Bulletin of the American Physical Society
Joint Fall 2009 Meeting of the Ohio Sections of the APS and AAPT
Volume 54, Number 9
Friday–Saturday, October 9–10, 2009; Delaware, Ohio
Session P1: Poster Session (4:30-5:30pm) |
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Chair: Brad Trees, Ohio Wesleyan University Room: Hamilton-Williams Campus Center Benes Room C |
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P1.00001: Effects of Nanoscal Holes on Schottky Solar Cells Vincent DeGeorge, Andrew Higgins, Sergei Urazhdin Increasingly efficient solar to electrical energy conversion is of increasing interest and demand as a viable and sustainable means of renewable energy. The effects of nanoscale patterning at the metal-semiconductor interface of a schottky solar cell are investigated. Effects beyond those produced by variations in the active area of the cell due to the patterning are expected to be observed. N-type GaAs(100) substrates were used in the fabrication of the thin film solar cells. A selection of samples was made porous on the nanoscale using electrochemical etching. Indium was deposited by thermal evaporation to form the metal-semiconductor schottky barrier. On the porous samples the evaporation was done at an angle so as to form intermittent discontinuities in the schottky barrier on the nanoscale. Both porous and nonporous schottky solar cells underwent current/voltage measurements under various lighting conditions in order to determine their photovoltaic characteristics. Photoresponse was indeed observed in the In-GaAs solar cells. However the collected data remains inconclusive as to the effects of the nanoscale discontinuities on the thin film cell. [Preview Abstract] |
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P1.00002: Linear attenuation coefficient and build up factor of MCP-96 alloy for radiation shielding and protection Deidre Hopkins, Muhammad Maqbool, Mohammed Islam Build-up factors and linear attenuation coefficients of MCP-96 alloy are determined for radiation shielding and protection, using $^{60}$Co and $^{137}$Cs gamma emitters. A narrow collimated beam of $\gamma $-rays is passed through various thicknesses of MCP-96 alloy and the attenuation in the intensity of the beam is determined. The thickness of the 4 x 4 cm$^{2}$ blocks varies from 0.5 cm to 6 cm. Plotting the thickness of the alloy and the corresponding intensity of the beam allowed us to determine its linear attenuation coefficient. The narrow beam geometry is then replaced by broad beam geometry by removing the collimator and the radiation beam is able to interact with the MCP-96 alloy at all possible positions facing the radiation source. Additional radiations obtained by the detector as a result from the scattering of radiation develops the build-up factor. The buildup factor is then calculated using the attenuated beam received by the detector in the broad beam geometry and in the narrow beam geometry. The buildup factor is found to be dependent on the thickness of the MCP-96 attenuator, the beam energy and the source to attenuator distance. These values are providing ways for dose correction in radiation oncology and radiation shielding and protection when MCP-96 is used as tissue compensator or for radiation protection purposes. [Preview Abstract] |
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P1.00003: Towards Closing the Window on Strongly Interacting Dark Matter: Far-Reaching Constraints from Earth's Heat Flow Gregory Mack, John Beacom, Gianfranco Bertone We point out a new and largely model-independent constraint on the dark matter scattering cross section with nucleons, applying when this quantity is larger than for typical weakly interacting dark matter candidates. When the dark matter capture rate in Earth is efficient, the rate of energy deposition by dark matter self-annihilation products would grossly exceed the measured heat flow of Earth. This improves the spin-independent cross section constraints by many orders of magnitude, and closes the window between astrophysical constraints (at very large cross sections) and underground detector constraints (at small cross sections). In the applicable mass range, from about 1 to about 10$^{10}$ GeV, the scattering cross section of dark matter with nucleons is then bounded from above by the latter constraints, and hence must be truly weak, as usually assumed. [Preview Abstract] |
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P1.00004: Stella Surface Imaging of LO Pegasi via Light-Curve Inversion Jessie Miller, Andrea Richard, Robert Harmon The purpose of this research was to map the starspots on LO Pegasi (HIP 106231), a K8 main-sequence star, in order to create an image of the star's photosphere. CCD images of LO Pegasi were taken during May, June, and July 2009 through B, V, R, and I photometric filters using a 0.2-m Meade Instruments LX200 Schmidt-Cassegrain telescope and Santa Barbara Instruments Group ST-8XE CCD camera at Perkins Observatory. Differential aperture photometry was performed on the images so as to create light curves in the form of plots of intensity vs. rotational phase. The lightcurves were processed via the Light-Curve Inversion (LI) algorithm. This algorithm creates a reconstructed image of the star's surface showing the locations of starspots. The locations of the spots visible on the 2009 are at lower latitudes than those deduced from the 2008 light curves. In addition, overall dimming observed of LO Pegasi since 2008 implies that there is a spot on the visible pole. Since a polar spot does not modulate the rotational light curve, it is not reproduced in our images. [Preview Abstract] |
