Bulletin of the American Physical Society
Joint Fall 2010 Meeting of the APS Ohio Section and AAPT Appalachian and Southern Ohio Sections
Volume 55, Number 8
Friday–Saturday, October 8–9, 2010; Marietta, Ohio
Session P1: Poster Session (4:15-5:30PM) |
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Room: Andrews Hall Great Room |
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P1.00001: Incident Angle Dependence of Organic Solar Cells Vincent DeGeorge, Brent Valle, Kenneth Singer We have been recently studying the use of interference effects to enhance optical absorption in polymer photovoltaic cells. These interference effects are expected to be angle dependent. We measure here the angle dependent absorption and compare with numerical simulations. The cells used were P3HT/PCBM active layer, organic photovoltaic cells. The angular dependence of the cells' reflection was measured using an Ocean Optics light source and spectrophotometer and a precision rotary stage apparatus. The experimental results were compared to a Matlab simulation of the characteristic matrix problem. Analysis showed that the reflection/absorption peaks predicted by the simulation largely coincided in wavelength to those observed in experiment. Moreover, no additional cavity resonance can be attributed to incidence angle. [Preview Abstract] |
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P1.00002: Evaluation of the dielectric constant for RF shimming at high field MRI Mohan Jayatilake, Judd Storrs, Wen-Jang Chu, Jing-Huei Lee Optimal image quality for Magnetic Resonance Imaging (MRI) at high fields requires a homogeneous RF (B1) field; however, the dielectric properties of the human brain result in B1 field inhomogeneities and signal loss at the periphery of the head. These result from constructive and destructive RF interactions of complex wave behaviour, which become worse with increasing magnetic field strength. Placement of a shim object with high-dielectric constant adjacent to the body has been proposed as a method for reducing B1 inhomogeneity by altering wave propagation within the volume of interest. Selecting the appropriate permittivity and quantity of material for the shim is essential. Whereas previous work has determined the dielectric properties of the shim empirically, this work introduces an improved theoretical framework for determining the requisite dielectric constant of the passive shim material directly by increasing the axial or minimizing the radial propagation constant. [Preview Abstract] |
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P1.00003: Weak Lensing Measurements with the Hubble Space Telescope Advanced Camera for Surveys Kellen Murphy We present the weak lensing analysis of imagery from 10 high-redshift clusters using the Hubble Advanced Camera for Surveys, from the ESO Distant Cluster Survey (EDisCS). Weak Gravitational Lensing is the miniscule bending of light from distant background galaxies by the presence of large foreground masses. Particularly, we examine images of galaxy clusters at reshifts z $<$ 1.0 (corresponding to a physical distance on the megaparsec scale) and look for distant elliptical galaxies (i.e. redshifts z $>>$ 1.0). These galaxies are expected to have an isotropic distribution in space, and their semi-major axes should subtend the entire possible space of orientation angles (i.e. when statistically measuring the mean ellipticity, we should find it averages to zero across a well-defined sample). These ten clusters, in particular, provide unprecedented depth and allow a perfect test bed on which to study the application of weak lensing tomography. [Preview Abstract] |
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P1.00004: Some Unsolved Problems, Questions, and Applications of the Brightsen Nucleon Cluster Model Florentin Smarandache Brightsen Model is opposite to the Standard Model, and it was build on John Weeler's Resonating Group Structure Model and on Linus Pauling's Close-Packed Spheron Model. Among Brightsen Model's predictions and applications we cite the fact that it derives the average number of prompt neutrons per fission event, it provides a theoretical way for understanding the low temperature / low energy reactions and for approaching the artificially induced fission, it predicts that forces within nucleon clusters are stronger than forces between such clusters within isotopes; it predicts the \textit{unmatter} entities inside nuclei that result from stable and neutral union of matter and antimatter, and so on. But these predictions have to be tested in the future at the new CERN laboratory. [Preview Abstract] |
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P1.00005: Tunable Infrared Laser Photodetachment Spectroscopy of Ce$^{-}$ Y.-G. Li, R.M. Alton, S.E. Lou, D.J. Matyas, R.L. Field III, N.D. Gibson, C.W. Walter, D. Hanstorp The negative ion of cerium has been investigated using tunable infrared laser photodetachment spectroscopy. The relative cross section for neutral atom production was measured with a crossed laser-beam---ion-beam apparatus over selected photon energy ranges between 0.56 -- 0.7 eV. The photodetachment spectrum reveals several sharp peaks due to negative ion resonances. The energies and widths of the resonances were determined by fitting with Fano profiles. The results suggest that at least some of these resonances are due to transitions from the Ce$^{-}$ (4$f$5$d^{2}$6$s^{2} \quad ^{4}H_{9/2})$ excited fine-structure level, which was recently predicted to be bound by 0.562 eV [1].\\[4pt] [1] S.M. O'Malley and D.R. Beck, \textit{Phys. Rev. A} \textbf{79}, 012511 (2009). [Preview Abstract] |
