Engineering Commons^™

Interplay Between Chain Stiffness And Excluded Volume Of Semiflexible Polymers Confined In Nanochannels, Abhiram Muralidhar, Douglas R. Tree, Yanwei Wang, Kevin D. Dorfman

Faculty Publications

The properties of channel-confined semiflexible polymers are determined by a complicated interplay of chain stiffness and excluded volume effects. Using Pruned-Enriched Rosenbluth Method (PERM) simulations, we study the equilibrium properties of channel-confined polymers by systematically controlling chain stiffness and excluded volume. Our calculations of chain extension and confinement free energy for freely jointed chains with and without excluded volume show excellent agreement with theoretical predictions. For ideal wormlike chains, the extension is seen to crossover from Odijk behavior in strong confinement to zero-stretching, bulk-like behavior in weak confinement. In contrast, for self-avoiding wormlike chains, we always observe that the linear …

Preparation Of Radiation-Grafted Powders For Use As Anion Exchange Ionomers In Alkaline Polymer Electrolyte Fuel Cells, Simon D. Poynton, Robert C. T. Slade, Travis J. Omasta, William E. Mustain, Ricardo Escudero-Cid, Pilar Ocón, John R. Varcoe

Faculty Publications

A novel alkaline exchange ionomer (AEI) was prepared from the radiation-grafting of vinylbenzyl chloride (VBC) onto poly(ethylene-co-tetrafluoroethylene) [ETFE] powders with powder particle sizes of less than 100 μm diameter. Quaternisation of the VBC grafted ETFE powders with trimethylamine resulted in AEIs that were chemically the same as the ETFE-based radiation-grafted alkaline anion exchange membranes (AAEM) that had been previously developed for use in low temperature alkaline polymer electrolyte fuel cells (APEFC). The integration of the AEI powders into the catalyst layers (CL) of both electrodes resulted in a H2/O2 fuel cell peak power density of 240 mW cm−2 …

Student Mentoring In Research: Laser-Activated Drug Delivery To Cancer Cells, William G. Pitt

Journal of Undergraduate Research

Summary of Scope of Proposal This proposal was submitted in October of 2011 to organize and fund a mentoring group in the Pitt lab in Chemical Engineering. Marjan Javadi, then a PhD candidate in Chemical Engineering, and 5 uldergraduate students participated in this research group. The purpose was 2-­‐fold, both scientific and pedagogical. On the scientific side, Marjan was working on her PhD research to develop a novel drug delivery system called an eLiposome that encapsulated a drug along with a nanoemulsion that turns from liquid to gas upon exposure to ultrasound. The ultrasound can be non-­‐invasively (no surgery or …

Predicting Gas-Phase Reaction Rates For Elementary Diatomic Substitutions Using Molecular Dynamics Simulations, Karl Fails, Dr. Richard Rowley

Journal of Undergraduate Research

The purpose of this study was to examine a new method for predicting elementary gas-phase reaction rates using molecular dynamics simulations. The diatomic substitution reaction:was to be used as a test model for its simplicity. Molecular dynamics simulations were to be used to calculate the motion of the interacting atoms. Any associations, dissociations and substitutions were to be counted and recorded.

The Effects Of Combining Ultrasonic Frequency And Antibiotics To Escherichia Coli Biofilms In An In Vivo System, Rachel L. Robison, Dr. William G. Pitt

Journal of Undergraduate Research

Prosthetic devices are commonly used in modern medicine. There are two types of prosthetic devices, implanted and transdermal. Implanted devices such as vascular grafts, heart valves, and prosthetic joints frequently become colonized by bacteria due to improper surgical techniques or post-operative infections.2 Transdermal devices such as catheters or electrical leads often become infected when bacteria from the patient’s skin migrates along the transdermal device and gains entrance into the body.1 If this occurs, microorganisms can cause serious infection at the site of the prosthetic device.

