Bulletin of the American Physical Society
2017 Annual Meeting of the APS Mid-Atlantic Section
Volume 62, Number 19
Friday–Sunday, November 3–5, 2017; Newark, New Jersey
Session K1: Poster Session |
Hide Abstracts |
Room: Ballroom, Campus Center, NJIT |
|
K1.00001: Enhancing Physics Outreach Locally, Regionally, and Nationally through the Society of Physics Students (SPS): Tips and Suggestions from your local SPS Zone 3 Councilors. Roberto Ramos, Hannah Buckner University physics student clubs experience varying levels of successes in promoting the discipline of physics and the welfare of physics majors. In this presentation, we discuss how local Society of Physics Students (SPS) chapters can improve and enhance their service by taking advantage of the programming set in place by the National Council of the Society of Physics Students. By participating in joint chapter activities, zone meetings, national physics congresses, and SPS national awards, chapter members can learn from other chapters, from best practices, receive encouragement, obtain scholarships and funding, and expand on how they see themselves promoting physics in society. To facilitate this process, local SPS Zone 3 councilors will be on hand to provide tips and suggestions on getting involved with SPS locally, regionally and nationally. Chapter members and advisors can obtain information and advice about outreach programs, SPS national awards, scholarships and internships, participation in zone meetings, be mutually encouraged and inspired, and provide feedback about their chapter needs. [Preview Abstract] |
|
K1.00002: Student Responses to a Flipped Physics Class Environment with Built-in Feedback Quizzes Despina Nakos, Roberto Ramos We analyze student responses to several Introductory Physics classes in a university setting, taught in a "flipped" class format. The classes span algebra- and calculus-based physics courses. Outside class, students viewed over 100 online video lectures on Classical Mechanics, Electricity and Magnetism, and Modern Physics prepared by this author and in some cases, by a third-party lecture package available over YouTube. Inside the class, students solved and discussed problems and conceptual issues in greater detail. A pre-class online quiz was deployed as a built-in mechanism of feedback and validation. We report on the student reactions to the feedback mechanism, student responses using data based on anonymous surveys, as well as on learning gains from FCI/CSEM inventory pre/post tests. Students preferred the online quizzes as a mechanism to validate their understanding. The learning gains based on FCI and CSEM surveys were significant. [Preview Abstract] |
|
K1.00003: Neutrosophic Goal Programming Ibrahim M. Hezam, Mohamed Abdel-Baset, Florentin Smarandache In this paper, the goal programming in neutrosophic environment is introduced. The degree of acceptance, indeterminacy and rejection of objectives is considered simultaneous. In the two proposed models to solve Neutrosophic Goal Programming Problem (NGPP), our goal is to minimize the sum of the deviation in the model (I), while in the model (II), the neutrosophic goal programming problem NGPP is transformed into the crisp programming model using truth membership, indeterminacy membership, and falsity membership functions. Finally, the industrial design problem is given to illustrate the efficiency of the proposed models. The obtained results of Model (I) and Model (II) are compared with other methods. [Preview Abstract] |
|
K1.00004: Pristine Mica: substrate base for micro/nanotechnologies via gold deposition Brian Evans, Tyler Adams, Chadd Miller, Indrajith Senevirathne Mica has many useful properties in the chemical and physics world. The ability of mica to be cleaved in layers to form pristine layers allows it to be an excellent substrate for micro/nanotechnologies via gold deposition. The smoother starting base provides a more consistent and precise base for the development of the film with minimal strain on the interface. Two different cleaving processes, Tape cleaving and Blade cleaving, where conducted to form pristine layers of mica. Tape cleaving utilized adhesive tape to peel apart the mica to reveal a fresh pristine layer. Blade cleaving utilized a Razor blade which was used to separate the layers of mica. The Atomic Force Microscope (AFM) in intermittent contact mode was used to image the surfaces. Measurements of surface roughness and consistency were obtained for each of the surfaces. These were compared in order to establish a set of rules to get better mica surfaces. [Preview Abstract] |
|
K1.00005: Gold Films and Coatings on Mica and Their Properties Studied Via Atomic Force Microscope (AFM) Tyler Adams, Brian Evans, Chadd Miller, Indrajith Senevitathne Gold thin films deposited via magnetron sputter on clean mica can yield a variety of different structures and there are many variables that can change these nanoscale films. Several processing procedures were used to understand changes in the thin films. The preparation of a mica substrate was one of the first things studied. A standard clean was conducted each time as well as cleaving by two methods to expose a fresh, clean surface of mica. Gold was then deposited through magnetron sputtering to yield clean, consistent, and smooth surfaces. The films were then imaged using the AFM to test the surface morphology and structure properties. This was used as a baseline and a set of procedures for future gold film deposition. [Preview Abstract] |
|