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P1.00006: Tunable Infrared Laser Photodetachment Spectroscopy of La$^{-}$ R.M. Alton, Y.-G. Li, D.J. Matyas, S.E. Lou, C.W. Walter, N.D. Gibson The negative ion of lanthanum has been investigated using tunable infrared laser photodetachment spectroscopy. The relative cross section for neutral atom production was measured with a crossed laser beam-ion beam apparatus over selected photon energy ranges between 0.3 -- 0.5 eV. The photodetachment spectrum reveals several sharp peaks due to negative ion resonances. The energies and widths of the resonances were determined by fitting with Fano profiles. The results are compared with theoretical calculations on excited states of La$^{-}$ [1].\\[4pt] [1] S.M. O'Malley and D.R. Beck, \textit{Phys. Rev. A} \textbf{81}, 032503 (2010). [Preview Abstract] |
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P1.00007: The stability mechanism of MJ0305 Hyundeok Song, Thomas Beck Methanococcus jannaschii (MJ) is a methane-producing thermophile, which was discovered in a 2600m-deep Pacific Ocean vent in 1983. It has the ability to thrive at high temperatures and high pressures, which are unfavorable for most life forms. There have been some experiments to study its stability under extreme conditions, but still the origin of the stability of MJ is not exactly known. MJ0305 is MJ's chloride channel protein. We have investigated the stability mechanism of MJ0305 by computer simulation. The structure of MJ0305 was built by homology modeling. We compared the stability of MJ0305 with mesophilic Ecoli at 300K, 330K, 360K, and 1atm, 130atm, 260atm by computer simulation to test the effects of both temperature and pressure. Our results show that high temperatures and high pressures significantly affect the salt bridges and hydrogen bonds. High temperatures decreased the average number of hydrogen bonds for Ecoli and MJ0305. However, high pressures at 360K increased the number of salt bridges for Ecoli and MJ0305. The radius of gyration of MJ0305 was decreased at high temperatures. Increased compactness at high temperatures, and Increased salt bridges at high pressures make MJ0305 more stable. This research may have impacts on renewable energy and chemical sensors. [Preview Abstract] |
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P1.00008: Dynamics of linear polymers in a microchannel fluid flow Prasenjit Bose, Petru Fodor, Miron Kaufman Examination of the dynamics of polymers in a fluid flow is an important topic of research because of potential biomedical applications. We simulated the motion of a linear polymer caried in a laminar fluid flow inside a rectangular channel. Our model polymer is made up of beads which are connected by springs. When the polymer is released in the fluid elastic and advection forces act on each bead. The Newton's 2nd law for each bead is integrated numerically using 4th order Runge-Kutta technique. The dynamics of this nonlinear mechanical system depends on the values of the spring equilibrium distance (a), mass of a bead (m), the initial fluid inflow constant (B), and the spring constant (k). Various trials were conducted by varying some of these parameters and the results were recorded and plotted. It was observed that the motion of the polymer was more noisy for higher values of a and k. The variation of time periods with the changing parameters was studied numerically. [Preview Abstract] |
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P1.00009: Low frequency Raman study of the nucleosides Craig Koontz, Scott Lee In both transcription and replication, the two helices of the DNA molecule move apart. Consequently, vibrations involving the relative motions of large portions of the molecule with respect to one another are of intrinsic interest. Such vibrations have relatively low frequencies because they involve weak bonds and large masses. Low frequency modes are difficult to observe in Raman spectroscopy because they are very close to the signal from the Rayleigh scattered light (which is very intense). In this poster, we will describe our results for the eight nucleosides: adenosine, deoxyadenosine, guanosine, deoxyguanosine, cytidine, deoxycytidine, uracil and deoxythymidine. [Preview Abstract] |
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P1.00010: Study of Protein Dynamics in Viscous Solvent Krista Freeman, Alexander Agapov, Alexei Sokolov, Kiril Streletzky The dynamic processes apparent in glycerol:water:lysozyme solutions over a large temperature range were studied with Dielectric Spectroscopy (DS) and Dynamic Light Scattering Spectroscopy (DLS).~ Analysis of the DS spectra reveals a decoupling of large-scale protein motions from the main structural relaxation of glycerol.~ Further studies show a decoupling of protein rotation, large-scale protein motions, and protein diffusion (as measured by DLS) from solution viscosity.~ The decoupling is analogous to that of chain and segmental polymer dynamics with small-scale heterogeneities explained by preferential hydration of the protein in solution.~~ [Preview Abstract] |
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P1.00011: Characterization of Biological Molecules with Time-Domain Terahertz Spectroscopy Meagan Bechel, Jason Deibel, Saber Hussian, Stanley Smith, Sayta Ganti, Michael Moulton Terahertz (THz) spectroscopy is distinctly appealing for characterization of biological molecules because many biological compounds have vibrational modes within the THz range. These vibrational modes often lead to a unique spectrum for each substance, allowing easy differentiation. The aim of this study is to utilize time-domain terahertz spectroscopy to calculate the frequency-dependent absorption coefficient and refractive index for several amino acids and proteins, including bovine and human serum albumin, glycine, and L- and D-histidine. The histidine study seeks to investigate the optical isomer differention capabilities of THz spectroscopy. It is also hoped that the characterization of proteins will lead to further studies examining the conformational changes related to disease detection. [Preview Abstract] |
