Microstructure And Mechanical Properties Of Titanium Nitride Optical Coatings Made By Dc Magnetron Sputtering,
2013
University of Texas at El Paso
Microstructure And Mechanical Properties Of Titanium Nitride Optical Coatings Made By Dc Magnetron Sputtering, Gustavo Martinez
Open Access Theses & Dissertations
Titanium nitride (TiNx) thin films were grown by DC (Direct Current) magnetron sputtering method onto Si(100) substrates by varying time of deposition to produce films with variable thickness (dTiN) in the range of 20-120 nm. The grown TiNx films were characterized by studying their structure, composition, and mechanical properties. Nuclear reaction analysis (NRA) combined with Rutherford backscattering spectrometry (RBS) analyses indicate that the grown films were stoichiometric TiN. Grazing incidence X-ray diffraction (GIXRD) measurements indicate that the texturing of the TiN films changes as a function of dTiN. The (111) and (002) peaks appear initially; with increasing dTiN, (111) becomes …
Structure And Electronic Properties Of Pure And Nitrogen Doped Nanocrystalline Tungsten Oxide Thin Films,
2013
University of Texas at El Paso
Structure And Electronic Properties Of Pure And Nitrogen Doped Nanocrystalline Tungsten Oxide Thin Films, Vemnkata Rama Sesha Ravi Kumar Vemuri
Open Access Theses & Dissertations
Tungsten oxide (WO3) is a multifunctional material which has applications in electronics, sensors, optoelectronics, and energy-related technologies. Recently, electronic structure modification of WO3 to design novel photocatalysts has garnered significant attention. However, a fundamental understanding of nitrogen induced changes in the structure, morphology, surface/interface chemistry, and electronic properties of WO3 is a prerequisite to producing materials with the desired functionality and performance. Also, understanding the effect of thermodynamic and processing variables is highly desirable in order to derive the structure-property relationships in the W-O/W-O-N material system. The present work was, therefore, focused on studying the effects …
Flexural Rigidity Characterization Of Retrofitted Frp Plates,
2013
Old Dominion University
Flexural Rigidity Characterization Of Retrofitted Frp Plates, Steven J. Makonis Jr., Stella B. Bondi, Zia Razzaq
Civil & Environmental Engineering Faculty Publications
Presented herein is a procedure and numerical results for flexural rigidity characterization of Fiber Reinforced Polymer (FRP) plates retrofitted with various types of fabrics. The FRP plates were retrofitted with Kevlar® 49 (Aramid), Carbon Fiber (Harness-Satin H5), and Unidirectional Carbon Fiber (T700 Aerospace Grade) fabrics, respectively. The FRP plate flexural rigidity values were calculated with a central finitedifference iterative scheme while utilizing the experimental load-deflection relations based on bending tests. The tests were performed on each plate by applying a concentrated load at the center. A fourth-order partial differential equation of plate equilibrium was adopted to estimate the plate flexural …
Cross-Plane Thermal Properties Of Transition Metal Dichalcogenides,
2013
University of Dayton
Cross-Plane Thermal Properties Of Transition Metal Dichalcogenides, Christopher Muratore, Vikas Varshney, Jaime J. Gengler, Jianjun Hu, John E. Bultman, Timothy M. Smith, Patrick J. Shamberger, Bo Qiu, Xiulin Ruan, Ajit K. Roy, Andrey A. Voevodin
Chemical and Materials Engineering Faculty Publications
In this work, we explore the thermal properties of hexagonal transition metal dichalcogenide compounds with different average atomic masses but equivalent microstructures. Thermal conductivity values of sputtered thin films were compared to bulk crystals. The comparison revealed a >10 fold reduction in thin film thermal conductivity. Structural analysis of the films revealed a turbostratic structure with domain sizes on the order of 5–10 nm. Estimates of phonon scattering lengths at domain boundaries based on computationally derived group velocities were consistent with the observed film microstructure, and accounted for the reduction in thermal conductivity compared to values for bulk crystals.