K1.00006: Label Free Nucleotide Sensing Based Upon Back Gated Graphene Field Effect Transistors Adithya Sriram, Ramya Vishnubhotla Early detection of nucleic acid biomarkers for chronic diseases is essential for their diagnoses and therapeutic monitoring. All-electronic biosensor systems based on graphene field effect transistors (GFETs) have shown promise for this application. We have developed a scalable and reproducible method for fabricating arrays of GFET biosensors to detect DNA targets of different lengths as well as mRNA targets. Specificity for the nucleic acid target is achieved by functionalizing the GFET with complementary single-stranded probe DNA. For all targets, varying the concentration of the target nucleic acid caused reproducible shifts in the Dirac voltage of the GFET sensor, in quantitative agreement with the Langmuir-Hill theory of equilibrium binding. The sensor detection limit decreased as the length of the DNA target increased, with sensitivity on the aM level for targets of length 80 mer. Similarly, for the mRNA target, as the concentration of the target increased, the Dirac voltage shifted by greater intervals, tested in a range between the nM and micromolar level. These sensors are developing towards an inexpensive and quick method of biomarker detection. This work was supported by the National Science Foundation through grant number EFRI 2-DARE 1542879. [Preview Abstract] |
|
K1.00007: Excitation Profile of Bi$_{\mathrm{2}}$Se$_{\mathrm{3}}$, Bi$_{\mathrm{2}}$Te$_{\mathrm{2}}$Se, and Bi$_{\mathrm{2}}$Te$_{\mathrm{3}}$ Single Crystals by Raman Scattering Alexander Lee, Girsh Blumberg, Hsiang- Hsi Kung, Sang-Wook Cheong, Roberto Merlin, Ibrahim Boulares Topological Insulators are a class of materials where strong SO coupling results in an insulating bulk and the formation of exotic Dirac fermion metallic surface states. The Raman cross section as a function excitation energy provides information about resonance conditions for interband transitions. Here, we present the results of Raman scattering experiments on Bi$_{\mathrm{2}}$Se$_{\mathrm{3}}$, Bi$_{\mathrm{2}}$Te$_{\mathrm{2}}$Se, and Bi$_{\mathrm{2}}$Te$_{\mathrm{3}}$ single crystals. We present the excitation profile of the phonon intensities of these materials in the visible regime (1.65--3.1eV), corrected for optical constants and spectrometer response, and demonstrate that the cross section for the bulk and surface phonons peaks close to/at the same energy. This indicates that surface resonance effects are responsible for the surface mode intensity increase. Furthermore, we demonstrate that the bulk phonons follow the standard anharmonic decay model as a function of temperature, whereas the surface modes show significant deviation from this model. Electron-phonon interaction may be a major scattering mechanism for Dirac fermions; therefore, a systematic understanding of the behavior of surface phonons in these materials at finite temperatures is important for their applications to spintronic devices. [Preview Abstract] |
|
K1.00008: Abstract Withdrawn
|
|
K1.00009: Hybrid Improper Ferroelectricity in Highly Cleavable Single Crystals of Dion-Jacobson-Compound CsBiNb2O7 Xiachen Fang, Rongwei Hu, Yazhong Wang, Feiting Huang, Sang-Wook Cheong Recently, “hybrid” improper ferroelectrics, a relatively new mechanism leading to ferroelectricity has drawn researchers' interests intensively. Among which, a subfamily of the layered perovskites, Dion-Jacobson (D-J) compounds with general chemical formula A[A'$_{\mathrm{n-1}}$B$_{\mathrm{n}}$O$_{\mathrm{3n+1}}$] is especially interesting because of its large polarization compared with all the other known hybrid improper ferroelectrics like the double-layered Ruddlesden-Popper perovskites with the chemical formula of A$_{\mathrm{3}}$B$_{\mathrm{2}}$O$_{\mathrm{7.\thinspace }}$We have grown high quality single crystals of Dion-Jacobson compound CsBiNb$_{\mathrm{2}}$O$_{\mathrm{7\thinspace }}$using self-flux method. Strong ferroelectric polarization in CsBiNb$_{\mathrm{2}}$O$_{\mathrm{7\thinspace }}$single crystal as well as its high coercivity has been confirmed and quantified during polarization-electric field measurement. Using Piezoelectric Force Microscopy, we perform a systematic study on the ferroelectric domain structure and dynamics of CsBiNb$_{\mathrm{2}}$O$_{\mathrm{7}}$. Further study on the high cleavability of Dion-Jacobson compounds indicates that they might be a good candidate to approach 2-D ferroelectric system. [Preview Abstract] |
|
K1.00010: Thiolated Surfaces: Creation, their Qualities, and Packing: a basis for other nano/micro technologies Chadd Miller, Tyler Adams, Brian Evans, Indrajith Senevirathne Self-Assembled Monolayers (SAMs) of thiols are a useful base for the creation of nanotechnologies that interact with many complex systems and may be used as a basis for many detection systems. Thiol based SAMs consist of a thiol ``head'' group that bonds to a clean flat Au(111) and an easily modifiable ``tail'' group, so that the SAM can be customized to yield desired surface properties. We have used sputter deposited and commercially available Au films in the study. Our work centered specifically on the alkanethiols 11-Mercapto-1-Undecanol, 1-Undecanethiol, and 1-Dodecanethiol. Thiol SAMs were formed on Au(111). The surface properties of gold substrates before and after thiol deposition were analyzed using an Atomic Force Microscope (AFM) AFM-workshop TT on intermittent contact mode. Our results show interesting patterns in the surface arrangement of the thiols on gold, as well as a noticeable difference in the AFM images of each type of thiol. [Preview Abstract] |
