Bulletin of the American Physical Society
2015 Annual Meeting of the Far West Section of the APS
Thursday–Saturday, October 29–31, 2015; Long Beach, California
Session S2: Materials Science |
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Chair: Thomas Gredig, California State University, Long Beach Room: CBA-122 |
Saturday, October 31, 2015 2:00PM - 2:12PM |
S2.00001: The effects of lipid membrane mobility on microtubule gliding. Joseph Lopes, Linda Hirst, Jing Xu Motor proteins, discovered in recent decades, are critical for the transport of intra-cellular cargo. Single motor transport properties have been documented in experiments involving transport of silica beads, but their group function with lipid vesicles similar to intracellular cargo remains unknown. In these experiments the geometry of motor transport is inverted, with microtubules gliding on motors bound to the surface of a lipid bilayer. Fluorescence recovery after photo bleaching was used to characterize the diffusion of lipid compositions with two different phases, and microtubule velocity is compared between the lipid membranes and bare glass gliding. [Preview Abstract] |
Saturday, October 31, 2015 2:12PM - 2:24PM |
S2.00002: Effect of active kinesin density on microtubules during formation of spools Amanda Tan, Dail Chapman, Linda Hirst, Jing Xu Active self-assembly systems are energy driven and can organize into various structures. Microtubules and their associated motor proteins, such as kinesin, are widely used to study active self-assembly of higher order structures, such as linear bundles and spools. Microtubules are polymers composed of tubulin that are found in the cytoskeleton. Kinesin motors convert ATP into energy through hydrolysis and walk along microtubules. Microtubules functionalized with biotin and streptavidin will bind together and form bundles and spools when gliding. The spools are able to maintain its shape and continue to rotate in the presence of ATP. We use gliding assays to investigate the effect of the density of active motors on microtubules during spool formation. By tuning the velocity of gliding microtubules, we can effectively tune the kinesin density on microtubules. There was no significant change in average spool circumference and no reduction in spool density over a 10-fold reduction in microtubule gliding velocity. We find spool characteristics are robust against active kinesin density on microtubules. [Preview Abstract] |
Saturday, October 31, 2015 2:24PM - 2:36PM |
S2.00003: Self-assembled nano-particle micro-shells template by liquid crystal (LC) and ligand sorting Tayebeh Riahinasab The assembly of different nano-particle types into 3D organized structures is one of the most important subjects in the nanotechnology field. In this regard, we utilize a liquid crystal host phase in a new process for the generation on micron-scale vesicle like nano-particle shells stabilized by ligand-ligand interactions. The constructs formed consist of a mechanically robust, thin spherical layer, composed of closely packed quantum dots (QDs) and stabilized by local crystallization of the mesogenic ligands. Mesogenic ligands have the potential to provide control over the dispersion and stabilization of nano-particles in liquid crystal (LC) phases. We apply polarized optical microscopy and small angle x-ray scattering (SAXS) to characterize quantum dots dispersion on different length scales. [Preview Abstract] |
Saturday, October 31, 2015 2:36PM - 2:48PM |
S2.00004: Electrical and Chemical Characterization of Cu(In,Ga)(Se,S)$_{2}$ Solar Cells Malte Koehler, Michael Richter, Janet Neerken, Stephan Heise, Juergen Parisi Chalkopyrid thin film solar cells like CIGS and CIGSSe have reached comparable efficiencies like polycrystalline silicon based solar cells within the last years. Still some research has to be done to increase its efficiency even further. This work focuses on the relationship between the electrical and the chemical parameters of these solar cells. The composition of the absorber layer can vary laterally over a solar cell due to inhomogeneous deposition processes. The Ga/(Ga$+$In) and the S/(S$+$Se) ratios influence the band structure and therefore have a big impact on the electrical parameters of these solar cells. These depth dependent ratios were investigated on a nanometer scale using energy dispersive X-ray spectroscopy in a transmission electron microscope (TEM-EDX) and on a millimeter scale using glow discharge optical emission spectroscopy (GDOES). [Preview Abstract] |
Saturday, October 31, 2015 2:48PM - 3:00PM |
