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Impact Of Chain Architecture On The Thickness Dependence Of Physical Aging Rate Of Thin Polystyrene Films, Gregory Brown, Elizabeth Lewis, Bryan D. Vogt 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, Levi Sandbulte 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 ...


Characterizing The Local Oxidation Nanolithography On Highly Oriented Pyrolytic Graphite, Zachary H. Swart, Alex J. Ulrich, Collin D. Wick, Adarsh D. Radadia 2019 Selected Works

Characterizing The Local Oxidation Nanolithography On Highly Oriented Pyrolytic Graphite, Zachary H. Swart, Alex J. Ulrich, Collin D. Wick, Adarsh D. Radadia

Adarsh D. Radadia

No abstract provided.


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 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

Halil Ceylan

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 ...


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 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 Arabzadeh

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 ...


Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen 2019 Iowa State University

Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen

Jonathan C. Claussen

Porous carbon is becoming an important and promising high-surface area scaffold material for various energy-based applications including catalysis. Here we demonstrate the growth of urchin-like platinum nanoparticles (PtNPs) on carbon monoliths derived from basswood that work as catalysts for micro underwater vehicle (MUV) propulsion via H2O2 decomposition. The carbon monoliths were constructed of natural basswood that was carbonized in argon (Ar) and subjected to a subsequent CO2 activation process that rendered the material into a hardened 3D porous activated carbonized wood (ACW) with inner channel voids measuring 10-70 μm in diameter. The PtNP nanourchins (500 nm or less in total ...


Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen 2019 Iowa State University

Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen

Shan Hu

Porous carbon is becoming an important and promising high-surface area scaffold material for various energy-based applications including catalysis. Here we demonstrate the growth of urchin-like platinum nanoparticles (PtNPs) on carbon monoliths derived from basswood that work as catalysts for micro underwater vehicle (MUV) propulsion via H2O2 decomposition. The carbon monoliths were constructed of natural basswood that was carbonized in argon (Ar) and subjected to a subsequent CO2 activation process that rendered the material into a hardened 3D porous activated carbonized wood (ACW) with inner channel voids measuring 10-70 μm in diameter. The PtNP nanourchins (500 nm or less in total ...


Revealing The Nature Of Antiferroquadrupolar Ordering In Cerium Hexaboride: Ceb6, C. K. Barman, Prashant Singh, Duane Johnson, Aftab Alam 2019 Indian Institute of Technology

Revealing The Nature Of Antiferroquadrupolar Ordering In Cerium Hexaboride: Ceb6, C. K. Barman, Prashant Singh, Duane Johnson, Aftab Alam

Duane D. Johnson

The cerium hexaboride (CeB6) f-electron compound displays a rich array of low-temperature magnetic phenomena, including a “magnetically hidden” order, identified as multipolar in origin via advanced x-ray scattering. From first-principles electronic-structure results, we find that the antiferroquadrupolar(AFQ) ordering in CeB6 arises from crystal-field splitting and yields a band structure in agreement with experiments. With interactions of p electrons between Ce and B6 being small, the electronic state of CeB6 is suitably described as Ce(4f1)3+(e−)(B6)2−. The AFQ state of orbital spins is caused by an exchange interaction induced through spin-orbit interaction, which also splits the ...


Dropwise Condensation On Multi-Scale Bioinspired Metallic Surfaces With Nano-Features, Daniel Orejon, Alexandros Askounis, Yasuyuki Takata, Daniel Attinger 2019 The University of Edinburgh and Kyushu University

Dropwise Condensation On Multi-Scale Bioinspired Metallic Surfaces With Nano-Features, Daniel Orejon, Alexandros Askounis, Yasuyuki Takata, Daniel Attinger

Daniel Attinger

Non-wetting surfaces engineered from intrinsically hydrophilic metallic materials are promising for self-cleaning, anti-icing and/or condensation heat transfer applications where the durability of the coating is an issue. In this work, we fabricate and study the wetting behaviour and the condensation performance on two metallic non-wetting surfaces with varying number and size of the roughness tiers without further hydrophobic coating procedure. On one hand, the surface resembling a rose petal exhibits a sticky non-wetting behaviour as drops wet the microscopic roughness features with the consequent enhanced drop adhesion, which leads to filmwise condensation. On the other hand, the surface resembling ...


