Mesoscale Computational Studies Of Thin-Film Bijels,
2018
University of Arkansas, Fayetteville
Mesoscale Computational Studies Of Thin-Film Bijels, Joseph M. Carmack
Graduate Theses and Dissertations
Bijels are a relatively new class of soft materials that have many potential applications in the technology areas of energy, medicine, and environmental sustainability. They are formed by the arrest of binary liquid spinodal decomposition by a dispersion of solid colloidal nanoparticles. This dissertation presents an in-depth simulation study of Bijels constrained to thin-film geometries and in the presence of electric fields. We validate the computational model by comparing simulation results with previous computational modeling and experimental research. In the absence of suspended particles, we demonstrate that the model accurately captures the rich kinetics associated with diffusion-based surface-directed spinodal decomposition. …
A Nanoindentation Study Of The Fatigue Properties Of Al/A-Si Core-Shell Nanostructures,
2018
University of Arkansas, Fayetteville
A Nanoindentation Study Of The Fatigue Properties Of Al/A-Si Core-Shell Nanostructures, Jason Steck
Mechanical Engineering Undergraduate Honors Theses
Nanostructure-textured surfaces can reduce friction and increase the reliability of micro- and nanoelectromechanical systems (NEMS/MEMS). For MEMS incorporating moving parts, the fatigue properties of nanostructures pose a challenge to their reliability in long-term applications. In this study, the fatigue behavior of hemispherical Al/a-Si core-shell nanostructures (CSNs), bare hemispherical Al nanodots, and a flat Al/a-Si layered thin film have been studied using nanoindentation and nano-scale dynamic mechanical analysis (nano-DMA) techniques. Fatigue testing with nano-DMA shows that the deformation resistance of CSNs persists through 5.0 × 104 loading cycles at estimated contact pressures greater than 15 GPa. When the a-Si shell …
Non-Covalent Functionalization Of Graphene Films For Uniform Nanoparticle Deposition Via Atoic Layer Deposition,
2018
University of Arkansas, Fayetteville
Non-Covalent Functionalization Of Graphene Films For Uniform Nanoparticle Deposition Via Atoic Layer Deposition, Ty Seiwert
Mechanical Engineering Undergraduate Honors Theses
Graphene functionalized with platinum (Pt) and palladium (Pd) has proven to be highly effective as a hydrogen sensor. Deposition methods such as Atomic layer deposition (ALD) can be further enhanced by pretreating the graphene with a non-covalent surfactant prior to nanoparticle deposition. In this study, graphene-based sensing devices will be fabricated by ALD deposition. The graphene will be non-covalently functionalized using sodium dodecyl sulfate (SDS) anionic surfactant prior to ALD deposition. The aim of this study is to test the deposition pattern achieved by varying the amount of time that graphene is treated with the SDS surfactant. Initially, ALD deposition …
Concomitant Crystallization In Propylene/Ethylene Random Copolymer With Strong Flow At Elevated Temperatures,
2018
Tianjin University
Concomitant Crystallization In Propylene/Ethylene Random Copolymer With Strong Flow At Elevated Temperatures, Lirong Zheng, Lucia Fernandez-Ballester, Gerrit W. M. Peters, Zhe Ma
Department of Mechanical and Materials Engineering: Faculty Publications
Flow-induced crystallization of α- and γ-phases was studied for a propylene/ethylene random copolymer with 3.4 mol % ethylene at two high temperatures of 132 and 142 °C by combining a pressure-driven slit flow device with real-time synchrotron wide-angle X-ray diffraction. At 132 °C, it was found that both α- and γ-phases were generated at shear stresses ranging from 0.091 to 0.110 MPa and that the γ-phase always appeared later than the α-phase. However, for 142 °C and the same stresses, only the α-phase formed. Only upon cooling the partially crystallized copolymer did the γ-phase emerge. The lack of γ-crystals obtained …
Surface Area And Electrocatalytic Properties Of Feni Nanoparticles For The Oxygen Evolution Reaction (Oer),
2018
University of Arkansas, Fayetteville
Surface Area And Electrocatalytic Properties Of Feni Nanoparticles For The Oxygen Evolution Reaction (Oer), James Burrow
Chemical Engineering Undergraduate Honors Theses
Iron-nickel bimetallic electrocatalysts have recently emerged as some of the best candidates for the oxygen evolution reaction (OER) in alkaline electrolyte. Understanding the effects of composition and morphology of iron-nickel nanoparticles is crucial for optimization and enhanced electrocatalyst performance. Both physical surface area and electrochemical surface area (ECSA) are functions of morphology. In this study, four different iron-nickel nanoparticle catalysts were synthesized. The catalysts were varied based on morphology (alloy versus core-shell) and composition (low, medium, and high stabilizer concentration). Brunauer-Emmett-Teller (BET) surface area analysis was conducted on three of the synthesized iron-nickel nanoparticles using a physisorption analyzer while electrochemical …
