percent. Repeated experiments with different drop sizes show that drop size of the glycerol-air system may affect the results. …

A Study Of A Buoyancy Balanced Gas-Liquid Contacting System, Jaw-Ruey Leu

Chemical and Biological Engineering ETDs

In a conventional gas-liquid contacting system that provides a long gas-liquid contact time, a pressurized gas is released at the bottom of a pool of liquid to form gas bubbles; the bubbles move upward through the liquid and break at the surface of the liquid. A large amount of work is spent in pressurizing the gas. Even though it is theoretically possible to recover work from rising bubbles, a work recovery scheme has not been incorporated into a conventional system.

A buoyancy-balanced gas-liquid contacting system concept has recently been introduced. The system comprises two processing zones filled with a liquid, …