Bulletin of the American Physical Society
Joint Spring 2010 Meeting of the Texas Sections of the APS, AAPT, and SPS
Volume 55, Number 3
Thursday–Saturday, March 18–20, 2010; Austin, Texas
Session F2: Applied, General, Biological, and Chemical Physics |
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Chair: Paul Nacozy, Austin Community College Room: Robert Lee Moore Hall 5.112 |
Friday, March 19, 2010 3:15PM - 3:27PM |
F2.00001: Microsecond MD Simulations of Nano-patterned Polymer Brushes on Self-Assembled Monolayers Creighton Buie, Liming Qiu, Kwan Cheng, Soyeun Park Nano-patterned polymer brushes end-grafted onto self-assembled monolayers have gained increasing research interests due to their unique thermodynamic properties and their chemical and biomedical applications in colloids, biosensing and tissue engineering. So far, the interactions between the polymer brushes with the surrounding environments such as the floor and solvent at the nanometer length scale and microsecond time scale are still difficult to obtained experimentally and computationally. Using a Coarse-Grained MD approach, polymer brushes of different monomeric lengths, grafting density and hydrophobicity of the monomers grafted on self-assembled monolayers and in explicit solvent were studied. Molecular level information, such as lateral diffusion, transverse height and volume contour of the brushes, were calculated from our microsecond-MD simulations. Our results demonstrated the significance of the hydration of the polymer in controlling the conformational arrangement of the polymer brushes. [Preview Abstract] |
Friday, March 19, 2010 3:27PM - 3:39PM |
F2.00002: Amyloid protein unfolding and insertion kinetics on neuronal membrane mimics Liming Qiu, Creighton Buie, Mark Vaughn, Kwan Cheng Atomistic details of beta-amyloid (A$\beta $ ) protein unfolding and lipid interaction kinetics mediated by the neuronal membrane surface are important for developing new therapeutic strategies to prevent and cure Alzheimer's disease. Using all-atom MD simulations, we explored the early unfolding and insertion kinetics of 40 and 42 residue long A$\beta $ in binary lipid mixtures with and without cholesterol that mimic the cholesterol-depleted and cholesterol-enriched lipid nanodomains of neurons. The protein conformational transition kinetics was evaluated from the secondary structure profile versus simulation time plot. The extent of membrane disruption was examined by the calculated order parameters of lipid acyl chains and cholesterol fused rings as well as the density profiles of water and lipid headgroups at defined regions across the lipid bilayer from our simulations. Our results revealed that both the cholesterol content and the length of the protein affect the protein-insertion and membrane stability in our model lipid bilayer systems. [Preview Abstract] |
Friday, March 19, 2010 3:39PM - 3:51PM |
F2.00003: The Design and Fabrication of Bismuth Hall Effect Biosensors Capable of Detecting Superparamagnetic Nanoparticles Anthony Sigillito, Martin Rudolph, J.J. Heremans, Vicki Soghomonian, Ray Kallaher Because of their high sensitivity, accuracy, and low cost, the use of Hall biosensors promises to be an effective diagnostic technique that may aid in the early diagnosis of disease. Hall biosensors put out a voltage proportional to the strength of the magnetic field created by a magnetically labeled biomolecule attached to the surface of the sensor. These sensors were fabricated using bismuth thin films because bismuth has a low toxicity, low cost, and large Hall coefficient, making it an ideal material for medical applications. Hall bars were characterized by taking magnetoresistance measurements and were found to have good qualities for detecting the superparamagnetic nanoparticles that can be attached to biomolecules. One sensor was exposed to nanoparticles as a test of its efficacy with positive results. This research suggests that bismuth Hall biosensors are a promising alternative to traditional diagnostic techniques. [Preview Abstract] |
Friday, March 19, 2010 3:51PM - 4:03PM |
F2.00004: Wrist-mounted Ultrasonic Device Todd Neer This project shows an ultrasonic device can be made small enough to be worn on the wrist and therefore added as a function for a running watch. An existing ultrasonic device was modified by stripping the circuit board to necessary components, replacing the 9V battery with a smaller alternative, and fitting it to a wrist mounted case. The wrist-mounted device shows a 68{\%} mass reduction and 84{\%} volume reduction and emits an ultrasonic frequency of 21-22kHz. [Preview Abstract] |
Friday, March 19, 2010 4:03PM - 4:15PM |
F2.00005: Iridium Satellite Signal Exploitation Peter McDonough The Iridium Satellite constellation is unique to satellite communication networks in that it allows for transmission of data between satellites instead of relying on transmission by the bent pipe methodology. As such, this network is far more secure than other satellite communication networks, and forces interception to occur within the locale of the transmission from modem to satellite or within the locale of the downlink from the satellite other modem. The purpose of this project was to demonstrate the security weaknesses within the Iridium protocol, showing that it was possible to track one of these satellites with a high gain antenna, resulting in the ability to anticipate transmission, to acquire the location of that transmission, and to uncover the content of that transmission. This project was completed as part of the summer student program at the Southwest Research Institute. The presentation will demonstrate the thought process used in chronological order, essentially demonstrating how I achieved the result from my point of view as the summer progressed. [Preview Abstract] |
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