Bulletin of the American Physical Society
Joint Spring 2013 Meeting of the Texas Sections of the APS and AAPT and Zone 13 of the SPS
Volume 58, Number 3
Thursday–Saturday, April 4–6, 2013; Stephenville, Texas
Session E1: Poster Session (3:00 - 4:00PM) |
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Chair: Travis Salzillo, Tarleton State University Room: Science Building 2nd Floor |
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E1.00001: Optical Foucault Pendulum Richard Selvaggi, Charles Rogers This experiment uses the concept of a photon clock to measure the trajectory of light in a rotating cavity. Our hypothesis asks what affect does motion have on the measured trajectory of photons? Does measuring the trajectory by the non-accelerated reference frame differ from the same measurement made by the accelerated reference frame? Will not producing and not measuring, or producing but not measuring, or not producing but measuring, or producing and measuring the photons in the non-accelerated reference frame but reflecting it through the accelerated reference frame produce the same or different results? The apparatus set-up, operation, and measured results are presented. [Preview Abstract] |
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E1.00002: Effects of coherent population trapping on Raman scattering Marshall Rogers, Stephen Schiller, Yuri Rostovtsev We study Raman scattering in molecular media by applying two laser fields in a two-photon resonance with vibrational transition. The role of rotational levels has been investigated. It is shown that the molecular vibrational coherence strongly depends on the effect of coherent population trapping for rotational levels. The obtained results are important for application of Raman spectroscopy to molecular detection for engineering, chemical, and biological applications. [Preview Abstract] |
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E1.00003: Correlation Between Corotating Interaction Regions' Magnetic Orientations and Magnetic Storm Strengths Near Earth Joseph Schinco, Blake Barnett, Kevin Pham, Ramon Lopez The solar wind occasionally contains irregularities called CIRs, or corotating interaction regions. A CIR occurs when a region of slow moving solar wind (slow-speed stream) is followed by a region of fast moving solar wind (high-speed stream). This setup causes a compression in the rear part of the slow-speed stream, since the high-speed stream eventually ``catches up'' and applies pressure to it. CIRs have been known to be directly linked to some magnetic storms in the near Earth environment. Although we do know that CIRs can create magnetic storms, we do not yet know if a specific magnetic type of CIR creates stronger storms than the rest. We have analyzed data from the solar wind that will allow us to compare multiple magnetic types of CIRs, in order to see which ones create the strongest storms. [Preview Abstract] |
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E1.00004: How the Fluctuation Amplitude of the Interplanetary Magnetic Field's Z Component Affects Geomagnetic Storm Strength Cezanne Narcisse, Spencer Durrenberger, Jaime Sterrett, Soha Aslam, Kevin Pham, Ramon Lopez A corotating interacting region (CIR) is a region of compressed solar wind caused by a high speed stream (speeds \textgreater 500 km/s) that catches up to slower solar wind in which the source corotates with the sun. We are collecting data to find two case in which proton density, solar wind speed, and average magnetic field are similar except for the fluctuation amplitude of the interplanetary magnetic field's (IMF) z component. We used geomagnetic indices to quantify their related geomagnetic storm strengths. Our goal is to compare the geomagnetic storm strengths caused by the IMF's fluctuation in CIRs. [Preview Abstract] |
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E1.00005: Searching for the Evidence of Reduction of Viscous Potential for Northward Interplanetary Magnetic Field Denver Scott, Michael Mishler, Aaron Baca, Shree Bhattarai, Ramon Lopez Solar wind consists of ionized particles originating from the Sun that carries along with it the solar magnetic field, which we call the interplanetary magnetic field (IMF). The interaction of solar wind with the geomagnetic field occurs mainly by two different processes: viscous interaction and magnetic reconnection. The viscous interaction is generated due to velocity shear across the magnetopause forming a circulation pattern in the magnetosphere. Magnetic reconnection occurs in strongly conducting plasma, where magnetic fields realign and magnetic energy is transformed into kinetic, and/or thermal energies. The result of viscous interaction and magnetic reconnection during northward IMF produces a four-cell convection pattern in the ionosphere. We will be using OMNI data to obtain sustained, strong northward Bz, and analyze the ground based SuperDARN (Super Dual Auroral Radar Network) data in an attempt to see if the viscous potential is reduced for northward IMF during periods when Bz was three times greater than the magnitude of By. [Preview Abstract] |
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E1.00006: Analyzing solar wind magnetic field reversals for a variety conditions in an MHD simulation Spencer Durrenberger, Brett Shock, Robert Bruntz, Ramon Lopez The solar wind flows out from the Sun, made up of charged particles and a magnetic field that interacts with Earth's magnetic field. We are simulating periods of steady magnetic field that also contain a reversal of the direction of that magnetic field. The solar wind produces motion in the plasma in the ionosphere, which is a layer of the uppermost part of the Earth's atmosphere that contains charged particles. We are looking at changes between modes of ionospheric circulation due to reversal events. We are simulating these events to analyze the changes in the magnetosphere and ionosphere, then changing the input values of these events to better understand the timing of changes in ionospheric modes, and under what conditions different modes occur. We will also be comparing some simulation results to actual observations. [Preview Abstract] |
