Bulletin of the American Physical Society
Spring 2021 Meeting of the APS Ohio-Region Section
Volume 66, Number 3
Friday–Saturday, April 9–10, 2021; Virtual Meeting Hosted by John Carroll University, Cleveland Heights, OH; Time Zone: Eastern Daylight Time, USA
Session A06: Poster Session (4:30-6:00 PM) |
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Chair: Roy Day, John Carroll University |
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A06.00001: Dynamics of water and ethanol intercalated in graphene oxide. Gobin Acharya, Eugene Mamontov, Madhusudan Tyagi, Peter Hoffmann Graphene oxide (GO) membranes were recently suggested for applications in separation of ethanol from water using a vapor permeation method. Understanding microscopic diffusivity of water and ethanol in graphene oxide membranes is important for separations applications. We will discuss the dynamics of water and ethanol between the direction perpendicular to the plane and in-plane direction. We used quasi elastic neutron scattering (QENS) to measure the temperature dependence of the diffusivity of water and ethanol, and its anisotropy by the utilization of Q-dependence of QENS signals obtained from BASIS at Oak Ridge National Lab. We will also discuss how dynamic measurements from QENS can be correlated with atomic force microscopy measurements of the temperature dependence of viscosity in water/ethanol confined in GO. [Preview Abstract] |
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A06.00002: Photo-Seebeck effect in methylammonium lead iodide thin films Alec J. Coutris, Ibrahim A. Alfurayj, Clemens Burda, Jeffrey S. Dyck In recent years, the world has seen an increased dependence on renewable sources of energy. Among these, solar energy presents a growing field with many potential areas of research, including development of a viable active region in solar cells where light can be converted to electricity. Perhaps the most captivating emerging group of materials is the family of perovskites with structure ABX3, where A and B are cations and X is an anion. One potentially viable and efficient perovskite is methylammonium lead iodide (CH3NH3PbI3) or MAPbI3. While MAPbI3 is of great interest to researchers, some of its most fundamental transport properties have yet to be thoroughly studied. In this research, we measure the Seebeck coefficient of thin films of MAPbI\textlnot 3 as a function of conductivity for various light intensities and wavelengths. Seebeck data is very difficult to obtain without photoexcitation, and we utilize narrow-band high-power light emitting diode (LED) light sources spanning blue to infrared to populate the electronic conduction and valence bands. Our results are in rough agreement with accepted Boltzmann transport theory, and our modeling will help elucidate relationships between the concentration of free charge carriers, and their effective masses and scattering mechanisms. [Preview Abstract] |
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A06.00003: Thickness and Temperature Dependence of the Dielectric Function of Bi$_{\mathrm{2}}$Se$_{\mathrm{3}}$ Xiaoyu Wang, Frank Peiris, Maria Hilse, Roman Engel-Herbert We have determined the dielectric functions of a series of Bi$_{\mathrm{2}}$Se$_{\mathrm{3}}$ films grown on sapphire substrates. Temperature dependent in-situ ellipsometry spectra were obtained for several samples with varying thicknesses ranging from 5 nm to 60 nm. After the dielectric functions were modeled using the in-situ spectra, they were represented by Kramers-Kronig consistent oscillators. We observe that the dielectric function of Bi$_{\mathrm{2}}$Se$_{\mathrm{3\thinspace }}$has a slight thickness dependence and that it also varies with temperature. Specifically, the oscillators red-shift as temperature increases, which was modeled using a Bose-Einstein distribution. [Preview Abstract] |
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A06.00004: Dielectric Functions of (Bi$_{\mathrm{x}}$In$_{\mathrm{1-x}})_{\mathrm{2}}$Se$_{\mathrm{3}}$ Films Grown on Sapphire Substrates Aofeng Bai, Frank Peiris, Maria Hilse, Roman Engel-Herbert Analyzing a series of in-situ ellipsometry spectra of MBE-grown (Bi$_{\mathrm{x}}$In$_{\mathrm{1-x}})_{\mathrm{2}}$Se$_{\mathrm{3}}$ films grown on sapphire substrates, we have explored how their dielectric functions varies with alloy concentration. Starting with the nominal thicknesses determined by RHEED, we fit both the thickness and the dielectric function of each film. The sapphire substrate was modelled with birefringent optical constants. The dielectric functions of (Bi$_{\mathrm{x}}$In$_{\mathrm{1-x}})_{\mathrm{2}}$Se$_{\mathrm{3}}$ films were modelled using several Kramers-Kronig consistent oscillators. Upon further analysis, we have deduced how some of the main oscillator-parameters change with alloy concentration, which will be important if (Bi$_{\mathrm{x}}$In$_{\mathrm{1-x}})_{\mathrm{2}}$Se$_{\mathrm{3}}$ alloys are to be used in optoelectronic applications. [Preview Abstract] |
