Iowa State College
Austrak Pty Ltd
Rose-Hulman Institute of Technology
Montana Tech Library
University of Kentucky
University of Tennessee - Knoxville
Embry-Riddle Aeronautical University - Daytona Beach
Impact Of Chain Architecture On The Thickness Dependence Of Physical Aging Rate Of Thin Polystyrene Films,
2020
University of Akron
Impact Of Chain Architecture On The Thickness Dependence Of Physical Aging Rate Of Thin Polystyrene Films, Gregory Brown, Elizabeth Lewis, Bryan D. Vogt
Williams Honors College, Honors Research Projects
The dynamics of polymer thin films have been demonstrated to be significantly altered from the bulk, but the origins of such differences are not well defined. In this work, we seek to understand the differences in the structural dynamics (or physical aging) of polystyrene (PS) through branching and other well defined architectures (comb and centipede). The aging dynamics of ultrathin films (< 30 nm) differ from relatively thick films (100-150nm) with linear PS thin films aging more rapidly than the relatively “bulk-like” thick films. Ellipsometric measurements are used to characterize the physical aging rate of the films. The change in film thickness and refractive index as the films are held below the glass transition temperature (Tg) provides a simple measure of the physical aging. In this study, four different architectures (linear, comb, 4 arm star, and centipede) will be investigated. For each PS architecture, the aging rate will be determined for film thickness ranging ...
Mandela Splash Pad Pre-Construction Plan,
2019
University of Nebraska at Omaha
Mandela Splash Pad Pre-Construction Plan, Levi Sandbulte
Theses/Capstones/Creative Projects
In the construction industry, it is the responsibility of the general contractor to take the architect’s ideas and turn it into a real building. Many times this requires ample communication and several drafts. This efficient execution of this process is vital to the completion of a successful project. In this project, I practice this communication process. The challenge presented by the owner is to build an affordable splash pad, and without impacting the construction schedule of the Early Childhood Development Center (ECDC) that is being built on the same property at the same time. This proposal gives the owner ...
A Parametric Study For In-Pile Use Of The Thermal Conductivity Needle Probe Using A Transient, Multilayered Analytical Model,
2019
University of Idaho
A Parametric Study For In-Pile Use Of The Thermal Conductivity Needle Probe Using A Transient, Multilayered Analytical Model, Courtney Hollar, Austin Fleming, Kurt Davis, Ralph Budwig, Colby Jensen, David Estrada
Materials Science and Engineering Faculty Publications and Presentations
By utilizing an in-pile measurement, thermal conductivity can be determined under prototypic conditions over a range of burnup. In this work we develop a multilayer quadrupoles analytical model to describe the transient thermal interactions between a line heat source (i.e. needle probe) and cylindrical nuclear fuel geometry for inpile thermal conductivity measurements. A finite element analysis of the detailed needle probe geometry was compared to results from the analytical model to verify the assumptions made in the analytical model. Experimentally, the needle probe was used to measure the thermal properties of polytetrafluoroethylene (PTFE) and stainless steel 304 with three ...
Uncompensated Polarization In Incommensurate Modulations Of Perovskite Antiferroelectrics,
2019
Ames Laboratory
Uncompensated Polarization In Incommensurate Modulations Of Perovskite Antiferroelectrics, Tao Ma, Zhongming Fan, Bin Xu, Tae-Hoon Kim, Ping Lu, Laurent Bellaiche, Matthew J. Kramer, Xiaoli Tan, Lin Zhou
Xiaoli Tan
Complex polar structures of incommensurate modulations (ICMs) are revealed in chemically modified PbZrO3 perovskite antiferroelectrics using advanced transmission electron microscopy techniques. The Pb-cation displacements, previously assumed to arrange in a fully-compensated antiparallel fashion, are found to be either antiparallel but with different magnitudes, or in a nearly orthogonal arrangement in adjacent stripes in the ICMs. Ab initio calculations corroborate the low-energy state of these arrangements. Our discovery corrects the atomic understanding of ICMs in PbZrO3-based perovskite antiferroelectrics.
