Chemical Engineering Commons^™

Electrochemical Fabrication Of Elastin-Containing Bi-Layered Scaffold For Vascular Tissue Engineering Applications, Thuy-Uyen Ky Nguyen

Theses and Dissertations

Lack of a viable vascular graft for the replacement of diseased small diameter blood vessels (< 4 mm) has encouraged the development of a self-repairing tissue engineered vascular graft (TEVG) as a promising alternative source. Although many different fabrication approaches have been devised to generate TEVGs using both natural and synthetic biomaterials, a functional TEVG that can serve as an effective replacement of diseased small-diameter blood vessels (< 4 mm) is still elusive mainly due to concerns associated with thrombosis and intimal hyperplasia. One approach to improve the clinical outcome of vascular grafts is to develop a 3D biomimetic scaffold that provides the essential physicochemical cues (i.e., compositional, topographical) to modulate cellular response (i.e., cell phenotype, endothelialization, de novo elastic matrix production) and thereby aid in tissue repair and remodeling. This approach entails the development of a novel 3D scaffold that provides an aligned collagen platform to guide smooth muscle cell (SMC) orientation

and insoluble elastic matrix (i.e., native form of elastin) to promote SMC contractility and thereby prevent overproliferation and hence alleviate concerns with intimal hyperplasia. In addition, the scaffold must comprise of a smooth luminal side to support the formation of a continuous endothelium that is essential to prevent thrombosis. Most existing biofabrication methodologies to generate vascular scaffolds (e.g., extrusion, electrospinning) have limited scope because of the inability to incorporate insoluble elastic matrix within the aligned collagen framework due to the disparity in the size …

A Numerical Simulation Optimizing Droplet Motion Driven By Electrowetting, Jake M. Lesinski

Master's Theses

A numerical simulation of electrowetting on a dielectric was performed in COMSOL to grant insight on various parameters that play a critical role in system performance. The specific system being simulated was the Open Drop experiment and the parameters being investigated were the applied voltage, contact angle at the advancing triple point, and droplet overlap onto neighboring actuated electrodes. These parameters were investigated with respect to their effect on droplet locomotion performance. This performance was quantified by the droplets velocity and the dielectrophortic (DEP) force’s magnitude; the DEP force was calculated from integration of the Maxwell Stress Tensor, however, the …

Thermal Characterization Of Graphene/Polyethylene Nanocomposites, Ahmed Z. A. Abuibaid

Chemical and Petroleum Engineering Theses

Practically, almost all polymers are solidified from the melts for product-forming purposes. Therefore, the evolution of solid structure (crystallization behavior) from their molten form has prime importance in manufacturing high performance materials. Polyethylene (PE) is one of the most commonly used semi crystalline polymers all over the world. In this thesis, nanocomposites of PE with thermal reduced graphene (TRG) (PE/TRG) were prepared via solvent blending and the crystallization of PE has been investigated using a differential scanning calorimeter (DSC). The nanocomposites were crystallized from the melts under both isothermal and dynamic conditions, and evolution of crystal formation is studied using …

Designing A Simulator For An Electrically-Pumped Organic Laser Diode, Robert Hulbert

Master's Theses

Organic semiconductors provide an alternative set of basis materials to fabricate electronic devices like PN Junctions, LEDs, and FETs. These materials have several benefits over traditional inorganic semiconductors including their mechanical flexibility, reliance on renewable resources, and inexpensive large-scale manufacturability. Despite the contemporary device implementations with organic semiconductors, a solid-state electrically-pumped organic laser diode does not exist. However, organically-based lasers do exist by utilizing the organic material strictly for optical gain. The challenge occurs when charge carriers appear in the organic material. The charge carriers must reach a concentration such that population inversion occurs producing optical gain. However, between the …

Electrochemically Reactive Membranes For Efficient Biomass Recovery, Pollutant Degradation And Commercialization, Likun Hua

