Chemical Engineering Commons^™

Synthesis And Characterization Of Chemically Functionalized Shape Memory Nanofoams For Unattended Sensing Applications, Anna Paola Soliani

All Dissertations

The work in this dissertation is devoted to the synthesis and characterization of novel materials for off-line unattended sensing: shape-memory grafted nanofoams. The fabrication process and characterization of highly efficient, polymeric nanosensor element with the ability to selectively detect analytes and retain memory of specific exposure events is reported. These shape memory nanofoams could potentially act as efficient and highly sensitive coatings for evanescent waveguide-based optical monitoring systems. On exposure to specific analytes, the polymeric coatings locally change their internal structure irreversibly at the nanolevel, affecting the local optical properties such as refractive index. Currently, enrichment polymer layers (EPLs) are …

Thermally Responsive Polymer Electrolytes For Inherently Safe Electrochemical Energy Storage, Jesse Kelly

All Dissertations

Electrochemical double layer capacitors (EDLCs), supercapacitors and Li-ion batteries have emerged as premier candidates to meet the rising demands in energy storage; however, such systems are limited by thermal hazards, thermal runaway, fires and explosions, all of which become increasingly more dangerous in large-format devices. To prevent such scenarios, thermally-responsive polymer electrolytes (RPEs) that alter properties in electrochemical energy storage devices were designed and tested. These RPEs will be used to limit or halt device operation when temperatures increase beyond a predetermined threshold, therefore limiting further heating. The development of these responsive systems will offer an inherent safety mechanism in …

The Development Of A Laminated Copolyester Electric Guitar, Addison S. Karnes

Electronic Theses and Dissertations

This thesis is an investigation of the fabrication and assembly methodologies employed in the development of a proof-of-principle prototype electric guitar composed of laminated copolyester. The objective of the project was to develop the processes and procedures to create an optimized physical and visual bond between layers to minimize vibratory dissipation, thus maximizing sustain. A high speed CNC router, abrasive waterjet, laser engraver-cutter, as well as various manual fabrication and assembly methods were investigated in the construction of the guitar prototypes. The lamination processes explored include low-temperature, heat-assisted pressure bonding, solvent and chemical welding, and contact adhesives. The project concluded …

Backfolding Of Wormlike Chains Confined In Nanochannels, Abhiram Muralidhar, Douglas R. Tree, Kevin D. Dorfman

Faculty Publications

Using pruned-enriched Rosenbluth method (PERM) simulations of a discrete wormlike chain model, we provide compelling evidence in support of Odijk’s prediction of two distinct Odijk regimes for a long wormlike chain confined in a nanochannel. In both cases, the chain of persistence length lp is renormalized into a series of deflection segments of characteristic length D2/3lp1/3, where D is the channel size. In the first (classic) Odijk regime, these deflection segments are linearly ordered. In the second Odijk regime, thin, long wormlike chains can backfold at a length scale quantified by the global persistence length. We …

Microwave-Assisted Synthesis Of Pd Nanoparticles Supported On Fe3o4, Co3o4, And Ni(Oh)2 Nanoplates And Catalysis Application For Co Oxidation, Hany A. Elazab

Chemical Engineering

In this paper, we report a simple, versatile, and rapid method for the synthesis of Pd nanoparticle catalysts supported on Fe3O4, Co3 O4, and Ni(OH)2 nanoplates via microwave irradiation. The important advantage of microwave dielectric heating over convective heating is that the reactants can be added at room temperature (or slightly higher temperatures) without the need for high-temperature injection. Furthermore, the method can be used to synthesize metal nanoparticle catalysts supported on metal oxide nanoparticles in one step. We also demonstrate that the catalyst-support interaction plays an important role in the low temperature oxidation of CO. The current results reveal …

Field-Limited Migration Of Li-Ions In Li-Ion Battery, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

The migration of Li-ions in lithium-ion battery cannot be simply described by Fick's second law; the interactions among ionic migration, field, and stress need to be taken into account when analyzing the migration of Li-ions. Using the theory of thermal activation process, the flux for ionic migration under concurrent action of electric field and mechanical stress is found to be a nonlinear function of the gradient of electric potential and the gradient of stress. Electric field can either accelerate or retard the growth of the lithiation layer, depending on polarity of the field.