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P1.00012: Design and Characterization of Thermally~Responsive Nanoparticles:~Exploring Structure, Shape and Dynamics with Light Scattering Kaitlin Vandemark, Ali Ghoorchian, Kiril Streletzky, Nolan Holland Environmentally responsive nanoparticles synthesized from elastic-like polypeptides (ELP) present a promising system for applications as biosensors, drug delivery vehicles, and viscosity modifiers. These nanoparticles undergo a transition from a soluble state at room temperature to micelles above the transition. The size, shape, and dynamics of micelles above the transition as well as effects of the solvent salt concentration and pH on the transition are important to understand from scientific and application points of view. This system has been characterized with high resolution multiangle Dynamic and Static Light Scattering Spectroscopies. We confirmed the transition of the system from ELP extended trimers and their non-spherical formations into compact micelles. We discovered that micellar size and structure are sensitive to pH of the solution and that samples show signs of aging upon storing and air exposure. We found that micelles generally exhibit properties of the hyperbranched spheres while their shape becomes much more elongated in the window of pH: 10.1-10.3. We also found that the size of micelles strongly depends on salt concentration displaying at three different size regimes (2Rh: 20-45nm at 0-15mM; 100-150nm at 25-40mM; 250nm at 45mM) with different salt concentration dependences. [Preview Abstract] |
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P1.00013: Measuring Solvent Content of Macromolecular Crystals Using Fluorescence Recovery after Photobleaching Matthew Siewny, Jan Kmetko We work out a novel protocol for measuring the solvent content (the fraction of crystal volume occupied by solvent) in biological crystals by the technique of fluorescence recovery after photobleaching (FRAP). Crystals of proteins with widely varying known solvent content (lysozyme, thaumatin, catalase, and ferritin) were grown in their native solution doped with sodium fluorescein dye and hydroxylamine (to prevent dye from binding to amine groups of the proteins.) The crystals were irradiated by a broadband, high intensity light through knife slits, leaving a rectangular area of bleached dye within the crystals. Measuring the flow of dye out of the bleached area allowed us to construct a curve relating the diffusion coefficient of dye to the channel size within the crystals, by solving the diffusion equation analytically. This curve may be used to measure the solvent content of any biological crystal in its native solution and help determine the number of proteins in the crystallographic asymmetric unit cell in x-ray structure solving procedures. [Preview Abstract] |
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P1.00014: A Model of Smarandache Geometry in Quantum Mechanics Ion Patrascu Let's consider a simple model of a Smarandache Geometry built in the following way: - an Euclidean plane $\alpha$, where through any exterior point to a given line (d) there is only one parallel line; - and an Elliptic sphere (S), where lines are defined as the big sphere circles, and points are the regular points on the sphere's surface; this is a Riemannian model of an Elliptic Geometry; - suppose the plane $\alpha$ cuts the sphere (S) upon a big sphere circle (C) into two equal parts; let's A and B be two distinct points on (C), which simultaneously belongs to both: the Euclidean plane $\alpha$ and to the Non-Euclidean sphere (S); therefore, the plane $\alpha$ together with the sphere (S) form a model (M) of a Smarandache Geometry. This model can be interpreted in Quantum Mechanics as follows: - \textbf{a particle (P) that it is and it is not in a place in the same time}, is like this circle (C) which is a line [if (C) is referred to the sphere (S)] and it is not a line [if (C) is referred to the plane $\alpha$] in the model (M) simultaneously; \textbf{- a particle (R) which is in two places in the same time}, is like line AB (i.e. the line which passes through the above distinct points A and B) in the model (M); which means that `line' AB is a straight line in the classical sense in the Euclidean plane $\alpha$, while `line' AB is the big sphere circle (C) in the Non-Euclidean sphere (S), therefore line AB is simultaneously in two different places (and has two different forms). [Preview Abstract] |
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P1.00015: Dinosaur kinematics: A statistical analysis provides evidence of predation by theropods Scott Lee Dinosaur trackways provide interesting information about the locomotion of these extinct animals. A statistical analysis of the known trackways made by theropods (carnivorous dinosaurs) shows that they usually moved by walking with an average speed of 2.4 $\pm $ 1.5 m/s. Fast running, determined by the relative stride length greater than 3, is observed in about 10{\%} of the trackways, with speeds on the order of 10 m/s. These trackways are believed to have been formed during predation. [Preview Abstract] |
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