Bulletin of the American Physical Society
Fall 2012 Meeting of the APS Ohio-Region Section
Volume 57, Number 6
Friday–Saturday, October 5–6, 2012; Detroit, Michigan
Session ED: Biophysics, Applied Physics, and Education |
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Chair: Xiang-Qiang (Rosie) Chu, Wayne State University Room: McGregor Conference Center E |
Saturday, October 6, 2012 8:00AM - 8:12AM |
ED.00001: Nanomechanics and dynamics of confined water and other liquids Peter Hoffmann From oil recovery to molecular biology, nanoconfined water plays an important role in many areas of research. However, the mechanics and dynamics of nanoconfined water are not well understood. Over the last ten years, a number of groups have measured the mechanics of confined water using atomic force microscopy (AFM) or surface force apparatus (SFA) - often with contradictory results. At Wayne State University, we have developed high resolution AFMs for ultra-small amplitude, linear measurements of the mechanics and dynamics of confined liquids. We have shown that water shows a distinct slow-down in dynamics under confinement (PRB 2004), co-discovered a dynamic ``solidification'' in a model liquid (Langmuir 2006), and showed that normal and shear stiffness are closely related in confined liquids (Rev. Sci. Instr. 2008). Recently, we found dynamic solidification also in water layers (PRL 2010), a finding that explains the contradictory findings in earlier measurements and points to surprisingly complex behavior in this seemingly simple system. Here we will review these findings, as well as present new findings that show the profound effects of ion concentration on these dynamical effects, as well as measurements of colloidal systems, which illustrate that some findings at the molecular scale can be understood from purely geometric considerations and are not dependent on molecular-scale interactions. [Preview Abstract] |
Saturday, October 6, 2012 8:12AM - 8:24AM |
ED.00002: Manipulating Water Droplet Behavior on Aluminum Surfaces Using Micro-lithography Muidh Alheshibri, Tyler Brest, Andrew Sommers, Khalid Eid In this work, we use photolithography to create alternating hydrophobic/hydrophilic Cu micro-channels on an aluminum surface. The contact angle that is formed between water droplets and the surface is clearly asymmetrical due to the different surface properties at the contact line between the droplets and the patterned surface. An HDFT self-assembled mono-layer allows for a large change in the water droplet contact angle on the copper, but seems to have no effect on the aluminum surface. We will show our results on the effect of the surface patterning, oxidation of the metal and surface roughness on water droplet behavior. [Preview Abstract] |
Saturday, October 6, 2012 8:24AM - 8:36AM |
ED.00003: Low Energy Positron Interactions with Biological Molecules Indika Wanniarachchi, Caroline Morgan, Bernhard Schlegel, Gary Kedziora, Larry Burgrraf, Michael Pak, Sharon Hammes-Schiffer There is some experimental evidence that positrons can produce distinctive molecular fragmentation patterns. It is known that tuning the incident positron energy to near resonance with molecule vibrations can strongly enhance the positron annihilation probability for a molecule. This suggests that fragmentation induced by slow positrons may provide valuable complementary information to existing techniques for identification and study of proteins. In order to study this concept, we are developing a general quantum method for reliably calculating the density distribution for positrons bound to large biological molecules using NEO/GAMESS. We find that the outer molecular orbitals as well as the higher p orbitals on the O atoms contribute heavily to the total annihilation rate. ~Using the basis sets and approximations we have tested to predict where annihilation occurs can ultimately help us understand the resulting fragmentation patterns of larger biological molecules. [Preview Abstract] |
Saturday, October 6, 2012 8:36AM - 8:48AM |
ED.00004: Photothermal Therapy of Cancer Cells mediated by Blue Hydrogel Nanoparticles Taeyjuana Curry, Tamir Epstein, Raoul Kopelman Coomassie Blue dye has been covalently linked into a polyacrylamide nanoparticle matrix, so as to form nontoxic, biologically compatible, biodegradable and cell-specific targetable nanoparticles for photothermal therapy (PTT) of cancer. The nanoparticles were found to be approximately 80-95 nm in diameter, with an absorbance value of 0.52. Using an inexpensive, low intensity LED array light source (590nm, 25mW/cm$^{2})$, with 20 minute excitation times, at 37\r{ }, PTT induced hyperthermia/thermolysis in HeLa cells, in vitro, resulting in virtually complete cell death when observed 3 hours after exposure. These multifunctional particles have been previously used in cancer delineation, for surgery, and in photoacoustic imaging studies; the addition of the PTT function now enables a multi-pronged medical approach to cancer. [Preview Abstract] |
Saturday, October 6, 2012 8:48AM - 9:00AM |