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P1.00005: The Gas and Stellar Kinematics of NGC 4552 Peter Kircher, Jason Pinkney We present kinematics and photometry of the Elliptical galaxy NGC 4552. This is part of a program to measure masses of supermassive black holes in galaxies. Our photometry is derived from V and I band CCD images from the ground and from the Hubble Space Telescope (HST). We find that fitting the 2D surface brightness distribution with parametric Sersic models does not match the light profile as well as standard ellipse fitting. The combined (HST+ground) light profile is used to find the enclosed mass profile of the galaxy. The stellar line of sight velocity distribution is measured from CaII absorption lines at 8498, 8542, and 8662 {\AA} in ground-based long-slit spectroscopy. The stellar velocity dispersion is about 300 km/s, which predicts a black hole mass of about $7\times10^8 M_{mdot}$. Our ground-based long-slit spectra reveal H$\alpha$-emitting ionized gas with a large dispersion and slight rotation. Our HST spectra show that the rotation is more well-ordered at small radii than at large radii, suggesting that a gas disk model can be used to determine a black hole mass. However, HST imaging shows that the subtle dust (which usually follows the gas) is not quite settled into a disk. [Preview Abstract] |
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P1.00006: A Spectroscopic Study of Stars and Star Clusters Anthony Wong, Soeren Meibom We present a study of spectra obtained with the Hectchelle spectrograph on the MMT for late-type stars in the open clusters M67 and NGC6811. We have tested and further developed codes for reducing and classifying Hectochelle spectra. We determine the effective temperature, surface gravity, metallicity, and projected rotational velocity from Hectochelle spectra via cross-correlation with synthetic template spectra. From analysis of solar spectra as well as spectra for members of the well-studied open cluster M67, we find that the most accurate and precise stellar properties are determined when the spectral region containing the Magnesium-B triplet is excluded from the cross- correlation. In this manner, we obtain an age for M67 of 3.9 Gyr. Finally, we use Hectochelle spectra for 1157 stars in the field of the open cluster NGC 6811 to identify 139 candidate cluster members. Our spectral analysis of the NGC 6811 members give a mean cluster radial velocity of 8.7 km/s, a mean cluster metallicity of -0.1, as well as a cluster age of $\sim$1 Gyr and a cluster distance of 955 pc, derived from isochrone fitting to the members in the color-magnitude diagram. [Preview Abstract] |
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P1.00007: The Role of the Equation of State in the Theory of Stellar Energy Dmitri Rabounski The mathematical theory of stellar energy and the internal constitution of stars is based on two equations of equilibrium (mechanical and heat equilibrium), which determine a star as a sphere of substance producing radiation, and are dependent on the equation of state. Eddington's version of the theory (1920's) uses the equation of state of ideal gas, and converges with thermonuclear source of energy. However, huge deficit of solar neutrinos, still registered during decades commencing in the first observations (1960's, Davies and Bahcall), has indicated that stars are not thermonuclear fusion reactors. On the other hand, Jeans' concept of liquid sun and stars (1920's), which never met mathematical basis, is supported by a most recent analysis (Robitaille P.-M. NY Times, 2002, March 17; Progress in Physics, 2006, v.2, 17-21; 2007, v.1, 70-81). Therefore, I suggest the use of the equation of state of incompressible liquid in the equations of equilibrium. This step will lead, after calculation of the respective models of stars, and comparing them to observational data (the mass-luminosity relation, etc.), to another picture of the internal constitution of stars and another source of stellar energy. [Preview Abstract] |
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P1.00008: On the Speed of Rotation of the Isotropic Space (the Home of Photons) Dmitri Rabounski This paper applies the mathematical method of chronometric invariants, which are physical observable quantities in the General Theory of Relativity (Zelmanov A.L., Soviet Physics Doklady, 1956, v.1, 227-230). The isotropic region of the four-dimensional space-time is considered. This is the home for massless light-like particles (e.g. photons). It is shown that the isotropic space rotates, at each its point, with a linear velocity equal to the velocity of light. Even if the problem is tackled in the simplified conditions of Special Relativity, the same result is obtained. It is shown that the light-speed rotation of the isotropic space has a purely geometrical origin due to the space-time metric, where time is presented as the fourth coordinate, expressed through the velocity of light. This presentation is dedicated to Hermann Minkowski, on the 100th anniversary of his ``Raum und Zeit''. [Preview Abstract] |
