Bulletin of the American Physical Society
2008 Joint Fall Meeting of the Texas and Four Corners Sections of APS, AAPT, and Zones 13 and 16 of SPS, and the Societies of Hispanic & Black Physicists
Volume 53, Number 11
Friday–Saturday, October 17–18, 2008; El Paso, Texas
Session J2: Nanoscience and Biological Systems |
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Chair: Jordan Gerton, The University of Utah Room: Union East, 3rd Floor Templeton |
Saturday, October 18, 2008 1:30PM - 1:54PM |
J2.00001: A Nanoscale Tale Invited Speaker: Experimentalists constantly seek to overcome technical limitations. This is especially true in the world of biophysics, where the drive to study molecular targets such as ion channels, a type of membrane transport protein, has resulted in methodological breakthroughs that have merited the Nobel Prize (Hodgkin and Huxley, 1963; Neher and Sakmann, 1991). In this presentation I will explain how nanoscale phenomena that are essential for sensory perception underlie the ability of dancers, gymnasts, and musicians to excel at their artistic endeavors. I will describe how our investigations of sensory mechanotransduction and the quest for improved signal amplification inspired a scientific journey that has culminated in an exciting new line of collaborative NIH-funded research with nanomaterials (quantum dots). I will conclude with a general discussion of how training in physics offers an ideal foundation for interdisciplinary research in health related fields, such as those that deal with neuroscience and disorders of the nervous system. [Preview Abstract] |
Saturday, October 18, 2008 1:54PM - 2:18PM |
J2.00002: Status and Growth of Underground Science at WIPP Invited Speaker: The science community is increasingly taking advantage of research opportunities in the government-owned Waste Isolation Pilot Plant (WIPP), 655m underground near Carlsbad, NM. Discoveries so far include viable bacteria, cellulose, and DNA in 250 million-year old salt, preserved in an ultra-low background-radiation setting. Supplementing the overburden's shielding against cosmic radiation, terrestrial background from the host formation is less than five percent that of average crustal rock. In the past, WIPP accommodated development and testing of neutral current detectors for the Sudbury Neutrino Observatory and dark matter research, and it currently hosts two experiments pursuing neutrino-less double-beta decay. That scientists can listen to whispers from the universe in proximity to megacuries of radioactive waste lends, of course, credibility to the argument that WIPP itself is very safe. Almost a century of regional petroleum and potash extraction history and more than three decades of WIPP studies have generated a comprehensive body of knowledge on geology, mining technology, rock mechanics, geochemistry, and other disciplines relevant to underground science. Existing infrastructure is being used and can be expanded to fit experimental needs. WIPP's exemplary safety and regulatory compliance culture, low excavating and operating cost, and the high probability of the repository operating at least another 40 years make its available underground space attractive for future research and development. Recent proposals include low-photon energy counting to study internal dose received decades ago, investigations into ultra-low radiation dose response in cell cultures and laboratory animals (e.g., hormesis vs. linear no-threshold) and detectors for dark matter, solar and supernova neutrinos, and proton decay. Additional proposals compatible with WIPP's primary mission are welcome. [Preview Abstract] |
Saturday, October 18, 2008 2:18PM - 2:30PM |
J2.00003: Formation and Characterization of Stacked Nanoscale Layers of Polymers and Silanes on Silicon Surfaces Rosie Ochoa, Brian Davis, Hiram Conley, Katie Hurd, Matthew R. Linford, Robert C. Davis Chemical surface patterning at the nanoscale is a critical component of chemically directed assembly of nanoscale devices or sensitive biological molecules onto surfaces. Complete and consistent formation of nanoscale layers of silanes and polymers is a necessary first step for chemical patterning. We explored methods of silanizing silicon substrates for the purpose of functionalizing the surfaces. The chemical functionalization, stability, flatness, and repeatability of the process was characterized by use of ellipsometry, water contact angle, and Atomic Force Microscopy (AFM). We found that forming the highest quality functionalized surfaces was accomplished through use of chemical vapor deposition (CVD). Specifically, surfaces were plasma cleaned and hydrolyzed before the silane was applied. A polymer layer less then 2 nm in thickness was electrostatically bound to the silane layer. The chemical functionalization, stability, flatness, and repeatability of the process was also characterized for the polymer layer using ellipsometry, water contact angle, and AFM. [Preview Abstract] |
Saturday, October 18, 2008 2:30PM - 2:42PM |
J2.00004: Nanoshaving and Nanografting of Water Soluble Polymers on Glass and Silicon Dioxide Surfaces with Applications to DNA Localization Brian Davis, Hiram Conley, Rosie Ochoa, Katie Hurd, Matthew R. Linford, Robert C. Davis Chemical surface patterning at the nanoscale is a critical component of chemically directed assembly of nanoscale devices or sensitive biological molecules onto surfaces. Here we present a scanning probe lithography technique that allows for patterning of aqueous polymers on glass or silicon dioxide surfaces. The surfaces were functionalized by covalently bonding a silane monolayer with a known surface charge to either a glass slide or a silicon wafer. A polymer layer less then 2 nm in thickness was electrostatically bound to the silane layer, passivating the functionalized surface. An Atomic Force Microscope (AFM) probe was used to remove a portion of the polymer layer, exposing the functional silane layer underneath. Employing this method we made chemically active submicron regions. These regions were backfilled with a fluorescent polymer and Lambda-DNA. Chemical differentiation was verified through tapping mode AFM and optical fluorescent microscopy. Lines with a pitch as small as 20nm were observed with AFM height and phase mode data. [Preview Abstract] |
Saturday, October 18, 2008 2:42PM - 2:54PM |
J2.00005: Molecular Dynamics Simulation of protein unfolding on lipid nanodomains Liming Qiu, Mark Vaughn, Kwan Cheng Beta amyloid (beta-40), a short peptide associated with Alzheimer disease, can exist in the alpha-helix, beta-sheet or global conformation depending on its environment. The role of self-assembling lipid nanodomains on the conformational transition of this peptide was examined using Coarse-grained MD simulations. A stable cholesterol superlattice consisting of phosphatidylcholine and cholesterol was constructed to mimic the neuronal membrane. The unfolding kinetics of beta-40 on this superlattice surface as compared with that in solution was determined. Our results suggest a critical role of the nanostructure of lipid surface on protein unfolding at a biologically relevant time scale of hundreds of nanoseconds. [Preview Abstract] |
Saturday, October 18, 2008 2:54PM - 3:06PM |
J2.00006: The small angle x-ray scattering of globular proteins in solution during heat denaturation Jose Banuelos, Jacob Urquidi The ability of proteins to change their conformation in response to changes in their environment has consequences in biological processes like metabolism, chemical regulation in cells, and is believed to play a role in the onset of several neurodegenerative diseases. Factors such as a change in temperature, pressure, and the introduction of ions into the aqueous environment of a protein can give rise to the folding/unfolding of a protein. As a protein unfolds, the ratio of nonpolar to polar groups exposed to water changes, affecting a protein's thermodynamic properties. Using small angle x-ray scattering (SAXS), we are currently studying the intermediate protein conformations that arise during the folding/unfolding process as a function of temperature for five globular proteins. Trends in the observed intermediate structures of these globular proteins, along with correlations with data on protein thermodynamics may help elucidate shared characteristics between all proteins in the folding/unfolding process. Experimental design considerations will be discussed and preliminary results for some of these systems will be presented. [Preview Abstract] |
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