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Growth And Stability Of Pb Intercalated Phases Under Graphene On Sic, Shaojiang Chen, Patricia A. Thiel, E. Conrad, Michael C. Tringides 2020 Iowa State University and Ames Laboratory

Growth And Stability Of Pb Intercalated Phases Under Graphene On Sic, Shaojiang Chen, Patricia A. Thiel, E. Conrad, Michael C. Tringides

Chemistry Publications

Graphene intercalation is a novel way to control graphene's band structure and generate two-dimensional quantum materials with unusual spintronic and electronic properties. Despite its importance, information about the intercalation mechanism is lacking, especially the role of low density domain boundaries between regions of graphene of different thickness. With high resolution surface diffraction we have systematically studied Pb intercalation on epi-graphene grown on SiC, with domain boundaries between buffer and single layer graphene. By examining the evolution of different diffraction spots as a function of temperature, the location of Pb and stability of the intercalated phases underneath were determined.


Stability Of Group Four Monochalcogenides In Water And Air, William Shattuck 2020 University of Arkansas, Fayetteville

Stability Of Group Four Monochalcogenides In Water And Air, William Shattuck

Theses and Dissertations

Previously published works have simulated the behavior of monolayer group IV monochalcogenides and predicted them to have very useful electronic properties. These simulations have also predicted that monolayers of group IV monochalcogenides will degrade quickly when exposed to water, even in extremely low concentrations. We hypothesize that thin samples of these materials will show signs of degradation if left in air and in water for an extended period of time.

Samples of each of the four monochalcogenides (GeS, GeSe, SnS and SnSe) were exfoliated onto clean oxidized silicon substrates. Chemical analysis showed the SnSe samples were contaminated, so they were ...


Understanding The Fundamentals Of Ionic Conductivity In Polymer Electrolytes, Eric Wayne Stacy 2020 University of Tennessee, Knoxville

Understanding The Fundamentals Of Ionic Conductivity In Polymer Electrolytes, Eric Wayne Stacy

Doctoral Dissertations

The rate of advancement for mobilized electronic technologies is outpacing the development of small efficient batteries. Lithium-ion batteries are currently the most widely used energy storage device for consumer electronics. Traditional lithium-ion batteries use a liquid electrolyte to separate the cathodes and anodes; however, conventional liquid electrolytes have inherent problems, such as consisting of flammable carbonate components, hazardous material, and have a significant cost/weight in the battery. In addition, the liquid electrolyte cannot prevent the growth of lithium dendrites during the charge/discharge cycle of the lithium-ion battery. These dendrites can connect the anode to the cathode of the ...


Approaches To Studying Bacterial Biofilms In The Bioeconomy With Nanofabrication Techniques And Engineered Platforms., Michelle Caroline Halsted 2020 University of Tennessee, Knoxville

Approaches To Studying Bacterial Biofilms In The Bioeconomy With Nanofabrication Techniques And Engineered Platforms., Michelle Caroline Halsted

Doctoral Dissertations

Studies that estimate more than 90% of bacteria subsist in a biofilm state to survive environmental stressors. These biofilms persist on man-made and natural surfaces, and examples of the rich biofilm diversity extends from the roots of bioenergy crops to electroactive biofilms in bioelectrochemical reactors. Efforts to optimize microbial systems in the bioeconomy will benefit from an improved fundamental understanding of bacterial biofilms. An understanding of these microbial systems shows promise to increase crop yields with precision agriculture (e.g. biosynthetic fertilizer, microbial pesticides, and soil remediation) and increase commodity production yields in bioreactors. Yet conventional laboratory methods investigate these ...