Degradation Of Orange G Through Persulfate Activated Nanoscale Zerovalent Iron Composites And Boron-Doped Diamond Electrodes,
2018
University of Arkansas, Fayetteville
Degradation Of Orange G Through Persulfate Activated Nanoscale Zerovalent Iron Composites And Boron-Doped Diamond Electrodes, Suzana Ivandic
Chemical Engineering Undergraduate Honors Theses
Properly treated wastewater is necessary for water reuse and to avoid unnecessary impacts on the environment. The poultry industry utilizes large amounts of water for poultry processing. The need for innovative ways to treat organic contaminants in the poultry wastewater industry is especially necessary due to increased poultry consumption. The U.S. Department of Agriculture projected Americans would consume approximately 92 pounds of chicken per person in 2017.1 Dissolved air flotation (DAF) is currently used in poultry wastewater treatment, but DAF does not remove organic contaminants efficiently per effluent standards. Implementation of processes that degrade contaminants directly would benefit the …
Improving The Selectivity And Reducing The Leakage Of Dna Strand Displacement Systems,
2018
Boise State University
Improving The Selectivity And Reducing The Leakage Of Dna Strand Displacement Systems, Shohei Kotani
Boise State University Theses and Dissertations
Because of the elegance of Watson-Crick base pairing and the programmability of toehold-mediated strand displacement, DNA is a model material for designing, building, and testing molecular assemblies. DNA assemblies are categorized as structural when they are at thermodynamic equilibrium and dynamic when they are not. Through programmed perturbations, metastable assemblies perform physical, chemical, and computational work. When integrated into a diagnostic package, disease-specific nucleic acid sequences can be identified, amplified, and analyzed via standard DNA nanotechnology rules. In order for these rules to make an impact, two critical challenges in the field have been undertaken in this dissertation. First, the …
Glucose Level Estimation Based On Invasive Electrochemical, And Non-Invasive Optical Sensing Methods,
2018
University of Arkansas, Fayetteville
Glucose Level Estimation Based On Invasive Electrochemical, And Non-Invasive Optical Sensing Methods, Sanghamitra Mandal
Graduate Theses and Dissertations
The purpose of this research is to design and fabricate sensors for glucose detection using inexpensive approaches. My first research approach is the fabrication of an amperometric electrochemical glucose sensor, by exploiting the optical properties of semiconductors and structural properties of nanostructures, to enhance the sensor sensitivity and response time. Enzymatic electrochemical sensors are fabricated using two different mechanisms: (1) the low-temperature hydrothermal synthesis of zinc oxide nanorods, and (2) the rapid metal-assisted chemical etching of silicon (Si) to synthesize Si nanowires. The concept of gold nano-electrode ensembles is then employed to the sensors in order to boost the current …
Design, Fabrication, And Characterization Of All-Inorganic Quantum Dot Light Emitting Diodes,
2018
University of Arkansas, Fayetteville
Design, Fabrication, And Characterization Of All-Inorganic Quantum Dot Light Emitting Diodes, Ramesh Vasan
Graduate Theses and Dissertations
Quantum dot light emitting diodes are investigated as a replacement to the existing organic light emitting diodes that are commonly used for thin film lighting and display applications. In this, all-inorganic quantum dot light emitting diodes with inorganic quantum dot emissive layer and inorganic charge transport layers are designed, fabricated, and characterized. Inorganic materials are more environmentally stable and can handle higher current densities than organic materials. The device consists of CdSe/ZnS alloyed core/shell quantum dots as the emissive layer and metal oxide charge transport layer. The charge transport in these devices is found to occur through resonant energy transfer …
Immunostimulatory Effects Of Antigen-Conjugated Inp/Zns Quantum Dot Nanoparticles In An Avian Model,
2018
University of Arkansas, Fayetteville
Immunostimulatory Effects Of Antigen-Conjugated Inp/Zns Quantum Dot Nanoparticles In An Avian Model, Christopher Lyle
Graduate Theses and Dissertations
Due to their unique physicochemical and enhanced immunostimulatory properties, quantum dot (QD) nanoparticles have shown increasing promise in biomedical research applications including bioimaging, drug delivery, and as vaccine adjuvants. Toxicity, however, remains a concern for the use of QD in these applications and thus, there is an increased demand for effective in vitro and in vivo systems to measure the bioactivity of QD. In this study in vitro and in vivo chicken models were used to investigate the effects of QD on innate and adaptive immunity. Chicken macrophage cultures were treated in vitro with QD to measure macrophage activation and …