Influence Of Naoh Concentration On Transfer Process Of Graphene,
2019
Singh Center for Nanotechnology
Influence Of Naoh Concentration On Transfer Process Of Graphene, Francisco Saldana, Chengyu Wen, George Patrick Watson
Protocols and Reports
The process of transferring a monolayer of graphene using two different concentrations of sodium hydroxide (NaOH) solution unto a silicon dioxide (SiO2) coated Si chip using electrochemistry was performed. The transfer process is crucial for the delamination of a continuous graphene monolayer film from copper foil. After examining and inspecting the integrity of the graphene monolayer, it was observed that the lower concentration to NaOH led to slower rate of hydrogen bubble generation; this condition was found to be less destructive and yielded a graphene film with fewer visible tears.
Photodegradation Modeling Based On Laboratory Accelerated Test Data And Predictions Under Outdoor Weathering For Polymeric Materials,
2019
Virginia Tech
Photodegradation Modeling Based On Laboratory Accelerated Test Data And Predictions Under Outdoor Weathering For Polymeric Materials, Yuanyuan Duan, Yili Hong, William Q. Meeker, Deborah L. Stanley, Xiaohong Gu
William Q Meeker
Photodegradation, driven primarily by ultraviolet (UV) radiation, is the primary cause of failure for organic paints and coatings, as well as many other products made from polymeric materials exposed to sunlight. Traditional methods of service life prediction involve the use of outdoor exposure in harsh UV environments (e.g., Florida and Arizona). Such tests, however, require too much time (generally many years) to do an evaluation. To overcome the shortcomings of traditional methods, scientists at the U.S. National Institute of Standards and Technology (NIST) conducted a multiyear research program to collect necessary data via scientifically-based laboratory accelerated tests. This ...
Application Of Active And Edible Films Of Sodium Caseinate To Extend The Shelf-Life Of Argentine Pategrás Cheese,
2019
Investigation Center of Social Bees (CIAS), Exacts and Natural Sciences Faculty, Mar del Plata National University, Dean Funes 3350, 7600 Mar del Plata, Buenos Aires, Argentina. National Council of Scientific and Technical Research (CONICET), Moreno 3527 3er.piso - Mar del Plata, Buenos Aires, Argentina.
Application Of Active And Edible Films Of Sodium Caseinate To Extend The Shelf-Life Of Argentine Pategrás Cheese, Brenda S. Álvarez, Natalia Damiani, Marina Czerner, Josefa F. Martucci, Liesel B. Gende
Journal of Applied Packaging Research
Argentine Pategrás cheese is one of the most popular types of cheese in Argentina. The main spoilage causes in these products are microbiological contamination and lipid rancidity. Semi-hard cheeses are usually covered with a paraffin wax that favors its preservation. When pieces are stored, cutting faces must be protected to prevent desiccation and contamination. Active biodegradable films are an alternative to the traditional materials, in particular, casein-based edible films are attractive for food applications. In the present work, active films of sodium caseinate with oregano (Origanum vulgare) and laurel (Laurus nobilis) essential oils were produced for packaging a processed Pategrás ...
Design, Construction, And Preliminary Investigations Of Otta Seal In Iowa,
2019
Iowa State University
Design, Construction, And Preliminary Investigations Of Otta Seal In Iowa, Sharif Y. Gushgari, Yang Zhang, Ali Nahvi, Halil Ceylan, Sunghwan Kim, Ali Arabzadeh, Charles T. Jahren, Charles Øverby
Ali Nahvi
Faced with limited financial resources, pavement engineers constantly seek more durable and economical technologies for road preservations and rehabilitations. Consequently, there have been many efforts to study resurfacing strategies, including various types of sealing for local roads. Among different sealing methodologies, Otta seal is a technique that has not yet been sufficiently studied in the U.S.A. For this investigation, the first Otta seal site in the state of Iowa was constructed using a double-layer Otta seal design over 6.4 km of cracked asphalt pavement. Otta seal design and construction details are documented and discussed, and test sections ...