Dissertations

Micropollution in natural waters such as rivers and groundwater aquifers is a widespread problem that prevents these potentially potable sources from being used as drinking water. In the United States, approximately two-thirds of the over 1,200 most serious hazardous waste sites in the nation are contaminated with trichloroethylene (TCE), a potentially carcinogenic compound. Other emerging and environmentally persistent organic micropollutants include polyromantic hydrocarbons (PAHs), organophosphate flame retardants, endocrine disrupting compounds (EDCs), pesticides, herbicides, pharmaceuticals and personal care products (PPCPs). Membrane filtration is one of the most efficient separation processes widely used for water treatment and pollutant removal. However, traditional membrane …

Speciation Of Gaseous Oxidized Mercury Molecules Relevant To Atmospheric And Combustion Environments, Francisco J. Guzman

Dissertations

Mercury is a pervasive and highly toxic environmental pollutant. Major anthropogenic sources of mercury emissions include artisanal gold mining, cement production, and combustion of coal. These sources release mostly gaseous elemental mercury (GEM), which upon entering the atmosphere can travel long distances before depositing to environmental waters and landforms. The deposition of GEM is relatively slow, but becomes greatly accelerated when GEM is converted to gaseous oxidized mercury (GOM) because the latter has significantly higher water solubility and lower volatility. Modeling GOM deposition requires the knowledge of its molecular identities, which are poorly known because ultra-trace (tens to hundreds part …

N8- Polynitrogen Stabilized On Carbon-Based Supports As Metal-Free Electrocatalyst For Oxygen Reduction Reaction In Fuel Cells, Zhenhua Yao

Dissertations

The sluggish oxygen reduction reaction (ORR) kinetics at the cathode is one of the key factors limiting the performance of polymer electrolyte membrane fuel cell (PEMFC). Platinum-based materials are the most widely studied catalysts for this ORR reaction while their large-scale practical application in fuel cells is hindered due to their scarcity and low stability. Therefore, highly active, low cost and robust non-Pt catalysts are being developed to overcome the drawbacks. Recently, a novel polynitrogen N8- (PN) stabilized on multiwall carbon nanotube (MWNT) was synthesized under ambient condition for the first time by our group and demonstrated high ORR activities. …

Engineered Excipients Via Dry Particle Coating, Liang Chen

Dissertations

Excipients with good flowability, bulk density as well as compaction properties are desired for use in tableting since they play important roles in formulation development and processing, including, handling, mixing, feeding and compaction. However, it is often difficult to manufacture excipients that simultaneously possess all three desirable properties, particularly if their size is fine. In addition, it is desirable that the excipients promote direct compression of poorly compactable fine cohesive drug powders at sufficiently high drug loading, and not just achieve the desired high functional properties in placebo formulations. This dissertation aims to developed engineered excipients towards this unmet industry …

Enzyme-Assisted Development Of Hydrogels As Medical Materials With Injectable, Biodegradable And Biocompatible Properties, Yung-Hao Tsou

Dissertations

Hydrogels were first discovered in the year 1960 by Wichterle and Lim [1], and in the following decades, they have been widely studied because of their unique characteristics including their hydrophilic nature, biocompatibility, and capacity to mimic the extracellular matrix (ECM). Hydrogels based on natural or synthetic polymers have continued to be of interest for tissue engineering and drug delivery due to their ability to encapsulate living cells and control the release rate of drugs or other bioactive molecules such as pharmaceutical proteins.