Nonlinear Modeling, Estimation And Predictive Control In Apmonitor, John Hedengren, Reza Asgharzadeh Shishavan, Kody M. Powell, Thomas F. Edgar

Faculty Publications

This paper describes nonlinear methods in model building, dynamic data reconciliation, and dynamic optimization that are inspired by researchers and motivated by industrial applications. A new formulation of the ℓ₁-norm objective with a dead-band for estimation and control is presented. The dead-band in the objective is desirable for noise rejection, minimizing unnecessary parameter adjustments and movement of manipulated variables. As a motivating example, a small and well-known nonlinear multivariable level control problem is detailed that has a number of common characteristics to larger controllers seen in practice. The methods are also demonstrated on larger problems to reveal algorithmic …

Investigating The Release Mechanism Of Calcein From Eliposomes At Higher Temperatures, Ghaleb A. Husseini, William G. Pitt, Jacob B. Williams, Marjan Javadi

Faculty Publications

Numerous nanocarriers are currently being investigated as drug delivery vehicles for transporting chemotherapeutics to cancer cells. Our research group has recently synthesized a new generation of echogenic liposomes based on the concept of encapsulating one or more nanoemulsion droplets inside a liposome (called an “eLiposome”). The concept is to use a nanoemulsion droplet with a low boiling point near body temperature, thus requiring only a small acoustic nudge to vaporize the droplet from liquid to gas and break open the eLiposome, thus releasing its contents. The purpose of this note is twofold. First, we wanted to show experimentally that eLiposomes …

Growth And Properties Of Carbon Microcoils And Nanocoils, Muneaki Hikita, Robyn Bradford, Khalid Lafdi

Chemical and Materials Engineering Faculty Publications

Various types of coiled carbon filaments have been synthesized using chemical vapor deposition and other methods. These carbon filaments exhibit unique electrical and mechanical properties due to their versatile shapes and structures. To form coiled shapes, different types of catalyst compositions and reactive gases have been explored. Generally, coiled carbon filaments are classified by coil diameter and shape (e.g., microcoil and nanocoil). In this review, coiled carbon filaments are classified into three growth mechanism categories:

(1) bidirectional double helical growth;

(2) bidirectional twisted growth; and

(3) tip single helical or twisted growth.

Next, their synthesis methods and hypothetical growth mechanisms …

Gasification Of Biomass, Coal, And Petroleum Coke At High Heating Rates And Elevated Pressure, Aaron D. Lewis

Theses and Dissertations

Gasification is a process used to convert any carbonaceous species through heterogeneous reaction to obtain the desired gaseous products of H2 and CO which are used to make chemicals, liquid transportation fuels, and power. Both pyrolysis and heterogeneous gasification occur in commercial entrained-flow gasifiers at pressures from 4 to 65 atm with local gas temperatures as high as 2000 °C. Many gasification studies have been performed at moderate temperatures, heating rates, and pressures. In this work, both pyrolysis and char gasification experiments were performed on coal, petroleum coke, and biomass at conditions pertinent to commercial entrained-flow gasifiers. Rapid biomass pyrolysis …

Slow Release Of Ions From Internalized Silver Nanoparticles Modifies The Epidermal Growth Factor Signaling Response, Kristen K. Comfort, Elizabeth I. Maurer, Saber M. Hussain

Chemical and Materials Engineering Faculty Publications

Due to their distinctive physiochemical properties, including a robust antibacterial activity and plasmonic capability, hundreds of consumer and medical products contain colloidal silver nanoparticles (AgNPs). However, even at sub-toxic dosages, AgNPs are able to disrupt cell functionality, through a yet unknown mechanism. Moreover, internalized AgNPs have the potential to prolong this disruption, even after the removal of excess particles. In the present study, we evaluated the impact, mechanism of action, and continual effects of 50 nm AgNP exposure on epidermal growth factor (EGF) signal transduction within a human keratinocyte (HaCaT) cell line. After AgNP expose, EGF signaling was initially obstructed …

Preparation Of Active, Stable Supported Iron Catalysts And Deactivation By Carbon Of Cobalt Catalysts For Fischer-Tropsch Synthesis, Kamyar Keyvanloo

Theses and Dissertations

The first half of this dissertation reports the development of supported Fe FT catalysts including the effects of various, carefully chosen preparation methods on the performance of alumina-supported iron/copper/potassium (FeCuK/Al2O3); it was determined that non-aqueous slurry impregnation and co-impregnation yielded catalysts with activities as high as any reported in the literature. Furthermore, the effects of support properties including pore size, hydroxyl group concentration, and support stabilizer were investigated for FeCuK/Al2O3 catalysts containing 20 or 40% Fe. For the first time, we report the performance of a supported Fe FT catalyst that is not only more active and stable than any …

Going From Microbial Ecology To Genome Data And Back: Studies On A Haloalkaliphilic Bacterium Isolated From Soap Lake, Washington State, Melanie R. Mormile

Biological Sciences Faculty Research & Creative Works

Soap Lake is a meromictic, alkaline (∼pH 9.8) and saline (∼14-140 g liter^-1) lake located in the semiarid area of eastern Washington State. Of note is the length of time it has been meromictic (at least 2000 years) and the extremely high sulfide level (∼140 mM) in its monimolimnion. As expected, the microbial ecology of this lake is greatly influenced by these conditions. A bacterium, Halanaerobium hydrogeniformans, was isolated from the mixolimnion region of this lake. Halanaerobium hydrogeniformans is a haloalkaliphilic bacterium capable of forming hydrogen from 5- and 6-carbon sugars derived from hemicellulose and cellulose. Due …