Gd5si4-Pvdf Nanocomposite Films And Their Potential For Triboelectric Energy Harvesting Applications, S. M. Harstad, P. Zhao, N. Soin, A. A. El-Gendy, Shalabh Gupta, Vitalij K. Pecharsky, J. Luo, Ravi L. Hadimani 2019 Virginia Commonwealth University

Gd5si4-Pvdf Nanocomposite Films And Their Potential For Triboelectric Energy Harvesting Applications, S. M. Harstad, P. Zhao, N. Soin, A. A. El-Gendy, Shalabh Gupta, Vitalij K. Pecharsky, J. Luo, Ravi L. Hadimani

Ravi L. Hadimani

The triboelectric energy generators prepared using the combination of self-polarized, high beta-phase nanocomposite films of Gd5Si4-PVDF and polyamide-6 (PA-6) films have generated significantly higher voltage of 425 V, short-circuit current density of 30 mA/m(2) and a charge density of similar to 116.7 C/m(2) as compared to corresponding values of 300 V, 30 mA/m(2) and 94.7 mu C/m(2), respectively for the pristine PVDF-(PA-6) combination. The magnetic measurements of the Gd5Si4-PVDF films display a ferromagnetic behavior as compared to diamagnetic nature of pristine PVDF. The presence of magnetic nanoparticles in the ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans 2019 Iowa State University and Ames Laboratory

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

James W. Evans

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans 2019 Iowa State University and Ames Laboratory

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

Wenyu Huang

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans 2019 Iowa State University and Ames Laboratory

Reshaping, Intermixing, And Coarsening For Metallic Nanocrystals: Nonequilibrium Statistical Mechanical And Coarse-Grained Modeling, King C. Lai, Yong Han, Peter M. Spurgeon, Wenyu Huang, Patricia A. Thiel, Da-Jiang Liu, James W. Evans

Patricia A. Thiel

Self-assembly of supported 2D or 3D nanocrystals (NCs) by vacuum deposition and of 3D NCs by solution-phase synthesis (with possible subsequent transfer to a support) produces intrinsically nonequilibrium systems. Individual NCs can have far-from-equilibrium shapes and composition profiles. The free energy of NC ensembles is lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening are key, e.g., for avoiding catalyst degradation. This review focuses on postsynthesis evolution of metallic NCs. Atomistic-level modeling typically utilizes stochastic lattice-gas models to access appropriate time and length scales ...


Mechanisms Of Enhanced Thermal Stability Of Polarization In Lead-Free (Bi 1/2na 1/2) 0.94ba 0.06tio 3/Zno Ceramic Composites, Zhongming Fan, Lin Zhou, Tae-Hoon Kim, Ji Zhang, Shan-Tao Zhang, Xiaoli Tan 2019 Iowa State University

Mechanisms Of Enhanced Thermal Stability Of Polarization In Lead-Free (Bi 1/2na 1/2) 0.94ba 0.06tio 3/Zno Ceramic Composites, Zhongming Fan, Lin Zhou, Tae-Hoon Kim, Ji Zhang, Shan-Tao Zhang, Xiaoli Tan

Xiaoli Tan

(Bi 1/2Na 1/2)TiO 3-based solid solutions, one of the major systems of lead-free piezoelectric ceramics, exhibit a low thermal depolarization temperature ( T d~100°C). It was reported that by incorporating 30 mol% ZnO particles to form a ceramic composite of (Bi 1/2Na 1/2) 0.94Ba 0.06TiO 3/ZnO, the depolarization process can be shifted up to ~250 °C. In the present work, a variety of advanced transmission electron microscopy techniques, including in situ heating, annular bright-field, high-angle annular dark-field, geometric phase analysis, energy-dispersive spectrum and electron energy-loss spectroscopy, are employed to investigate the ...


Structure And High Performance Of Lead-Free (K0.5na0.5)Nbo3 Piezoelectric Nanofibers With Surface-Induced Crystallization At Lowered Temperature, Yasmin Mohamed Yousry, Kui Tao, Xiaoli Tan, Ayman Mahmoud Mohamed, Yumei Wang, Shuting Chen, Seeram Ramakrishna 2019 Institute of Materials Research and Engineering and National University of Singapore

Structure And High Performance Of Lead-Free (K0.5na0.5)Nbo3 Piezoelectric Nanofibers With Surface-Induced Crystallization At Lowered Temperature, Yasmin Mohamed Yousry, Kui Tao, Xiaoli Tan, Ayman Mahmoud Mohamed, Yumei Wang, Shuting Chen, Seeram Ramakrishna

Xiaoli Tan

Lead-free potassium and sodium niobate (KNN) nanofiber webs with random and aligned configurations were prepared by electrospinning process from polymer-modified chemical solution. The crystallization process, structure, composition, dielectric, ferroelectric and piezoelectric properties of the nanofibers and nanofiber webs were investigated. Theoretical analysis and experimental results showed that the surface-induced heterogeneous nucleation resulted in the remarkable lower crystallization temperature for the KNN nanofibers with {100} orientation of the perovskite phase in contrast to the bulk KNN gel, and thus well-controlled chemical stoichiometry. Low dielectric loss, large electric polarization, and high piezoelectric performance were obtained in the nanofiber webs. In particular, the ...