Polyurethane-Carbon Microfiber Composite Coating For Electrical Heating Of Concrete Pavement Surfaces,
2019
Iowa State University
Polyurethane-Carbon Microfiber Composite Coating For Electrical Heating Of Concrete Pavement Surfaces, Alireza Sassani, Ali Arabzadeh, Halil Ceylan, Sunghwan Kim, Kasthurirangan Gopalakrishnan, Peter C. Taylor, Ali Nahvi
Ali Nahvi
Electrically-heated pavements have attracted attention as alternatives to the traditional ice/snow removal practices. Electrically conductive polymer-carbon composite coatings provide promising properties for this application. Based on the concept of joule heating, the conductive composite can be utilized as a resistor that generates heat by electric current and increases the surface temperature to melt the ice and snow on the pavement surface. This research investigates the feasibility of applying an electrically conductive composite coating made with a Polyurethane (PU) binder and micrometer-scale carbon fiber (CMF) filler as the electrical heating materials on the surface of Portland cement concrete (PCC) pavements ...
Polyurethane-Carbon Microfiber Composite Coating For Electrical Heating Of Concrete Pavement Surfaces,
2019
Iowa State University
Polyurethane-Carbon Microfiber Composite Coating For Electrical Heating Of Concrete Pavement Surfaces, Alireza Sassani, Ali Arabzadeh, Halil Ceylan, Sunghwan Kim, Kasthurirangan Gopalakrishnan, Peter C. Taylor, Ali Nahvi
Alireza Sassani
Electrically-heated pavements have attracted attention as alternatives to the traditional ice/snow removal practices. Electrically conductive polymer-carbon composite coatings provide promising properties for this application. Based on the concept of joule heating, the conductive composite can be utilized as a resistor that generates heat by electric current and increases the surface temperature to melt the ice and snow on the pavement surface. This research investigates the feasibility of applying an electrically conductive composite coating made with a Polyurethane (PU) binder and micrometer-scale carbon fiber (CMF) filler as the electrical heating materials on the surface of Portland cement concrete (PCC) pavements ...
Polyurethane-Carbon Microfiber Composite Coating For Electrical Heating Of Concrete Pavement Surfaces,
2019
Iowa State University
Polyurethane-Carbon Microfiber Composite Coating For Electrical Heating Of Concrete Pavement Surfaces, Alireza Sassani, Ali Arabzadeh, Halil Ceylan, Sunghwan Kim, Kasthurirangan Gopalakrishnan, Peter C. Taylor, Ali Nahvi
Ali Arabzadeh
Electrically-heated pavements have attracted attention as alternatives to the traditional ice/snow removal practices. Electrically conductive polymer-carbon composite coatings provide promising properties for this application. Based on the concept of joule heating, the conductive composite can be utilized as a resistor that generates heat by electric current and increases the surface temperature to melt the ice and snow on the pavement surface. This research investigates the feasibility of applying an electrically conductive composite coating made with a Polyurethane (PU) binder and micrometer-scale carbon fiber (CMF) filler as the electrical heating materials on the surface of Portland cement concrete (PCC) pavements ...
Polyurethane-Carbon Microfiber Composite Coating For Electrical Heating Of Concrete Pavement Surfaces,
2019
Iowa State University
Polyurethane-Carbon Microfiber Composite Coating For Electrical Heating Of Concrete Pavement Surfaces, Alireza Sassani, Ali Arabzadeh, Halil Ceylan, Sunghwan Kim, Kasthurirangan Gopalakrishnan, Peter C. Taylor, Ali Nahvi
Halil Ceylan
Electrically-heated pavements have attracted attention as alternatives to the traditional ice/snow removal practices. Electrically conductive polymer-carbon composite coatings provide promising properties for this application. Based on the concept of joule heating, the conductive composite can be utilized as a resistor that generates heat by electric current and increases the surface temperature to melt the ice and snow on the pavement surface. This research investigates the feasibility of applying an electrically conductive composite coating made with a Polyurethane (PU) binder and micrometer-scale carbon fiber (CMF) filler as the electrical heating materials on the surface of Portland cement concrete (PCC) pavements ...