Multiple Scattering Events In Human Blood Solutions, Xunhai Xu

Journal of Undergraduate Research

Recently, modem medical technology has enabled surgeons and other medical scientists to perform certain organ transplantation within human beings successfully. However, thromboembolization, the formation of thromboemboli (usually of irregular shapes with sizes approximately 10,000 times bigger than that of red blood cell), is likely to occur with such operations. The cause of the thromboemboli is believed to be the interaction between human blood and the foreign materials. Since thromboemboli is a much larger particles than normal blood cells (such as red blood cell, white blood cell and single platelet), their existence in the blood solution might be detrimental to the …

High Temperature Polymer Dielectrics For Electric Vehicle Capacitor Applications, Kylen Johns

Chemical and Biological Engineering ETDs

Currently there is a push for low cost, high energy materials with high operating temperatures that can simultaneously reduce cost, weight, and volume in the automotive industry. Economically feasible high performance capacitors are critical to the Department of Energys goal to advance technologies that will ensure energy security and reduce the use of petroleum while reducing cost and environmental impacts. [1] Recent studies have been done to improve the inverter systems in hybrid electric vehicles (HEVs). HEVs require inverters to convert direct current to alternating current which prevents damage to the battery and powers the electric motor. Current thin film …

Facile Synthesis Of High Surface Area Molybdenum Carbide And Nitride: An Application In Support Materials For Oxygen Reduction Reaction, Aaron Roy

Chemical and Biological Engineering ETDs

A method to synthesize high surface area α-MoC(1-x) without the temperature programmed reduction (TPR) of MoO3 is described. This method was then used, in conjunction with a novel in situ method to obtain highly dispersed PtMoz supported on α- MoC(1-x), to explore the suitability of such materials as catalysts for oxygen reduction reaction (ORR) in a proton exchange membrane fuel cell (PEMFC). Mg2(Mo3O8) and Zn2(Mo3O8), alternative tetravalent Mo intermediates to MoO2, were obtained through the thermal decomposition of Mg(MoO4) and Zn(MoO4) in mixtures of CO and H2. A novel sacrificial support method was developed where MgO and ZnO were investigated …

Exploration Of Tm-Nx Orr Electrocatalysts From First Principle Calculations, Sadia Afrin Kabir

Chemical and Biological Engineering ETDs

Fuel Cells are promising candidates for the energy conversion technologies in particular for non-stationary applications. However, current fuel cells rely on rare and expensive Platinum catalysts and the power generation is limited by the sluggish oxygen reduction reaction (ORR) at the cathode. An interesting alternative material set which continues to attract significant attention are TM-Nx (TM = Fe, Co, x = 2 - 4) based non-PGM electrocatalysts where the defect motifs are embedded in a carbon matrix during pyrolysis. By studying the material properties of individual defects we can determine how the chemistry and morphology of these TM-Nx motifs are …

Model Systems For The Study Of Active Phase Evolution In Complex Bimetallic Catalysts (Pdzn), Jonathan Paiz

Chemical and Biological Engineering ETDs

This study used PdZn as a model system to investigate phase transformations and its influence on reactivity. Aerosol synthesis was used to study the oxide precursors of the PdZn system, spin coating was used to synthesize model PdZn nanoparticles for phase transformations studies and preliminary work with CO oxidation coupled with methanol steam reforming (MSR) was used to gain insight into in-situ surface reactivity of PdZn for MSR. Multiple characterization techniques including XRD, Raman Spectroscopy, XPS, EDX along with TEM and STEM were used to gain valuable insight into the nature of the samples used in these studies. Investigations into …

Multinode Acoustic Systems For High Throughput Cellular Analysis, Pearlson Prashanth Austin Suthanthiraraj

Chemical and Biological Engineering ETDs

For decades, flow cytometry is used as the gold standard for cellular analyses as it measures multiple properties of single cells. Traditional flow cytometry uses the hydrodynamic focusing technique where the sheath fluid focuses cells in the sample into a narrow stream. Although such precise focusing provides accurate optical measurements, high sheath fluid pressure and high linear velocities limit analysis rate to 50,000 particles/s. Such rates are too low for detecting rare events where one cell may have to be detected in a population of about a billion cells. Therefore, it is necessary to eliminate the sheath fluid and improve …

Evaluation Of The Tendency Of Biomaterials To Produce Microemboli, Jesse Hamilton

Journal of Undergraduate Research

Many people in today’s society depend on devices that contact their blood. Devices such as dialyzers and blood oxygenators are used every day in hemodialysis or coronary bypass. More permanent fixtures are also used such as artificial kidneys and hearts. These devices are wonderful and have contributed to longer and fuller lives for many people. However, man’s attempt to simulate the functions of the human body are simple at best, and there are serious problems that arise. These problems are tolerated by the medical profession at present because (1) they are not completely understood, and (2) the risks posed by …

In-Package Nonthermal Plasma Degradation Of Pesticides On Fresh Produce, N. Misra, Shashi Pankaj, Tony Walsh, Finbarr O'Regan, Paula Bourke, Patrick J. Cullen