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E1.00007: Temperature Dependent DNA Charge Transport Chris Wohlgamuth, Marc McWilliams, Jason Slinker Charge transport (CT) through DNA has been extensively studied, and yet the mechanism of this process is still not yet fully understood. DNA CT has been utilized in sensing proteins and DNA fragments, it has been postulated that it may assist DNA damage prevention and repair, and further understanding of this process will elucidate the biological implications of DNA CT and advance sensing technology. Therefore, we have investigated the temperature dependence of DNA CT by measuring the electrochemistry of DNA monolayers modified with a redox-active probe. We compare square wave voltammetry of distinct DNA sequences under identical experimental conditions. Accordingly, we compare well matched DNA duplexes to those containing a single base pair mismatch. Additionally, we vary the probe location within the well matched DNA duplex in order to investigate distance dependent kinetics. Furthermore, a comparison of an A-T rich and G-C rich duplex is performed. Using a model put forth by O'Dea and Osteryoung and applying a nonlinear least squares analysis we are able to determine the charge transport rates (k), transport coefficients ($\alpha$), and the active surface concentration ($\Gamma^*$) of the DNA monolayer. The transport rates of CT are shown to follow Arrhenius behavior. [Preview Abstract] |
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E1.00008: Biological Effects of Electromagnetic Fields on Bacterial Properties Derek Smith, Babak Keyghobadi, Beheshte Eftekhari, Samina Masood Previous experiments have shown a significant effect from electromagnetic fields (EMFs) upon bacteria, such as an altered growth rate. We review previous experiments and their results in order to summarize the effects of EMFs upon bacteria, with a special interest in gram-negative bacteria. Emphasis is also placed upon the experimental equipment used for testing, the shape-dependent effects upon bacteria, the effects of varying field strengths, and the effects of using a liquid growth medium. Our preliminary study shows the effect of magnetic field is non-ignorable on most of the bacterial species. [Preview Abstract] |
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E1.00009: Antihydrogen-Gravity Experiment: An Analytical Model For Parallel Plate Geometry J.R Rocha, Carlos Ordonez An analytical model is developed for an experiment that may be used to determine whether antihydrogen falls up or down in Earth's gravitational field. The model is the third iteration of an ongoing development to reduce the experimental run time necessary for an experiment at the CERN Antiproton Decelerator facility. The experiment relies on methods developed by existing research collaborations: production, confinement, and detection of antihydrogen. The configuration consists of two parallel plates that have an axis of symmetry directed away from the center of the Earth. They are separated by a small vertical distance and include a series of circular apertures. An antihydrogen annihilation located a short distance beyond each barrier, within a ``shadow'' region, are asymmetric on the top or bottom annulus. The analytical model is used to determine the probability that an antiatom annihilates within one of the shadow regions, which would indicate the direction of the acceleration of antihydrogen due to gravity. [Preview Abstract] |
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E1.00010: Electronic structure of planar aggregates of boron clusters Carlos Diaz, Luis Basurto, Tunna Baruah, Rajendra Zope Using simulated annealing, random searches and basin hopping, we have searched for low lying isomers of boron cluster containing 27 atoms in its neutral and charged states. For those searches, the interatomic potential between boron atoms is described using density functional theory at the generalized gradient approximation level. The structures of low lying isomers found in our searches are predominantly quasi-planar. Several of these structures are seen as growth of smaller size boron clusters. The population of low energy neutral boron cluster isomers was used to study the influence that charge has on the structural pattern of charged boron clusters. The calculations indicate that the boron clusters also tend to prefer quasi-planar geometries. These are the largest planar boron cluster aggregates reported so far. Electronic properties such as ionization energies, vertical detachment energies and electron affinities and also the infrared and Raman spectra of neutral clusters will be presented. [Preview Abstract] |
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E1.00011: A New Algorithm Development on the Frequency Analysis Richard Kyung, Eugene Lee A numerical algorithm to analyze the frequencies of beam structures is developed based on mode synthesis method. The physical domains are assumed to be composed of group of sub-domains or components that are interconnected with each other. After reducing the degrees of freedom of each element by means of the new algorithm, natural mode shapes of each of the components are found. The dynamic characteristics obtained are combined into a complete domain. The effects of dividing for the domain and the number of modes adopted in the interface region are also taken into consideration. The results are compared to those from the commercial program that can carry out modal analysis such ANSYS. The proposed algorithm is applied to the domains with a large number of sub-domains, and the results show numerical efficiency over the classical modal analysis. [Preview Abstract] |