Investigation Of Nanomaterial Based Photovoltaic Panel Packaging Materials,
2018
University of Arkansas, Fayetteville
Investigation Of Nanomaterial Based Photovoltaic Panel Packaging Materials, Xingeng Yang
Graduate Theses and Dissertations
In this research, nanomaterial-based packaging materials for photovoltaic (PV) panels are investigated. A hydrophobic/anti-reflective surface coating which not only repels water from the top glass of a PV panel but at the same time reduces its light reflectance is investigated. COMSOL simulation results indicate that taller ellipsoid rod (aspect ratio = 5) reflects less light than shorter rod (aspect ratio = 0.5) in the desired spectrum for solar energy harvest from 400nm-700nm. The addition of a polymer layer on these ellipsoid rods broadens the light incident angle from 23° to 34°, from which light can be efficiently absorbed. Based on …
State Dependent Function And Dynamics In Cerebral Cortical Networks,
2018
University of Arkansas, Fayetteville
State Dependent Function And Dynamics In Cerebral Cortical Networks, Leila Fakhraei
Graduate Theses and Dissertations
Cerebral cortex exhibits vigorous ongoing, internal neural activity even with no sensory input is present or the animal is minimally engaged in a task or behavior. This internal ongoing activity is not static; the ‘cortical state’ varies ranging from synchronous and highly correlated activity to asynchronous and weakly correlated neural activity. The main goal of the work presented here is to understand how changes in cortical states effect several aspects of cortical function and dynamics.
To meet this goal, we did three separate projects. First, we compared the predictability of neuronal network dynamics across cortical states in somatosensory cortex of …
Phase Transitions In Monochalcogenide Monolayers,
2018
University of Arkansas, Fayetteville
Phase Transitions In Monochalcogenide Monolayers, Mehrshad Mehboudi
Graduate Theses and Dissertations
Since discovery of graphene in 2004 as a truly one-atom-thick material with extraordinary mechanical and electronic properties, researchers successfully predicted and synthesized many other two-dimensional materials such as transition metal dichalcogenides (TMDCs) and monochalcogenide monolayers (MMs). Graphene has a non-degenerate structural ground state that is key to its stability at room temperature. However, group IV monochalcogenides such as monolayers of SnSe, and GeSe have a fourfold degenerate ground state. This degeneracy in ground state can lead to structural instability, disorder, and phase transition in finite temperature. The energy that is required to overcome from one degenerate ground state to another …
Effects Of Hydration And Mineralization On The Mechanical Behavior Of Collagen Fibrils,
2018
University of Arkansas, Fayetteville
Effects Of Hydration And Mineralization On The Mechanical Behavior Of Collagen Fibrils, Marco Fielder
Graduate Theses and Dissertations
Bone is a composite biomaterial with a structural load-bearing function. Understanding the biomechanics of bone is important for characterizing factors such as age, trauma, or disease, and in the development of scaffolds for tissue engineering and bioinspired materials. At the nanoscale, bone is primarily composed of collagen protein, apatite crystals, and water. Though several studies have characterized nanoscale bone mechanics as the mineral content changes, the effect of water, mineral, and carbon nanotube (CNT) content and distribution in fibril gap and overlap regions is unexplored. This study used molecular dynamics to investigate the change in collagen fibril deformation mechanisms as …
Self-Assembled Barium Titanate Nanoscale Films By Molecular Beam Epitaxy,
2018
University of Arkansas, Fayetteville
Self-Assembled Barium Titanate Nanoscale Films By Molecular Beam Epitaxy, Timothy Allen Morgan
Graduate Theses and Dissertations
One challenge of investigating ferroelectrics at the nanoscale has been controlling the stoichiometry during growth. Historically, the growth of barium titanate (BaTiO3) by molecular beam epitaxy has relied on a growth technique called shuttered RHEED. Shuttered RHEED controls the stoichiometry of barium titanate through the precise deposition of alternating layers of BaO and TiO2. While this approach has achieved 1% control of stoichiometry, finding self-limiting mechanisms to lock-in stoichiometry has been the focus of the growth community. The Goldschmidt tolerance factor predicts an unstable perovskite when barium sits in the titanium lattice site. The BaO-TiO2 phase diagram predicts a low-solubility …
