Bulletin of the American Physical Society
17th Annual Meeting of the APS Northwest Section
Volume 61, Number 7
Thursday–Saturday, May 12–14, 2016; Penticton, British Columbia, Canada
Session B2: Condensed Matter I |
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Chair: Joshua Folk, University of British Columbia Room: PC 122 |
Friday, May 13, 2016 1:30PM - 1:42PM |
B2.00001: Investigation of GaAs/GaP core/shell Nanowires via Off-Axis Electron Holography James McNeil, Ali Darbandi, Azadeh Akhtari-Zavareh, Simon Watkins, Karen Kavanagh In this talk I will outline the application of a transmission electron microscope (TEM) to study electrical properties of GaAs/GaP core/shell nanowires using a form of electron interferometry known as off-axis electron holography (OAEH). The epitaxial GaP surface layer is designed to passivate the surface states of the GaAs nanowire. This system also has a unique property that the mean inner potentials (MIP) of the two crystalline volumes are almost identical. I will demonstrate that the phase and amplitude information of reconstructed hologram can be applied simultaneously to remove geometrical dependencies for this system, enabling the search for built in fields near the heterostructure interface. The sensitivity of OAEH in mapping electrostatic fields which permeate into the vacuum from charging nanowires with nm resolution will also be discussed. [Preview Abstract] |
Friday, May 13, 2016 1:42PM - 1:54PM |
B2.00002: ABSTRACT WITHDRAWN |
Friday, May 13, 2016 1:54PM - 2:06PM |
B2.00003: Macroscopic drop impacts with inclined flexible fibres Salome Hussein, Stuart Bradley, Geoff Willmott, Matheu Broom The impact of drops on flexible surfaces and structures of comparable size to the drops is an active and open field of inquiry. This situation arises in horticulture because of the spray application of pollen in solution or other substances. For example, kiwifruit vines are relatively undesirable to bees, making natural pollination unreliable. Unfortunately, current methods for artificial pollination are incredibly inefficient -- sometimes wasting the majority of harvested pollen, an expensive substance to collect, process, and store. A study was therefore done on the interaction of droplets with relevant structures on the kiwifruit blossom. The impact of drops upon stigma at different speeds and angles was recorded with a high-speed camera. Several observed categories of impact phenomena are described here, along with comparisons to predictions from theoretical models of simpler situations with similar geometry and length scales. Some phenomena can be approximated as impacts with a cantilevered elastic beam, which allows one to make quantitative measurements of mass and momentum transfer from drop to structure. The results demonstrate how critical the fluid properties are to useful interactions between the applied solution and flower anatomy with different wetting morphologies. [Preview Abstract] |
Friday, May 13, 2016 2:06PM - 2:18PM |
B2.00004: Differential effects of sterols on phospholipid acyl chain packing in binary and ternary mixes Drake Mitchell, Matthew Davis We examined the effects of the cholesterol, ergosterol and cholestane on phospholipid acyl chain packing in 16:0,18:1 PC and ternary mixtures where di-18:0 PC/di-18:1 PC/cholesterol forms coexisting liquid ordered (Lo) and liquid disordered (Ld) phases. Ensemble acyl chain order was assessed via time-resolved fluorescence measurements of DPH. Analysis in terms of the P2-P4 Model enabled separation of probe motion and orientational order. In 16:0,18:1 PC ergosterol and cholesterol increased probe order to a similar extent. Cholestane had essentially no effect on probe order and a small effect on probe motion. Effects of the 3 sterols were also examined in a ternary mix of di-18:1 PC/di-18:0 PC/sterol selected from the middle of the Lo/Ld coexistence region of the di:18:1/di-18:0/chol phase diagram at 23C. In the ternary mix the effects of cholesterol and ergosterol on ensemble acyl chain order were distinguishable, with ergosterol having a smaller effect. In this mix cholestane had a pronounced ordering effect and reduced the rate of probe motion. The results suggest that sterol structure plays a more significant role in altering acyl chain interactions in mixtures with the potential to form coexisting Lo/Ld domains than in single component bilayers. [Preview Abstract] |
Friday, May 13, 2016 2:18PM - 2:30PM |
B2.00005: Predictions of Stable Cu Isotope Partitioning in Biological Systems Alexander Tennant, Michael Wieser Copper (Cu) is a essential trace metal in biological systems, and has been implicated in many neurodegenerative diseases. The exact cause, and the role of Cu, in many of these diseases remains unclear, and are currently the subjects of extensive study. Often overlooked, is that there exist two stable isotopes of Cu, $^{63}$Cu and $^{65}$Cu, meaning the stable isotope analysis of Cu in these systems has the potential to reveal unique insights regarding processes involved in Cu transport and retention. We present the first results of a study characterizing predictions from density functional theory of the scale of potential isotope effects resultant from interactions between select Cu binding sites of important proteins related to Cu transport and and disease. This study will help establish the potential range and extent of stable Cu isotopic variations as a result of interactions between complex biomolecules from a perspective seldom explored for transition metals. Using these results, it may also be possible to establish and distinguish the Cu isotopic signature of individual proteins and processes. Information such as this may prove invaluable in determining Cu sources and processes related to biologic function and disease. [Preview Abstract] |
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