Iowa State College
California Polytechnic State University, San Luis Obispo
University of South Florida
University of Nebraska at Lincoln
Quattrone Nanofabrication Facility
The University of Western Ontario
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 ...
The Influence Of Asphalt Ageing On Induction Healing Effect On Porous Asphalt Concrete,
2019
Delft University of Technology
The Influence Of Asphalt Ageing On Induction Healing Effect On Porous Asphalt Concrete, Shi Xu, Xueyan Liu, Amir Tabakovic, Erik Schlangen
Articles
Induction healing is a proven technology which is able to improve the self‐healing capacity of asphalt concrete. Healing is achieved via electromagnetic current produced by passing induction machine, where steel asphalt constituents heat up which in turn soften the bitumen in the asphalt layer, allowing it to flow and close cracks, repairing the damage. This paper reports on the study which investigated the influence of ageing on the healing capacity of Porous Asphalt (PA) concrete. Porous Asphalt concrete mix was prepared first, then subjected to an accelerated (laboratory) ageing process using a ventilated oven. In order to further evaluate ...
Ice-Binding Protein From Shewanella Frigidimarinas Inhibits Ice Crystal Growth In Highly Alkaline Solutions,
2019
University of Colorado at Boulder
Ice-Binding Protein From Shewanella Frigidimarinas Inhibits Ice Crystal Growth In Highly Alkaline Solutions, Elizabeth Delesky, Shane D. Frazier, Jaqueline D. Wallat, Kendra L. Bannister, Chelsea Marie Heveran, Wil V. Srubar Iii
University Libraries Open Access Fund Supported Publications
The ability of a natural ice-binding protein from Shewanella frigidimarina (SfIBP) to inhibit ice crystal growth in highly alkaline solutions with increasing pH and ionic strength was investigated in this work. The purity of isolated SfIBP was first confirmed via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and size-exclusion chromatography with an ultraviolet detector (SEC-UV). Protein stability was evaluated in the alkaline solutions using circular dichroism spectroscopy, SEC-UV, and SDS-PAGE. SfIBP ice recrystallization inhibition (IRI) activity, a measure of ice crystal growth inhibition, was assessed using a modified splat assay. Statistical analysis of results substantiated that, despite partial denaturation and ...
Sure Abstract - Spring 2019: Biomimetic Metamaterial Scales Enhancing Thermal Coatings’ Mechanical Properties For Turbine Blades,
2019
University of Central Florida
Sure Abstract - Spring 2019: Biomimetic Metamaterial Scales Enhancing Thermal Coatings’ Mechanical Properties For Turbine Blades, Ryan Horton
Ryan Horton
No abstract provided.
The Effects Of Silica On The Properties Of Vitreous Enamels,
2019
Missouri University of Science and Technology
The Effects Of Silica On The Properties Of Vitreous Enamels, Signo Tadeu Dos Reis, Mike Koenigstein, Liang Fan, Genda Chen, Luka Pavic, Andrea Mogus-Milankovic
Genda Chen
Ground coat enamels for low carbon steel that contain silica as a mill addition have been developed to study the changes of their properties. Acid-resistant commercial enamel where silica addition was varied from 0 to 10.0 wt % was used for this investigation. The effects of the addition on the corrosion resistance, thermal properties, electrical properties, and mechanical adherence of the enamel to low carbon steel were studied. The corrosion resistance of the steel enameled coupons was tested using a salt spray (fog) apparatus for time periods reaching 168 h at room temperature. It was found that, although the density ...
Slip Of Shuffle Screw Dislocations Through Tilt Grain Boundaries In Silicon,
2019
Iowa State University
Slip Of Shuffle Screw Dislocations Through Tilt Grain Boundaries In Silicon, Hao Chen, Valery Levitas, Liming Xiong
Aerospace Engineering Publications
In this paper, molecular dynamics (MD) simulations of the interaction between tilt grain boundaries (GBs) and a shuffle screw dislocation in silicon are performed. Results show that dislocations transmit into the neighboring grain for all GBs in silicon. For Σ3, Σ9 and Σ19 GBs, when a dislocation interacts with a heptagon site, it transmits the GB directly. In contrast, when interacting with a pentagon site, it first cross slips to a plane on the heptagon site and then transmits the GB. The energy barrier is also quantified using the climbing image nudged elastic band (CINEB) method. Results show that Σ3 ...