Tannic Acid Coated Gold Nanorods Demonstrate A Distinctive Form Of Endosomal Uptake And Unique Distribution Within Cells,
2013
Air Force Research Laboratory
Tannic Acid Coated Gold Nanorods Demonstrate A Distinctive Form Of Endosomal Uptake And Unique Distribution Within Cells, Emily A. Untener, Kristen K. Comfort, Elizabeth I. Maurer, Christin M. Grabinski, Donald A. Comfort, Saber M. Hussain
Chemical and Materials Engineering Faculty Publications
One of the primary challenges associated with nanoparticle-dependent biological applications is that endosomal entrapment in a physiological environment severely limits the desired targeting and functionality of the nanoconstructs. This study sought to overcome that challenge through a systematic approach of gold nanorod (GNR) functionalization: evaluating the influence of both aspect ratio and surface chemistry on targeted cellular internalization rates and preservation of particle integrity. Owing to their unique spectral properties and enhanced surface area, GNRs possess great potential for the advancement of nanobased delivery and imaging applications. However, their ability for efficient intracellular delivery while maintaining their specific physiochemical parameters …
Advances And Challenges Of Intermediate Temperature Solid Oxide Fuel Cells: A Concise Review,
2012
Fuels and Energy Technology Institute and Department of Chemical Engineering Curtin University, Perth, WA 6102, Australia;
Advances And Challenges Of Intermediate Temperature Solid Oxide Fuel Cells: A Concise Review, Sanping Jiang
Journal of Electrochemistry
Fuel cell is an electrochemical energy conversion device to directly convert the chemical energy of fuels to electricity. Among all types of fuel cells, solid oxide fuel cells (SOFCs) operating at intermediate temperatures of 600~800 oC offer an attractive option that is much more fuel flexible than low temperature fuel cells such as proton exchange membrane fuel cells, and is suitable for a wide range of applications. However, two main challenges remain towards the commercial viability and acceptance of the SOFC technologies: the cost and durability. Both are critically dependent on the process, fabrication, performance, chemical and microstructural stability …
Ternary Alloy Electrocatalysts For Oxygen Reduction Reaction,
2012
Department of Chemistry, State University of New York at Binghamton, Binghamton, New York 13902, USA;
Ternary Alloy Electrocatalysts For Oxygen Reduction Reaction, Jin Luo, Lefu Yang, Binghui Chen, Chuanjian Zhong
Journal of Electrochemistry
Proton exchange membrane fuel cell represents an important electrochemical energy conversion device with many attractive features in terms of efficiency of energy conversion and minimization of environmental pollution. However, the large overpotential for oxygen reduction reaction at the cathode and the low activity, poor durability and high cost of platinum-based catalysts in the fuel cells constitute a focal point of major barriers to the commercialization of fuel cells. The development of nanostructured catalysts shows promises to addresses some of the challenging problems. The ability to engineer the composition and nanostructure of nanoalloy catalysts is important for developing active, robust and …
Electrocatalytic Activity Of Palladium Nanocatalysts Supported On Carbon Nanoparticles In Formic Acid Oxidation,
2012
Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States;State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China;
Electrocatalytic Activity Of Palladium Nanocatalysts Supported On Carbon Nanoparticles In Formic Acid Oxidation, Jie Huang, Zhiyou Zhou, Yang Song, Xiongwu Kang, Ke Liu, Wancheng Zhou, Shaowei Chen
Journal of Electrochemistry
Palladium nanostructures were deposited onto carbon nanoparticle surface by a chemical reduction method. Transmission electron microscopic studies showed that whereas the resulting metal-carbon (Pd-CNP) nanocomposites exhibited a diameter of 20 to 30 nm, the metal components actually showed a cauliflower-like surface morphology that consisted of numerous smaller Pd nanoparticles (3 to 8 nm). Electrochemical studies showed that the effective surface area of the Pd-CNP nanoparticles was about 40% less than that of Pd black, possibly because the Pd nanoparticles were coated with a layer of carbon nanoparticles; yet, the Pd-CNP nanocomposites exhibited marked enhancement of the electrocatalytic activity in formic …
