Chemical Engineering Dissertations

Extracellular and intracellular phenomena in microfluidic flow

Dwayne Vickers — Mon, 11 Mar 2013 08:57:20 PDT

Adhesion-based microfluidic cell separation techniques have been utilized for a wide range of applications, from cancer diagnostics to tissue engineering. This separation approach typically involves the functionalization of a microfluidic channel with molecules that bind to one or more cell types and the capture of cells from a flowing stream. A major advantage of the adhesion-based separation approach, particularly from the standpoint of clinical applications, is label-free operation. Traditional cell separation approaches, such as fluorescence- and magnet-activated cell sorting (FACS and MACS), by contrast, require pre-processing through labeling of sample cell suspensions with fluorescent or magnetic tags. The efficacy of...

Mechanistic studies and modeling of self-emulsifying drug delivery systems for the oral delivery of hydrophobic drugs

Fulden Buyukozturk — Tue, 29 Jan 2013 12:53:26 PST

The oral route for drug delivery is not possible for approximately 50% of currently marketed drug compounds due to low solubility in water. Lipid based drug delivery systems, and in particular self-emulsifying drug delivery systems (SEDDS), show great potential for enhancing oral bioavailability, as well as offering the advantage of minimal processing and inherent stability, but have not been broadly applied, largely due to lack of general formulation guidance and lack of knowledge of how these systems function to enhance bioavailability. It is hypothesized that a systems-based model incorporating key processes involved in oral absorption will enable prediction of the...

Design, synthesis & evaluation of human Aurora kinase and phosphodiesterase inhibitors for anti-trypanosomal drug discovery via target repurposing

Stefan Ovidiu Ochiana — Tue, 08 Jan 2013 11:51:22 PST

Neglected tropical diseases (NTDs) represent a group of infectious diseases that blight the lives of approximately one billion people, and collectively cause around 550,000 deaths each year. These diseases are generally concentrated in low-income countries from Africa and Latin America, but are also known to take a heavy toll in parts of South Asia. The current therapies have many limitations such as cost, route of administration, toxicity and the emergence of resistance. The current work is focused on targeting the pathogenic parasite that causes African sleeping sickness, Trypanosoma brucei (T.b.), by designing new inhibitors by a "target repurposing approach." The...

Fabrication of super invar micro- and nano- structures by electrodeposition for low thermal expansion applications

Ha Na Kim — Fri, 04 Jan 2013 06:55:29 PST

Electrodeposited alloys of Super Invar composition, 64 wt % Fe, 31 wt % Ni, and 5 wt % Co, are of both theoretical research and practical interest due to the anomalous codeposition behavior, the preferential deposition of less noble metal, and to the material's low coefficient of thermal expansion, CTE. A better understanding of anomalous codeposition allows for controlling the deposition rates of individual Fe, Ni, and Co metal during codeposition and hence the composition. In addition, electrodeposited Super Invar alloys are of practical interests due to their potential applications in industry, particularly in micro-electro-mechanical systems (MEMS) due to the...

Identifying and investigating metabolic pathways activated in high-producing California poppy suspension cultures

John Thornton Oldham — Wed, 20 Jun 2012 06:01:10 PDT

Plant cell culture offers an alternative production system capable of providing consistent, high yields of pharmaceutical compounds. Currently, 9 pharmaceutical compounds have been produced through plant cell culture. However, further increases in productivity for other compounds from plant cell cultures will require a greater understanding of metabolic pathways which limit production. Proteins and pathways with changes in abundance in high-producing cell lines represent potential targets for further increases in production. In this thesis, Eschscholzia californica cultures which produce benzophenanthridine alkaloids, including the anti-microbial and anticancer drug sanguinarine, were used as a model system to study metabolic bottlenecks using proteomics.

Enhancements...

Integrating RHEED-TRAXS and molecular beam epitaxy for real-time compositional control of functional oxide deposition processes

Bing Sun — Thu, 10 May 2012 05:27:21 PDT

Real-time chemical analysis during film growth by Molecular Beam Epitaxy (MBE) has been unattainable because traditional Ultra High Vacuum (UHV) tools such as X-ray Photoelectron Spectroscopy (XPS) or Auger electron spectroscopy (AES) cannot be used at pressures above 10-8 Torr, and MBE growth pressure are typically 10-6 to 10-5 Torr. Real-time chemical analysis and stoichiometry control is important, however, because stoichiometry changes of less than one percent in materials such as functional oxides can cause measurable changes in their physical properties. Indirect measurements of stoichiometry, such as surface Reflection High Energy Electron Diffraction (RHEED) pattern, are often misleading. RHEED -...

