Bulletin of the American Physical Society
2021 Joint Spring Meeting of the Texas Sections of APS, AAPT and Zone 13 of the SPS
Volume 66, Number 2
Thursday–Sunday, April 8–11, 2021; Virtual
Session C13: Poster Session (12:30-2:00 PM CT) |
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C13.00001: Optoelectronic and antibacterial studies of hydrothermally grown microcrystalline ZnO, as-received and after interactions with s. aureus bacteria Dustin Johnson, Jacob Tzoka, John Reeks, Iman Ali, Shauna McGillivray, Yuri Strzhemechny The most fundamental mechanisms driving antibacterial action of ZnO are still being vigorously debated. Among those -- the influence of the ZnO crystal surfaces and morphology, especially in due to the nature of the charged polar and uncharged nonpolar surfaces of the anisotropic wurtzite ZnO crystal lattice. To address this, we developed a hydrothermal method to grow microscale ZnO crystals with tunable morphologies ranging from predominantly polar to predominantly nonpolar surfaces. The size of the grown crystals prevents them from being internalized by the s. aureus cells, which have a diameter of ca. 500 nm. Using this platform, we investigated the impact of morphology and surface polarity on the interactions between ZnO and bacteria. SEM and EDX studies confirmed the quality and morphology of our samples before interactions with bacteria. SEM and EDX were also employed to analyze changes due to interactions with s. aureus. Photoluminescence and surface photovoltage studies were used to characterize the electronic structure and the near-surface charge dynamics in our samples. Optoelectronic investigations were performed before and after interactions with bacteria. Comparative studies revealed that the antibacterial action of ZnO microparticles is primarily rooted in the interactions between the ZnO surfaces and the extracellular material. We also confirm that growth media and environment have a substantial impact on these interactions. [Preview Abstract] |
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C13.00002: AuSi Eutectic Dynamic and Meso-Pyramid Formation Nathan Dice Novel mesoscopic pyramid-like structures are produced on silicon [100] substrates by depositing thin films of gold and silicon and annealing in vacuum. Eutectic dynamics provides the theoretical framework whereby on can understand the fundamental principles governing their formation. Cross-sectional Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) are used to identify the sequence of steps from a continuous thin film to mesoscopic Au pyramids. The temperature dependence of the pyramid's elemental composition is correlated with the Au-Si eutectic binary phase diagram, where it is found that the process follows boundary between phases that lead to the composition associated with the lowest melting point of the Au-Si eutectic. A dealloying process explains the bulk and surface morphologies of the Au pyramids. In the case of the bulk, voids form within the pyramid, creating a sponge-like morphology. The surface morphology consists of chevrons of plateaus troughs. Our understanding of the eutectic dynamics creates new opportunities in non-linear optics, as well as Surfaced Enhanced Raman Scattering (SERS) sensors. [Preview Abstract] |
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C13.00003: Simulation and prediction of gravitational molecular dynamic systems, using diverse pseudopotentials and regression algorithms. Edwin Tomy George, Cesar Diaz Caraveo, Adrian De la Rocha, Jorge Alberto Munoz The present work simulates the dynamics of two gravitationally bounded bodies. This simulation is repeated with different initial conditions to generate data that is fed to regression models capable of predicting the future characteristics of the system with initial conditions, the objective being not needing to use time-consuming simulations for future calculations. The system itself consists of bodies in a one-dimensional space which are gravitationally attracted to each other, their masses, velocities and initial positions being the initial conditions. To accurately simulate the system, the use of pseudopotentials was needed to reduce the excess energy added when the particles come closer, caused by numerical errors that arise because Newton's Law of Gravity tends towards infinity in bodies that are infinitely close to each other. Different pseudopotentials were tested, comparing the accuracy of the simulation. The following modified Law of Gravity with the pseudopotential was selected, where lower variable lambdas are more accurate but time-consuming: GMm/(r\textasciicircum 2$+$e\textasciicircum (-r/lambda)). After generating the simulations needed for the data, regression models where trained to predict different outcomes. A linear regression model was used to predict the final position of the particles, with a mean error of \textasciitilde 8{\%}. A logistic model was used to predict if the system experienced collision or not. The next step on the present work is to use neural networks to improve the accuracy and implement more parameters. [Preview Abstract] |