Articles

In-package nonthermal plasma (NTP) technology is a novel technology for the decontamination of foods and biological materials. This study presents the first report on the potential of the technology for the degradation of pesticide residues. A cocktail of pesticides, namely Azoxystrobin, Cyprodinil, Fludioxonil and Pyriproxyfen was tested on strawberries. The concentrations of these pesticides were monitored in priori and post- plasma treatment using GC-MS/MS. An applied voltage and time dependent degradation of the pesticides was observed for treatment voltages of 60, 70 and 80 kV and treatment durations ranging from 1 to 5 min, followed by 24 h in-pack storage. …

An Injectable, Calcium Responsive Composite Hydrogel For The Treatment Of Acute Spinal Cord Injury, Christopher A. Mckay, Rebecca D. Pomrenke, Joshua S. Mclane, Nicholas J. Schaub, Elise K. Desimone, Lee A. Ligon, Ryan J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Immediately following spinal cord injury, further injury can occur through several secondary injury cascades. As a consequence of cell lysis, an increase in extracellular Ca²⁺ results in additional neuronal loss by inducing apoptosis. Thus, hydrogels that reduce extracellular Ca²⁺ concentration may reduce secondary injury severity. The goal of this study was to develop composite hydrogels consisting of alginate, chitosan, and genipin that interact with extracellular Ca²⁺ to enable in situ gelation while maintaining an elastic modulus similar to native spinal cord (∼1000 Pa). It was hypothesized that incorporation of genipin and chitosan would regulate hydrogel electrostatic characteristics …

Complexation Reactions And Structure Of The Iron-Molybdenum Cofactor Of Nitrogenase, Dean Wheeler

Journal of Undergraduate Research

As described in the proposal submitted last year for this project, there is a great need to further understand the dynamics and processes of the nitrogenase system. Using this chemical system a limited number of microorganisms are able to break down atmospheric nitrogen so it may be used by other organisms. The heart of the matter-where the reduction of nitrogen takes place-is a small cluster of atoms located inside the dinitrogenase protein. This cluster is known as the iron-molybdenum cofactor or FeMoco.

Methane Recovery At Springville Wastewater, Rochelle Phillips, Dr. William Hecker, Dr. Vincent Wilding

Journal of Undergraduate Research

During the treatment of municipal wastewater, several means are used to accomplish the breakdown of the wastewater and its solid components into innocuous substances. At one point, the filtered solids are combined in a digester with various bacteria. These bacteria convert the waste into carbon dioxide, methane gas, water, and small amounts of hydrogen sulfide.

Thermophile Biochemistry, Charles Larsen

Journal of Undergraduate Research

During the 1960s, Dr. Thomas Brock studied life in the hot springs of Yellowstone National Park. There he found new strains of bacteria capable of living at temperatures above 75°C, which at the time represented the highest temperature at which life was known to exist. Dr. Brock’s discovery has sparked a world wide research effort to understand thermophilic bacteria, both their biochemistry and industrial applicability.

Catalytic Hydrogen Transfer Of Ketones Over Atomic Layer Deposited Highly-Dispersed Platinum Nanoparticles Supported On Multi-Walled Carbon Nanotubes, Chengjun Jiang, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

Hydrogen transfer of ketones, catalyzed by highly dispersed platinum nanoparticles supported on multi-walled carbon nanotubes (MWCNTs), was studied. Pt nanoparticles were deposited on gram quantities of non-functionalized MWCNTs by atomic layer deposition (ALD) at 300 C, using (methylcyclopentadienyl) trimethylplatinum and oxygen as precursors. TEM analysis showed that ~ 1.4 nm Pt nanoparticles were highly dispersed on MWCNTs. The heterogeneous hydrogen-transfer reactions of acetophenone indicated that an acetophenone conversion of 100% and a 1-phenylethanol selectivity of 99.0% could be obtained with a ketone to Pt mass ratio of 24,690 and a ketone to KOH mass ratio of 22 at 150 C …

Compounds And Methods For Reducing Oxidative Stress, Thomas Dziubla, J. Zach Hilt, Dipti Biswal, David B. Cochran, Paritosh Wattamwar

Chemical and Materials Engineering Faculty Patents

Antioxidant polymeric compounds are provided that comprise a plurality of monomeric portions, where each monomeric portion includes an antioxidant molecule interposed between at least two acrylate molecules, and where at least one acrylate molecule of each monomeric portion is linked by a diamine molecule to an acrylate molecule of an adjacent monomeric portion to thereby form the polymer. Methods of synthesizing polymeric compounds and methods of using the antioxidant polymeric compounds to reduce oxidative stress are also provided.