Analysis Of Advanced Supercritical Carbon Dioxide Power Cycles For Concentrated Solar Power Applications, Saeb Mostaghim Besarati

USF Tampa Graduate Theses and Dissertations

Solar power tower technology can achieve higher temperatures than the most common commercial technology using parabolic troughs. In order to take advantage of higher temperatures, new power cycles are needed for generating power at higher efficiencies. Supercritical carbon dioxide (S-CO₂) power cycle is one of the alternatives that have been proposed for the future concentrated solar power (CSP) plants due to its high efficiency. On the other hand, carbon dioxide can also be a replacement for current heat transfer fluids (HTFs), i.e. oil, molten salt, and steam. The main disadvantages of the current HTFs are maximum operating temperature …

Balloon Diameter Measurement And Altitude Determination Through Gas And Thermal Properties, Geoff Suiter

Von Braun Symposium Student Posters

No abstract provided.

The Stochastic Dynamics Of Tethered Microcantilevers In A Viscous Fluid, Brian A. Robbins, Milad Radiom, William A. Ducker, John Y. Walz, Mark R. Paul

Chemical and Materials Engineering Faculty Publications

We explore and quantify the coupled dynamics of a pair of micron scale cantilevers immersed in a viscous fluid that are also directly tethered to one another at their tips by a spring force. The spring force, for example, could represent the molecular stiffness or elasticity of a biomolecule or material tethered between the cantilevers. We use deterministic numerical simulations with the fluctuation-dissipation theorem to compute the stochastic dynamics of the cantilever pair for the conditions of experiment when driven only by Brownian motion. We validate our approach by comparing directly with experimental measurements in the absence of the tether …

Photonic Crystal-Based Flow Cytometry, Justin William Stewart

USF Tampa Graduate Theses and Dissertations

Photonic crystals serve as powerful building blocks for the development of lab-on-chip devices. Currently they are used for a wide range of miniaturized optical components such as extremely compact waveguides to refractive-index based optical sensors. Here we propose a new technique for analyzing and characterizing cells through the design of a micro-flow cytometer using photonic crystals. While lab scale flow cytometers have been critical to many developments in cellular biology they are not portable, difficult to use and relatively expensive. By making a miniature sensor capable of replicating the same functionality as the large scale units with photonic crystals, we …

Influence Of Pt:Ru Ratio In Nanotubes Array Structures On The Electrocatalytic Activity Of Methanol Oxidation, Jin-Hua Yuan, Feng-Bin Wang, Xing-Hua Xia

Journal of Electrochemistry

Bimetallic PtRu nanotubes array electrodes (NTAEs) with varied Pt to Ru atomic ratios have been prepared by electrochemical codeposition in 3-aminopropyltri-methoxysilane modified porous anodic alumina (PAA) membranes. The structure and morphology of the catalysts were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Electrochemical results showed that the NTAEs with varied atomic ratios could be achieved by controlling the precursor concentration for deposition. The prepared nanoarrays composed of Pt or PtRu alloy promoted the mass-normalized activity toward the sluggish electrooxidation reaction of methanol due to the increased catalytic activity and real surface area, as well as the …

Electrochemistry Of Glucose Oxidase Modified On Porin-Phospholipid Biomimic Membrane, Kun-Qi Wang, Zuo-Ming Zhang, Wei Xing, Chang-Peng Liu, Xing Zhou

Journal of Electrochemistry

Biomimic membrane with nano-channels, which is made up of porin MspA and 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) is constructed on glassy carbon substrate, and glucose oxidase (GOD) is modified on it. The direct electrochemical reaction and electrocatalytic behavior to oxygen and glucose of GOD on the GOD/MspA-DMPC/GC electreode are expounded by the cyclic voltammetric method. The study shows that GOD immobilized on porin MspA and DMPC biomimic membrane displays direct and surface-controlled electrochemical reaction nearby formal potential (E0′) of the flavoprotein active centre (FAD/FADH), and the electrochemical reaction contains two electrons and two protons exchange in 0.1 mmol·L^-1 phosphate buffer solution (PBS) …

Effect Of Imidazole Ionic Liquids On The Electro-Oxidation Of P-Methoxy Toluene, Qiong Chen, Ying-Hong Zhu, Ying Zhu, Yan-Fang Li, Chun-An Ma

Journal of Electrochemistry

The interactions between four Imidazole ionic liquids (EMIMBF₄, BMIMBF₄, BMIMHSO₄, BMIMAc) and p-methoxy toluene were investigated by ultraviolet spectroscopy. The red shifts of absorption peak were obviously observed, and the fine structures of the spectroscopy were disappeared on the long wave district. p-MT producing stable excited state was benefit from the interaction with solvent molecules. The electro-oxidation behavious of p-MT were studied in the four ILs on platinum electrode by cyclic voltammetry (CV) and chronoamperometry (CP), and the diffusion coefficients (D) and activation energies (ED) were calculated. The results indicated that the electro-oxidation process …