Electrocatalytic Oxidation Of Formic Acid On Pd/Ni Heterostructured Catalyst,
2012
Shanghai Advanced Research Institute, Chinese Academy of Sciences (CAS), Shanghai 201210, China;Graduate School of the CAS, Beijing 100039, China;
Electrocatalytic Oxidation Of Formic Acid On Pd/Ni Heterostructured Catalyst, Mingjun Ren, Liangliang Zou, Ju Chen, Ting Yuan, Qinghong Huang, Haifeng Zhang, Hui Yang, Songlin Feng
Journal of Electrochemistry
A Pd/Ni bimetallic nanostructured electrocatalyst was fabricated via a two-step reduction route. Owing to an epitaxial growth of Pd atoms on the surface of Ni nanoparticles, heterostructured Pd/Ni nanocomposites were formed and verified by high resolution transmission electron microscopy combined with energy-dispersion X-ray spectroscopy. X-ray diffraction confirmed that the as-prepared Pd/Ni nanocomposites possessed a single face-centered-cubic (fcc) Pd structure, probably due to a weaker diffraction intensity of metallic Ni and/or overlapping by that of Pd. The intrinsic catalytic activity on the Pd/Ni is higher than that on the Pd. Moreover, the durability of formic acid oxidation on the Pd/Ni was …
Adsorption And Electrooxidation Of Carbon Monoxide On Platinum Surfaces Modified With Sulfur,
2012
Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA;
Adsorption And Electrooxidation Of Carbon Monoxide On Platinum Surfaces Modified With Sulfur, A. Mattox Mathew, W. Henney Matthew, Johnson Adam, Zou Shouzhong
Journal of Electrochemistry
Adsorbed sulfur is commonly considered as a reaction poison. However, small amounts of sulfur on platinum significantly increase the surface reactivity toward carbon monoxide (CO) electrooxidation. For the solution CO oxidation, the onset potential was shifted up to over 300 mV negative to that on S-free surface, and the extent of the negative potential shift increases with the sulfur coverage (Xs) up to about 0.6. The enhanced CO oxidation also depends on the solution pH. For the adsorbed CO, at low sulfur coverages (Xs < 0.3), the oxidation peak potential is about 40 mV negative to that of the corresponding clean Pt. However, at higher coverages, the peak potential is about 30 mV more positive. Surface-enhanced Raman spectra show that the adsorption of sulfur significantly redshifts the Pt-CO stretching frequency. These observations are explained by the weakening of the Pt-CO bond and the hindrance of CO diffusion by Sads.
Kinetic Study Of Photoelectrochemical Oxidation Of Lignin Model Compounds On Tio2 Nanotubes,
2012
Department of Chemistry, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada;
Kinetic Study Of Photoelectrochemical Oxidation Of Lignin Model Compounds On Tio2 Nanotubes, Min Tian, Daniel Liba, Aicheng Chen
Journal of Electrochemistry
In this study, TiO2 nanotubes were prepared via the electrochemical oxidation of titanium substrates in a non-aqueous electrolyte and their morphology and microstructures were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photoelectrochemical oxidation of two lignin model compounds, 1-(3,4-dimethoxyphenoxy)-2-(2-methoxyphenoxy)-1,3-propanediol (DMP) and 3-hydroxy-1-(3,4-dimethoxyphenoxy)-2-(2-methoxyphenoxy)-1,3-propanone (HDM), was investigated. A new band appeared at ~304 nm during the photoelectrochemical oxidation of DMP. The rate of DMP intermediate formation was amplified with the increase of initial concentrations, while it was diminished with increased temperature. Despite the similarity in structure between HDM and DMP, there are only small increases in absorbance …
Electrochemical Performance Of Screen-Printed Composite Coatings Of Conducting Polymers And Carbon Nanotubes On Titanium Bipolar Plates In Aqueous Asymmetrical Supercapacitors,
2012
Department of Chemical and Environmental Engineering, and Energy and Sustainability Research Division, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK;
