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, 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
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 ...
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
Aerospace Engineering Publications
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 ...
Application-Specific Oxide-Based And Metal-Dielectric Thin Film Materials Prepared By Rf Magnetron Sputtering Preprints201908.0184.V1.Pdf, Mohammad Nur-E-Alam, Wade Lonsdale, Mikhail Vasiliev, Kamal Alameh
Processing Manipulation Of Carbon Content In Cu-34.6%Mn, 2019 Purdue University
Processing Manipulation Of Carbon Content In Cu-34.6%Mn, Samuel Inman
The Journal of Purdue Undergraduate Research
No abstract provided.
Micrometeoroid Impacts On Periodic Spacecraft Structures, 2019 Purdue University
Micrometeoroid Impacts On Periodic Spacecraft Structures, Victoria West, Luis Buades, Hanson-Lee Harjono
The Journal of Purdue Undergraduate Research
No abstract provided.
Design Of High-Strength Refractory Complex Solid-Solution Alloys, 2019 Ames Laboratory
Design Of High-Strength Refractory Complex Solid-Solution Alloys, Prashant Singh, Aayush Sharma, Andrei V. Smirnov, Mouhamad S. Diallo, Pratik K. Ray, Ganesh Balasubramanian, Duane D. Johnson
Nickel-based superalloys and near-equiatomic high-entropy alloys containing molybdenum are known for higher temperature strength and corrosion resistance. Yet, complex solid-solution alloys offer a huge design space to tune for optimal properties at slightly reduced entropy. For refractory Mo-W-Ta-Ti-Zr, we showcase KKR electronic structure methods via the coherent-potential approximation to identify alloys over five-dimensional design space with improved mechanical properties and necessary global (formation enthalpy) and local (short-range order) stability. Deformation is modeled with classical molecular dynamic simulations, validated from our first-principle data. We predict complex solid-solution alloys of improved stability with greatly enhanced modulus of elasticity (3× at 300 K ...
Twinning-Induced Pseudoelastic Behavior In (Mow)85(Tati)7.5zr7.5, 2019 Iowa State University
Twinning-Induced Pseudoelastic Behavior In (Mow)85(Tati)7.5zr7.5, Aayush Sharma, Valery I. Levitas, Prashant Signh, Anup Basak, Ganesh Balasubramanian, Duane D. Johnson
We provide a critical atomistic evidence of pseudoelastic behavior in complex solid-solution BCC Mo-W-Ta-Ti-Zr alloy. Prior to this work, only limited single-crystal BCC solids of pure metals and quaternary alloys have shown pseudoelastic behavior at low temperatures and high strain rates. The deformation mechanisms investigated using classical molecular simulations under tensile-compressive loading reveal temperature-dependent pseudoelastic behavior aided by twinning during the loading-unloading cycle. The pseudoelasticity is found to be independent of loading directions with identical cyclic deformation characteristics during uniaxial loading. Additionally, temperature variation from 77 to 1500 K enhances the elastic strain recovery in the alloy.
Ambient Synthesis Of Nanomaterials By In Situ Heterogeneous Metal/Ligand Reactions, 2019 Iowa State University and Ames Laboratory
Ambient Synthesis Of Nanomaterials By In Situ Heterogeneous Metal/Ligand Reactions, Boyce S. Chang, Brijith Thomas, Jiahao Chen, Ian D. Tevis, Paul Karanja, Simge Çınar, Amrit Venkatesh, Aaron Rossini, Martin M. Thuo
Martin M. Thuo
Coordination polymers are ideal synthons in creating high aspect ratio nanostructures, however, conventional synthetic methods are often restricted to batch-wise and costly processes. Herein, we demonstrate a non-traditional, frugal approach to synthesize 1D coordination polymers by in situ etching of zerovalent metal particle precursors. This procedure is denoted as the heterogeneous metal/ligand reaction and was demonstrated on Group 13 metals as a proof of concept. Simple carboxylic acids supply the etchant protons and ligands for metal ions (conjugate base) in a 1 : 1 ratio. This scalable reaction produces a 1D polymer that assembles into high-aspect ratio ‘nanobeams’. We demonstrate ...
Optimizing The Valorization Of Industrial By-Products For The Induction Healing Of Asphalt Mixtures, 2019 Technological University Dublin
Optimizing The Valorization Of Industrial By-Products For The Induction Healing Of Asphalt Mixtures, Amir Tabakovic, Marta Vila-Cortavitarte, Daniel Jato-Espino, Daniel Castro-Fresno
Self-healing within asphalt pavements is the process whereby road cracks can be repaired automatically when thermal and mechanical conditions are met. To accelerate and improve this healing process, metal particles are added to asphalt mixtures. However, thisapproach is costly both in economic and environmental terms due to the use of virgin metallic particles. So, even though the self-healing of asphalt mixtures has been widely addressed in experimental terms over the years, there is a lack of research aimed at modelling this phenomenon, especially with the purpose of optimizing the use of metal particles through the valorization of industrial by-products. As ...