ED.00005: Controlled RGD Peptide Adsorption on Aggregation-Free, Size-Selected Hydroxyapatite Nanoparticle Substrates Parimal Bapat, Bonnie Culpepper, Susan Bellis, Renato Camata Numerous studies of cell attachment, differentiation, and proliferation have been carried out on nanostructured hydroxyapatite (HA) surfaces with cell adhesive peptides containing the RGD (Arg-Gly-Asp) motif. Although these studies have yielded useful insights into the role of RGD peptides in cell-HA biomaterial interactions, the heterogeneity of typical nanophase HA materials makes it difficult to decouple the effects of nanotopography and biochemical cues. In this work we have used aggregation-free, size-controlled HA nanoparticles with mean size in the 20-70 nm range, synthesized by gas-phase laser ablation and deposited on atomically flat bioinert substrates that may help overcome this challenge. Nanoparticle deposits with adjustable number concentration were characterized by transmission electron microscopy, atomic force microscopy, and X-ray diffraction. RGD peptides modified by the addition of a polyglutamate sequence and a fluorescent conjugate, were coated onto the HA nanoparticle substrates. Intensity histograms of fluorescent microscopy images show that peptide adsorption on the substrates scales with the concentration of HA nanoparticles. High HA nanoparticle concentrations also lead to peptide clustering tunable in the 100-1200 cm$^{-2}$. [Preview Abstract] |
Saturday, October 6, 2012 9:00AM - 9:12AM |
ED.00006: Organic photovoltaic based on copper phthalocyanine with high open circuit voltage and significant current and voltage stability Khalil Hamam, Mohammad Al-amar, Clement Burns Organic semiconductors are under investigation as a possible material to create low cost solar cells. We fabricated photovoltaic devices consisting of copper phthalocyanine (CuPc) modified with a sulfonated group /perylene-3, 4, 9, 10-tetracarboxylic dianhydride (PTCDA)/ bathocuproine (BCP) A large open circuit voltage (V$_{OC})$ of 0.74 V was recorded, superior to cells based on~ CuPc/PTCDA (V$_{OC}$ =0.55V). Our solar cells exhibits little change in their voltage and current for more than 7 months, superior to many organic solar cells which degrade significantly over days or weeks. [Preview Abstract] |
Saturday, October 6, 2012 9:12AM - 9:24AM |
ED.00007: Investigation of High Pressure, Multi-Hole Diesel Fuel Injection Using High Speed Imaging Steven Morris, Ethan Eagle, Margaret Wooldridge Research to experimentally capture and understand transient fuel spray behavior of modern fuel injection systems remains underdeveloped. To this end, a high-pressure diesel common-rail fuel injector was instrumented in a spherical, constant volume combustion chamber to image the early time history of injection of diesel fuel. The research-geometry fuel injector has four holes aligned on a radial plane of the nozzle with hole sizes of 90, 110, 130 and 150 $\mu$m in diameter. Fuel was injected into a non-reacting environment with ambient densities of 17.4, 24.0, and 31.8 kg/m3 at fuel rail pressures of 1000, 1500, and 2000 bar. High speed images of fuel injection were taken using backlighting at 100,000 frames per second (100 kfps) and an image processing algorithm. The experimental results are compared with a one-dimensional fuel-spray model that was historically developed and applied to fuel sprays from single-hole fuel injectors. Fuel spray penetration distance was evaluated as a function of time for the different injector hole diameters, fuel injection pressures and ambient densities. The results show the differences in model predictions and experimental data at early times in the spray development. [Preview Abstract] |
Saturday, October 6, 2012 9:24AM - 9:36AM |
ED.00008: Imaging Studies of the Effects of Ethanol/Gasoline Blends on Spark-Assisted HCCI Mohammad Fatouraie, Margaret Wooldridge Spark assist (SA) has been demonstrated to extend the operating limits of homogeneous charge compression ignition (HCCI) modes of engine operation. This experimental investigation focuses on the effects caused by the SA HCCI operation on ignition and combustion properties of 100{\%} indolene and 70{\%} indolene/30{\%} ethanol blends. The spark assist effects are compared to base line HCCI for each blend by varying spark timing at different fuel/air equivalence ratio ($\phi $= 0.4--0.6). High speed imaging is used to understand the effects of flame propagation on heat release rates. Ethanol generally improves engine performance with higher indicated mean effective pressure (IMEP) and higher stability compared to 100{\%} indolene. SA advances phasing within a range of 5 CAD at lower engine speeds (700 rpm) and 11 CAD at higher engine speeds (1200 rpm). SA does not affect heat release rates until immediately (within 5 CAD) prior to autoignition. Unlike previous studies, flames were not observed for all SA conditions. During SA operation, more fuel mass was burned by flame propagation with gasoline compared to E30. [Preview Abstract] |
Saturday, October 6, 2012 9:36AM - 9:48AM |
ED.00009: A Team-taught Physical Science Course James Sullivan, Amber Pleiman During the summer of 2012 the authors co-taught a course designed to acquaint current and future teachers to various aspects of Physics and Chemistry. The course was woven around the basic concept of energy and emphasized laboratory work in groups. [Preview Abstract] |
Saturday, October 6, 2012 9:48AM - 10:00AM |
ED.00010: Quantized conductance in educational labs: a consequence of nano-scale confinement Tony Silvidi, Robert Tolley, Herbert Jaeger, Khalid Eid We developed a robust and inexpensive setup to demonstrate the quantization of conductance in a macroscopic gold wire with a nano-constriction. Our setup uses a manually operated bending beam and a micrometer to break and reconnect the gold wire and get the quantized behavior. Alternatively, we use a piezo-crystal to precisely control the motion by manually changing an applied DC voltage across the piezo-crystal. We also will review our work on using an Arduino to control the piez-crystal via a computer in order to run the demonstration in a classroom or as an experiment either in a course in nano-science and technology or in contemporary physics. This is a direct demonstration of the emergence of quantum mechanical behavior due to the wave nature of matter and due to the confinement at the nano- or atomic scale. [Preview Abstract] |
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