Bulletin of the American Physical Society
Fall 2010 Meeting of the New England Section of APS
Volume 55, Number 13
Friday–Saturday, October 29–30, 2010; Providence, Rhode Island
Session E2: APS Contributed Session II |
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Room: Barus and Holley 161 |
Saturday, October 30, 2010 8:00AM - 8:20AM |
E2.00001: Investigating Early Stage Crystal Growth Process Using Blotless Microfluidic Cryo-TEM Jinkee Lee, Arijit Bose, Anubhav Tripathi We study the early stages of calcium carbonate crystal growth using blotless microfluidic chip integrated cryogenic transmission electron microscopy (cryo-TEM). We also explore the interaction of polymer additives on crystal growth process (CaCl$_{2}$ (0.01M) + Na$_{2}$CO$_{3}$ (0.01M) (+ polymer additives) $\to $ CaCO$_{3}$+2NaCl). Three types of carboxylated hyperbranched polyglycerol were used as the polymer additives for retarding crystallization CaCO$_{3}$. A blotless microfludic CEVS is newly designed to capture crystal growth process at time scales on .5 to 100 seconds. This computer controlled CEVS removes blotting and relaxation step which generally takes at least 3 second. The chemical reaction can be allowed to occur both on the TEM grid as well inside the microfluidic channel. Our results show that upon mixing CaCl$_{2}$ and Na$_{2}$CO$_{3}$ solutions, emulsion like amorphous structure are initially formed. Subsequently, in 1 -2 seconds, these structures decompose into CaCO3-veterite nanoparticles. The polymer additives are shown to retard this crystallization processes even 12 seconds. The crystalline or amorphous diffraction patterns were collected to verify this finding. This new CEVS system can be used broadly to study early time structures in nanoscale systems under the very controlled conditions for chemical, biological and pharmaceutical researches and industries. [Preview Abstract] |
Saturday, October 30, 2010 8:20AM - 8:40AM |
E2.00002: Nanowire-nanopore transistor sensor for DNA detection Ping Xie, Qihua Xiong, Ying Fang, Quan Qing, Charles Lieber Nanopore sequencing, as a promising low cost, high throughput sequencing technique, has been proposed more than a decade ago. Due to the incompatibility between small ionic current signal and fast translocation speed and the technical difficulties on large scale integration of nanopore for direct ionic current sequencing, alternative methods rely on integrated DNA sensors have been proposed, such as using capacitive coupling or tunnelling current etc. But none of them have been experimentally demonstrated yet. Here we show that for the first time an amplified sensor signal has been experimentally recorded from a nanowire-nanopore field effect transistor sensor during DNA translocation. Independent multi-channel recording was also demonstrated for the first time. Our results suggest that the signal is from highly localized potential change caused by DNA translocation in none-balanced buffer condition. Given this method may produce larger signal for smaller nanopores, we hope our experiment can be a starting point for a new generation of nanopore sequencing devices with larger signal, higher bandwidth and large-scale multiplexing capability and finally realize the ultimate goal of low cost high throughput sequencing. [Preview Abstract] |
Saturday, October 30, 2010 8:40AM - 9:00AM |
E2.00003: Translocation dynamics of hybridized DNA oligomers studied by solid-state nanopores Venkat Balagurusamy, Paul Weinger, Xinsheng Ling We have earlier detected 12-base hybridizations in trimer DNA complexes formed by three single-stranded DNA oligomers hybridized at their ends sequentially, using nanopores of $\sim $10 nm diameter. These complexes are connected to a polystyrene bead at one end to slow down their translocation [1]. These experiments tested the feasibility of HANS (Hybridization-assisted nanopore sequencing) approach for DNA sequencing. HANS uses oligomers of DNA bound to a long single-stranded DNA in order to obtain the positional information of the bases that make up the long target DNA molecule. Subsequently, we have carried out translocation experiments at different voltages with nanopores $\sim $5 nm diameter. The measured time lapses between the passage of consecutive double-strand DNA segments in a trimer complex allow us to study the translocation dynamics. The measured mean-first-passage time between two consecutive hybridization segments is found to be consistent with theoretical estimates. \\[4pt] [1] V.S.K.Balagurusamy, P.Weinger and X.S.Ling, \textit{Nanotechnology} \textbf{21}, 335102 (2010). [Preview Abstract] |
Saturday, October 30, 2010 9:00AM - 9:20AM |
E2.00004: Actin -- myosin interaction Cynthia Prudence, Yana Reshetnyak, Oleg Andreev Muscle contraction is resulted from the interaction of myosin with actin and ATP. The study of kinetics of binding of myosin subfragment 1 (S1) to F-actin revealed the two step binding, which were modeled by initial binding of S1 to one actin monomer (state 1) and then to the second neighboring monomer (state 2). The results of time-resolved cross-linking of S1 and F-actin upon their rapid mixing in stopped flow apparatus directly demonstrated that myosin head initially binds through the loop 635-647 to the N-terminus of one actin and then through the loop 567-574 to the N-terminus of the second actin (Andreev {\&} Reshetnyak, 2007, J. Mol. Biol. 365(3), 551-554). The computational docking of S1 with F-actin demonstrated that both actin monomers are located in the same strand of F-actin with the first and second actins being close to the pointed and barbed ends of F-actin, respectively. The closing of the main cleft in 50 kDa of S1 might prevent binding of S1 with two actins since the distance between loops 635-647 and 567-574 became too short to interact with N-termini of two actins simultaneously. Depending on degree of saturation of F-actin with S1s there are two structurally different complexes are formed: at complete saturation each S1 binds only one actin and its cleft is closed while at partial saturation S1 interacts with two actins and its cleft is opened. The transition between one- and two-actin binding states of myosin accompanying with opening the cleft in central domain of S1 might be associated with force generation. The formation of actin-myosin interface would be associated with the energy release that might be used in part for the generation of force in muscle. [Preview Abstract] |
Saturday, October 30, 2010 9:20AM - 9:40AM |
E2.00005: Explorations of climate predictability based on long term global sea surface temperature observations Constantin Andronache While the detailed weather prediction is limited to about two weeks, skilful seasonal forecast is possible in the presence of slow varying boundary conditions (BC) of the atmosphere. Such conditions are satisfied by the sea surface temperature anomalies (SSTA) over large oceanic regions. These BC typically evolve on a much slower time scale than daily weather events and atmospheric predictability can be increased significantly. SSTA tend to have persistence or long memory, due largely to the thermal inertia of the oceans, caused by their heat storage capacity. The ocean communicates its thermal inertia to the atmosphere largely via the surface turbulent fluxes of sensible and latent energy. We use the NOAA Extended Reconstructed Sea Surface Temperature (SST) to investigate sources of predictability at seasonal time scale. We show that: 1) SSTA has a memory or persistence that depends largely on regional location in the global ocean, with the largest values in tropical Pacific; 2) A given SSTA distribution from a particular month, can have corresponding similar configurations in the past, largely due an oscillatory behavior of major SSTA perturbations; 3) Correlation of SSTA from different regions of the global ocean provide a valuable mean to explore climatic teleconnections. [Preview Abstract] |
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