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P1.00009: Emission Spectroscopy of Rare Gas Plasma David Davenport, Naveed Piracha We report on the emission spectroscopy of rare gas plasma. The spectra were taken using Ocean Optics spectrometer and hollow cathode lamps in the spectral range from 250 nm -- 700 nm. The spectra were analyzed and transition assignments were developed. We formulated data on the widths of line spectra, transition intensities and electron temperature using spectroscopic diagnostic techniques. [Preview Abstract] |
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P1.00010: Improving the a-Si:H and nc-Si:H Back Reflectors Modeled with ZnO Stacks Stephanie Ash, Lila Dahal, Michelle Sestak, Robert Collins, Dinesh Attygalle, Zhuang Huang This report looks to find the best model that will give the optimal reflectance from the ZnO, least absorption in the Ag, most absorption in the Si and the least amount of total reflection by creating a multi-layer ZnO with alternating indices of refraction on a Ag back-reflector. The ZnO high is an intrinsic ZnO and the ZnO low is created theoretically by introducing more free carriers modeled by the Drude behavior in the ZnO dielectric functions. Later, ITO layers with alternating indices of refraction were also placed in the model to improve its performance. The best results are shown and discussed. Finally, some suggestions of work that could be further made on this project are presented. [Preview Abstract] |
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P1.00011: Pressure effects on the solvent denaturation of NADH Erik Alquist, Lauren Regueyra, Joshua Jasensky, M. Junaid Farooqi, Paul Urayama Nicotinamide adenine dinucleotide (NADH) plays a central role in cellular metabolism as an electron donor via an NAD+/NADH redox reaction. NADH conformational state -- whether it is folded or unfolded -- has physiological significance because it takes on an unfolded conformation when bound to proteins. This study examines the effects of pressure on the solvent denaturation of NADH (20$\mu $M NADH in MOPS buffer solution, pH7.4). Using a quartz capillary-based high-pressure chamber, the folding/unfolding transition of NADH was examined through excited-state emission spectroscopy (337 nm excitation) at physiological pressures up to 50 MPa. By using a two-state solvent-denaturation model to determine thermodynamic parameters of solvent denaturation and by using an Arrhenius relationship, the change in volume for the folding-unfolding reaction is determined. [Preview Abstract] |
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P1.00012: Self-Assembly of Guanosine Molecules in Solutions Zheng Li, Maxwell Orseno, Prasenjit Bose, Kiril Streletzky, Alex Jamieson Guanosine and 3-Acetyl Guanosine monomers are expected to form cylindrical polymeric rods in a solution of KCl and H2O. Multi-angle Depolarized Dynamic Light Scattering (DDLS) and Static Light Scattering were used to study these solutions at various monomer concentrations. The correlation functions obtained from VV and VH experiments of DDLS were fitted to a sum of two stretched exponentials and their decay rates (G) were obtained using spectral time moment analysis. The diffusion coefficients deduced from G were analyzed to find length of the rods formed by Guanosine monomers. The concentration dependences of diffusion coefficients were compared with theoretical models of dilute and semi-dilute regimes. The fast mode of VV DDLS measurements was attributed to pure translation diffusion of rods; the slow VV mode had properties of large dynamic aggregates formed in solutions. The fast mode of VH DDLS had properties rotational diffusion, while the slow VH mode was found to be similar to the slow VV mode (large dynamic aggregates). SLS measurements at different solution concentrations yielded the aggregation concentration at which significant formation of rods occurs. The apparent molecular weight and radius of gyration of the rods were inferred from SLS spectra at different concentrations of Guanosine. [Preview Abstract] |
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P1.00013: Spectroscopic Study of Protein Dynamics in Viscous Solvent Krista Freeman, Alexander Agapov, Kiril Streletzky, Alexei Sokolov The dielectric properties of pure glycerol, glycerol-water, and glycerol-water-protein solutions were studied by Dielectric Spectroscopy and Depolarized Dynamic Light Scattering (DDLS) at a wide range of temperatures and frequencies. Analysis of the dielectric spectra revealed three relaxation processes related to protein dynamics (relaxations due to protein rotation, large scale protein motions, and protein-hydration water coupled dynamics) as well as two processes due to the solvent (low frequency relaxation of unknown origin and the main structural relaxation of glycerol). Preliminary investigations with DDLS suggest a direct correlation with the certain relaxations observed in the dielectric spectra. The current study aims to explore the influence of the solvent on the dynamics of the protein, such as preferential hydration of the protein in solution and the coupled or decoupled nature of the protein and solvent dynamics, using both spectroscopic methods mentioned above. In the dielectric studies, all protein solutions tested exhibit strong decoupling of the protein relaxation from the glycerol structural relaxation, especially closer to the glass transition temperature. The dielectric analysis also suggests weak preferential hydration of the protein in solution. [Preview Abstract] |