Optimization Of The Calcium Alginate Capsules For Self-Healing Asphalt,
2019
Delft University of Technology
Optimization Of The Calcium Alginate Capsules For Self-Healing Asphalt, Shi Xu, Amir Tabakovic, Xueyan Liu, Damian Palin, Erik Schlangen
Articles
Featured Application: This self-healing technology for asphalt pavements has the potential to greatly disrupt asphalt production methods (which have been stable over the past 100 years).This paper presents a development process of ‘calcium-alginate microcapsules encapsulating an asphalt bitumen rejuvenator’. The encapsulated rejuvenator is released when required (on demand) which rejuvenates the aged binder. Once crack is initiated and starts propagating it encounters a microcapsule, energy at tip of the crack opens the microcapsule, releasing the rejuvenator (healing agent). The rejuvenator will infuse into the aged binder soften it, allowing to flow, two broken edges to get into a contact ...
On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys,
2019
Iowa State University
On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys, Michael Y. Mendoza, Peyman Samimi, David A. Brice, Iman Ghamarian, Matt Rolchigo, Richard Lesar, Peter Collins
Materials Science and Engineering Publications
Laser Engineered Net Shaping (LENS™) was used to produce a compositionally graded Ti-xMo (0 ≤ x ≤ 12 wt %) specimen and nine Ti-15Mo (fixed composition) specimens at different energy densities to understand the composition–processing–microstructure relationships operating using additive manufacturing. The gradient was used to evaluate the effect of composition on the prior-beta grain size. The specimens deposited using different energy densities were used to assess the processing parameters influence the microstructure evolutions. The gradient specimen did not show beta grain size reduction with the Mo content. The analysis from the perspective of the two grain refinement mechanisms based on a ...
3d Bioprinting Of Stem Cells And Polymer/Bioactive Glass Composite Scaffolds For Bone Tissue Engineering,
2019
Missouri University of Science and Technology
3d Bioprinting Of Stem Cells And Polymer/Bioactive Glass Composite Scaffolds For Bone Tissue Engineering, Caroline Murphy, Krishna Kolan, Wenbin Li, Julie A. Semon, D. E. Day, Ming-Chuan Leu
Ming C. Leu
A major limitation of using synthetic scaffolds in tissue engineering applications is insufficient angiogenesis in scaffold interior. Bioactive borate glasses have been shown to promote angiogenesis. There is a need to investigate the biofabrication of polymer composites by incorporating borate glass to increase the angiogenic capacity of the fabri-cated scaffolds. In this study, we investigated the bioprinting of human adipose stem cells (ASCs) with a polycaprolac-tone (PCL)/bioactive borate glass composite. Borate glass at the concentration of 10 to 50 weight %, was added to a mixture of PCL and organic solvent to make an extrudable paste. ASCs suspended in Matrigel ...
Modeling Of Thermal And Mechanical Behavior Of Zrb₂-Sic Ceramic After High Temperature Oxidation,
2019
Missouri University of Science and Technology
Modeling Of Thermal And Mechanical Behavior Of Zrb₂-Sic Ceramic After High Temperature Oxidation, Jun Wei, Lokeswarappa R. Dharani, K. Chandrashekhara, Greg Hilmas, William Fahrenholtz
K. Chandrashekhara
No abstract provided.