In the first part of this dissertation, dopant-free photoluminescent hydrogels formed in situ by crosslinking of biocompatible …

The Use Of Electrical Resistance Tomography To Determine The Minimum Agitation Speed For Solids Suspension In Stirred Tank Reactors, Baran Teoman

Theses

Njs, the minimum agitation speed needed to just suspend all the solid particles in a solid-liquid mixture stirred in an agitated vessel, is a critical parameter to properly operate industrial tanks in a large number of industrial operations. As a result, a significant literature on Njs is available. The oldest and the most common method to measure Njs experimentally is that of Zwietering’s (Chem. Eng. Sci., 1958, 8, 244-253), where Njs can be visually obtained by determining when the solids stay at the bottom of the tank for no more than 1-2 seconds before being swept away. Although this has …

Glass Transition Temperature Of Particles For Drug Delivery, Yiqing Yang

Theses

Drug delivery plays an important role in targeted therapies and nanoparticles which can be used as drug carriers and it’s a frequently researched topic. Poly(lactic-co-glycolic acid) (PLGA), a highly biocompatible polymer, has been used as a drug delivery vehicle in many studies. One of the challenges facing drug delivery particles is the problem of burst release which is when a large amount of the drug is suddenly released from the particle once it is placed in the body. This is generally undesirable as usually a slow and controlled release is preferred. The glass transition temperature has an effect on drug …

Highly Effective Geni Alloy Contact Diffusion Barrier For Bisbte Long-Term Thermal Exposure, Erdong Song, Brian S. Swartzentruber, Chowdary R. Koripella, Julio A. Martinez

Publications and Research

A GeNi alloy diffusion barrier for contacts on bismuth antimony telluride is proposed. Multiple gold contact diffusion barriers were tested at different thermal aging conditions in air and reducing atmospheres. Among all diffusion barriers, the GeNi alloy barrier shows the best performance for bulk samples with no substantial degradation of the contact resistance, no contact color change, and no change of thermoelectric properties. We observed DAu−GeNi = (9.8 ± 2.7) × 10−20 m2/s within the GeNi alloy barrier, which is 4 times smaller than DAu−BiSbTe. The presence of the initial Ge layer also proves to be effective in reducing nickel …

Challenges For Natural Hydrogels In Tissue Engineering, Esmaiel Jabbari

Faculty Publications

Protein-based biopolymers derived from natural tissues possess a hierarchical structure in their native state. Strongly solvating, reducing and stabilizing agents, as well as heat, pressure, and enzymes are used to isolate protein-based biopolymers from their natural tissue, solubilize them in aqueous solution and convert them into injectable or preformed hydrogels for applications in tissue engineering and regenerative medicine. This review aims to highlight the need to investigate the nano-/micro-structure of hydrogels derived from the extracellular matrix proteins of natural tissues. Future work should focus on identifying the nature of secondary, tertiary, and higher order structure formation in protein-based hydrogels derived …

Challenges For Natural Hydrogels In Tissue Engineering, Esmaiel Jabbari

Faculty Publications

Protein-based biopolymers derived from natural tissues possess a hierarchical structure in their native state. Strongly solvating, reducing and stabilizing agents, as well as heat, pressure, and enzymes are used to isolate protein-based biopolymers from their natural tissue, solubilize them in aqueous solution and convert them into injectable or preformed hydrogels for applications in tissue engineering and regenerative medicine. This review aims to highlight the need to investigate the nano-/micro-structure of hydrogels derived from the extracellular matrix proteins of natural tissues. Future work should focus on identifying the nature of secondary, tertiary, and higher order structure formation in protein-based hydrogels derived …

Hypermongone C Accelerates Wound Healing Through The Modulation Of Inflammatory Factors And Promotion Of Fibroblast Migration, Sara E. Moghadam, Moridi Mahdi Farimani, Sara Soroury, Samad N. Ebrahimi, Ehsan Jabbarzadeh

Faculty Publications

The physiology of wound healing is dependent on the crosstalk between inflammatory mediators and cellular components of skin regeneration including fibroblasts and endothelial cells. Therefore, strategies to promote healing must regulate this crosstalk to achieve maximum efficacy. In light of the remarkable potential of natural compounds to target multiple signaling mechanisms, this study aims to demonstrate the potential of hypermongone C, a polycyclic polyprenylated acylphloroglucinol (PPAP), to accelerate wound closure by concurrently enhancing fibroblast proliferation and migration, promoting angiogenesis, and suppressing pro-inflammatory cytokines. This compound belongs to a family of plants (Hypericum) that traditionally have been used to treat injuries. …