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P1.00014: Raman spectral analysis of wet-spun films of CaDNA with varying amounts of CaCl$_{2}$ as a function of relative humidity M. Schwenker Smith, Scott Lee, Allan Rupprecht Raman spectroscopy has been used to probe the amount of DNA in the B conformation in wet-spun films of CaDNA which contain varying amounts of CaCl$_{2}$ as a function of relative humidity. This determination is made by measuring the intensity of the B-form marker band (at about 834 cm$^{-1})$ relative to a vibrational mode localized in the bases. Our experiments show that CaDNA is in the B conformation from 98{\%} relative humidity (rh) down to 75{\%} and is disordered at lower humidities. Interestingly, a maximum in the relative amount of B-DNA is observed near 80{\%} rh. [Preview Abstract] |
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P1.00015: Approximate Entropies for Stochastic Time Series and EKG Time Series of Patients with Epilepsy and Pseudoseizures Brian Vyhnalek, Ulrich Zurcher, Rebecca O'Dwyer, Miron Kaufman A wide range of heart rate irregularities have been reported in small studies of patients with temporal lobe epilepsy [TLE]. We hypothesize that patients with TLE display cardiac dysautonomia in either a subclinical or clinical manner. In a small study, we have retrospectively identified (2003-8) two groups of patients from the epilepsy monitoring unit [EMU] at the Cleveland Clinic. No patients were diagnosed with cardiovascular morbidities. The control group consisted of patients with confirmed pseudoseizures and the experimental group had confirmed right temporal lobe epilepsy through a seizure free outcome after temporal lobectomy. We quantified the heart rate variability using the approximate entropy [ApEn]. We found similar values of the ApEn in all three states of consciousness (awake, sleep, and proceeding seizure onset). In the TLE group, there is some evidence for greater variability in the awake than in either the sleep or proceeding seizure onset. Here we present results for mathematically-generated time series: the heart rate fluctuations \textit{$\xi $} follow the $\Gamma $ statistics i.e., \textit{p($\xi )=\Gamma $}$^{-1}$\textit{(k) $\xi $}$^{k}$ exp\textit{(-$\xi )$}. This probability function has well-known properties and its Shannon entropy can be expressed in terms of the $\Gamma $-function. The parameter $k$ allows us to generate a family of heart rate time series with different statistics. The ApEn calculated for the generated time series for different values of $k $mimic the properties found for the TLE and pseudoseizure group. Our results suggest that the ApEn is an effective tool to probe differences in statistics of heart rate fluctuations. [Preview Abstract] |
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P1.00016: Environmental and Structural Effects on Intramolecular Charge Transfer Exhibited by 4-Aminobenzoic Acid and its Derivatives Mitchell Thayer, Sarah Schmidtke This study inspected intramolecular charge transfer in a variety of conditions by methodically adjusting the parent compound structure and solvent properties under spectroscopic analysis. 4-aminobenzoic acid and its derivatives were analyzed in three buffers of varying pH (2, 7, 10). The various compounds were used to study structural effects, while the placement in buffers allowed control of the protonation states of the molecules. The samples were each scanned for absorbance to determine excitation wavelengths which were used for subsequent fluorescent spectroscopic analysis. The charge transfer, when exhibited, is recognized by dual fluorescence. Varying the temperature of the scans allowed analysis of the thermodynamic driving forces for the reaction while the particular solvent-solute combinations that exhibited the phenomenon lend insight to the conditions conducive to charge transfer. To study what controlled the extent of the phenomenon, titrations were carried out to determine the amine pKa and computational models were generated to inspect hybridization and its influence on photophysical behavior. [Preview Abstract] |
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P1.00017: Drug Loading Capacity of Environmentally Sensitive Polymeric Microgels Ryan McDonough, Kiril Streletzky, Mekki Bayachou, Pubudu Peiris Microgel nanoparticles consisting of cross-linked polymer hydroxypropyl cellulose chains have a temperature dependent volume phase transition, prompting the use of microgels for controlled drug transport. Drug particles aggregate in the slightly hydrophobic interior of microgels. Microgels are stored in equilibrium until the critical temperature (Tv) is reached and the volume phase transition limits available space, thus expelling the drugs. Our study was designed to test this property of microgels using amperometric electrochemical methods. A critical assumption was that small molecules inside microgels would not interact via diffusion with the electrode surface and thus total current would be decreased across the electrodes in a microgel sample. A room temperature (Troom) flow amperometric measurement comparing microgel/tylenol solution with control tylenol samples yielded about 20\% tylenol concentration reduction of the microgel sample. Results from the steady state electrochemical experiment confirm the presence of about 20\% tylenol concentration drop of the microgel sample compared to control sample at Troom. Using the steady-state experiment with a cyclic temperature ramp from Troom to beyond Tv showed that the tylenol concentration change between the temperature extremes was greater for the microgel solution than for the control solution. [Preview Abstract] |