Characterizing Childhood And Diet In Migration Period Hungary, Kirsten A. Verostick 2020 University of South Florida

Characterizing Childhood And Diet In Migration Period Hungary, Kirsten A. Verostick

Graduate Theses and Dissertations

This project investigates children, childhood and diet of two different Migration Period (4th-8th century AD) populations, the Gepids and the Avars, in the Great Hungarian Plain. The main goal was to assess whether there are differences in treatment of children and differences in breastfeeding and weaning practices in these distinct sites and populations. Secondarily, this research also focused on characterizing diet for the Gepids and the Avars at four different sites from the Migration Period, to understand how the migration and settling into the region and the assimilation of other groups into the two populations affected their ...


High Layer Uniformity Of Two-Dimensional Materials Demonstrated Surprisingly From Broad Features In Surface Electron Diffraction, Shen Chen, Michael Horn von Hoegen, Patricia A. Thiel, Adam Kaminski, Benjamin Schrunk, Thanassis Speliotis, Edward Henry Conrad, Michael C. Tringides 2020 Iowa State University and Ames Laboratory

High Layer Uniformity Of Two-Dimensional Materials Demonstrated Surprisingly From Broad Features In Surface Electron Diffraction, Shen Chen, Michael Horn Von Hoegen, Patricia A. Thiel, Adam Kaminski, Benjamin Schrunk, Thanassis Speliotis, Edward Henry Conrad, Michael C. Tringides

Chemistry Publications

Paradoxically a very broad diffraction background, named the Bell-Shaped-Component (BSC), has been established as a feature of graphene growth. Although the BSC has been present in the earlier literature it has been ignored. Recent diffraction studies as a function of electron energy have shown that the BSC is not related to scattering interference. The BSC is a very strong effect, but its origin is still unclear. Here, additional experiments are carried out as a function of temperature while monitoring changes in the intensity of different spots over the range that single-layer-graphene (SLG) grows. Quantitative fitting of the profiles shows that ...


Protein Conformational Entropy Is Not Slaved To Water, Bryan S Marques, Matthew A Stetz, Christine Jorge, Kathleen G Valentine, A Joshua Wand, Nathaniel V Nucci 2020 Rowan University

Protein Conformational Entropy Is Not Slaved To Water, Bryan S Marques, Matthew A Stetz, Christine Jorge, Kathleen G Valentine, A Joshua Wand, Nathaniel V Nucci

Faculty Scholarship for the College of Science & Mathematics

Conformational entropy can be an important element of the thermodynamics of protein functions such as the binding of ligands. The observed role for conformational entropy in modulating molecular recognition by proteins is in opposition to an often-invoked theory for the interaction of protein molecules with solvent water. The "solvent slaving" model predicts that protein motion is strongly coupled to various aspects of water such as bulk solvent viscosity and local hydration shell dynamics. Changes in conformational entropy are manifested in alterations of fast internal side chain motion that is detectable by NMR relaxation. We show here that the fast-internal side ...


Period Estimation And Noise In A Neutrally Stable Stochastic Oscillator, Kevin R. Sanft, Ben F. M. Intoy 2020 University of North Carolina Asheville

Period Estimation And Noise In A Neutrally Stable Stochastic Oscillator, Kevin R. Sanft, Ben F. M. Intoy

Spora: A Journal of Biomathematics

The periods of the orbits for the well-mixed cyclic three-species Lotka-Volterra model far away from the fixed point are studied. For finite system sizes, a discrete stochastic approach is employed and periods are found via wavelet analysis. As the system size is increased, a hierarchy of approximations ranging from Poisson noise to Gaussian noise to deterministic models are utilized. Based on the deterministic equations, a mathematical relationship between a conserved quantity of the model and the period of the population oscillations is found. Exploiting this property we then study the deterministic conserved quantity and period noise in finite size systems.