Electrochemical Performance Of Screen-Printed Composite Coatings Of Conducting Polymers And Carbon Nanotubes On Titanium Bipolar Plates In Aqueous Asymmetrical Supercapacitors, Xiaohang Zhou, George Z. Chen
Journal of Electrochemistry
Composites of conducting polymers (polypyrrole and polyaniline) with acid treated multi-walled carbon nanotubes were formulated into printable aqueous inks, with the aid of functional additives (benzethonium chloride as a surfactant with or without polyvinyl alcohol as a binder). The inks were screen-printed as fairly uniform coatings of various mass loading densities and areas (up to 75 mg cm-2 and 100 cm2) on thin titanium plates (0.1 mm in thickness). These screen-printed plates were used to fabricate both unit cell and multi-cell stack of asymmetrical supercapacitors with screen-printed negative electrodes of activated carbon (pigment black) in aqueous electrolytes …
Grain Size And Texture Effects On Deformation Behavior Of Az31 Magnesium Alloy,
2012
Missouri University of Science and Technology
Grain Size And Texture Effects On Deformation Behavior Of Az31 Magnesium Alloy, W. Yuan, R. S. Mishra
Materials Science and Engineering Faculty Research & Creative Works
Cold rolled AZ31 magnesium alloy sheet was subjected to friction stir processing to generate four average grain sizes ranging from 0.8 to 9.6 μm. the processed material exhibited a strong basal fiber texture with the c-axis tilted about 35-55° towards the processing direction. the grain size and texture dependence of mechanical behavior were evaluated by using tensile testing along two orthogonal directions. Remarkably high ductility of ~65% was achieved in relatively coarse-grained material that fractured without developing necking when tested in the processing direction. the ductility decreased significantly to ~10% for ultrafine grained material as the tensile yield strength increased …
High Performance Low Temperature Solid Oxide Fuel Cells With Novel Electrode Architecture,
2012
University of South Carolina - Columbia
High Performance Low Temperature Solid Oxide Fuel Cells With Novel Electrode Architecture, Yu Chen, Qian Liu, Zhibin Yang, Fanglin Chen, Minfang Han
Faculty Publications
In this study, we have fabricated high performance low temperature solid oxide fuel cells (LT-SOFCs) with both acicular anodes and cathodes with thin Gd-doped ceria (GDC) electrolyte film. The acicular Ni-Gd0.1Ce0.9O2−δ (Ni-GDC) anode was prepared using freeze drying tape casting, while the hierarchically porous cathode with nano-size Sm0.5Sr0.5CoO3 (SSC) particles covering an acicular GDC skeleton was prepared by a combination of freeze drying tape casting and self-rising approaches. The acicular electrodes with 5–200 μm pores/channels enhance mass transport, while SSC particles of about 50 nm in the cathode promote …
Epr And Endor Studies Of Point Defects In Lithium Tetraborate Crystals,
2012
Air Force Institute of Technology
Epr And Endor Studies Of Point Defects In Lithium Tetraborate Crystals, Douglas A. Buchanan
Theses and Dissertations
Lithium tetraborate (Li2B4O7 or LTB) is a promising material for both radiation dosimetry and neutron detection applications. LTB crystals can be grown pure or doped with different impurities including transition-metal and rare-earth ions. Research in this dissertation focuses on undoped LTB crystals and LTB crystals doped with copper and silver. Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to characterize point defects in the lithium tetraborate crystals. Thermoluminescence (TL), photoluminescence (PL), photoluminescence excitation (PLE), and optical absorption (OA) are also used. An intrinsic hole trap associated with lithium vacancies is characterized with …
Effects Of Crossflow Velocity And Transmembrane Pressure On Microfiltration Of Oil-In-Water Emulsions,
2012
Wright State University - Main Campus
Effects Of Crossflow Velocity And Transmembrane Pressure On Microfiltration Of Oil-In-Water Emulsions, Nikolai V. Priezjev, Tohid Darvishzadeh
Mechanical and Materials Engineering Faculty Publications