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A06.00005: Remote Investigation of the Photoconductivity Mechanisms of Methylammonium Lead Iodide Perovskite Thin Films David R. Sprenger, Jeffrey S. Dyck Methylammonium lead iodide (MAPbI3) thin films are a promising alternative to conventional silicon for use in solar cells. While the photoconductivity of these materials has been well-studied, some details of their conductive behavior is not yet well-understood. Typically, photoconductivity is studied with the use of solar simulators. We make an extension to this approach by employing multiple narrow-band light emitting diode light sources and examine the intensity dependence in detail. During recent months of the pandemic, it was desirable to seek ways to acquire data remotely to the degree possible. A remote, automated approach allows for consistent data collection while also remaining within public health guidelines. In a preliminary analysis, the computer-automated data acquisition program offers promising results. In the future, the program can be used to better understand the connection between film degradation and the photoconductivity. [Preview Abstract] |
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A06.00006: Single molecule force spectroscopy to determine specific receptor densities on live cancer cells under varying conditions Ramesh Tripathi, Peter Hoffmann We have used atomic force microscopy to study the single-molecule interaction between the ligand and receptors in live cancer cells under different vitro conditions. We focused our study on discoidin domain receptors (DDR), a cardinal player in cancer metastasis. DDRs are receptors that dimerize in response to collagen and initiate a signaling path within the cell. We constructed hydrogel substrates of varying stiffness and collagen concentration. The goal of the research is to determine receptor levels, dynamics, and interactions as a function of cell type and environment. Using an improved AFM analysis method, we were able to determine not only binding probability and kinetic parameters, but also densities of the ligands. We will present preliminary results from this research. [Preview Abstract] |
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A06.00007: Study on the Dynamics of Gene Mutation Due to DNA Adducts Yea Na Kang Density-functional theory and quantum mechanical modelling technique were used to study electronic structure of gene molecules. Using the DFT, the electron system was explained using computational simulations the progression of oxidation of DNA in nerve cells, which occurs during the enzymatic metabolism from benzo[a]pyrene to benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide(BPDE). In the process, intercalation resulted in the formation of guanine benzopyrene through binding with guanine bases in the DNA. In the DNA intercalation, thermodynamic changes were observed while the guanine benzopyrene intercalates to form an adduct which the binding causes the alteration of the structure and the abnormal replication proceeds to gene mutation. Physical properties such as optimized energy, dipole moment and electrostatic potential maps were calculated to figure out how different the values of the different atoms in a molecule affect the stability of the system. Results showed that the optimization energy of the studied molecule increased as the weight and size of molecules increased. Optimization energy of the complex G-BPDE : C and C : G( 3093.631kJ/mol) showed highest among the tested samples. [Preview Abstract] |
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A06.00008: Stereochemical Analysis of Porphyrins and Chelators to Control Free Radicals Jeewon Han Photodynamic Therapy, or PDT, is a method of cancer treatment which uses a photosynthesizer, oxygen, and a light of a determined frequency. Normally, reactive oxygen species are damaging to normal cells around them and therefore should be eliminated, but their destructive properties also allow them to eliminate cells harmful to the body, such as cancer cells. In photodynamic therapy, the high reactive oxygen species interact with biomolecules and produce oxidative radicals, which is cytotoxic in action. The free radicals then destroy the tumor cell through inducing apoptosis or necrosis. In this study, various molecules that can help remove reactive oxygen species from normal cells and the different isomers of porphyrin and cyclodextrin, photosynthesizers, were analyzed and compared to reveal which compound would work best. Also, to eliminate the toxic levels of redox metals in nerve cells, especially copper and iron, through selective chelation, this research investigated various iron chelators (EDTA, DTPA among others) from multiple dimensions, including optimization energy, electrostatic potential map, and dipole moment. [Preview Abstract] |
