Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session G46: SPS Undergraduate V |
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Sponsoring Units: SPS Chair: Kendra Redmond, American Institute of Physics Room: Hilton Baltimore Holiday Ballroom 5 |
Tuesday, March 19, 2013 11:15AM - 11:27AM |
G46.00001: Reverse Micelle Synthesis of Gadolinium Nanoparticles R.H. Fukuda, M.M. Castro, P.-C. Ho, S. Attar, M. Golden, D. Margosan Nanotechnology is an area of great interest due to its variety of applications such as nano-medicine. The reverse micelle method has been used to synthesize Gd nanoparticles by our research group. Through this method, a surfactant protectively cages particles of Gd in the presence of polar methanol and nonpolar hexane. This method can control particle size by growth temperature and the molar ratio of polar solvent to surfactant. The Gd was reduced from its chloride compound by using sodium borohydride. The final products have been derived either through a method of liquid liquid extraction or filtration. Scanning electron microscopy (SEM) paired with energy dispersive x-ray spectroscopy (EDX) was used to examine the size, shape, and composition of the products. The size and shape were also examined using a Leica light microscope between SEM analyses. We found that liquid liquid extraction does not work in the solvent combination of methanol-hexane due to the instability of the reverse micelles. Additionally, the process of carbon coating SEM samples may have destroyed the reverse micelle structures. [Preview Abstract] |
Tuesday, March 19, 2013 11:27AM - 11:39AM |
G46.00002: Ferromagnetic Nanoparticles for Biomedical Applications Frank Holder, Cristina Iftode, Tabbetha Dobbins This work examines the cytotoxicity of barium hexaferrite to fibroblast (HEK-293) cells and also the response of barium hexaferrite to magnetic fields. Cytotoxicity is a great way for pharmacies to measure for toxic compounds. Cytotoxicity assays are widely used by the pharmaceutical industry to screen new compounds which may be introduced to the cells. Results show the cytotoxicity of nanoparticles of barium hexaferrite. We chose barium hexaferrite because it is a magnetic material---so it can be driven using an applied magnetic field. This would be useful in biomedical applications where these particles may be added to direct treatment to various parts of the body and across the cell wall membrane by an applied magnetic field. [Preview Abstract] |
Tuesday, March 19, 2013 11:39AM - 11:51AM |
G46.00003: Morphological, Thermal, and Magnetic Analysis of Ball-Milled $\gamma $-Fe$_2$O$_3$ and Fe$_3$O$_4$ Nanoparticles for Biomedical Application Philip Burnham, Georgia C. Papaefthymiou, Arthur Viescas, Calvin Li, Norman Dollahon Superparamagnetic iron oxide nanoparticles are promising agents for hyperthermia cancer treatment, because, when exposed to an alternating magnetic field, they impart heat to surrounding tissue. A comparison of $\gamma $-Fe$_2$O$_3$ and Fe$_3$O$_4$ nanoparticles for such application is presented. The particles were obtained via surfactant-assisted high energy ball-milling in a hexane/oleic acid carrier-fluid environment. Particles with diameters of 5 to 16 nm were prepared with mass ratios (oleic acid):($\gamma $-Fe$_2$O$_3)$ of 0:1, 1:5, 1:10 and 1:20, with milling times of 3, 6, 9, and 12 hours. TEM micrographs revealed spherical morphology and the effect of oleic acid shells. Optimal size distributions were obtained for high oleic acid contents. At room temperature, a reduced internal magnetic field $\sim$480 kOe) was recorded via M\"{o}ssbauer spectroscopy compared to bulk $\gamma $-Fe$_2$O$_3$ $\sim$500 kOe), due to magnetic relaxation; Fe$_3$O$_4$ particles produced similar results. For the $\gamma $-Fe$_2$O$_3$ and Fe$_3$O$_4$ nanoparticles with 20{\%} oleic acid by mass, comparative ZFC/FC magnetization (H$_{\mathrm{app}}=$ 200 Oe in temperature range from 2 to 400 K) and hysteresis loops (T $=$ 2 K and 300 K up to H$_{\mathrm{app}}=$6 kOe) were obtained. Thermal transport characteristics were verified by Specific Absorption Rate (SAR) measurements using an AC magnetic field ($f=$282 kHz). Differences and similarities in behavior will be discussed. [Preview Abstract] |
Tuesday, March 19, 2013 11:51AM - 12:03PM |
G46.00004: Multi-scale Size Distributions of Colloidal Gold Clusters Measured by Ultrasmall Angle X-ray Scattering (USAXS) and Dynamic Light Scattering (DLS) Ashli Nieves, Jan Ilavsky, Tabbetha Dobbins Gold colloids are of interest as: (1) catalysts for energy conversion and (2) absorption agents for laser photothermal therapy. This research examines the agglomerate sizes (using DLS) and primary particle sizes (using USAXS) for gold nanoparticles synthesized by trisodium citrate reduction of gold chloroauric acid (HAuCl4). USAXS data was collected at the Advanced Photon Source, beamline 15ID-D. Model fitting of the data show primary particle sizes of 7nm to 14nm formed. DLS results show these particles to aggregate into a bimodal set of clusters centered on approximately 20nm and approximately 200nm. Preliminary results aimed at effectively breaking apart these aggregates are presented. [Preview Abstract] |