Fatigue-Resistant High-Performance Elastocaloric Materials Via Additive Manufacturing,
2019
University of Maryland at College Park
Fatigue-Resistant High-Performance Elastocaloric Materials Via Additive Manufacturing, Huilong Hou, Emrah Simsek, Tao Ma, Nathan S. Johnson, Suxin Qian, Cheikh Cissé, Drew Stasak, Naila Al Hasan, Lin Zhou, Yunho Hwang, Reinhard Radermacher, Valery I. Levitas, Matthew J. Kramer, Mohsen Asle Zaeem, Aaron P. Stebner, Ryan T. Ott, Jun Cui, Ichiro Takeuchi
Valery I. Levitas
Elastocaloric cooling, which exploits the latent heat released and absorbed as stress-induced phase transformations are reversibly cycled in shape memory alloys, has recently emerged as a frontrunner in non-vapor-compression cooling technologies. The intrinsically high thermodynamic efficiency of elastocaloric materials is limited only by work hysteresis. Here, we report on creating high-performance low-hysteresis elastocaloric cooling materials via additive manufacturing of Titanium-Nickel (Ti-Ni) alloys. Contrary to established knowledge of the physical metallurgy of Ti-Ni alloys, intermetallic phases are found to be beneficial to elastocaloric performances when they are combined with the binary Ti-Ni compound in nanocomposite configurations. The resulting microstructure gives rise ...
Exploring The Role Of Electronic Structure On Photo-Catalytic Behavior Of Carbon-Nitride (C3n4) Polymorphs,
2019
University of Calcutta and Lady Brabourne College
Exploring The Role Of Electronic Structure On Photo-Catalytic Behavior Of Carbon-Nitride (C3n4) Polymorphs, Sujoy Datta, Prashant Singh, Debnarayan Jana, Chhanda B. Chaudhuri, Manoj K. Harbola, Duane D. Johnson, Abhijit Mookerjee
Duane D. Johnson
We provide a comprehensive account of structural, electronic, and optical properties of carbon-nitride (C3N4) polymorphs. We employ density-functional theory with two different basis sets for better predictions of structural and electronic band-gap properties: (a) a localized tight-binding basis with an improved semi-empirical exchange functional for more rapid and robust predictions; and (b) a plane-wave basis using a hybrid functional for validation. The predicted lattice constants, bulk moduli, and band gaps are in good agreement with existing experiments and theory, which verifies our predictions are reliable and basis-set independent. The optimal band gap, HOMO-LUMO position, and optical properties show the suitability ...
Nanogaps On Atomically Thin Materials As Non-Volatile Read/Writable Memory Devices,
2019
University of Kentucky
Nanogaps On Atomically Thin Materials As Non-Volatile Read/Writable Memory Devices, Douglas Robert Strachan, Abhishek Sundararajan, Mathias Joseph Boland
Physics and Astronomy Faculty Patents
The present invention relates to the presence of nanogaps across a metal dispersed over an atomically-thin material, such that the nanogap exposes the atomically-thin material. The resulting device offers an ultra-short gap with ballistic transport and demonstrated switching in the presence of a gate or dielectric material in close proximity to the channel.
Composition-Dependent Stability Of The Medium-Range Order Responsible For Metallic Glass Formation,
2019
Iowa State University and Ames Laboratory
Composition-Dependent Stability Of The Medium-Range Order Responsible For Metallic Glass Formation, Feng Zhang, Min Ji, Xiao-Wei Fang, Yang Sun, Cai-Zhuang Wang, Mikhail I. Mendelev, Matthew J. Kramer, Ralph E. Napolitano, Kai-Ming Ho
Ralph E. Napolitano
The competition between the characteristic medium-range order corresponding to amorphous alloys and that in ordered crystalline phases is central to phase selection and morphology evolution under various processing conditions. We examine the stability of a model glass system, Cu–Zr, by comparing the energetics of various medium-range structural motifs over a wide range of compositions using first-principles calculations. We focus specifically on motifs that represent possible building blocks for competing glassy and crystalline phases, and we employ a genetic algorithm to efficiently identify the energetically favored decorations of each motif for specific compositions. Our results show that a Bergman-type motif ...