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E1.00012: Density functional theory (DFT) study of the electronic structure of Bi$_2$O$'$Ti$_2$O$_6$ for hydrogen production by water splitting David Barker, Cedric Mayfield, Vaidyanathan Subramanian, Muhammad Huda BTO pyrochlore (Bi$_2$O$'$Ti$_2$O$_6$) is a promising photocatalyst material for hydrogen production by water-splitting. Study of such materials is crucial for the understanding of energy conservation, and to better understand the optical and electronic properties of pyrochloric materials. However, BTO's electrical and optical properties have not yet been studied in greater detail. In this study, density functional theory (DFT) was used to calculate the volume of the cell as well as the energy, and as a result of this calculation the most stable crystal structure was determined. In addition, previous studies have indicated that Fe doped BTO has preferable electronic structure as a photocatalyst. Here, this is studied in depth by placing Fe at different sites in BTO and observing how electronic properties are affected. For example, through the study of the band structure for both BTO and Fe doped BTO; band gaps and the nature of the gaps will be presented, as well as the optical properties of both systems. Examination of the solubility of Fe in different sites of BTO, the most stable structure for Fe doped BTO, the formation energy and the contributions of the different atoms orbitals on the total band structure will be presented as well. [Preview Abstract] |
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E1.00013: Phase Transitions within Ferrofluid and Piezoelectic fluid Bryan Wofford Ferrofluids and piezoelectric fluids undergo phase transitions under the action of magnetic and electric fields, respectively. These materials are simple metamaterials. We are in the process of probing the properties of ferrofluids ultrasonically. Preliminary results and experimental designs will be presented. [Preview Abstract] |
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E1.00014: Characterization of multiferroic BiFeO$_{3}$ synthesized by RF magnetron sputtering Gregory Spencer, Rye Johnson, Anup Bandyopadhyay Bismuth ferrite is a material which exhibits multiferroic behavior including the simultaneous appearance of both ferroelectric and antiferromagnetic properties. It is of great practical interest for device applications because of its relatively high ferroelectric Curie temperature (T$_{\mathrm{C}}$ $\sim$ 1100 K) and high Neel temperature (T$_{\mathrm{N}}$ $\sim$ 643 K) which are both well above room temperature. BiFeO$_{3}$ (BFO) has been synthesized by a variety of methods including MBE, pulsed laser deposition, and sputtering. We report on the synthesis and characterization of thin BFO thins by RF sputter deposition onto an STO/Si substrate at temperatures from 400$^{\circ}$ C to 600$^{\circ}$ C. The resulting polycrystalline films, ranging in thickness from $\sim$ 80 to 200 nm, were characterized by X-ray diffraction to determine the crystallinity. We have also measured the magnetic behavior by vibrating sample magnetometer as a function of temperature between 4K and 300K. Imaging and EDS by SEM was performed to study the film morphology as well as AFM imaging. The SEM images revealed structures that formed spontaneously during the thicker film depositions. These results and comparison with others will be presented. [Preview Abstract] |
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E1.00015: Ellipsometric Analysis of Silicon Nanoparticles Formed by Rapid Thermal Annealing Chad Waxler, Gregory Spencer, Anup Bandyopadhyay Since the discovery of visible photoluminescence (PL) of silicon nanostructures, interests in silicon nanoparticles has increased due to their possible applications in photovoltaics and optoelectronic devices. In this study, we investigate the surface morphology and optical properties of silicon nanoparticles formed on a silicon-on-insulator substrate by rapid thermal annealing in an argon environment at atmospheric pressure. We analyze the formation of silicon nanoparticles as a function of silicon layer thickness (3-10 nm), annealing temperature (600-800$ ^{\circ}$ C), and annealing duration (30-120 seconds) using atomic force microscopy (AFM) and we analyze the optical properties via effective medium approximations (EMA) models using a variable angle spectroscopic ellipsometer (VASE). [Preview Abstract] |
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E1.00016: Heating induced structural and chemical behavior of KD2PO4 in the 25$^\circ$C -- 215$^\circ$C temperature range Andres Encerrado Manriquez, Adan Anchondo, Joshua Morris, Cristian Botez We have used powder x-ray diffraction (XRD) to investigate the structural and chemical modifications undergone by KD2PO4 (DKDP) upon heating from room temperature to 215$^\circ$C. Full-profile (Le Bail) analysis of our temperature-resolved data shows no evidence of polymorphic structural transitions or deuterium-hydrogen isotope exchange occurring below Ts $=$ 185$^\circ$C. The lattice parameters of DKDP vary smoothly upon heating to Ts and are approximately 0.4\% greater than those of its isostructural hydrogenated counterpart KH2PO4 (KDP). Moreover, XRD isotherms collected at Ts indicate the absence of any structural or chemical changes in DKDP at this temperature. Upon further heating, however, the tetragonal DKDP phase becomes unstable, as evidenced by its transition to a monoclinic DKDP modification and eventual chemical decomposition via dehydration. [Preview Abstract] |