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C13.00004: Virialization of gravitational molecular dynamics systems and the impact of different pseudopotentials on the simulation. Cesar Diaz, Edwin Tomy George, Adrian De La Rocha Galan, Jorge Munoz The present work analyzes the behavior of two massive particles bounded in gravitational attraction, simulated using molecular dynamics techniques. When dealing with molecular dynamics simulations, it is often necessary to include an attenuated or increased force between the particles. This artificial force is called a pseudopotential, and in the case of this project, it is required to reduce as much as possible a problem of energy creation that occurs because the gravitational force tends to infinity when the objects are infinitely close to each other. The pseudopotential used is a changed version from Newton's Law of Gravitation, which includes a parameter called soften added to the denominator. This work tests different ways to calculate this soften parameter. The accuracy of each of the pseudopotentials is measured by a parameter called the virial factor. According to the classical mechanics' virial theorem, the result of this parameter is always -2 in nature. However, it was observed that the more negative the parameter is, the better the simulation conserves the energy of the particles. Preliminary results show this virial factor has maxima and minima in certain functions, and it is greater in magnitude when the time-step of the simulation is decreased. [Preview Abstract] |
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C13.00005: A Search for GW170817-like Nearby GRBs in the \textit{Swift}/BAT Sample Avery Cook Following the remarkable neutron star binary merger known as GW170817, much research has been conducted to uncover its nature and investigate whether its nearby location presents an opportunity to unveil similar events. GW170817 was accompanied by a kilonova, plus a delayed radio afterglow related to an off-axis jet that differs from those previously observed in gamma-ray bursts (GRBs). It has thus been suggested that such delayed emission may have been missed in previously known GRBs. In this context, I will present the results of an analysis aimed at determining whether previously detected GRBs, lacking accurate localization and an early afterglow detection, could have originated from events similar to GW170817. Specifically, I will discuss the results of a late-time radio follow-up campaign of a subset of short GRBs in the \textit{Swift}/BAT sample. The goal of this campaign, carried out with the Jansky Very Large Array (VLA), is to determine whether any of the GRBs in our sample is associated with delayed radio emission. I will show how such late-time emission, using its time variability and spectral energy distribution, can be used to constrain whether nearby ejecta similar to GW170817 were produced in any of the considered GRBs. [Preview Abstract] |
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C13.00006: Analyzing RR Lyrae Stars Using TESS Data Garath Vetters, William Hennig, Faith Olsen, Andrew Tom, Kenneth Carrell The Transiting Exoplanet Survey Satellite (TESS) has a primary mission of observing exoplanets. However, by precisely measuring the brightness of a large number of stars, it is an ideal tool to use in order to look for stellar variability. We have used TESS data and a program written in python to classify stars into three types of RR Lyrae variables: RRab, RRc, and RRd. ~Moreover, particular attention will be placed on looking for interesting phenomena only recently discovered by the latest generation of space telescopes. [Preview Abstract] |
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C13.00007: Photon Propagation in a Scintillator and How It Affects Light Efficiency Tim Ramos, Andrew Whitbeck Scintillators are materials that have the capability to convert high energy radiation such as beta-particles or gamma rays into visible light. Scintillators have a property such that when these particles strike it, photons are emitted inside the scintillator which can be detected by a photodetector such as a silicon photomultiplier or a photomultiplier tube. The light being produced is called scintillation light. Our work studies the nature of photons moving in a scintillator. We have developed a simulation toolkit for analyzing light collection efficiency with respect to the dimensions of the scintillator, the refractive index of the scintillator, a random line generator (charged particle path), and whether an air gap exists. This poster will present a diagram and flow chart of a python-based numerical simulation of light propagation in a scintillator. We will also present some first-principles calculations and of how light efficiency is collected under certain conditions, which serve as a validation of our simulations. Finally, we will discuss results~of polishing actual scintillators and taking light measurements of them. [Preview Abstract] |