Advancing The Understanding Of Environmental Transformations, Bioavailability And Effects Of Nanomaterials, An International Us Environmental Protection Agency—Uk Environmental Nanoscience Initiative Joint Program,
2018
US Environmental Protection Agency
Advancing The Understanding Of Environmental Transformations, Bioavailability And Effects Of Nanomaterials, An International Us Environmental Protection Agency—Uk Environmental Nanoscience Initiative Joint Program, Mitch M. Lasat, Kian Fan Chung, Jamie Lead, Steve Mcgrath, Richard J. Owen, Sophie Rocks, Jason M. Unrine, Junfeng Zhang
Plant and Soil Sciences Faculty Publications
Nanotechnology has significant economic, health, and environmental benefits, including renewable energy and innovative environmental solutions. Manufactured nanoparticles have been incorporated into new materials and products because of their novel or enhanced properties. These very same properties also have prompted concerns about the potential environmental and human health hazard and risk posed by the manufactured nanomaterials. Appropriate risk management responses require the development of models capable of predicting the environmental and human health effects of the nanomaterials. Development of predictive models has been hampered by a lack of information concerning the environmental fate, behavior and effects of manufactured nanoparticles. The United …
Rare Earth - Free Permanent Magnetic Material,
2018
Lincoln, NE
Rare Earth - Free Permanent Magnetic Material, Laura H. Lewis, Jeffrey E. Shield, Katayun Barmak Viziri
Department of Mechanical and Materials Engineering: Faculty Publications
The invention provides rare earth - free permanent magnetic materials and methods of making them . The materials can be used to produce magnetic structures for use in a wide variety of commercial applications , such as motors , generators , and other electromechanical and electronic devices . Magnets fabricated using the materials can be substituted for magnets requiring rare earth elements that are costly and in limited supply . The invention provides two different types of magnetic materials . The first type is based on an iron - nickel alloy that is doped with one or more doping elements …
Method Of Fabricating A Continuous Nanofiber,
2018
Lincoln, Nebraska
Method Of Fabricating A Continuous Nanofiber, Yuris Dzenis
Department of Mechanical and Materials Engineering: Faculty Publications
A method of fabricating a continuous nanofiber is described . The method includes preparing a solution of one or more polymers and one or more solvents and electrospinning the solution by discharging the solution through one or more liquid jets into an electric field to yield one or more continuous nanofibers . The electrospinning process ( i ) highly orients one or more polymer chains in the one or more continuous nanofibers along a fiber axis of the one or more continuous nanofibers , and ( ii ) suppresses polymer crystallization in the one or more continuous nanofibers . The …
Method For Production Of Germanium Nanowires Encapsulated Within Multi-Walled Carbon Nanotubes,
2018
University of Kentucky
Method For Production Of Germanium Nanowires Encapsulated Within Multi-Walled Carbon Nanotubes, Mark Crocker, Rodney Andrews, Arumugam Pandurangan, Dali Qian
Center for Applied Energy Research Faculty Patents
A method is provided for producing germanium nanowires encapsulated within multi-walled carbon nanotubes. The method includes the steps of performing chemical vapor deposition using a combined germanium and carbon source having a general formula of GeR(4-x)Lx, where x=0, 1, 2, or 3; R is selected from a group consisting of alkyl, cycloalkyl or aryl and L=hydrogen, halide or alkoxide and growing germanium nanowires encapsulated within multi-walled carbon nanotubes on a substrate. A reaction product of that method or process is also provided.
Spectro-Electrochemical Platforms For Dynamic Analyses Of Catalytic Cascade Systems,
2018
University of New Mexico - Main Campus
Spectro-Electrochemical Platforms For Dynamic Analyses Of Catalytic Cascade Systems, Nalin I. Andersen
Nanoscience and Microsystems ETDs
The development of spectro-electrochemical platforms that facilitate the dynamic analyses of complex catalytic cascade systems was explored in this research. These systems facilitated multiple modalities of catalysts and were used as platforms for monitoring catalytic transformations quasi-in situ. The analytical platforms allowed for the characterization of intermediates and products using surface-enhanced Raman spectroscopy (SERS). The design and fabrication of these devices proved to be reproducible, made of materials that can be manipulated for multiple applications, and incorporate fluid mechanics, electrochemistry, and multimodal catalysis. Microfluidic technology offers capabilities for understanding catalytic cascade systems by providing precise dynamic control of …
