Bulletin of the American Physical Society
2018 Annual Spring Meeting of the APS Ohio-Region Section and the AAPT Michigan Section
Volume 63, Number 7
Friday–Saturday, March 23–24, 2018; East Lansing, Michigan
Session G2: Contributed: Applied Physics and Materials Science II |
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Room: Biomedical and Physical Sciences Building 1420 |
Saturday, March 24, 2018 2:00PM - 2:12PM |
G2.00001: Percolation Through Voids Around Structurally Disordered Sand Grains Nicholas McGuigan, Donald Priour Fluid flow or charge transport through porous materials takes place within voids around impermeable grains. With increasing density of grains, fluid flow diminishes, ultimately ceasing at the percolation transition separating configurations macroscopically navigable; and those which block fluid flow in the bulk limit. Theoretical studies of void networks have generally been confined to monodispersed systems of identical particles, with no calculations of percolation thresholds for geometrically diverse grains. In addition to positional and orientational disorder, we incorporate structural disorder by imposing random variations in the geometries and sizes of grains, akin to realistic porous materials. We consider cubes distorted into rectangular solids with random proportions. More comprehensibly, we also examine configurations of structurally disordered tetrahedra and parallelepipeds with both random perturbations in edge lengths and dihedral angles. Reflecting the fact that grains in practice are irregular polyhedral with various numbers of faces, we also implement structural disorder by using Voronoi tessellation to carve out irregularly shaped grains. Intuitively, this approach mimics the formation of grains in nature from fractured larger objects. [Preview Abstract] |
Saturday, March 24, 2018 2:12PM - 2:24PM |
G2.00002: Modified Propagation of Belousov-Zhabotinsky Waves in a Quasi-1D System Jack Mershon, Chase Fuller, Niklas Manz The Belousov-Zhabotinsky (BZ) reaction was used to investigate the effect of fluid flow on the behavior of reaction-diffusion waves. Solutions were filled into glass capillary with inner diameter of 0.45 mm to create a quasi-1D system. The solutions were then advected by fluid flow. Normal reaction-diffusion waves were subjected to flow in opposition to the wave's propagation at a rate equal to the wave's speed without flow. The advection resulted in the initial fronts propagating at a significantly reduced speed than normal, though some forward propagation was still observed suggesting that the flow was not sufficient to stop forward wave propagation. Additionally, investigations into anomalous solutions behavior in these circumstances were investigated. We will report about initial experimental findings of the fluid flow effect on the wavelength of the waves and the effect on the anomalous behavior. [Preview Abstract] |
Saturday, March 24, 2018 2:24PM - 2:36PM |
G2.00003: The physical nature of Primary battery Liu Yuhong, Han Yongquan The reaction mechanism of the primary battery is that the sulfate ion in the copper sulfate solution is easier to “grab” the “zinc ion” combination in the zinc. Sulfate ions “grab” the “zinc ions” in zinc flakes, which is the process of plasma formation. The "zinc ions" in the zinc move toward the surface of the zinc sheet (the surface that is soaked in the copper sulfate solution). The zinc sheet and the copper sheet are connected by wires and are a unified conductor. The "zinc ions" move toward the surface of the zinc rod and form zinc. Positively charged, negatively charged copper plasma. The power plasma is transmitted in the solution. Copper and zinc bipolar exist in dilute CuSO4. Since zinc is more active than copper, it easily loses electrons, and zinc is oxidized into Zn2$+$ to enter the solution. Since the speed of the current is the speed of light, it is much faster than the speed of chemical reaction. Therefore, the lost electrons of the zinc film can only pass through the wire “flowing” to the copper sheet. The Cu2$+$ in the solution acquires electrons from the copper sheet and is reduced to copper atoms, the power source is the plasma, and the current is the transmission of the power plasma in the conductor. [Preview Abstract] |
Saturday, March 24, 2018 2:36PM - 2:48PM |