Evaluation Of Biodegradability Characteristics Of Cellulose-Based Film As Per Is/Iso 14855-1, 2019 Indian Institute of Packaging, Mumbai
Evaluation Of Biodegradability Characteristics Of Cellulose-Based Film As Per Is/Iso 14855-1, Narayan C. Saha Dr, Gaurav Madhu Dr, Diksha B. Kadu Ms
Journal of Applied Packaging Research
Biodegradable polymers (especially those derived from plant sources) begin their lifecycle as renewable resources, usually in the form of starch or cellulose. In this paper, the evaluation of biodegradability of cellulose-based polymer film under controlled composting conditions as per the guidelines of IS/ISO 14855 (Part-1) standard has been described. Microcrystalline cellulose (MCC) powder was taken as positive-control polymer. The apparatus used to analyse the degree and rate of biodegradation was developed indigenously. The validation of the biodegradability testing apparatus was also performed as per the prescribed test method given in IS/ISO 14855-1.
Implementing Population-Based Mass Drug Administration For Malaria: Experience From A High Transmission Setting In North Eastern Uganda, Richard Elliott
Materials Science and Engineering Faculty Publications and Presentations
Background: Mass drug administration (MDA) is a suggested mean to accelerate efforts towards elimination and attainment of malaria-free status. There is limited evidence of suitable methods of implementing MDA programme to achieve a high coverage and compliance in low-income countries. The objective of this paper is to assess the impact of this MDA delivery strategy while using coverage measured as effective population in the community and population available.
Methods: Population-based MDA was implemented as a part of a larger program in a high transmission setting in Uganda. Four rounds of interventions were implemented over a period of 2 years at ...
Dependence Of The Absolute Value Of The Penetration Depth In (Ba1–X Kx) Fe2 As2 On Doping, 2019 Technion–Israel Institute of Technology
Dependence Of The Absolute Value Of The Penetration Depth In (Ba1–X Kx) Fe2 As2 On Doping, Avior Almoalem, Alon Yagil, Kyuil Cho, Serafim Teknowijoyo, Makariy A. Tanatar, Ruslan Prozorov, Yong Liu, Thomas A. Lograsso, Ophir M. Auslaender
Thomas A. Lograsso
We report magnetic force microscopy (MFM) measurements on the iron-based superconductor Ba1−xKxFe2As2. By measuring locally the Meissner repulsion with the magnetic MFM tip, we determine the absolute value of the in-plane magnetic penetration depth (λab) in underdoped, optimally doped, and overdoped samples. The results suggest an abrupt increase of λab as doping is increased from xopt, which is potentially related to the presence of a quantum critical point. The response of superconducting vortices to magnetic forces exerted by the MFM tip for x=0.19 and 0.58 is compatible with previously observed structural symmetries at those doping levels.
Reliable Thermodynamic Estimators For Screening Caloric Materials, 2019 Ames Laboratory
Reliable Thermodynamic Estimators For Screening Caloric Materials, Nikolai A. Zarkevich, Duane D. Johnson
Duane D. Johnson
Reversible, diffusionless, first-order solid-solid phase transitions accompanied by caloric effects are critical for applications in the solid-state cooling and heat-pumping devices. Accelerated discovery of caloric materials requires reliable but faster estimators for predictions and high-throughput screening of system-specific dominant caloric contributions. We assess reliability of the computational methods that provide thermodynamic properties in relevant solid phases at or near a phase transition. We test the methods using the well-studied B2 FeRh alloy as a “fruit fly” in such a materials genome discovery, as it exhibits a metamagnetic transition which generates multicaloric (magneto-, elasto-, and baro-caloric) responses. For lattice entropy contributions ...
Investigation Of The Electrode Polarization Effect For Biosensor Applications, 2019 Southern Methodist University
Investigation Of The Electrode Polarization Effect For Biosensor Applications, Anil Koklu
Mechanical Engineering Research Theses and Dissertations
My research focuses on electrokinetic transport. Particularly, in this dissertation, we focus on fabrication and testing of micro electrodes with nanostructured surfaces to minimize the electrode polarization (EP) effects for biosensor applications. In the first study, electrochemical deposition of gold nanoparticles on to planar gold electrodes was used to generate rough surfaces. Dendritic nanostructures that reduced EP up to two orders of magnitude was obtained by optimizing the deposition conditions. These structures also enhanced dielectrophoresis (DEP) response of our bio-chips, making them usable in physiological buffers. In further studies we discovered a universal scaling of EP in the frequency domain ...