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P1.00018: Measuring and Modeling the Influence of Hydrostatic Pressure on the Magnetotransport Properties of Pure Sb$_{2}$Te$_{3}$ Single Crystals Stephen Tacastacas, Jeffrey S. Dyck, Cestmir Drasar, Petr Lostak The effect of hydrostatic pressure up to 16 kbar was investigated in conjunction with the temperature dependence of the magnetotransport properties on a pure Sb$_{2}$Te$_{3}$ single crystal. The results show that an increase in pressure suppresses the electrical resistivity of the sample and increases the magnetoresistance. The Hall coefficient decreased modestly with increasing pressure, and showed some dependence on magnetic field. Below 100 K, the dependence of the resistivity on magnetic field was distinctly non-parabloic. To explain the results one must allow for the possible participation of more than one band in the transport, or for the single-band values of the Hall and structural factor to be different from unity. A single valence band model was used to fit both the magnetoresistance and the Hall effect data which takes into account both the Hall and structural factors as free parameters to determine the sample's carrier concentration and the carrier mobility. The results will be discussed in the context of the potential need to incorporate a second band. [Preview Abstract] |
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P1.00019: Theoretical Modeling of the Thermal Conductivity of Nanostructured PbTe Diego Hernandez, Jeffrey S. Dyck, Yixin Zhao, Clemens Burda Thermoelectric materials are able to convert heat energy into electrical energy and vice versa. One route toward increasing thermoelectric efficiency is by creating nanometer-sized inclusions in traditional thermoelectric materials that would scatter acoustic phonons, which transmit thermal energy, more strongly than free charge carriers. For this study, pellets of bulk, polycrystalline lead telluride with varying concentrations of PbSe nanoparticle additives were prepared by pressing mixed powders. Measurements of thermal conductivity were performed from 8 K to 300 K. Experimental thermal conductivity data were compared to a model of the lattice thermal conductivity based on Debye theory. The model takes into account grain boundary, phonon-phonon, and point defect scattering, and an additional scattering term that describes scattering by spherical nanoparticles. Interestingly, the theoretical analysis reveals that the addition of the nanoparticle scattering term does not improve the fitting significantly. However, we are able to see trends that support the hypothesis that some fraction of the nanoparticles are behaving as the model predicts. [Preview Abstract] |
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P1.00020: Computational polymer physics: Hard-sphere chain in solvent systems Avinash Gautam, Daniel Gavazzi, Mark Taylor In this work we present results for chain conformation in two simple chain-in-solvent systems constructed from hard-sphere monomers of diameter D. The first system consists of a flexible chain of fused hard spheres (i.e., bond length L=D) in a monomeric hard-sphere solvent. The second system consists of a flexible tangent hard-sphere chain (L=D) in a dimeric hard-sphere solvent with L=D. These systems are studied using Monte Carlo simulations which employ both single-site crankshaft and multi-site pivot moves to sample the configuration space of the chain. We report chain structure, in terms of site-site probability functions, as a function of solvent density. In all cases, increasing solvent density leads to an overall compression of the chain. At high solvent density the chain conformation is closely coupled to the local solvent structure and we speculate that incommensurate structures may lead to interesting conformational transitions. [Preview Abstract] |
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P1.00021: Conformation of a Lennard-Jones Chain in Explicit Solvent: A Solvation Potential Approach Shishir Adhikari, Mark Taylor Computer modeling of polymer systems is important both for developing new materials and understanding how biological macromolecules function. This type of modeling is made difficult by the large system sizes required to study a polymer chain in solvent. The problem can be formally simplified by mapping the ``many-body'' chain-in-solvent system to a single chain plus a ``few-body'' effective potential that mimics the role of the solvent. This few-body potential (where few = the number of chain monomers) depends on the instantaneous conformation of the chain and is, in general, not practical to compute. Thus, one generally assumes a two-site decomposition of this potential. Here we use Monte Carlo simulation techniques to study a Lennard-Jones chain-in-solvent system. We construct a set of ``exact'' two-site solvation potentials for a 5-mer chain thereby demonstrating the validity of the two-site approximation. We then construct approximate solvation potentials for long chains, which combine exact short chain results with the pure solvent potential of mean force. Our solvation potential results compare well with simulation results for the full chain-in-solvent systems. [Preview Abstract] |