Phase Stability For The Pd-Si System: First-Principles, Experiments, And Solution-Based Modeling,
2019
Ames Laboratory
Phase Stability For The Pd-Si System: First-Principles, Experiments, And Solution-Based Modeling, S. H. Zhou, Y. Huo, Ralph E. Napolitano
Ralph E. Napolitano
The relative stabilities of the compounds in the binary Pd-Si system were assessed using first-principles calculations and experimental methods. Calculations of lattice parameters and enthalpy of formation indicate that Pd5Si-μPd5Si-μ, Pd9Si2-αPd9Si2-α, Pd3Si-βPd3Si-β, Pd2Si-γPd2Si-γ, and PdSi-δPdSi-δ are the stable phases at 0 K (–273 °C). X-ray diffraction analyses (XRD) and electron probe microanalysis (EPMA) of the as-solidified and heat-treated samples support the computational findings, except that the PdSi-δPdSi-δ phase was not observed at low temperature. Considering both experimental data and first-principles results, the compounds Pd5Si-μPd5Si-μ, Pd9Si2-αPd9Si2-α, Pd3Si-βPd3Si-β, and Pd2Si-γPd2Si-γ are treated as stable phases down to 0 K (−273 °C), while ...
A Computational Study Of Diffusion In A Glass-Forming Metallic Liquid,
2019
Ames Laboratory
A Computational Study Of Diffusion In A Glass-Forming Metallic Liquid, T. Wang, F. Zhang, L. Yang, X. W. Fang, S. H. Zhou, Matthew J. Kramer, Cai-Zhuang Wang, Kai-Ming Ho, Ralph E. Napolitano
Ralph E. Napolitano
Liquid phase diffusion plays a critical role in phase transformations (e.g. glass transformation and devitrification) observed in marginal glass forming systems such as Al-Sm. Controlling transformation pathways in such cases requires a comprehensive description of diffusivity, including the associated composition and temperature dependencies. In the computational study reported here, we examine atomic diffusion in Al-Sm liquids using ab initio molecular dynamics (AIMD) and determine the diffusivities of Al and Sm for selected alloy compositions. Non-Arrhenius diffusion behavior is observed in the undercooled liquids with an enhanced local structural ordering. Through assessment of our AIMD result, we construct a general ...
Enthalpy Of Mixing In Al–Tb Liquid,
2019
Ames Laboratory
Enthalpy Of Mixing In Al–Tb Liquid, Shihuai Zhou, Carl Tackes, Ralph Napolitano
Ralph E. Napolitano
The liquid-phase enthalpy of mixing for Al–Tb alloys is measured for 3, 5, 8, 10, and 20 at% Tb at selected temperatures in the range from 1364 to 1439 K. Methods include isothermal solution calorimetry and isoperibolic electromagnetic levitation drop calorimetry. Mixing enthalpy is determined relative to the unmixed pure (Al and Tb) components. The required formation enthalpy for the Al3Tb phase is computed from first-principles calculations. Based on our measurements, three different semi-empirical solution models are offered for the excess free energy of the liquid, including regular, subregular, and associate model formulations. These models are also ...
Detonation Synthesis Of Alpha-Variant Silicon Carbide,
2019
Missouri University of Science and Technology
Detonation Synthesis Of Alpha-Variant Silicon Carbide, Martin Langenderfer, Catherine E. Johnson, William Fahrenholtz, Vadym Mochalin
William Fahrenholtz
A recent research study has been undertaken to develop facilities for conducting detonation synthesis of nanomaterials. This process involves a familiar technique that has been utilized for the industrial synthesis of nanodiamonds. Developments through this study have allowed for experimentation with the concept of modifying explosive compositions to induce synthesis of new nanomaterials. Initial experimentation has been conducted with the end goal being synthesis of alpha variant silicon carbide (α-SiC) in the nano-scale. The α-SiC that can be produced through detonation synthesis methods is critical to the ceramics industry because of a number of unique properties of the material. Conventional ...
