Nanoparticle Cerium Oxide And Mixed Cerium Oxides For Improved Fuel Cell Lifetime,
2014
University of New Mexico
Nanoparticle Cerium Oxide And Mixed Cerium Oxides For Improved Fuel Cell Lifetime, Stephen Stewart
Chemical and Biological Engineering ETDs
While there is a rich body of literature concerning of properties of bulk cerium oxide and cerium cations in solution, the discussion has been inappropriately applied to nanoscale cerium oxide resulting in many unexpected or unexplained results. In particular, there is very limited understanding about the properties of cerium oxide and its potential use as a radical scavenger, and how the catalytic properties of cerium oxide change as the particle size approaches the nanoscale. For example, the involvement of Ce+4 and Ce+3 cations in reactions such as hydrogen peroxide decomposition have been investigated for both cerium cations and bulk cerium …
Poly(N-Isopropyl Acrylamide)-Coated Surfaces: Investigation Of Cytotoxicity With Mammalian Cells And The Mechanism Of Cell Detachment,
2014
University of New Mexico
Poly(N-Isopropyl Acrylamide)-Coated Surfaces: Investigation Of Cytotoxicity With Mammalian Cells And The Mechanism Of Cell Detachment, Marta Cooperstein
Chemical and Biological Engineering ETDs
With the increase in life expectancy and with growing numbers of an aging population, there is a rising need worldwide for replacement tissues and organs. One way to address this growing need is through engineered tissues, such as those generated from stimulus-responsive polymers. Stimulus-responsive polymers undergo a physical or chemical change when a stimulus is applied. One such material is poly(N-isopropyl acrylamide), (pNIPAM), which undergoes a conformation change in a physiologically relevant temperature range to release intact mammalian cell monolayers capable of being used to engineer tissues. Two factors currently limit the use of cell sheets for this purpose: 1) …
Modeling Of Kinetically Limited Growth Rate For Solution-Synthesized Germanium Nanocrystals,
2014
University of New Mexico
Modeling Of Kinetically Limited Growth Rate For Solution-Synthesized Germanium Nanocrystals, Nicholas Shoop
Chemical and Biological Engineering ETDs
Solution synthesis is a common method of generating semiconductor nanocrystals. For solution synthesis, many studies have assumed that the growth rate is diffusion-limited with an unphysically low diffusion constant. In this thesis, a model is developed that considers both diffusion and surface kinetics. The diffusion coefficient of Ge monomers through the solvent, octadecene, at elevated synthesis temperatures is estimated to be on the order of 10-5 to 10-4 cm2/sec, while the mass transfer boundary layer thickness is estimated to be on the order of a few nanometers, similar to the nanocrystal size. These two realistic conditions strongly suggest that the …
Development Of Novel Synthetic Methods For Size-Tunable Synthesis Of Superparamagnetic Iron Oxide Nanoparticles,
2014
University of New Mexico
Development Of Novel Synthetic Methods For Size-Tunable Synthesis Of Superparamagnetic Iron Oxide Nanoparticles, Erika Vreeland
Chemical and Biological Engineering ETDs
The properties of magnetic nanoparticles vary dramatically with size, so reproducibly controlling size is critical for practical applications. This is particularly true when moving into clinical settings, where regulatory approval requires demonstrated reproducibility in efficacy that can only be achieved with excellent size control. A number of methods for the synthesis of magnetic nanoparticles have been published, although the thermal decomposition of iron(III) precursors in organic solvents has been shown to yield high quality particles with low shape and size dispersity. Currents methods lack reproducibility resulting from non-stoichiometric starting materials, and reliance on reaction parameters, such as temperature ramp rate, …
Fundamental Studies On Copper Zeolites For Catalytic No X Abatement,
2014
Purdue University
Fundamental Studies On Copper Zeolites For Catalytic No X Abatement, Anuj Arun Verma
Open Access Dissertations
Stringent regulations in mobile NOx emissions have resulted in the development of Standard Selective Catalytic Reduction (SCR) as the dominant NOx abatement technology in lean burn diesel engines. Standard SCR is a reaction of nitric oxide (NO) with ammonia (NH3), in the presence of oxygen (O 2) to form nitrogen (N2) and water (H2O). Copper containing zeolites show commercially viable SCR performance. Cu-SSZ-13 (CHA framework), a member of this family, is a preferred catalyst for SCR applications because it shows exceptional hydrothermal stability in addition to commercially viable SCR performance. Our work focuses …
Correlation Between Microstructure And Thermionic Electron Emission From Os-Ru Thin Films On Dispenser Cathodes,
2014
University of Kentucky
Correlation Between Microstructure And Thermionic Electron Emission From Os-Ru Thin Films On Dispenser Cathodes, Phillip D. Swartzentruber, Thomas John Balk, Michael P. Effgen