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P1.00022: Study of aluminum-doped zinc oxide powders using x-ray diffraction James C. Gallagher, James B. Miller, Stephanie Hsieh Zinc oxide has been proposed as a material for next generation gas sensors. In this study, aluminum-doped zinc oxide powders were synthesized via sol gel chemistry using zinc acetate, aluminum tri-tert butoxide and aluminum acetylacetonate precursors. The aluminum-to-zinc ratio in the zinc oxide powders ranged from 0-5\%. The powders were calcined at temperatures from 300$^{\circ}$C to 700$^{\circ}$C, and their mean crystallite sizes were analyzed using x-ray diffraction. A maximum in mean crystallite size was observed at $\approx$0.25-1\% aluminum, the same composition region for which other researchers have reported a maximum in electrical conductivity. It is also found that adding high amounts ($>$2\% Al:Zn ratio) of aluminum to the zinc oxide can retard sintering at higher temperatures. [Preview Abstract] |
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P1.00023: Infrared studies of novel iron-based superconductors Adam Koncz, S.V. Dordevic, N. Stojilovic, Rongwei Hu, C. Petrovic The discovery of new iron-based superconductors last year has excited the scientific community. Besides copper oxides, this is the only other example of materials that superconduct at temperatures higher than 50 K. In this project we have used infrared spectroscopy to study the optical properties of FeTe$_{0.87}$S$_{0.13}$ at varies energy scales. We have also examined how the optical properties changed as a function of temperature and high magnetic fields (up to 18 Tesla). Our results show that the superconducting state in iron-based superconductors develops from unconventional normal state, without well defined quasiparticles. This demonstrates the potential of infrared spectroscopy to provide insight into the unique properties of these novel materials. [Preview Abstract] |
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P1.00024: Delta Function Potential Randomly Placed within an Infinite Square Well Josh Stoffel, Mellita Caragiu A simple and elegant equation has been derived for calculating the energy spectrum of a quantum particle encountering a delta function potential arbitrarily placed within an infinite square well. The solutions to this exact equation can be expressed in terms of analytical solutions to a simpler equation, to which correction terms can be added, to any desired precision. Formulas for the first order correction terms are derived, for any value of the energy eigenvalues; distinction is being made between rational versus irrational values for the coordinate of the delta function potential. [Preview Abstract] |
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P1.00025: Schr\"{o}dinger Equation and the Quantization of the Celestial Systems Florentin Smarandache, V. Christianto In the present article, we argue that it is possible to generalize Schr\"{o}dinger equation to describe quantization of celestial systems. While this hypothesis has been described by some authors, including Nottale, here we argue that such a macroquantization was formed by topological superfluid vortice. We also provide derivation of Schr\"{o}dinger equation from Gross-Pitaevskii-Ginzburg equation, which supports this superfluid dynamics interpretation. [Preview Abstract] |
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P1.00026: Scaling Model for Symmetric Star Polymers Durgesh Rai, Ramnath Ramachandran, Gregory Beaucage Star polymers have been widely investigated for its synthesis, structure and properties owing to their suitability in various applications. SANS has emerged as a useful tool to understand the architecture of these structures for their qualitative analysis. We will present a scaling model to analyze SANS data for dilute C60 connected Poly-urethane star polymers having six arms. A Unified Function Fit is employed for analyzing star polymers has been presented and tested under good and \textit{$\theta $}-solvent conditions. The understanding of architecture of the star polymer is extended by considering rigid, zero entropy states, where at one extreme, the arms get linearly extended while at the other extreme, they collapse into densely packed spherical state. A generalized model for symmetric star polymers implicating the understanding of the star conformations under different solvent conditions will be presented. [Preview Abstract] |
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P1.00027: Libration Patterns in Synchronized Orbits of Natural Satellites David Carpenter, Barbara Andereck The synchronization of the orbital periods of the natural satellites of planets resembles the synchronization of mechanical oscillators. When the satellites are of comparable mass, each gravitationally influences the orbits of the other satellites. Eccentricities of the orbits cause nonlinear oscillations. The satellites can therefore modulate each other's periods slightly through altering each other's eccentricities. In this study, Mathematica 7 was used to model a planet with only two satellites, based on the orbital properties of Jupiter and two of its satellites, Io and Europa. This was chosen because Io, Europa and Ganymede actually are synchronized with orbital periods in ratios of 1:2:4. The orbits are also phase-locked, with conjunctions between Io and Europa always occurring at Io's perijove, and at Europa's apojove. If the angle between the semimajor axes of the two orbits is deliberately displaced in the model, libration of the axes occurs. The characteristics of these libration patterns were investigated by mapping the changing location of the perijoves over thousands of orbits. By varying the distances of the satellites from the planet, the increase in the strength of perturbations as period resonances were approached was also studied. [Preview Abstract] |