Non-Canonical Amino Acid Labeling In Proteomics And Biotechnology, Aya M. Saleh, Kristen M. Wilding, Sarah Calve, Bradley Charles Bundy, Tamara L. Kinzer-Ursem

Faculty Publications

Metabolic labeling of proteins with non-canonical amino acids (ncAAs) provides unique bioorthogonal chemical groups during de novo synthesis by taking advantage of both endogenous and heterologous protein synthesis machineries. Labeled proteins can then be selectively conjugated to fluorophores, affinity reagents, peptides, polymers, nanoparticles or surfaces for a wide variety of downstream applications in proteomics and biotechnology. In this review, we focus on techniques in which proteins are residue- and site-specifically labeled with ncAAs containing bioorthogonal handles. These ncAA-labeled proteins are: readily enriched from cells and tissues for identification via mass spectrometry-based proteomic analysis; selectively purified for downstream biotechnology applications; or …

The Effect Of Fabric Architecture On The Processing And Properties Of Composites Made By Vacuum Assisted Resin Transfer Molding, Francois Ntakobatagize, Oscar Ntakontagize, Donald A. Klosterman

Chemical and Materials Engineering Faculty Publications

The goal of this research project was to evaluate and compare the effect of fabric architecture on the processing and properties of composites made by Vacuum Assisted Resin Transfer Molding (VARTM). The fabric architectures investigated included plain weave, satin weave, and warp-knit unidirectional. The fiber types included E-glass and standard modulus carbon fiber. Flat panels were fabricated with a lab scale VARTM process using an epoxy resin system. Fabric plies were cut to 45 cm x 30 cm (18 in. x 12 in.), and the number of plies used depended on the fiber areal weight of each fabric to produce …

Fabrication Of Enhanced Carbon Based Biocompatible And Biodegradable Microelectronic Materials Derived From Lignocellulosic Biomass, Harrison Thomas Hawkins

Theses and Dissertations

The development of materials capable of harmlessly being broken down and removed from the body is a crucial step towards the development of short-term application electronic biomedical implants. Once developed, these implants, known as bioresorbable electronics, will open a wide array of temporary applications in the field of biomedical implantable devices. Necessary to the operation of bioresorbable electronics within the body is a power source that is similarly biocompatible and biodegradable. To this end, enhanced carbon-based materials and a bio-ionic liquid were developed for the fabrication of a preliminary implantable and bioresorbable battery and tested for functional properties. Electrodes were …

Modeling Of Vapor Sorption In Nanoparticle Chemiresistors, Alexandra Oliveira

Honors Scholar Theses

Chemical vapor sensors possess a number of uses in a variety of fields, from environmental and health monitoring to food safety and national security concerns, such as the detection of improvised explosive devices. Many sensors currently in the market have the ability to detect the presence of a select few compounds and measure the concentration at which the species is present. However, these types of sensors require that the vapor to be investigated is known beforehand; they cannot be used for identification except on a case by case basis. In response to this issue, one branch of vapor sensor research …

Symmetry And Dopant Diffusion In Inverted Nanopyramid Arrays For Thin Crystalline Silicon Solar Cells, Seok Jun Han

Chemical and Biological Engineering ETDs

In this dissertation, we enhance the efficiency of thin flexible monocrystalline silicon solar cells by breaking symmetry in light trapping nanostructures and improving homogeneity in dopant concentration profile. These thin cells are potentially less expensive than conventional thick silicon cells by using less silicon material and making the cells more convenient to be handled when supported on polymer films. Moreover, these cells are widely applicable due to their flexibility and lightweight. However, for high efficiencies, these cells require effective light trapping and charge collection. We achieve these in cells based on 14-mm-thick free-standing silicon films with light-trapping arrays of nanopyramidal …