Chemical and Materials Engineering Faculty Publications
Osmium-ruthenium films with different microstructures were deposited onto dispenser cathodes and subjected to 1000 h of close-spaced diode testing. Tailored microstructures were achieved by applying substrate biasing during deposition, and these were evaluated with scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy before and after close-spaced diode testing. Knee temperatures determined from the close-spaced diode test data were used to evaluate cathode performance. Cathodes with a large {10-11} Os-Ru film texture possessed comparatively low knee temperatures. Furthermore, a low knee temperature correlated with a low effective work function as calculated from the close-spaced diode data. It is proposed …
Preparation & Characterization Of High Purity Cu2 Znsn(Sxse1-X)4 Nanoparticles,
2014
Purdue University
Preparation & Characterization Of High Purity Cu2 Znsn(Sxse1-X)4 Nanoparticles, Bethlehem G. Negash
Open Access Theses
Research in thin film solar cells applies novel techniques to synthesize cost effective and highly efficient absorber materials in order to generate electricity directly from solar energy. Of these materials, copper zinc tin sulfoselenide (Cu2ZnSn(SxSe1-x) 4) nanoparticles have shown great promise in solar cell applications due to optimal material properties as well as low cost & relative abundance of materials.1,2 Sulfoselenide nanoparticles have also a broader impact in other industries including electronics3, LED 4, and biomedical research5. Of the many routes of manufacturing these class of semiconductors, …
Solvent System Selection For Xylooligosaccharides Separation By Centrifugal Partition Chromatography Using Conductor-Like Screening Model For Real Solvents,
2014
Purdue University
Solvent System Selection For Xylooligosaccharides Separation By Centrifugal Partition Chromatography Using Conductor-Like Screening Model For Real Solvents, He Zhang
Open Access Theses
The production of value-added, bio-based industrial commodity chemicals is an important area in science right now and this study provides an initial step in the recovery of bio-based chemicals from hemicellulose. Hemicellulose is a long chain polymer mostly consisting of xylose, which is a five-carbon sugar, and a variety of other compounds that are ubiquitous in plant life. The hemicellulose polymer chain can be depolymerized into smaller components, called xylooligosaccharides (XOS) with different chain lengths of xylose linked by beta-1-4 glycosidic bonds, using either hot water, or dilute sulfuric acid. The xylooligosaccharides can then be purified from one another from …
Correlating Molecular Architecture Of A Radical Polymer Based Copolymer With Its Electrical Transport Properties,
2014
Purdue University
Correlating Molecular Architecture Of A Radical Polymer Based Copolymer With Its Electrical Transport Properties, Holly Chan
Open Access Theses
The design and synthesis of electrically-conductive macromolecules can lead to significant improvements in the performance of polymer-based energy conversion devices (e.g., thermoelectric devices). For these organic electronic devices, conjugated polymers have dominated the area of conductive polymers; however, these materials are usually synthesized using conditions that lead to poorly-defined polymers. Furthermore, in these increasingly-standard polymers, the charge transport ability of the polymer thin films is largely affected by the degree of crystallinity, which is a difficult property to control in a reproducible fashion. Therefore, we seek to explore a new class of amorphous, non-conjugated polymers containing a stable radical …
Measurement And Modeling Of Fire Behavior In Leaves And Sparse Shrubs,
2014
Brigham Young University - Provo
Measurement And Modeling Of Fire Behavior In Leaves And Sparse Shrubs, Dallan R. Prince
Theses and Dissertations
Wildland fuels and fire behavior have been the focus of numerous studies and models which provide operational support to firefighters. However, fuel and fire complexity in live shrubs has resulted in unexpected and sometimes aggressive fire behavior. The combustion of live fuels was studied and modeled, and the results were assimilated into a shrub-scale fire behavior model which assumes fire spread by flame-fuel overlap. Fire spread models have usually assumed that radiation heat transfer is responsible for driving fire spread, but that assumption is a topic of continuing debate, and appears to contradict some experimental observations. A convection-based shrub-scale fire …
Pharmacokinetic Characterization Of Procoagulation Proteins,
2014
University of Nebraska-Lincoln
Pharmacokinetic Characterization Of Procoagulation Proteins, Nicholas C. Vanderslice
Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research