Electrodeposited Au/FeAu porous nanowires for enhanced catalytic activity and stability of reactions on titania

Savidra Chavez Lucatero — Tue, 10 Jan 2012 05:55:48 PST

Environmentally clean hydrogen fuel represents a number of advantages over popularly utilized petroleum-based derivatives. Among alternative technologies, hydrogen can be generated by direct electrolysis of water upon irradiating a semiconductor material with light of energy greater than its energy band gap. A strategy to improve the photocatalytic efficacy of bare semiconductors and promote the sluggish kinetics of the oxidation reaction has been the incorporation of noble metals onto their surface. In particular, the Au-TiO₂ system has been effective at enhancing and shifting the photoactivity to irradiation of longer wavelengths through relatively more efficient electron transfer processes involved in redox reactions....

Biomimetic replication of intestinal basement membrane topography

Courtney Allyn Pfluger — Thu, 27 Oct 2011 05:21:31 PDT

Replication of native tissue extracellular matrix (ECM) using CVD or microfabrication techniques enables creation of cell culture scaffolds with precisely biomimetic, irregular, and multi-scale native tissue topography. Topological cues have been shown to be very important in controlling cell phenotype in literature. However little has been done to investigate the effect of topography on cell behavior using exact replicas of native ECM, which often involves multi-scale and irregular topographies. Hence, we proposed a novel, alternative approach to creating cell culture scaffolds with exact replication of ECM topography by using actual native tissues as molds or templates from which to produce...

Biomimesis of intestinal crypt micro-topography and extracellular matrix chemistry for intestinal cell culture

Lin Wang — Tue, 11 Oct 2011 06:14:34 PDT

In small intestine, a monolayer of enterocytes rests on extracellular matrix (ECM) mainly comprised of collagen (Col), laminin (Ln) and fibronectin (Fn), with convoluted topography consisting of finger-like projections (villi) with deep invaginations (crypts) between the villi. The small intestinal epithelial cell phenotype varies with position relative to crypt-villus structure. It is hypothesized that a biomimetic cell culture substrate with intestinal ECM-like topography and chemical makeup may induce in vitro intestinal cell culture expressing a phenotype more similar to native enterocytes.

The goal of this thesis work is to develop a topologically, chemically, and physiologically biomimetic intestinal cell culture system;...

Magnetic particle based microfluidic separation of cancer cells from whole blood for applications in diagnostic medicine

Brian Dennis Plouffe — Wed, 05 Oct 2011 07:52:58 PDT

Metastasis, or the process in which tumor cells spread and grow from a primary tumor site to a distant secondary site, is a significant problem in cancer research today. Metastases have also been shown to causes 90% of all cancer-related deaths, i.e. half-a-million people in the US each year. Detection of circulating tumor cells (CTCs) in whole blood demonstrates that there is a connection between the primary tumor and metastases. Therefore, there is a need to create technologies to enable biological CTC studies. This could contribute to understanding of the spreading of cancer and development of various new drugs and...

Size- and adhesion-based microfluidic cell separation fortissue engineering and clinical diagnostics

James Vincent Green — Thu, 02 Jun 2011 12:47:33 PDT

Myocardial infarction is a condition that affects more than 7 million individuals in the United States. Conventional therapies are limited by the inability of the myocardium to regenerate after injury and the shortage of organs for transplantation. A novel alternative to conventional therapies is the in vitro cultivation of cell-based cardiac grafts that can be surgically attached to the myocardium. This tissue engineering approach relies on starting with a sample of donor tissue and harvesting from it pure populations of one or more important cell types (such as cardiomyocytes or cardiac progenitor cells). Currently, existing techniques for cardiomyocyte separation and...

Molecular beam epitaxy integration of magnetic ferrites with wide bandgap semiconductor 6H-SiC for next-generation microwave and spintronic devices

Zhuhua Cai — Wed, 25 May 2011 05:53:24 PDT

Ferrite/ferroelectric heterostructures have attracted much attention in recent years because of their unique ability to potentially enable dual magnetic and electric field tunability. The simultaneous magnetic and electric tunability in such structures can be applied in a wide range of microwave planar devices (e.g., tunable phase shifters, resonators, and delay lines) and spintronics (e.g., magnetic tunneling junctions for magnetic sensors and nonvolatile magnetic memories). However, the attempts to engineer ferrite/ferroelectric heterostructures to operate at the frequencies higher than 5 GHz are limited. Barium hexaferrite (BaM, BaFe12O19) is an ideal candidate for high frequency microwave device applications because of its strong...