Tuesday, March 19, 2013 12:03PM - 12:15PM |
G46.00005: Dynamical properties of colloids immersed in a uniform electric field at high densities Matthew Wozniak, Manuel Valera, Athula Herat In light of the recent interest in the control of colloidal systems, we have explored specific properties of electrically interacting colloidal particles. We explored the structural and dynamical characteristics of mono-disperse systems of colloidal particles that are affected by dipole-dipole interactions while immersed in a uniform electric field and compared with the outcomes that could occur if different sizes of particles are mixed. We used molecular dynamics simulations to study the systems. We present results for the diffusion coefficient and other dynamical properties in the high density regime. [Preview Abstract] |
Tuesday, March 19, 2013 12:15PM - 12:27PM |
G46.00006: Synthesis and Characterization of Mg-doped ZnO Nanorods for Biomedical Applications H. Gemar, N.C. Das, A. Wanekaya, R. Delong, K. Ghosh Nanomaterials research has become a major attraction in the field of advanced materials research in the area of Physics, Chemistry, and Materials Science. Bio-compatible and chemically stable metal nanoparticles have biomedical applications that includes drug delivery, cell and DNA separation, gene cloning, magnetic resonance imaging (MRI). This research is aimed at the fabrication and characterization of Mg-doped ZnO nanorods. Hydrothermal synthesis of undoped ZnO and Mg-doped ZnO nanorods is carried out using aqueous solutions of Zn(NO$_{3})_{2}$ .6H$_{2}$O, MgSO$_{4}$, and using NH$_{4}$OH as hydrolytic catalyst. Nanomaterials of different sizes and shapes were synthesized by varying the process parameters such as molarity (0.15M, 0.3M, 0.5M) and pH (8-11) of the precursors, growth temperature (130$^{\circ}$C), and annealing time during the hydrothermal Process. Structural, morphological, and optical properties are studied using various techniques such as XRD, SEM, UV-vis and PL spectroscopy. Detailed structural, and optical properties will be discussed in this presentation. This work is partially supported by National Cancer Institute (1 R15 CA139390-01). [Preview Abstract] |
Tuesday, March 19, 2013 12:27PM - 12:39PM |
G46.00007: Study of Thermal Conductivity of Si Nanowires with micro-Raman Spectroscopy Bingqing Li, Kathryn F. Murphy, Daniel S. Gianola, X.M. Cheng Nanowires have played an increasingly important role in thermoelectric technology due to their high figure of merit ZT resulting from the reduced thermal conductivity, K, and good electrical conductivity. In this work, we report the measurement of K of individual silicon nanowires (SiNWs) by mapping Raman temperature profiles along the testing nanowires using a microelectromechanical system (MEMS) device and a micro-Raman system with a 530 nm laser beam. Thermal conductivity was measured as a function of uniaxial tensile stress applied to the SiNWs, which was varied from 0 to 1.2 GPa. The measured K results for the unstrained nanowires agree well with the predictions based on diffuse phonon boundary scattering. The dependence of SiNWs' thermal conductivity on engineering stress can provide significant information for nanowires fabrication. [Preview Abstract] |
Tuesday, March 19, 2013 12:39PM - 12:51PM |
G46.00008: Characterization of Carbon Nanotubes Synthesized Using Chemical Vapor Deposition Andrew Zeidell, Shawn Huston, Nathanael Cox, Brian Landi, Tonya Coffey, Phillip Russell, Brad Conrad Carbon Nanotubes were synthesized using a Chemical Vapor Deposition system with precursor Cyclopentadienyliron Dicarbonyl Dimer and were systematically characterized over a variety of growth conditions using several methods. Scanning Electron Microscopy (SEM) was used to investigate catalyst contamination, tube diameters, growth morphologies, and material alignment. Transmission Electron Microscopy (TEM) was employed to quantify nanotube wall crystallinity and sidewall defects. Raman Spectroscopy was used in conjunction with Thermo-Gravimetric analysis to ascertain the purity levels of each sample. Results are discussed in terms of related precursors and are used to evaluate the efficacy of the precursor and material quality. [Preview Abstract] |
Tuesday, March 19, 2013 12:51PM - 1:03PM |