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E1.00017: Regenerated Spider Silk Possess Mechanical Properties of Super- and Cyclic Contraction in Response to Environmental Humidity Shan Lu, Ganesh Swaminathan, Samuel Evans, Todd Blackledge Major Ampullate (MA) spider silk is among the most impressive biomaterials due to its unparalleled mechanical properties, such as super-contraction and cyclic response to changes in humidity. Electro-spinning enables the generation of engineered silk fibers with controlled parameters and dimentions for various medical and commercial applications. However, their applications hinge on the ability to reproduce the mechanical properties such as a precise expansion-contraction response existed in natural silk fibers. Here, we successfully reproduced MA spider-silk fibers from solutions of natural MA silk proteins via electrospinning, which exhibit the super-contraction and cyclic response to humidity change in a manner mirroring the natural fibers. [Preview Abstract] |
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E1.00018: Density Functional Study of the Oxygen Adsorption on the Cu(110) Surface Antoine Olenga, N.G. Fazleev Copper based catalysts are of importance to a number of industrial processes including the synthesis of methanol, the reduction and decomposition of nitrogen oxides, and treatment of waste water. In copper catalysis surface oxidation and oxidic overlayers are believed to play a crucial role. In this work using density functional theory within the generalized gradient approximation we have studied the stability and associated electronic properties of different adsorption phases of oxygen on the Cu(110) surface. Especially, we have focused on studies of changes in the interlayer spacing, electron work function, surface energy, electronic density, density of states, and band structure of the Cu(110) surface with oxygen coverage. We have examined the cases of the adsorption of oxygen at various coverages on the nonreconstructed and added row reconstructed Cu(110) surface. Calculations of electronic properties from first principles have been also performed for the (110) surface of Cu2O to use for comparison. The first-principles calculations in this work have been performed using DMOl3 code. The obtained theoretical results have been compared with available experimental data. [Preview Abstract] |
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E1.00019: Space Station Twin Paradox Florentin Smarandache Two twins \textit{T1} and \textit{T2} synchronize their clocks at the same location $L$. Then \textit{T2} travels at relativistic uniform speed to a space station $S$, where he stops. So far, each twin sees the other one younger, since in each twin inertial reference frame the other twin is moving. The time dilation and length contraction are respectively the same in both inertial reference frames. (There is a forth \underline {symmetry}.) Then twin \textit{T2} return from the space station $S$ to the Earth at the location $L$ with a relativistic speed. Again there is a back symmetry since each twin sees the other twin traveling, and again the time dilation and length contraction are respectively the same in both inertial reference frames. But, when \textit{T2} returns to earth he finds out that he is younger than \textit{T1}, since \textit{T2} was traveling while \textit{T1} didn't. (Now there is an \underline {asymmetry}!) [Preview Abstract] |
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E1.00020: Effects of the surface plasmon excitations on photoluminescence by CdSe/ZnS quantum dots Ankit Singh, Suresh Sharma We have studied the influence of localized surface plasmons (LSPs) and surface plasmon polaritons (SPPs) on the photoluminescence (PL) spectra of core/shell type CdSe/ZnS quantum dots. Thin film samples were deposited on glass slides, irradiated by 514-nm polarized beam from an Argon-ion laser, and PL spectra were measured by using a high-resolution 1.25-m JY-Horiba spectrometer equipped with liquid-nitrogen cooled CCD detector. In the first set of experiments, PL spectra were measured on QDs and QDs-Au NPs composites as functions of the intensity and polarization of the 514-nm laser beam. In the second set of experiments, PL spectra were measured by using the Kretschmann geometry, in which the SPPs are excited by $p-$polarized 514-nm laser beam incident upon 40-nm Au film deposited on a high-index prism. The QDs were deposited over the Au film by dissolving them in chloroform. We describe the manner in which the experiments were carried out by using several different configurations and present results, which show clearly the effects of the localized and travelling surface plasmons on PL emission. [Preview Abstract] |
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E1.00021: Quark Propagator in a Theory of Massless Fermions with Superfluidity Sajib Barman, Vivian Incera A QCD inspired effective theory of fermions is considered to study superfluidity. We calculate the quark propagator in a theory with fermion-fermion condensate at finite density. In this theory color degrees of freedom are absent and the quark-quark interaction is modeled through a Yukawa interaction term. The final goal of the work is to find the polarization operator for the scalar field. Finding the quark propagator is needed to then calculate the polarization operator, so the results to be presented are still partial. [Preview Abstract] |
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