The cessation of bleeding in mammals occurs due to a well-conserved sequence of protein activation known as the coagulation cascade. However, people who have a deficiency in one or more proteins in this cascade, whether due to genetics or blood loss, struggle to maintain hemostasis. In order to aid patients in the restoration of hemostasis, exogenous proteins are often administered in response to bleeding events. However, these proteins are limited and costly due to limited supply of donor blood available for the production of plasma-derived proteins and the high cost of mammalian cell bio-reactors required for the production of recombinant …
Optimal Aggregation Of Fcεri With A Structurally Defined Trivalent Ligand Overrides Negative Regulation Driven By Phosphatases,
2014
Missouri University of Science and Technology
Optimal Aggregation Of Fcεri With A Structurally Defined Trivalent Ligand Overrides Negative Regulation Driven By Phosphatases, Avanika Mahajan, Dipak Barua, Patrick Cutler, Diane S. Lidke, Flor A. Espinoza, Carolyn Pehlke, Rachel Grattan, Yuko Kawakami, Chang-Shung Tung, Andrew R. M. Bradbury, William S. Hlavacek, Bridget S. Wilson
Chemical and Biochemical Engineering Faculty Research & Creative Works
To investigate why responses of mast cells to antigen-induced IgE receptor (FcεRI) aggregation depend nonlinearly on antigen dose, we characterized a new artificial ligand, DF3, through complementary modeling and experimentation. This ligand is a stable trimer of peptides derived from bacteriophage T4 fibritin, each conjugated to a hapten (DNP). We found low and high doses of DF3 at which degranulation of mast cells sensitized with DNP-specific IgE is minimal, but ligand-induced receptor aggregation is comparable to aggregation at an intermediate dose, optimal for degranulation. This finding makes DF3 an ideal reagent for studying the balance of negative and positive signaling …
Horseradish Peroxidase-Attapulgite Clay Nanocomposites: Fabrication And Application To Sensing The Extracellular H2O2 Released From Cells,
2014
Jiangsu Key Laboratory of New Power Batteries, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, China;
Horseradish Peroxidase-Attapulgite Clay Nanocomposites: Fabrication And Application To Sensing The Extracellular H2O2 Released From Cells, Ping Wu, Chen-Xin Cai
Journal of Electrochemistry
The nanostructured attapulgite clay was employed as a support matrix for immobilizing horseradish peroxidase (HRP). FTIR and electrochemical methods demonstrated that HRP had been effectively assembled on attapulgite surface with the formation of HRP-attapulgite nanocomposites. The HRP-attapulgite hybrid was deposited on the glassy carbon (GC) electrode forming the HRP-attapulgite/GC electrode. Cyclic voltammetric results showed a pair of well-defined redox peaks, which were ascribed to direct electron transfer (DET) of HRP, with the formal potential E0′ = -335 mV (vs. SCE) in the phosphate buffer solution (PBS, pH 7.0). The dependence of E0′ on solution pH indicated …
The Ionic Diffusion Model For The Solid Oxide Cathode And Its Verification By The Electrolysis Of Ta2O5 In Molten Cacl2,
2014
College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China;
The Ionic Diffusion Model For The Solid Oxide Cathode And Its Verification By The Electrolysis Of Ta2O5 In Molten Cacl2, Hua-Lin Chen, Zhi-Yong Wang, Xian-Bo Jin, George Z. Chen
Journal of Electrochemistry
The deoxidation speed of a solid oxide cathode in molten CaCl2 can be estimated by the PRS steady diffusion model of O2-, which correlates the deoxidation speed with the precursor porosity, P, the metal-to-oxide molar volume ratio, R, and the cathode volume shrinkage S. The PRS model indicates that the porosity of the oxide cathode has important influence on the deoxidation speed, and provides a very simple equation for the prediction of the optimal cathode porosity. For the electrolysis of Ta2O5, the porosity of the cathode is better to be within 50%. …
Effects Of Oxygen Coverage And Hydrated Proton Model On The Dft Calculation Of Oxygen Reduction Pathways On The Pt(111) Surface,
2014
College of Chemistry and Chemical Engineering, Hunan University of Arts and Science, Changde 415000, Hunan, China;College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China;
Effects Of Oxygen Coverage And Hydrated Proton Model On The Dft Calculation Of Oxygen Reduction Pathways On The Pt(111) Surface, Li-Hui Ou, Sheng-Li Chen
Journal of Electrochemistry
DFT calculation is used to study various possible steps in the oxygen reduction reaction (ORR), including the adsorption and dissociation process of O2 and the serial protonation process of dissociated products to form H2O on the Pt(111) surface. By using slabs of different sizes, and different numbers of pre-adsorbed oxygen atoms, the coverage effects on the pathways are investigated. The calculated results using different hydrated proton models are also compared. It is shown that the initial step of the ORR is the formation of a protonated end-on chemisorbed state of OOH*, which can transform to an unprotonated …
Calculated Vs. Experimental Values For Volume And Surface Resistivity In Various Polymer Compounds,
2014
University of Wisconsin - Whitewater
Calculated Vs. Experimental Values For Volume And Surface Resistivity In Various Polymer Compounds, Megan Webster