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C13.00008: Finding Variable Sources In Large Data Sets Jackie Gray-Cherry, Kenneth Carrell For years now astronomers have been collecting data using a combination of ground and space-based telescopes. We have so much information that it is impossible to sift through it all in a reasonable time frame. So, to counteract this we need to figure out ways to efficiently and quickly analyze these data sets to find meaningful results. One way we can do this is by crossmatching data sets with each other and looking for differences. This provides us with potentially interesting candidates for follow-up analysis. We used a crossmatched catalog with potentially variable sources flagged and examined their lightcurves from The Transiting Exoplanet Survey Satellite (TESS). After going through a magnitude limited sample, we found 3 binary sources that were already confirmed in the Set of Identifications, Measurements and Bibliography for Astronomical Data (SIMBAD) and 3 sources that are unknown. [Preview Abstract] |
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C13.00009: Determining How the High Energy Particle Precipitation and the Very Low Frequency Wave (VLF) Precipitation from the Aurora Borealis Interact With Eachother Chloe Tovar The "High Energy Particles" undergraduate research team with the University of Houston is conducting research in hopes of determining explicit correlations between the high energy particle precipitation and the very low frequency (VLF) waves produced by the aurora borealis. Though the aurora produces a wide range of high energy particles, such as electrons with an energy range of 1-100 keV, the specific precipitation that will measure is x-ray radiation. The x-rays themselves have an energy range of 40 keV to 250 keV and are produced through Bremsstrahlung interactions of the electrons with the atmosphere. The reason focus is being given to the x-ray range is that previous research has shown correlation specifically between the x-ray radiation and the VLF waves. The VLF waves are natural emissions from the magnetosphere that is above the aurora. They are driven by plasma instabilities which are one part of space weather. [Preview Abstract] |
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C13.00010: The Precise Orbital Period of HAT-P-36 b Rebeca Soto Armendariz, Kenneth Carrell Follow-up observations of confirmed exoplanets are essential to obtain more accurate measurements of a planet’s period and transit midpoint. We observed the confirmed exoplanet HAT-P-36 b, first discovered by the Hungarian Automated Telescope Network (HATNet) Exoplanet Survey (Bakos et al. 2012). This planet can also be found in the Transiting Exoplanet Survey Satellite (TESS) database as TOI 1810.01. After processing the images obtained from our observing runs, we plotted their light curves to compare them with the data from HATNet, and the two-minute cadence and Full Frame Images (FFI) from TESS. Our resulting light curves match very closely the light curves we used as references. The data from HATNet was taken about ten years ago, the data from TESS was taken about one year ago, and our observations were made in March 2021. This means that the period and the transit midpoint of HAT-P-36 b have remained constant for over a decade. This type of science is helpful for planning spectroscopic follow-up observations and can be done by amateur astronomers using smaller aperture telescopes. This will save valuable time at bigger telescopes and will allow professional astronomers to more efficiently use their time. [Preview Abstract] |
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C13.00011: Relativistic Quantum Mechanics for Undergrads Akash Deep, Luis Grave de Peralta A quantum particle trapped in an infinite one-dimensional well is one of the simplest but most instructive and useful examples often taught in introductory Quantum Mechanics courses. However, solving the same problem when the particle moves at speeds close to the speed of the light in vacuum is considered too complicated even for graduated students. Not anymore, a recently explored Schr\"{o}dinger-like but relativistic wave equation allows us to solve the infinite one-dimensional well problem for a relativistic spin-0 particle of mass m, as easy as it is shown in textbooks for a non-relativistic particle. The Grave de Peralta (GdeP) and the Schr\"{o}dinger equations are so formally alike that just by removing the factor 2 in the last one and substituting it by the factor (gamma $+$ 1), one gets the first one. The factor gamma is the well-known Lorentz factor from the Einstein's special theory of relativity. At low particle speeds, the GdeP equation reproduces the results obtained using the Schr\"{o}dinger one and, at relativistic speeds, it reproduces the results obtained using the Dirac equation. Moreover, the GdeP equation allows for solving several interesting problems in quantum mechanics but using a different relativistic approach. [Preview Abstract] |
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C13.00012: Neutrino Oscillations in Quantum Field Theory Kendra Jean Jacques, Anna Roland, Preet Sharma Neutrino oscillations are a quantum mechanical phenomena and are very important in understanding the behavior of our Universe. The idea of neutrino oscillation was first put forward in 1957 by Bruno Pontecorvo, who proposed that neutrino–antineutrino transitions may occur in analogy with neutral kaon mixing. Neutrino oscillation arises from mixing between the flavor and mass eigenstates of neutrinos. As neutrinos travel through space they oscillate between the 3 flavors, namely electron neutrino, muon neutrino and tau neutrino. We have explained the 3-flavor neutrino oscillations through a quantum field theoretic explanation. [Preview Abstract] |