Synthesis and bandgap engineering of vanadosilicate AM-6 for photocatalytic applications

Mariam N. Ismail — Tue, 10 May 2011 09:34:18 PDT

Vanadosilicate AM-6 is a large-pore microporous material, isostructural with titanosilicate ETS-10. This material contains in its structure semiconducting monatomic ...V-O-V-O-V... chains that are embedded in a silica matrix. Microporosity, pore regularity, and the presence of stoichiometric amounts of vanadium in the silicate framework make AM-6 a promising material in both traditional and advanced zeolite-type materials applications. AM-6 has recently been demonstrated to exhibit photocatalytic activity in the visible light range. Diverse applications require AM-6 crystals with controlled characteristics such as purity, size, morphology, topography, and defect concentration. However, to date, AM-6 has only been synthesized using seeds of ETS-10, and...

Biopassive and bioactive coatings for neural implants

Anil Kumar Harapanahalli Achyuta — Wed, 27 Apr 2011 09:12:44 PDT

Tissue interfacing with biocompatible surfaces can be utilized to dictate key aspects of cell behavior in the vicinity of biomedical devices such as neural implants. Consequently, engineering implant materials that interact with the brain tissue used in the treatment of central nervous system (CNS) disorders becomes vital. This thesis emphasized on developing novel coatings (biopassive and bioactive) for neurological implants such as neuro-motor prostheses (NMP) and ventriculo-peritoneal (VP) shunts. NMPs are silicon-based devices that record electric potentials from neurons in the CNS and are currently under development as potential therapies for stroke and paralysis. One major challenge in the fabrication...

Titania nanotubes for solar energy and catalysis

Christiaan P. Richter — Fri, 18 Dec 2009 08:33:26 PST

Since their discovery in 2001, anodic titania nanotubes formed from titanium foils have shown potential for use in photocatalytic and catalytic applications. This dissertation investigates the fabrication process in detail. A new kind of titania nanotube that makes use of a chlorine based electrochemistry, as opposed to existing fluorine based chemistry, is introduced. The chlorine based process is very rapid compared to the existing process and yield nanotubes with smaller diameters (~ 15nm) and high aspect ratios (up to 1000 lengths to diameters). Several experiments that probe and reveal mechanistic aspects of nanotube formation on titanium foils are presented. In...

Synthesis and engineering of titanosilicate ETS-10 for enhanced photocatalytic activity in an optical fiber reactor

Zhaoxia Ji — Fri, 18 Dec 2009 08:33:25 PST

Semiconductor photocatalysis has attracted attention recently as an alternative to traditional physical, chemical, or biological technologies for environmental remediation. In 2007, the photocatalyst market has been predicted to reach US $30 billion in the near future. Engelhard titanosilicate ETS-10 is a microporous (4.9 Å x 7.6 Å) zeo-type material. The semiconductive monatomic ...Ti-O-Ti-O-Ti... chains in ETS-10 make this material a promising candidate for photocatalysis. ETS-10 photocatalyst has been reported to exhibit shape- and polarity-selectivity, and its activity could be further improved by post-synthesis acid treatment, ion-exchange, or transition metal modification. In the present investigation, systematic transition metal ion (V⁴⁺, Cr³⁺,...

Atomistic investigation into the interface engineering and heteroepitaxy of functional oxides on hexagonal silicon carbide through the use of a magnesium oxide template layer for the development of a multifunctional heterostructure

Trevor L. Goodrich — Fri, 18 Dec 2009 08:33:24 PST

Advancements in integrated circuit technology are quickly approaching the threshold of silicon semiconductor electronics. In order to break away from the confinements of standard device architecture and silicon's intrinsic material limitations, it is necessary to make an innovational change toward a new generation of novel materials with diverse functionality and superior mechanical, electrical, and magnetic properties that can perform under high-power, high-frequency, high-temperature application requirements. In order for the realization of a next-generation device, it will be necessary to diverge from traditional semiconductor processing into a wide bandgap semiconductor platform. Further, the realization of a next-generation device necessitates the development...