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 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

Civil, Construction and Environmental Engineering Publications

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 ...


Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen 2019 Iowa State University

Porous Wood Monoliths Decorated With Platinum Nano-Urchins As Catalysts For Underwater Micro-Vehicle Propulsion Via H2o2 Decomposition, Bolin Chen, Ahmed Gsalla, Anand Gaur, Yu Hui Lui, Xiaohui Tang, Jason Geder, Marius Pruessner, Brian J. Melde, Igor L. Medintz, Behrouz Shafei, Shan Hu, Jonathan C. Claussen

Mechanical Engineering Publications

Porous carbon is becoming an important and promising high-surface area scaffold material for various energy-based applications including catalysis. Here we demonstrate the growth of urchin-like platinum nanoparticles (PtNPs) on carbon monoliths derived from basswood that work as catalysts for micro underwater vehicle (MUV) propulsion via H2O2 decomposition. The carbon monoliths were constructed of natural basswood that was carbonized in argon (Ar) and subjected to a subsequent CO2 activation process that rendered the material into a hardened 3D porous activated carbonized wood (ACW) with inner channel voids measuring 10-70 μm in diameter. The PtNP nanourchins (500 nm or less in total ...


Permeability Of Oxygen And Carbon Dioxide Through Pinholes In Barrier Coatings, Petri Johansson, Johanna Lahti, Jorma Vihinen, Jurkka Kuusipalo 2019 Tampere University

Permeability Of Oxygen And Carbon Dioxide Through Pinholes In Barrier Coatings, Petri Johansson, Johanna Lahti, Jorma Vihinen, Jurkka Kuusipalo

Journal of Applied Packaging Research

Abstract

Packaging materials are typically made of multilayer structures combining polymers, metals and inorganic materials. Multilayer structures are selected in order to optimize the thickness and performance in packaging applications. Atomic layer deposited (ALD) aluminium oxide (Al2O3) layer provides good barrier properties against oxygen and carbon dioxide gases i.e. permeation of gases through ALD coated polymer films will reduce remarkably. The target was to study the effect of pinholes on the oxygen and carbon dioxide permeability of ALD coated extrusion-coated packaging paper. Pinholes were artificially generated by ultra violet (UV) laser drilling through the polymer layer ...


Dropwise Condensation On Multi-Scale Bioinspired Metallic Surfaces With Nano-Features, Daniel Orejon, Alexandros Askounis, Yasuyuki Takata, Daniel Attinger 2019 The University of Edinburgh and Kyushu University

Dropwise Condensation On Multi-Scale Bioinspired Metallic Surfaces With Nano-Features, Daniel Orejon, Alexandros Askounis, Yasuyuki Takata, Daniel Attinger

Mechanical Engineering Publications

Non-wetting surfaces engineered from intrinsically hydrophilic metallic materials are promising for self-cleaning, anti-icing and/or condensation heat transfer applications where the durability of the coating is an issue. In this work, we fabricate and study the wetting behaviour and the condensation performance on two metallic non-wetting surfaces with varying number and size of the roughness tiers without further hydrophobic coating procedure. On one hand, the surface resembling a rose petal exhibits a sticky non-wetting behaviour as drops wet the microscopic roughness features with the consequent enhanced drop adhesion, which leads to filmwise condensation. On the other hand, the surface resembling ...


Investigation Of Nondestructive Testing Methods For Friction Stir Welding, Hossein Taheri, Margaret Kilpatrick, Matthew Norvalls, Warren Harper, Lucas Koester, Timothy Bigelow, Leonard J. Bond 2019 Georgia Southern University

Investigation Of Nondestructive Testing Methods For Friction Stir Welding, Hossein Taheri, Margaret Kilpatrick, Matthew Norvalls, Warren Harper, Lucas Koester, Timothy Bigelow, Leonard J. Bond

Timothy A. Bigelow

Friction stir welding is a method of materials processing that enables the joining of similar and dissimilar materials. The process, as originally designed by The Welding Institute (TWI), provides a unique approach to manufacturing—where materials can be joined in many designs and still retain mechanical properties that are similar to, or greater than, other forms of welding. This process is not free of defects that can alter, limit, and occasionally render the resulting weld unusable. Most common amongst these defects are kissing bonds, wormholes and cracks that are often hidden from visual inspection. To identify these defects, various nondestructive ...


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