S2.00005: Experimental and Theoretical Solar Cell Degradation Under Monte-Carlo Modeled Dust Deposition Patricio Piedra Solar energy is very quickly becoming a crucial replacement of oil-derived energy. However, the efficiency of photovoltaic energy conversion gets reduced when dust becomes deposited on the solar panel. A large body of field experiments report energy conversion losses ranging from 1{\%} to 65{\%} depending on the location, tilt angle of the solar panel and mineralogical composition of the dust. Nonetheless, field experiments are ad hoc, and thus it remains challenging to derive universal patterns to predict photovoltaic efficiency of solar cells. In this study, we attempt to identify the key optical parameters that govern photovoltaic losses. A theoretical calculation of light transmission has been done for the particle-substrate system using the numerical scattering technique known as discrete dipole approximation (DDA). The DDA-substrate calculation has been validated using both Mie theory for free space and the T-matrix method for the sphere-substrate system. The coherence between the theoretical calculations is nearly perfect. In future study, we expect to validate these theoretical calculations using glass-dust light scattering measurements taken by an integrating sphere spectroradiometer. If the experimental validation of this calculation is successful, it will allow us to predict solar cell efficiency. This optical study can then be used to decide on materials for the solar panel, and to predict solar efficiency losses on locations that are not easily accessible such as space or deserts. [Preview Abstract] |
Saturday, October 31, 2015 3:00PM - 3:12PM |
S2.00006: A new procedure for measuring particle length using the resistive pulse technique with irregular single polymer micropores Preston Hinkle, Yinghua Qiu, Crystal Yang, Zuzanna Siwy, Arnout Imhof, Henriette Bakker Application of the resistive pulse technique using single micro- and nanopores is an effective way of characterizing some physical properties of nanoparticles including charge, concentration, and volume. In this work, we expand the resistive pulse technique by describing a procedure that can be used to distinguish particles of different lengths, and even measure the length of individual nanoparticles. The method works by translocating small spherical "tracer" particles through a a polymer pore with non-uniform radius, providing a one-to-one mapping of the local pore radius to the position-dependent current pulse amplitude. By calculating a weighted moving average of the tracer's pulse over a varying number of ion-current position data points, the signal becomes convoluted in the same way a rod's signal is the convolution of the local pore radius along the rod's length. Comparison of the rods' and convoluted tracers' signals allows for calculation of the particle length. Successful results from application of the procedure to distinguish two types of silica rods are shown. [Preview Abstract] |
Saturday, October 31, 2015 3:12PM - 3:24PM |
S2.00007: Demon Dynamics: Deterministic Chaos, the Szilard Map, and the Intelligence of Thermodynamic Systems Alexander Boyd, James Crutchfield We introduce a deterministic chaotic system—the Szilard Map—that encapsulates the measurement, control, and erasure protocol by which Maxwellian Demons extract work from a heat reservoir. Implementing the Demon’s control function in a dynamical embodiment, our construction symmetrizes Demon and thermodynamic system, allowing one to explore their functionality and recover the fundamental trade-off between the thermodynamic costs of dissipation due to measurement and due to erasure. The map’s degree of chaos—captured by the Kolmogorov-Sinai entropy—is the rate of energy extraction from the heat bath during control. Moreover, an engine’s statistical complexity quantifies the minimum necessary system memory for it to function. In this way, dynamical instability in the control protocol plays an essential and constructive role in intelligent thermodynamic systems. [Preview Abstract] |
Saturday, October 31, 2015 3:24PM - 3:36PM |
S2.00008: An optically excited LC in-plane switching driven by localized surface plasmon resonance Makiko Tsukamoto Quint We probe a new way to control a molecular orientation in a few micron thick liquid crystal (LC) films by utilizing the localized surface plasmon resonance (LSPR) of gold nano-particles (AuNPs). This LC molecular re-orientation is reversible and repeatable, and does not require any specific alignment coatings and additional applied electric field. Our LC thin film has AuNPs deposited on either single or double side of our glass slides with peak absorption at 532 nm wavelength. We measure the LC switching time-scales and threshold power requirements for both single and double sided AuNP deposition LC thin films. Additionally, the total transmission intensity increases strongly with incident power, but shows weak dependence with temperature. Moreover, we control and vary the in-plane switching of the LC molecules by altering the directionality of linear polarization of an incident beam. Based on our experimental results, our thin LC film with AuNPs has the potential to act as an optically excited LC switch and this will introduce a new approach and performance of LC devices. [Preview Abstract] |
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