Pressure-Stabilized Divalent Ozonide Cao3 And Its Impact On Earth’S Oxygen Cycles, Yanchao Wang, Meiling Xu, Liuxiang Yang, Bingmin Yan, Qin Qin, Xuecheng Shao, Yunwei Zhang, Dajian Huang, Xiaohuan Lin, Jian Lv, Dongzhou Zhang, Huiyang Gou, Ho-kwang Mao, Changfeng Chen, Yanming Ma 2020 Jilin University

Pressure-Stabilized Divalent Ozonide Cao3 And Its Impact On Earth’S Oxygen Cycles, Yanchao Wang, Meiling Xu, Liuxiang Yang, Bingmin Yan, Qin Qin, Xuecheng Shao, Yunwei Zhang, Dajian Huang, Xiaohuan Lin, Jian Lv, Dongzhou Zhang, Huiyang Gou, Ho-Kwang Mao, Changfeng Chen, Yanming Ma

Physics & Astronomy Faculty Publications

High pressure can drastically alter chemical bonding and produce exotic compounds that defy conventional wisdom. Especially significant are compounds pertaining to oxygen cycles inside Earth, which hold key to understanding major geological events that impact the environment essential to life on Earth. Here we report the discovery of pressure-stabilized divalent ozonide CaO3 crystal that exhibits intriguing bonding and oxidation states with profound geological implications. Our computational study identifies a crystalline phase of CaO3 by reaction of CaO and O2 at high pressure and high temperature conditions; ensuing experiments synthesize this rare compound under compression in a diamond anvil cell with ...


Pressure Driven Desalination Utilizing Nanomaterials, Fangyou Xie 2020 calpoly san luis obispo

Pressure Driven Desalination Utilizing Nanomaterials, Fangyou Xie

Master's Theses

Nanomaterials such as graphene oxide and carbon nanotubes, have demonstrated excellent properties for membrane desalination, including decrease of maintenance, increase of flux rate, simple solution casting, and impressive chemical inertness. Here, two projects are studied to investigate nanocarbon based membrane desalination. The first project is to prepare hybrid membranes with amyloid fibrils intercalated with graphene oxide sheets. The addition of protein amyloid fibrils expands the interlayer spacing between graphene oxide nanosheets and introduces additional functional groups in the diffusion pathways, resulting in increase of flux rate and rejection rate for the organic dyes. Amyloid fibrils also provide structural assistance to ...


Biophysical And Stable Isotopic Profiles Of The Salmon Louse Lepeophtheirus Salmonis (Krøyer, 1837), Emma Taccardi 2020 University of Maine

Biophysical And Stable Isotopic Profiles Of The Salmon Louse Lepeophtheirus Salmonis (Krøyer, 1837), Emma Taccardi

Electronic Theses and Dissertations

The salmon louse Lepeophtheirus salmonis is a parasitic copepod that infects wild and farmed salmonids throughout the northern hemisphere. L. salmonis represents the largest economic hurdle of the Atlantic salmon (Salmo salar) industry, with an estimated annual cost of nearly $1 billion globally due to production losses and anti-parasitic control measures. Salmon farming in Maine has existed for decades and is a critical economic driver, yet the region is underrepresented in global sea lice research. The aim of this work was to examine parasites in the context of animal trophic transfer and characterize physiological condition by quantifying the flow of ...


Embedded Gold Nanoparticles For Metal Enhanced Photoluminescence, Hasna Alali 2020 Western Michigan University

Embedded Gold Nanoparticles For Metal Enhanced Photoluminescence, Hasna Alali

Dissertations

Noble metal nanoparticles (MNPs) have attracted great attention in electronics, solar cells and catalysis. Their unique optical properties and biocompatibility makes them useful in biological applications like imaging, drug delivery, therapy and diagnostic. At the surface of MNPs the collective oscillation of free electrons resonates with a particular wavelength of incident light, generating the Localized Surface Plasmons Resonance (LSPR). LSPR results in absorption and scattering of incident light. Scattering results in reflecting photons and absorption leads to enhanced photoluminescence and quenching of fluorophores, if the fluorophore is in the vicinity of MNPs.

Most of the studies in this regard have ...