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A06.00009: Geographic Tongue as a Reaction-Diffusion System Margaret McGuire, Chase Fuller, John Lindner, Niklas Manz Geographic tongue (GT) or benign migratory glossitis is a condition of an unknown cause characterized by chronic lesions that slowly migrate across the surface of the tongue. The condition's wavefronts suggest that it can be modeled as a reaction--diffusion system. We present a model for geographic tongue pattern evolution using reaction--diffusion equations applied to portions of spheroids and paraboloids that approximate a tongue shape. We selected the Barkley model for our reaction-diffusion equations modified the reaction-diffusion system to account for surface curvature using the Laplace-Beltrami Operator then numerically integrated the model over spheroids using the Finite Element Method on desktop computers. We report images of simulations where wavefronts of excitation are initiated under different conditions on spheroids and paraboloids resembling the tongue. We show the propagation of these wave fronts and spirals and compare them to clinical images of geographic tongue. Finite-element decomposition of the differential equations on spheroids and paraboloids easily generated spiral and elliptical wave fronts similar to those observed clinically. The qualitative similarity between our simulations and patient data can be achieved without assuming anisotropic diffusion on the tongue's surface. In our next steps, we will use experimental time-series to measure real GT propagation speeds and determine diffusion constants to reproduce particular subjects' GT behavior as well as investigate the effects of inert obstacles like fungiform papillae or fissures in the tongue on GT evolution. [Preview Abstract] |
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A06.00010: Study on the Molecular Characteristics and Pharmacological Activity of Polyphenols as Antioxidants Hansol Kim, Richard Kyung Polyphenols are the largest group of phytochemicals widely used as biologically active compounds in pharmacology, medicine, and as potential agents for the prevention and treatment of oxidative stress-related diseases. Many of them have been found in plant-based foods and some are structurally and functionally related to flavonoids phenolic compounds. In this project, thermodynamic and stereochemical properties of several types of biochemical molecules that can be used as a biological antioxidant were studied. Computational and biomedical simulations were used, and have been proven useful in assessing the physicochemical stability of molecules. Molecular editing programs were used to model, optimize, and compare the resulting molecular optimization energies of the phenolic compounds. Various polyphenols were tested when OH groups and functional groups were differently attached to the molecules: those with more OH groups and substituents, and those attached farther apart, or were with less functional groups. For all the types of functional groups attached, the optimization energy of the compounds in which the clusters attached were distanced is usually lower than that of the isomer in which the functional groups are close to each other. [Preview Abstract] |
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A06.00011: Enantioselective and Diastereoselective Synthesis of Quinolines Using Reissert Compounds Jaeun Shin, Richard Kyung The Reissert reaction is a chemical reaction that transforms quinoline to quinaldic acid. Quinolines react with acid chlorides and potassium cyanide to produce Reissert compounds and the quinaldic acid is obtained by hydrolysis. In this project, we assessed the thermodynamic and stereochemical analysis for the intermediate and final products obtained in the Reissert reaction to figure out the spontaneous behavior and dynamics of the reaction. Molecular editing program was used to model, optimize, and quantify the chemical and physical properties of the molecular compounds obtained in the process. Alkylation of a Reissert compounds to produce isoquinolines was analyzed: For example, a computational simulation on the stereoselective asymmetric allylic alkylation of Reissert compounds yielding functionalized 1,2-dihydroisoquinolines bearing adjacent stereocenters was performed. The molecular editing program equipped with an auto-optimization feature determined the theoretical values of all the structure’s atomic and molecular properties of the intermediate and final products through the Density Functional Theory (DFT). This process allows users to build virtually any molecule and optimize its geometry according to various force field options. [Preview Abstract] |
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A06.00012: Projectile Momentum Uncertainty Effects in Electron Vortex Beam Collisions Alexander Plumadore, Allison Harris Ionization collisions have important consequences in many physical phenomena, and the mechanism that leads to ionization is not universal. Understanding how and why electrons are removed from atoms and molecules is crucial to forming a complete picture of the physics. Double differential cross sections (DDCS) have been used for decades to examine the physical mechanisms that lead to ionization and two separate pathways have been identified depending on the energy of the ionized electron. At low energies, the DDCS feature a broad distribution as a function of ionization angle, while at high energies, a sharp peak is observed in the distributions. The width of the DDCS peak can be directly traced to the target electron’s quantum mechanical momentum distribution and the results are well-known for plane wave projectiles. However, the recent development of sculpted particle wave packets introduces the opportunity to re-examine the mechanisms that lead to ionization. We present DDCS for (e,2e) ionization of atomic hydrogen for electron vortex projectiles and show that for vortex projectiles making close collisions with the target, the DDCS are sensitive to the projectile momentum uncertainty. [Preview Abstract] |