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P1.00028: A Matched Filter for Chaos Mark Stahl, Jonathan Blakely, Ned Corron In conventional communication theory, a matched filter provides optimal reception of information through additive Gaussian white noise. Chaos communication schemes have always performed worse than conventional schemes in the presence of noise due to the lack of a matched filter. We present a novel chaotic oscillator for which a matched filter exists. This oscillator differs from other known chaotic systems in that its waveform can be written as a linear superposition of a single basis function with random polarity at integer time steps. The matched filter is a linear filter with the time reversed basis function as its impulse response. We show experimental circuit implementations of both the oscillator and the matched filter. The matched filter output is shown to directly reveal the information content of the chaotic waveform. [Preview Abstract] |
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P1.00029: Quantum Dynamics of Nonlinear Oscillators Brad Trees, Elizabeth Segelken Motivated by an analogy to Josephson junctions, we studied the dynamics of a damped, driven pendulum in the quantum limit. We model the effects of damping by means of the quantum state diffusion method, in which the Hamiltonian in Schr\"odinger's equation is augmented by terms constructed from combinations of Lindblad operators. The dynamics were observed by looking at the time dependence of the expectation values of the pendulum's angular momentum and mechanical energy. We present our results. The next step is to couple two damped, driven quantum pendula and search for evidence of synchronization. This would suggest that it is possible to synchronize coupled small-area Josephson junctions, which must be treated in the quantum limit. [Preview Abstract] |
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P1.00030: Algebraic Model of the Nucleus Austin McGrath, Gabriela Popa The atomic nucleus can be found in discrete energies the same way the atom itself does. These energies are found in few groups separated by some distances. For these reason, the model that best describe the energy levels is called the shell model. The nuclei go from having one energy value to another by getting a extra energy (excitations) or by loosing some energy (emitting energy). There are several microscopic and macroscopic models that are able cu calculate these energies and the transition probabilities from one energy to another for certain groups of nuclei. We are working on using an algebraic model to describe heavy deformed nuclei with an atomic mass between 150 to 200. [Preview Abstract] |
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P1.00031: Lifetime Measurements in $^{71}$Se A.R. Howe, N.R. Baker, R.A. Kaye, S.R. Arora, J.K. Bruckman, S.L. Tabor, T.A. Hinners, C.R. Hoffman, S. Lee, J. D\"{o}ring In the light selenium isotopes, $^{71}$Se appears to be a transitional nucleus, showing signs of competing single particle and collective structures, but its level structure is not well known. The present work measured lifetimes in $^{71}$Se in order to quantify the degree of collectivity as a function of spin as the configuration of the unpaired neutron changes. $^{71}$Se nuclei were produced at high spin by a $^{54}$Fe($^{23}$Na,$\alpha$pn) fusion reaction at 80 MeV conducted at Florida State University. Fifteen lifetimes were measured from the resulting gamma-ray coincidence data using the Doppler-shift attenuation method. Experimental transition quadrupole moments $Q_t$ were inferred from the lifetimes and found to be in rough agreement with the predictions of cranked Woods-Saxon calculations. Comparisons with neighboring odd-mass nuclei confirmed that $^{71}$Se exhibits moderate collectivity. Based on coincidence relations and systematic arguments, the level scheme was enhanced and extended to higher spin. A band that was previously assigned positive parity was reassigned as the ``missing'' signature partner of an existing negative-parity band. [Preview Abstract] |
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P1.00032: The Proof of the ``Vortex Theory of Matter'' Konstantin Gridnev, Russell Moon, Victor Vasiliev According to the Vortex Theory, protons and electrons are three-dimensional holes connected by fourth-dimensional vortices. It was further theorized that when photons are absorbed then readmitted by atoms, the photon is absorbed into the proton, moves through the fourth-dimensional vortex, then reemerges back into three-dimensional space through the electron$^{2}$. To prove this hypothesis, an experiment was conducted using a hollow aluminum sphere containing a powerful permanent magnet suspended directly above a zinc plate. Ultraviolet light was then shined upon the zinc. The zinc emits electrons via the photoelectric effect that are attracted to the surface of the aluminum sphere. The sphere was removed from above the zinc plate and repositioned above a sensitive infrared digital camera in another room. The ball and camera were placed within a darkened box inside a Faraday cage. Light was shined upon the zinc plate and the picture taken by the camera was observed. When the light was turned on above the zinc plate in one room, the camera recorded increased light coming from the surface of the sphere within the other room; when the light was turned off, the intensity of the infrared light coming from the surface of the sphere was suddenly diminished. Five other tests were then performed to eliminate other possible explanations such as quantum-entangled electrons. [Preview Abstract] |