The Recreation Of Wound Patterns Using Various Tissue Simulants For Crime Scene Reconstruction, Breanne Steimle 2020 State University of New York College at Buffalo - Buffalo State College

The Recreation Of Wound Patterns Using Various Tissue Simulants For Crime Scene Reconstruction, Breanne Steimle

Forensic Science Master's Projects

Within the field of forensic science, there are limited reliable methods for the simulation of pattern injuries on human skin and tissue that may aid in aspects of crime scene reconstruction. The tissue simulant must be of sufficient integrity for recording blunt force trauma and bite mark impressions, electrocution, cutting, and gunshot wound related injuries for the purpose of re-enactment, court exhibition, and distance determination. For wound reenactments (such as blunt force trauma, bite mark impressions and electrocution), dead skin and tissue from human cadavers do not show wounding patterns that would occur on live tissue. This study examines different ...


Improved Antimicrobial Properties Of Silver Nanoparticles With Methylene Blue, Ermek Belekov 2020 Western Kentucky University

Improved Antimicrobial Properties Of Silver Nanoparticles With Methylene Blue, Ermek Belekov

Masters Theses & Specialist Projects

Photosensitizing agents are the cornerstone of photodynamic therapy (PDT) that play essential role in deactivation process of multidrug resistant pathogens and tumor treatments. In this work we studied a photosensitizing agent made from mixture of silver nanoparticles (Ag NPs) and methylene blue (MB) which possess improved important characteristics like high photostability and high singlet oxygen yield. Ag NPs were synthesized by pulsed laser ablation technique in different aqueous solutions like Polyvinylpyrrolidone (PVP), citrate and Deionized (DI) water. The synthesized Ag NPs were characterized in depth using with transmission electron microscopy (TEM), UVVisible (UV-Vis), and photoluminescence (PL) spectra. Ag NPs were ...


Visualization Of Brown Fat Using X-Ray Dark Field Imaging, Troy D. Jacobs 2020 Louisiana State University and Agricultural and Mechanical College

Visualization Of Brown Fat Using X-Ray Dark Field Imaging, Troy D. Jacobs

LSU Master's Theses

Introduction: Obesity has become a major societal issue. Many researchers are looking for ways to combat this growing epidemic. Brown adipose tissue (BAT) might be a way to help individuals overcome the challenges associated with weight loss and maintenance of weight loss, but a better understanding of BAT and how to control and utilize it is needed. BAT differs from white adipose tissue (WAT) in that BAT is rich with mitochondria and therefore is metabolically active. BAT is a source of non-shivering thermogenesis and can be activated both by cold exposure and pharmacologically. Current methods of assessing BAT activity are ...


Non-Adiabatic Quantum Dynamics Of The Ultracold Li+Lina→ Li2+Na Chemical Reaction, B. K. Kendrick, M. Li, H. Li, S. Kotochigova, J. F.E. Croft, Balakrishnan Naduvalath 2020 Los Alamos National Laboratory

Non-Adiabatic Quantum Dynamics Of The Ultracold Li+Lina→ Li2+Na Chemical Reaction, B. K. Kendrick, M. Li, H. Li, S. Kotochigova, J. F.E. Croft, Balakrishnan Naduvalath

Chemistry and Biochemistry Faculty Publications

We report non-adiabatic dynamics of the Li+LiNa→Li2+Na chemical reaction at cold and ultracold temperatures employing accurate ab initio electronic potential energy surfaces in a quantum dynamics formulation employing a diabatic representation. Results are compared against those from a single adiabatic ground state potential energy surface and a universal model based on the long-range interaction potential. We discuss signatures of non-universal behavior in the total rate coefficients as well as strong non-adiabatic effects in the state-to-state rotationally resolved rate coefficients.