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A06.00013: DENTIFYING PHOTONS FROM LONG-LIVED PARTICLES IN THE ATLAS DETECTOR Jammel Brooks WHILE INCREDIBLY SUCCESSFUL, THE STANDARD MODEL FAILS AT EXPLAINING SEVERAL KNOWN FEATURES OF THE UNIVERSE SUCH AS DARK MATTER AND THE HIERARCHY PROBLEM. ONE POSSIBLE EXPLANATION IS SUPERSYMMETRY, WHERE EACH OF THE CURRENTLY KNOWN PARTICLES HAS AT LEAST ONE SUPERSYMMETRIC PARTNER. DEPENDING ON THE PARAMETERS OF THE MODEL, CERTAIN SUPERSYMMETRIC PARTNERS THAT DECAY IN PART TO PHOTONS CAN REMAIN UNDETECTED BY THE ATLAS DETECTOR, WHILE LIVING LONG ENOUGH TO DECAY AWAY FROM THE PRIMARY INTERACTION. DUE TO THIS LONG-LIVED DECAY, THE PHOTONS LEAVE NON-STANDARD ENERGY DEPOSITS IN THE ATLAS DETECTOR AND AS SUCH LESS STRINGENT PHOTON IDENTIFICATION REQUIREMENTS MUST BE USED. THIS POSTER DESCRIBES THE EFFICIENCY MEASUREMENT OF THESE LOOSER PHOTON REQUIREMENTS, HOW WELL MC SIMULATIONS DESCRIBE DATA, AND THE ASSOCIATED UNCERTAINTIES. [Preview Abstract] |
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A06.00014: Analysis of the ROTSE I Data to Create an Unbiased Survey of Variable Stars Caroline Kuczek Eclipsing Binary systems are two stars orbiting around their center of mass at an angle such that the eclipse is visible from Earth. These systems can be used for distance measurements and are the only systems for which direct mass measurements can be made. This makes statistical analyses on these stars very valuable. In order to determine the location, orbit characteristics, and behavioral physics behind these systems through statistical analyses, an unbiased survey of variable stars seen by the ROTSE I telescope was constructed. This was done by filtering light curves and code development. [Preview Abstract] |
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A06.00015: A Renormalization Group Approach to Ordered Phases in Music Ryan Buechele, Jesse Berezovsky The organization of sounds into music has always been a fundamental part of human experience, and the desire to understand how this organization arises motivates the field of music theory. Explanations of musical ideas are often informed by historical experience, but Berezovsky has previously shown that musical harmony can be described in analogy to the thermodynamics of physical phase transitions. In the same way physical systems minimize their energy and maximize entropy, harmony in music can be treated as a tradeoff between minimizing dissonance and maximizing pitch variety. Berezovsky's model uses a mean-field approximation to describe interactions between the multitude of tones in a musical system; however, this work utilizes renormalization group (RG) theory as a more sophisticated treatment of the many degrees of freedom. With this new approach, we build on the mean-field results and explore in more detail how new phases emerge on a variety of fractal lattices. For D$=$2, we see a BKT transition, but an intermediate phase emerges for D\textgreater 2. By connecting the results to known systems of tuning and pitch organization, we further demonstrate the strength of this physical analogy and draw conclusions about the methods and reasons humans use for composing and performing music. [Preview Abstract] |
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A06.00016: Analyze the working distance of strong interaction Han Yong quan The diameter of a proton is about 10$^{\mathrm{-15}}$ meters, which happens to be the most effective distance for strong interaction. Why is this so? The radiation radius of any particle is: c/$\omega $, where c is the speed of light, and $\omega $ is the angular velocity of the object's rotation. The radiation of protons and neutrons due to high-speed rotation converges in the range of 0.5×10$^{\mathrm{-15}}$ meters, which is also its gravitational range. Since the radiation of protons and neutrons is converged in the range of 0.5×10$^{\mathrm{-15}}$ meters, the angular velocity of protons and neutrons must be very large, and the radiation intensity will be extremely large. The interaction caused by radiation entanglement is strong, and the electromagnetic force must be balanced, so that Protons and neutrons make up the nucleus. Therefore, within the nucleus, only two adjacent protons or neutrons can produce gravity. Gravity can be produced when the distance is less than 10$^{\mathrm{-15}}$ meters, and the gravitational field greater than 10$^{\mathrm{-15}}$ meters does not intersect and does not produce gravity [Preview Abstract] |
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