Comparison Of Thermal Properties Of Laser Deposition And Traditional Welding Process Via Thermal Diffusivity Measurement,
2019
Missouri University of Science and Technology
Comparison Of Thermal Properties Of Laser Deposition And Traditional Welding Process Via Thermal Diffusivity Measurement, Yu Yang, Omoghene Osaze Obahor, Yaxin Bao, Todd E. Sparks, Jianzhong Ruan, Jacquelyn K. Stroble, Robert G. Landers, Joseph William Newkirk, Frank W. Liou
Robert G. Landers
Laser deposition is an effective process for mold and die repair. In order to improve the part repair quality, the process impact on thermal diffusivity and thermal conductivity needs to be understood for laser deposited, welded and virgin H13. In this paper, H13 tool steel samples were made by laser deposition, welding and virgin H13 and then cut into pieces. Experiments were conducted to investigate the thermal diffusivity and conductivity. A laser flash method is used to test these samples. The future work and opportunities are also summarized.
Modeling Of Thermal And Mechanical Behavior Of Zrb₂-Sic Ceramic After High Temperature Oxidation,
2019
Missouri University of Science and Technology
Modeling Of Thermal And Mechanical Behavior Of Zrb₂-Sic Ceramic After High Temperature Oxidation, Jun Wei, Lokeswarappa R. Dharani, K. Chandrashekhara, Greg Hilmas, William Fahrenholtz
Lokeswarappa Dharani
No abstract provided.
Effect Of Polymer-Surface Mobility On Adhesion In Poly(Methyl Methacrylate)-Tape System,
2019
Missouri University of Science and Technology
Effect Of Polymer-Surface Mobility On Adhesion In Poly(Methyl Methacrylate)-Tape System, Bhavesh C. Gandhi, Frank D. Blum, Lokeswarappa R. Dharani
Lokeswarappa Dharani
The interaction between two polymer layers, especially adhesion between them, plays an important role in polymer processing and other applications. Detailed knowledge of the molecular structure and dynamics of polymer interfaces, and how they relate to macroscopic mechanical properties, should help designers construct more functional systems. Unfortunately, there have been few studies where both molecular and macroscopic studies have been performed on similar systems. In previous studies from our group, we have probed the dynamics of poly(methyl acrylate) (PMA) and thermal behavior of poly(methyl methacrylate) (PMMA) on silica. These studies helped us paint a picture for strongly bound ...
Effect Of Interfacial Mobility On Flexural Strength And Fracture Toughness Of Glass/Epoxy Laminates,
2019
Missouri University of Science and Technology
Effect Of Interfacial Mobility On Flexural Strength And Fracture Toughness Of Glass/Epoxy Laminates, T. W. H. Wang, Frank D. Blum, Lokeswarappa R. Dharani
Lokeswarappa Dharani
Mechanical testing and surface fractography were used to characterize the fracture of E-glass fiber reinforced epoxy composites as a function of the silane coupling agent used. gamma-Aminopropyltriethoxysilane (APS) and delta-aminobutyltriethoxysilane (ABS) were used because these have been shown to have different interfacial mobilities at multilayer coverage. The values of the properties studied generally increased from untreated c, as determined from a Mode I translaminar fracture toughness tests, for the untreated composites (10.5 ± 0.4 kJ/m2) was lower than that for the ABS-treated composites (14.3 ± 2.1 kJ/m2) which was lower than that for the APS-treated composites ...
Use Of Flexible Sensor To Characterize Biomechanics Of Canine Skin,
2019
University of South Carolina
Use Of Flexible Sensor To Characterize Biomechanics Of Canine Skin, Austin R. J. Downey, Jin Yan, Eric M. Zellner, Karl H. Kraus, Iris V. Rivero, Simon Laflamme
Civil, Construction and Environmental Engineering Publications
Background: Suture materials and techniques are frequently evaluated in ex vivo studies by comparing tensile strengths. However, the direct measurement techniques to obtain the tensile forces in canine skin are not available, and, therefore, the conditions suture lines undergo is unknown. A soft elastomeric capacitor is used to monitor deformation in the skin over time by sensing strain. This sensor was applied to a sample of canine skin to evaluate its capacity to sense strain in the sample while loaded in a dynamic material testing machine. The measured strain of the sensor was compared with the strain measured by the ...