Structure Of Chalcogen Overlayers On Au(111): Density Functional Theory And Lattice-Gas Modeling, Da-Jiang Liu, James W. Evans, Peter Spurgeon, Patricia A. Thiel 2020 Ames Laboratory

Structure Of Chalcogen Overlayers On Au(111): Density Functional Theory And Lattice-Gas Modeling, Da-Jiang Liu, James W. Evans, Peter Spurgeon, Patricia A. Thiel

Chemistry Publications

Ordering of different chalcogens, S, Se, and Te, on Au(111) exhibit broad similarities but also some distinct features, which must reflect subtle differences in relative values of the long-range pair and many-body lateral interactions between adatoms. We develop lattice-gas (LG) models within a cluster expansion framework, which includes about 50 interaction parameters. These LG models are developed based on density functional theory (DFT) analysis of the energetics of key adlayer configurations in combination with the Monte Carlo (MC) simulation of the LG models to identify statistically relevant adlayer motifs, i.e., model development is based entirely on theoretical considerations ...


Testing A Thermodynamic Approach To Collective Animal Behavior In Laboratory Fish Schools, Julia A. Giannini, James G. Puckett 2020 Gettysburg College

Testing A Thermodynamic Approach To Collective Animal Behavior In Laboratory Fish Schools, Julia A. Giannini, James G. Puckett

Physics and Astronomy Faculty Publications

Collective behaviors displayed by groups of social animals are observed frequently in nature. Understanding and predicting the behavior of complex biological systems is dependent on developing effective descriptions and models. While collective animal systems are characteristically nonequilibrium, we can employ concepts from equilibrium statistical mechanics to motivate the measurement of material-like properties in laboratory animal aggregates. Here, we present results from a new set of experiments that utilize high speed footage of two-dimensional schooling events, particle tracking, and projected static and dynamic light fields to observe and control the behavior of negatively phototaxic fish schools (Hemigrammus bleheri). First, we use ...


Characterization Of Three Phases Of Liquid Carbon By Tight-Binding Molecular Dynamics Simulations, Rong Cheng, Wen-Cai Lu, Kai-Ming Ho, Cai-Zhuang Wang 2020 Iowa State University, Ames Laboratory, and Qingdao University

Characterization Of Three Phases Of Liquid Carbon By Tight-Binding Molecular Dynamics Simulations, Rong Cheng, Wen-Cai Lu, Kai-Ming Ho, Cai-Zhuang Wang

Ames Laboratory Accepted Manuscripts

We have performed systematic molecular dynamics simulations to study the structures of liquid carbon at 5000 K with the weight density ranging from 1.4 to 3.5 g cm−3, using a three-center tight-binding potential of carbon. The simulation results show that the bonding characteristics of the liquid changes predominately from twofold to threefold, and then to fourfold coordination as the density increases. Signals of two structural changes at the densities of about 1.9 and 3.0 g cm−3 respectively are revealed by the slope changes in the density dependence of structural, electronic and dynamical properties. Our ...


Stabilizing The Crystal Structures Of Nafepo4 With Li Substitutions, Renhai Wang, Shunqing Wu, Feng Zhang, Xin Zhao, Zijing Lin, Cai-Zhuang Wang, Kai-Ming Ho 2020 Ames Laboratory and University of Science and Technology of China

Stabilizing The Crystal Structures Of Nafepo4 With Li Substitutions, Renhai Wang, Shunqing Wu, Feng Zhang, Xin Zhao, Zijing Lin, Cai-Zhuang Wang, Kai-Ming Ho

Ames Laboratory Accepted Manuscripts

Due to the high cost and insufficient resources of lithium, alternative sodium-ion batteries have been widely investigated for large-scale applications. NaFePO4 has the highest theoretical capacity of 154 mA h g−1 among the iron-based phosphates, which makes it an attractive cathode material for Na-ion batteries. Experimentally, LiFePO4 has been highly successful as a cathode material in Li-ion batteries because its olivine crystal structure provides a stable framework during battery cycling. In NaFePO4, maricite replaces olivine as the most stable phase. However, the maricite phase is experimentally found to be electrochemically inactive under normal battery operating voltages (0–4.5 ...


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