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P1.00033: Apparent non-conservation of linear momentum in collision of golf balls Ben Yu-Kuang Hu, Alice Chance We present data of a one-dimensional collision between a rolling and a stationary golf ball on a rough surface, obtained by video capture using an digital camcorder and analyzed using Logger Pro 3.7 software from Vernier Software and Technology LLC. The collisions appear {\em not} to conserve linear momentum. We argue, using conservation of {\em angular} momentum, that this apparent non-conservation of linear momentum is not, as might be expected, due to the sliding friction of the balls with the rough horizontal surface after they collide, but rather is due to the friction between the covers of the balls during the short time of contact during the collision. [Preview Abstract] |
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P1.00034: Using physics to find evidence of predatory behavior by dinosaurs Scott Lee Students are enthused by working on interesting and novel problems. Dinosaur problems are always greeted with interest and enthusiasm. In this poster, a methodology for estimating locomotion speeds from footprint pathways is developed. This technique is then applied to dinosaur footprints from the fossil record. This analysis allows for the detection of predatory behavior by dinosaurs. [Preview Abstract] |
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P1.00035: Plasma sheath around a large disk and associated sheath area T.E. Sheridan The structure of the plasma sheath around a thin, circular disk biased below the plasma potential is calculated by allowing a pulsed sheath to relax to a steady-state configuration using a hybrid code with cold, kinetic ions and Boltzmann electrons. The sheath area $A_{s}$ (i.e., the effective collecting area of the disk) is calculated for disk radii from 25 to 200 times the electron Debye length and biases from $-5$ to $-50$ times the electron temperature (in eV). The normalized sheath area, $A_{s}/A_{p}-1$, where $A_{p}$ is the disk's area, is found to have a power law dependence on both bias and radius over the range of values considered. An empirical analytical expression is given for the sheath area as a function of radius and bias, and the asymptotic behavior for large radius is identified. This work is directly applicable to the problem of ion collection by planar disk Langmuir probes. [Preview Abstract] |
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P1.00036: Fluorescence and UV-vis Spectroscopy of Synovial Fluids Marie J. Pinti, Nenad Stojilovic, Mark W. Kovacik Total joint arthroplasty involves replacing the worn cartilaginous surfaces of the joint with man-made materials that are designed to be biocompatible and to withstand mechanical stresses. Commonly these bearing materials consist of metallic alloys (TiAlV or CoCrMo) and UHMWPE. Following joint arthroplasty, the normal generation of micro-metallic wear debris particles that dislodge from the prosthesis has been shown to cause inflammatory aseptic osteolysis (bone loss) that ultimately results in the failure of the implant. Here we report our results on the novel use of Fluorescence and UV-vis spectroscopy to investigate the metallic content of synovial fluid specimens taken from postoperative total knee arthroplasties. Preliminary finding showed presence of alumina and chromium is some specimens. The ability to detect and monitor the wear rate of these implants could have far reaching implications in the prevention of metallic wear-debris induced osteolysis and impending implant failure. [Preview Abstract] |
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P1.00037: High-pressure, fluorescence-based sensing of calcium ions using Indo-1 Jordan Ryan, Erik Zachwieja, Sara R. Savage, Paul Urayama Because calcium is used as a near-universal signaling ion in biological systems, accurate sensing of calcium-ion concentration under pressure is important in understanding pressure effects on cellular physiology. Indo-1 is a dual-wavelength fluorophore with an emission spectrum that changes upon calcium-ion binding. Despite studies under physiological pressures of up to 50 MPa showing piezochromic behavior in the excited-state emission, Indo-1 continues to follow two-state binding-unbinding behavior. This demonstrates that Indo-1 remains useful under pressure as a probe for quantitative calcium-ion sensing. The two-state model is also used to determine the thermodynamic volume change upon calcium dissociation from Indo-1, which we find to be consistent with other metal-ion chelators. [Preview Abstract] |
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