Enzyme Attached On Polymeric Micelles As A Nanoscale Reactor, Moo-Yeal Lee, Kyung-Jin Hong, Seung Pil Han, Toshio Kajiuchi

Chemical & Biomedical Engineering Faculty Publications

Similar to what lipase does, a surface-active enzyme was developed by attaching peroxidase on combshaped polymaleic anhydride-alt-1-tetradecene (PMA-TD) in a microemulsion system composed of n-butyl acetate and buffer solution, and its catalytic characteristics of polyphenol synthesis were investigated in an aqueous solution. The modified peroxidase with PMA-TD tended to form self-assembled aggregates like micelles in the aqueous solution and could be concentrated at solvent/water interfaces without unfolding of the enzyme. The efficiency of conversion of 2,4-dichlorophenol to phenolic oligomers was approximately 2-fold improved with the modified peroxidase compared to native peroxidase. The K _m and V _max values …

Modulation Of Leukocyte Infiltration And Phenotype In Microporous Tissue Engineering Scaffolds Via Vector Induced Il-10 Expression, R. Michael Gower, Ryan M. Boehler, Samira M. Azarin, Christine F. Ricci, Joshua N. Leonard, Lonnie D. Shea

Faculty Publications

Biomaterial scaffolds are central to many tissue engineering strategies as they create a space for tissue growth and provide a support for cell adhesion and migration. However, biomaterial implantation results in unavoidable injury resulting in an inflammatory response, which can impair integration with the host and tissue regeneration. Toward the goal of reducing inflammation, we investigated the hypothesis that a lentiviral gene therapy-based approach to localized and sustained IL-10 expression at a scaffold could modulate the number, relative proportions, and cytokine production of infiltrating leukocyte populations. Flow cytometry was used to quantify infiltration of six leukocyte populations for 21 days …

Hydrodynamic And Mass Transport Properties Of Microfluidic Geometries, Thomas F. Leary

Dissertations, Theses, and Capstone Projects

Microfluidic geometries allow direct observation of microscale phenomena while conserving liquid volumes. They also enable modeling of experimental data using simplified transport equations and static force balances. This is possible because the length scales of these geometries ensure low Re conditions approaching the Stokesian limit, where the flow profile is laminar, viscous forces are dominant and inertial forces are negligible. This work presents results on two transport problems in microfluidic geometries. The first examines the heterogeneous binding kinetics in a microbead array, where beads with different chemical functionalities are sequentially captured in a well geometry over which analyte solution is …

Evaluation Of Electrocoagulation For The Removal Of Chromium (Vi) From Brackish Groundwater, Shaima S Hamdan

Theses

Electrocoagulation (EC) has been evaluated for the removal of Cr (VI) from brackish groundwater using three different bench-scale EC reactors, namely batch stirred tank reactor (BSTR), continuous stirred tank reactor (CSTR) and a continuous electrocoagulation column (ECC). Batch EC process was experimentally examined at room temperature and the results indicated that Fe-Fe electrode pair was the most efficient arrangement and was able to achieve 100 % Cr removal at an electrocoagulation time of 5 minutes, a current density of 7.94 mA/cm², and pH of 8. A kinetic study of batch EC was then performed using both pseudo-first-order and …

Magnetic Janus Particles And Their Applications, Bin Ren

Dissertations, Theses, and Capstone Projects

Magnetic properties are important since they enable the manipulation of particle behavior remotely and therefore provide the means to direct a particle’s orientation and translation. Magnetic Janus particles combine magnetic properties with anisotropy and thus are potential building blocks for complex structures that can be assembled from a particle suspension and can be directed through external fields. In this thesis, a method for the fabrication of three types of magnetic Janus particles with distinct magnetic properties is introduced, the assembly behavior of magnetic Janus particles in external magnetic and electric fields is systematically studied, and two potential applications of magnetic …