Stability Of The M2 Phase Of Vanadium Dioxide Induced By Coherent Epitaxial Strain,
2019
Missouri University of Science and Technology
Stability Of The M2 Phase Of Vanadium Dioxide Induced By Coherent Epitaxial Strain, N. F. Quackenbush, Yijia Gu
Yijia Gu
Tensile strain along the cR axis in epitaxial VO2 films raises the temperature of the metal insulator transition and is expected to stabilize the intermediate monoclinic M2 phase. We employ surface-sensitive x-ray spectroscopy to distinguish from the TiO2 substrate and identify the phases of VO2 as a function of temperature in epitaxial VO2/TiO2 thin films with well-defined biaxial strain. Although qualitatively similar to our Landau-Ginzburg theory predicted phase diagrams, the M2 phase is stabilized by nearly an order of magnitude more strain than expected for the measured temperature window. Our results reveal that the ...
Universal Emergence Of Spatially Modulated Structures Induced By Flexoantiferrodistortive Coupling In Multiferroics,
2019
Missouri University of Science and Technology
Universal Emergence Of Spatially Modulated Structures Induced By Flexoantiferrodistortive Coupling In Multiferroics, Eugene A. Eliseev, Sergei V. Kalinin, Yijia Gu, Maya D. Glinchuk, Victoria V. Khist
Yijia Gu
We proved the existence of a universal flexoantiferrodistortive coupling as a necessary complement to the well-known flexoelectric coupling. The coupling is universal for all antiferrodistortive systems and can lead to the formation of incommensurate, spatially modulated phases in multiferroics. Our analysis can provide a self-consistent mesoscopic explanation for a broad range of modulated domain structures observed experimentally in multiferroics.
Origin Of Interfacial Polar Order In Incipient Ferroelectrics,
2019
Missouri University of Science and Technology
Origin Of Interfacial Polar Order In Incipient Ferroelectrics, Yijia Gu, Nan Wang, Fei Xue, Long-Qing Chen
Yijia Gu
There are ample experimental evidences indicating that the ferroelastic domain walls of incipient ferroelectrics, such as SrTiO3 and CaTiO3, are polar. The emergence of such interfacial polar order at a domain wall is exciting and believed to arise from the coupling between a primary order parameter, such as a strain or an antiferrodistortive (AFD) order parameter, and polarization. There have been several mechanisms proposed to explain the emergence of interfacial polar order, including biquadratic coupling, AFD-antiferroelectric coupling, and flexoelectric coupling. Using CaTiO3 as an example, we demonstrate, using both asymptotic analytics and numerical calculation, that the flexoelectric ...
Thermodynamics Of Strained Vanadium Dioxide Single Crystals,
2019
Missouri University of Science and Technology
Thermodynamics Of Strained Vanadium Dioxide Single Crystals, Yijia Gu, Jinbo Cao, Junqiao Wu, Long-Qing Chen
Yijia Gu
Vanadium dioxide undergoes a metal-insulator transition, in which the strain condition plays an important role. To investigate the strain contribution, a phenomenological thermodynamic potential for the vanadium dioxide single crystal was constructed. The transformations under the uniaxial stress, wire, and thin film boundary conditions were analyzed, and the corresponding phase diagrams were constructed. The calculated phase diagrams agree well with existing experimental data, and show that the transformation temperature (and Curie temperature) strongly depends on the strain condition.
Thermotropic Phase Boundaries In Classic Ferroelectrics,
2019
Missouri University of Science and Technology
Thermotropic Phase Boundaries In Classic Ferroelectrics, Tom T. A. Lummen, Yijia Gu, Jianjun Wang
Yijia Gu
High-performance piezoelectrics are lead-based solid solutions that exhibit a so-called morphotropic phase boundary, which separates two competing phases as a function of chemical composition; as a consequence, an intermediate low-symmetry phase with a strong piezoelectric effect arises. In search for environmentally sustainable lead-free alternatives that exhibit analogous characteristics, we use a network of competing domains to create similar conditions across thermal inter-ferroelectric transitions in simple, lead-free ferroelectrics such as BaTiO3 and KNbO3. Here we report the experimental observation of thermotropic phase boundaries in these classic ferroelectrics, through direct imaging of low-symmetry intermediate phases that exhibit large enhancements in ...