G2.00004: Chromospheric Emission Lines: Rules of Formation. Pierre-Marie Robitaille In this work, for the first time, it is reported that strong metallic chromospheric emission lines (306-900 nm) are not random in origin. The following rules apply: 1) Strong lines have at least a single unpaired electron in the lower energy state reached (H, He II, Ca II H K, CaII triplet at 849-866 nm, all excited He I singlets and triplets, Mg I triplets at 516-518 nm, O I triplet at 777 nm are examples); 2) Line intensity does not result from random absorption-emission and temperature arguments as currently accepted; 3) Condensation reactions are involved as H is delivered through a metal hydride (e.g. H$_{\mathrm{2}}$, CaH, OH, FeH) to a condensed hydrogen structure (CHS), like spicules (e.g. CHS $+$ MH $\to $ CHS-HM* $\to $ CHS-H $+$ M* $\to $ CHS-H $+$ M $+$ hv); 4) Such processes distort the intensities of the lines relative to actual chromospheric abundances and laboratory values; 5) The transition electron is the one making the bond in the metal hydride; 6) Transitions which involve an electron in a closed shell ground state do not occur. The first exception appears to be recorded 4s$^{\mathrm{2}}$ transitions. Several of these may be improperly assigned, although many are real; 7) He lines (50.8-59.14 nm) arise by capture of H$^{\mathrm{+}}$ from H$_{\mathrm{2}}^{\mathrm{+}}$ and delivery to a CHS. H$^{\mathrm{+}}$ release from HeH$^{\mathrm{+}}$, leads to a 1s$^{\mathrm{2}}$ ground state on He. This is the second exception; 8) Two electron transitions from a d-shell ground state imply delivery of molecular hydrogen, whereby two paired electrons in the d-shell act to create a transient $\pi $-back donation molecular shell and the two hydrogen molecule electrons contribute a $\sigma $-donation (consider: 415.964 nm in ApJSS, 1968, 150(17), 1-364, which if Ti I as recorded, originates from 3d$^{\mathrm{3}}(^{\mathrm{2}}$D)4s$\to $3d4s$^{\mathrm{2}}$4p). [Preview Abstract] |
Saturday, March 24, 2018 2:48PM - 3:00PM |
G2.00005: Contact Interaction and Kronig-Penney Model in PT Quantum Mechanics Foster Thompson, Harsh Mathur, Katherine Brown We study two simple models of PT quantum mechanics that provide insight into the propagation of light through suitably engineered PT symmetric optical structures. We introduce the PT quantum mechanics analog of a delta function potential and analyze its bound and scattering states. This model can support up to two bound states (one more than the textbook delta function) and these states undergo the phenomenon of PT symmetry breaking wherein the two bound state energies degenerate and become a complex conjugate pair as parameters in the model are varied. The scattering states are also found to show PT symmetry breaking as the scattering phase shifts (which are no longer constrained to be real by unitarity) become complex. A scattering resonance develops with the onset of PT symmetry breaking in the bound states. The Kronig-Penney model of solid state physics is a one dimensional comb of delta functions. Here we consider a PT symmetric crystal formed by a periodic array of the PT symmetric delta function potentials. We find PT symmetry breaking and novel wave propagation phenomena in these simple models of PT symmetric crystals. [Preview Abstract] |
Saturday, March 24, 2018 3:00PM - 3:12PM |
G2.00006: Coarse-grained model for a motor protein on a microtubule Jutta Luettmer-Strathmann, Mansour Alanazi The function of cells relies on the transport of substances within the cell. In eukaryotic cells, active transport by motor proteins moving on a substrate plays an important role. The goal of this work is to model a motor protein walking on a microtubule. For the microtubule, we employ a combined micromechanical/interaction site model from the literature. This allows us to calculate deformations of microtubules with finite element methods and map the results to an interaction site model that includes details about the microtubule structure, for example a seam along the length of the microtubule. The motor protein is represented by a coarse-grained model that was developed in earlier work. In this work, we perform Brownian dynamics simulations of the walker on a fixed microtubule substrate. Calculations of average displacements of the walker show that the efficiency is lower than in biological systems and can be improved by adjusting protein model parameters. In agreement with recent experimental observations, we also find that the protein walker does not cross the seam of the microtubule. [Preview Abstract] |
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