G46.00009: Bi2Te3 Nanostructure Synthesis on Multiple Substrates Nicha Apichitsopa, Jerome T. Mlack, Nina Markovic The chalcogenide Bi2Te3 is a known and widely used thermoelectric material that has received renewed experimental interest due to the recent discovery of its topologically protected surface states. Nanodevices of this material are particularly interesting because of their high surface-to-volume ratio, which enhances surface-related transport properties by minimizing bulk contributions. Many synthesis processes for Bi2Te3 have been reported, such as as Au-catalyzed vapor-liquid-solid mechanism (VLS) and lithographically patterned galvanic displacement (LPGD). The VLS mechanism is much simpler than the highly-controlled LPGD; however, remnant of Au catalyst on the nanostructures can alter their electronic structure, resulting in modification of TI surface. We report the synthesis of Bi2Te3 nanostructures by VLS mechanism without using Au catalyst, which improves the quality of the nanostructures. [Preview Abstract] |
Tuesday, March 19, 2013 1:03PM - 1:15PM |
G46.00010: SAM surface domains of 1-mercaptoundecanoic acid and 1-dodecanethiol mixtures on Au(111) investigated via polarized probes Rose Pasquale, Reshani Senevirathne, Indrajith Senevirathne SAM (Self Assembled Monolayer) surfaces with --COOH terminus is bio active and therefore has many bioengineering applications. However complex devices patterned on surfaces require a deeper understanding of the surface domain architecture of SAMs with multi component mixtures of thiols. Varying concentration mixed solutions of 1-mercaptoundecanoic acid (hydrophilic -COOH end) and 1-dodecanethiol (hydrophobic --R), dissolved in 200 proof Ethanol with total 5mM concentration were prepared. These solutions were used in developing SAMs on clean flat Au(111) on mica. Resulting SAMs surfaces were investigated with regular and custom built positively and negatively polarized AFM (Atomic Force Microcopy) probes via contact, non contact and lateral force mode AFM with topography and phase imaging. Domains of distinct thiols were identified as selective self assembly on step edges and terraces. Surface roughness, corrugation and morphology at each domain were estimated. Total RMS surface roughness is estimated at $\sim$ 2.44nm for SAMs with 75{\%} 1-mercaptoundecanoic acid while for SAMs with 25{\%} 1-mercaptoundecanoic acid it is estimated at $\sim$ 2.68nm. [Preview Abstract] |
Tuesday, March 19, 2013 1:15PM - 1:27PM |
G46.00011: Characterization of Nanophosphors for Solid State Lighting Devices Grown by Microwave Plasma Assisted Deposition Process Jedidiah McCoy, Marek Merlak, Sarath Witanachchi Increasingly, greenhouse farming and urban agriculture are being looked at as a more efficient and more cost effective way to grow produce. Currently the lights used in greenhouses rely on light sources that emit a broad spectrum of light. However, only light at wavelengths around 460 nm (blue) and 670 nm (red) are absorbed by most plants for photosynthesis. Solid state lighting devices can be engineered to produce light to match the needs of the plant while reducing the energy cost. An investigation into the photoluminescence properties of the nanophosphor La$_2$O$_3$ doped with Bi was done in an effort to produce a phosphor emitting in blue wavelengths. The La$_2$O$_3$:Bi coatings were grown using a microwave plasma growth process. Microwave power and chamber pressure were varied to find the optimum synthesis conditions. Power was varied from 100Watts to 900Watts and chamber pressure was varied from 30Torr to 60Torr. The process utilized O$_2$ and CO$_2$ plasma. The nanophosphors were investigated by X-ray diffraction, electron microscopy, and photoluminescent spectroscopy. Photoluminescence was shown to be higher from samples synthesized in a CO$_2$ plasma. [Preview Abstract] |
Tuesday, March 19, 2013 1:27PM - 1:39PM |
G46.00012: Slip, Slide, or Roll? Mike Testa Using an atomic force microscope the research project, ``Slip, Slide, or Roll?'' investigates rolling and sliding friction on the nanoscale. The findings of this study may be used to develop improved mechanical lubricants and surfaces. Friction may seem like a simple idea that is familiar to everyone, yet scientific literature explaining what dictates the translational modes of nanoscale objects is surprisingly lacking. In the macroscopic world spherical objects energetically prefer rolling over sliding, for nanoscale objects this is not necessarily the case. We are testing the hypothesis that size, surface chemistry, and elastic modulus dictate whether spherical nanoscale objects will slide or roll when a lateral force is applied. In order to understand the conditions that cause nanoscale particles to transition between the two translational modes we precisely manipulate these variables and measure their effects. [Preview Abstract] |
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