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C13.00013: Optical Characteristics of the Plasmon-active Interface in the Metamaterials with Various Material Properties Daniel Seungmin Lee, Richard Kyung In this paper, various combinations of metamaterial layers in which the surface plasmon polariton occurs were studied. While the photon enters at a certain angle and stays along the surface or interface of the materials, surface plasmon polariton is observed. Different reflectivity was observed and an effective index was found through manual calculation and the use of computer programs. For the analysis, various wavelengths of the incident cosmic rays and visible lights were applied to different composite materials: dielectrics and metals. Refractive index(n) and extinction coefficient(k) for both metals and nonmetals at certain wavelengths were used and relative permittivity of metal and nonmetal was also used for the calculation. To verify the results obtained from manual calculation, computational simulations were performed using one and multiple periods of metal and dielectric combination. When Palladium, Manganese, and Vanadium were combined with certain oxides such as Molybdenum Trioxide, Silicon Oxide and Tantalum Pentoxide, optimum angles were not found for a specific wavelength. [Preview Abstract] |
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C13.00014: Relativistic Configuration Interaction method for accurate determination of energy levels, wavelengths, oscillator strengths and radiative rates singly and doubly excited states of Helium-like Plomb Soumaya Manai, Dhia Elhak Salhi, Sirine Ben Nasr, Haikel Jelassi The need for more accurate atomic data becomes more greater than before with the ongoing ITER project. Therefore, in recent years, there have been extensive spectroscopic studies, both experimental and theoretical, of helium isoelectronic sequence[1]. We provide accurate energies for the lowest singly excited 70 levels among 1snl(n ≤ 6,l ≤ (n − 1)) configurations and the lowest doubly excited 250 levels arising from the K-vacancy 2ln'l'(n'≤ 6,l'≤ (n'− 1)) configurations of He-like Pb. Accurate determination of wavelengths, oscillator strengths and radiative rates are carried out through the Relativistic Configuration Interaction method (RCI) implemented in the flexible atomic code (FAC)[2]. We have also considered relativistic effects (QED and Breit corrections). Several new energy levels were found out where no other theoretical or experimental results are available. We expect that our extensive calculations will be useful to experimentalists for astrophysical line identification and plasma diagnostics[3]. References: [1] D. H. Salhi, S. Ben Nasr, S. Manai and H. Jelassi, Accepted in Results in Physics, 2021. [2] M.F. Gu, Canadian Journal of Physics, 86 (2008) 675-689. [3] D. H. Salhi, P. Quinet and H. Jelassi, Atomic Data and Nuclear Data Tables, 126 (2019) 675–689. [Preview Abstract] |
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C13.00015: Efficient scheme for creating a W-type optical entangled coherent state. hanyu zhang W-type optical entangled coherent states have important applications in quantum communication. Previous works require performing measurement in the preparation of such W states. We here propose an efficient scheme for creating a W-type optical entangled coherent state without measurement. This scheme employs a setup composed of three microwave cavities and a superconducting flux coupler qutrit. Because no measurement is required, the W state can be generated deterministically. In addition, the system complexity is greatly reduced because of using only one qutrit to couple the three cavities. Numerical analysis shows that within current experimental technology, the W state can be prepared with high fidelity. This scheme is universal and can be extended to create the W-type optical entangled coherent state, by using three microwave or optical cavities coupled via a three-level natural or artificial atom. [Preview Abstract] |
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C13.00016: Calculating Relativistic Atomic Properties Using Monte Carlo Methods Steven Alexander, Gerardo Gonzalez, R.L. Coldwell There are a number of computational methods that can be used to calculate the energies and properties of nonrelativistic atoms. Fully relativistic calculations of these systems are much less common and more complicated. In part, this is because each relativistic particle generates four coupled components and the presence of negative energy states prohibits the use of most variational techniques. In this talk I will describe how variational Monte Carlo methods can be used to calculate the energy and properties of fully relativistic one-electron atoms. [Preview Abstract] |
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