This study addresses the issue of oil removal from water using hydrophilic porous membranes. The effective separation of oil-in-water dispersions involves high flux of water through the membrane and, at the same time, high rejection rate of the oil phase. The effects of transmembrane pressure and crossflow velocity on rejection of oil droplets and thin oil films by pores of different cross-section are investigated numerically by solving the Navier-Stokes equation. We found that in the absence of crossflow, the critical transmembrane pressure, which is required for the oil droplet entry into a circular pore of a given surface hydrophilicity, agrees …
Recovery Of Metallic Materials From Printed Wiring Boards By Green Pyrolysis Process,
2012
Missouri University of Science and Technology
Recovery Of Metallic Materials From Printed Wiring Boards By Green Pyrolysis Process, Alex Luyima, Lifeng Zhang, Jaan Kers, Viktor Laurmaa
Materials Science and Engineering Faculty Research & Creative Works
Currently, the main options for the treatment of electronic waste are involved in reuse, remanufacturing, and recycling, as well as incineration and land filling. Recycling of e-waste can be broadly divided into three major steps: (a) disassembly: selectively disassembly, targeting on singling out hazardous or valuable components for special treatment, is an indispensable process in recycling of e-waste; (b) upgrading: using mechanical processing and/or metallurgical processing to up-grade desirable materials content, i. e. preparing materials for refining process; (c) refining: in the last step, recovered materials are retreated or purified by using chemical (metallurgical) processing so as to be acceptable …
Analysis Of Solid Oxide Fuel Cell-Gas-Turbine Hybrid System Technology For Use In Aircraft,
2012
Wright State University
Analysis Of Solid Oxide Fuel Cell-Gas-Turbine Hybrid System Technology For Use In Aircraft, Jeremy Milliner, Rory Roberts
Explorations – The Journal of Undergraduate Research, Scholarship and Creativity at Wright State
Solid oxide fuel-cell-gas-turbine (SOFC/GT) hybrid systems are a technology that provides a more efficient source of energy for a variety of uses. One potential use is to provide more efficient energy to aircraft, which is the subject of this work. Potential applications to aircraft and results from a computer model of a SOFC/GT are presented here.
Quantum Dot Deposition Into Pdms And Application Onto A Solar Cell,
2012
California Polytechnic State University, San Luis Obispo
Quantum Dot Deposition Into Pdms And Application Onto A Solar Cell, Christopher Marcus Botros, Richard N. Savage
Master's Theses
Research to increase the efficiency of conventional solar cells is constantly underway. The goal of this work is to increase the efficiency of conventional solar cells by incorporating quantum dot (QD) nanoparticles in the absorption mechanism. The strategy is to have the QDs absorb UV and fluoresce photons in the visible region that are more readily absorbed by the cells. The outcome is that the cells have more visible photons to absorb and have increased power output. The QDs, having a CdSe core and a ZnS shell, were applied to the solar cells as follows. First, the QDs were synthesized …
An Experimental Investigation On The Trailing Edge Cooling Of Turbine Blades,
2012
Wright State University - Main Campus
An Experimental Investigation On The Trailing Edge Cooling Of Turbine Blades, Zifeng Yang, Hui Hu
Mechanical and Materials Engineering Faculty Publications
An experimental study was conducted to quantify the flow characteristics of the wall jets pertinent to trailing edge cooling of turbine blades. A high-resolution stereoscopic particle image velocimetry (PIV) system was used to conduct detailed flow field measurements to quantitatively visualize the evolution of the unsteady vortices and turbulent flow structures in the cooling wall jet streams and to quantify the dynamic mixing process between the cooling jet stream and the mainstream flows. The detailed flow field measurements were correlated with the adiabatic cooling effectiveness maps measured by using pressure sensitive paint (PSP) technique to elucidate underlying physics in order …