Pursuit - The Journal of Undergraduate Research at The University of Tennessee
Versatile due to their resistance to high stress environments including but not limited to extreme temperature, pressure, and stress, polymers additionally have many uses in electrical applications wherein antistatic or conductive properties are preferential, i.e. conductive seals, oil pipeline spheres, and gaskets, to name a few. Being a complex material, many factors may affect the electrical resistivity of a given polymer compound including type and amount of carbon black, type of rubber, cure time and temperature, and dispersion, amongst other factors. External conditions such as relative humidity and temperature also play key roles. This paper will analyze five different rubber …
X-Ray Digital Industrial Radiography (Dir) For Local Liquid Velocity (Vll) Measurement In Trickle Bed Reactors (Tbrs): Validation Of The Technique,
2014
Missouri University of Science and Technology
X-Ray Digital Industrial Radiography (Dir) For Local Liquid Velocity (Vll) Measurement In Trickle Bed Reactors (Tbrs): Validation Of The Technique, K. A. M. Salleh, M. F. A. Rahman, Hyoung-Koo Lee, Muthanna H. Al-Dahhan
Nuclear Engineering and Radiation Science Faculty Research & Creative Works
Local liquid velocity measurements in Trickle Bed Reactors (TBRs) are one of the essential components in its hydrodynamic studies. These measurements are used to effectively determine a reactor's operating condition. This study was conducted to validate a newly developed technique that combines Digital Industrial Radiography (DIR) with Particle Tracking Velocimetry (PTV) to measure the Local Liquid Velocity (VLL) inside TBRs. Three millimeter-sized Expanded Polystyrene (EPS) beads were used as packing material. Three validation procedures were designed to test the newly developed technique. All procedures and statistical approaches provided strong evidence that the technique can be used to measure …
Insights Into The Epitaxial Relationships Between One-Dimensional Nanomaterials And Metal Catalyst Surfaces Using Density Functional Theory Calculations,
2014
University of South Florida
Insights Into The Epitaxial Relationships Between One-Dimensional Nanomaterials And Metal Catalyst Surfaces Using Density Functional Theory Calculations, Debosruti Dutta
USF Tampa Graduate Theses and Dissertations
This dissertation involves the study of epitaxial behavior of one-dimensional nanomaterials like single-walled carbon nanotubes and Indium Arsenide nanowires grown on metallic catalyst surfaces. It has been previously observed in our novel microplasma based CVD growth of SWCNTs on Ni-Fe bimetallic nanoparticles that changes in the metal catalyst composition was accompanied by variations in the average metal-metal bond lengths of the nanoparticle and that in turn, affected nanotube chirality distributions. In this dissertation, we have developed a very simplistic model of the metal catalyst in order to explain the nanotube growth of specific nanotube chiralities on various Ni-Fe catalyst surfaces. …
Comparison Of One-Dimensional Turbulence And Direct Numerical Simulations Of Soot Formation And Transport In A Nonpremixed Ethylene Jet Flame,
2014
Brigham Young University - Provo
Comparison Of One-Dimensional Turbulence And Direct Numerical Simulations Of Soot Formation And Transport In A Nonpremixed Ethylene Jet Flame, David O. Lignell, Garrison C. Fredline, Adam D. Lewis
Faculty Publications
Accurate models of soot formation in turbulent flames are important for correctly predicting and simulating flames and fires. Modeling soot formation and transport is challenging due to the complex chemical formation processes, and differential diffusion of soot relative to a flame. Direct numerical simulations (DNS) have highlighted the importance of such transport on soot concentrations, however DNS is computationally expensive. The one-dimensional turbulence (ODT) model is able resolve a full range of length and timescales and solves the evolution of diffusive and reactive scalars in the natural physical coordinate. We present results of soot formation in ODT and compare the …
Simulation And Analysis Of Inhomogeneous Degradation In Large Format Limn2O4/ Carbon Cells,
2014
University of South Carolina - Columbia
Simulation And Analysis Of Inhomogeneous Degradation In Large Format Limn2O4/ Carbon Cells, Yiling Dai, Long Cai, Ralph E. White
Faculty Publications
Degradation phenomena are not distributed uniformly in a large-format cell. To better understand the inhomogeneous degradation in large-format cells, a two-dimensional model was developed for a LiMn2O4 (LMO)/Carbon cell. The model includes both the non-uniform porous electrode properties and the electrode mismatch. The simulation results show that when the anode edge is extended over the cathode edge, the LMO particles near the edge suffer larger potential difference, larger charge/discharge depth, and higher insertion-induced stress. Therefore, the predicted loss of LMO is more pronounced near the edge as has been seen experimentally. The influence of different design adjustable …