Enhanced Glt-1 Mediated Glutamate Uptake And Migration Of Primary Astrocytes Directed By Fibronectin-Coated Electrospun Poly-L-Lactic Acid Fibers, Jonathan M. Zuidema, María C. Hyzinski-García, Kristien Van Vlasselaer, Nicholas W. Zaccor, George E. Plopper, Alexander A. Mongin, Ryan J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Bioengineered fiber substrates are increasingly studied as a means to promote regeneration and remodeling in the injured central nervous system (CNS). Previous reports largely focused on the ability of oriented scaffolds to bridge injured regions and direct outgrowth of axonal projections. In the present work, we explored the effects of electro spun microfibers on the migration and physiological properties of brain astroglial cells. Primary rat astrocytes were cultured on either fibronectin-coated poly-l-lactic acid (PLLA) films, fibronectin-coated randomly oriented PLLA electro spun fibers, or fibronectin-coated aligned PLLA electro spun fibers. Aligned PLLA fibers strongly altered astrocytic morphology, orienting cell processes, actin …

Modeling The Construction Of Polymeric Adsorbent Media: Effects Of Counter-Ions On Ligand Immobilization And Pore Structure, Enrico Riccardi, Jee-Ching Wang, Athanasios I. Liapis

Chemical and Biochemical Engineering Faculty Research & Creative Works

Molecular dynamics modeling and simulations are employed to study the effects of counter-ions on the dynamic spatial density distribution and total loading of immobilized ligands as well as on the pore structure of the resultant ion exchange chromatography adsorbent media. The results show that the porous adsorbent media formed by polymeric chain molecules involve transport mechanisms and steric resistances which cause the charged ligands and counter-ions not to follow stoichiometric distributions so that (i) a gradient in the local nonelectroneutrality occurs, (ii) non-uniform spatial density distributions of immobilized ligands and counter-ions are formed, and (iii) clouds of counter-ions outside the …

A Dns Evaluation Of Mixing Models For Transported Pdf Modelling Of Turbulent Nonpremixed Flames, Alex Krisman, Joshua C.K. Tang, Evatt R. Hawkes, David O. Lignell, Jacqueline H. Chen

Faculty Publications

Transported probability density function (TPDF) methods are well suited to modelling turbulent, reacting, variable density flows. One of the main challenges to the successful deployment of TPDF methods is accurately modelling the unclosed molecular mixing term. This study examines three of the most widely used mixing models: the Interaction by Exchange with the Mean (IEM), Modified Curl (MC) and Euclidean Minimum Spanning Tree (EMST) models. Direct numerical simulation (DNS) data-sets were used to provide both initial conditions and inputs needed over the course of the runs, including the mean flow velocities, mixing frequency, and the turbulent diffusion coefficient. The same …

Multiphase Hydrodynamics And Distribution Characteristics In A Monolith Bed Measured By Optical Fiber Probe, Yuan Zhou, Milorad P. Dudukovic, Muthanna H. Al-Dahhan, Hui Liu

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Optical Fiber Probe Has Been for the First Time Applied to Investigate the Hydrodynamics and Gas-Phase Distribution at High Gas/liquid Ratios in a Two-Phase Flow Monolith Bed with 0.048 M Diameter and 400 Cpsi. Local Hydrodynamic Parameters Including Gas Holdup, Bubble Frequency, Bubble Velocity, and Bubble Length in Single Channels Were Measured by 16 Inserted Single-Point Optical Fiber Probes within the Bed under a Nozzle as the Liquid Distributor. the Following Findings Are Reported. (1) the Optical Fiber Probe Can Be Used as an Efficient and Convenient Technique for Measuring Local Hydrodynamic Parameters Inside the Channels of a Monolith …

Discrete Element Method Based Scale-Up Model For Material Synthesis Using Ball Milling, Priya Radhi Santhanam

Dissertations

Mechanical milling is a widely used technique for powder processing in various areas. In this work, a scale-up model for describing this ball milling process is developed. The thesis is a combination of experimental and modeling efforts.

Initially, Discrete Element Model (DEM) is used to describe energy transfer from milling tools to the milled powder for shaker, planetary, and attritor mills. The rolling and static friction coefficients are determined experimentally. Computations predict a quasi- steady rate of energy dissipation, Ed, for each experimental configuration. It is proposed that the milling dose defined as a product of Ed and milling …

A Progress Report On The Ultrasound Enhancement Of Antibiotic Action On Streptococcus Pneumoniae, Michael Le Bras, Dr. William G. Pitt

Journal of Undergraduate Research

Previous studies show that using antibiotic treatment together with ultrasound enhances the bactericidal effect of antibiotics on many bacterial species (6). The purpose of this research project is to apply these techniques to Streptococcus pneumoniae and the antibiotics ampicillin and gentamicin sulfate. The effectiveness of ampicillin and gentamicin sulfate coupled with the application of ultrasound on S. pneumoniae is the focus of this study.