|
K1.00011: Coordination Defects: a Novel Type of Grain Boundary-Producing Defect Benjamin Katz, Vincent Crespi A novel defect type in two-dimensional systems is presented, which involves the local coordination number of atoms in an otherwise regular structure. While point-like by itself, such a 'coordination defect' is shown to have a dramatic influence on the growth of the system following its formation due to its introduction of a mismatch in bond network topology and physical ring size. This defect can be of varying size, producing predictable changes in the growth of the system after its appearance. The potential growth pathways of an example graphene system are followed after the occurrence of such a defect using molecular dynamics and first-principles calculations; the inherent tension between the topological requirements and the actual chemical/physical structure that occurs as the system heals the defect can result in varied new morphologies, including a runaway feedback resulting in the spawning of one or more flat finite grain boundaries. Energy comparisons from first principles are used to evaluate the likelihood of this result under various conditions. The appearance of this defect type is predicted to have similar ramifications across a broad array of two-dimensional systems, potentially providing a new method of controlling grain boundary behavior and location. [Preview Abstract] |
|
K1.00012: Energy confinement and thermal boundary conductance effects on short-pulsed thermal ablation thresholds in thin films John Tomko, Ashutosh Giri, Brian Donovan, Daniel Bubb, Sean O'Malley, Patrick Hopkins Laser-induced ablation has become a general term referencing any laser-induced mass removal, with expected ejection mechanisms ranging from non-thermal, photomechanical spallation to a thermally driven vaporization process. On the nanoscale, the high densities of inclusions, defects, and interfaces can lead to thermal transport properties in materials that can be drastically varying from those intrinsic to their respective bulk phases. Thus, an understanding of the heat transport processes that drive material ablation in nanosystems in lacking. In this work, single-pulse ablation mechanisms of ultrafast laser pulses are studied for thin Au films on an array of substrates with varying physical properties. Using time-domain thermoreflectance, the interfacial properties of the thin-film systems are measured: in particular, the thermal boundary conductance. We find that an often used, and widely accepted relation describing threshold fluences breaks down at the nanoscale. Rather than relying solely on the properties of the ablated Au film, the ablation threshold of these Au/substrate systems is found the be dependent on the measured thermal boundary conductance. These results are discussed in terms of diffusive thermal transport and interfacial bond strength. [Preview Abstract] |
|
K1.00013: Effects of Surface Plasmonic Electric Field Enhancements on Thin Film Vanadium Dioxide's Insulator to Metal Transition State. Scott Madaras, Jason Creeden, Salinporn Kittiwatanakul, Jiwei Lu, Irina Novikova, Rosa Lukaszew We investigate the possibility to use an insulator to metal transition (IMT) in vanadium dioxide (VO$_{\mathrm{2}})$ films for a new type of efficient photodetectors. Our goal is to lower the optical power required to achieve IMT by using surface plasmons (SP) which are known to dramatically enhance the electric field at the interface with a noble metal. Thus, we study the effect of SP excitation in the layered structure consisting of a 31nm Au film and 5nm VO$_{\mathrm{2}}$ film, deposited on a glass substrate. Our theoretical model predicts that in such a structure a strong electric field enhancement, 89 times the field at the glass-Au interface, will occur in VO$_{\mathrm{2}}$ at 1064nm laser wavelength when SP are excited. A model of the SP electric field enhancement effect in VO$_{\mathrm{2}}$ coupled with the differences in fractional amounts of VO$_{\mathrm{2}}$ converted between metal and insulator is being used to design and guide experimental measurements. It is expected that, if successful, this method will reduce the optical power requirements for the photo-induced IMT. In the case of using this method in conjunction with ultrafast laser IMT transition methods, it may lower the required transition energy and possibly improve the VO$_{\mathrm{2}}$ time recovery between metal to insulator. [Preview Abstract] |
|
K1.00014: Full-Color Phosphor-Free InGaN/AlGaN Nanowire Light-Emitting Diodes Grown By Molecular Beam Epitaxy. Thang Bui, Moab Rajan Philip, Mehrdad Djavid, Hieu Nguyen III-nitride nanowires light-emitting diodes (LEDs) have been intensively investigated. Compared to thin-film structures, nanowires exhibit drastically reduced dislocations and polarization fields, promising for superior LEDs performance. However, a significant roadblock for the development of nanowire LEDs is the very low efficiency, limited by the lack of 3D carrier confinement, poor hole transport, and electron overflow. In this context, we have investigated the molecular beam epitaxial growth, fabrication and characterization of full-color InGaN/AlGaN nanowire LEDs, wherein the emission characteristics are controlled by adjusting the properties of InGaN active region. Moreover, during the epitaxial growth of the InGaN/AlGaN, multiple AlGaN downward-bending shell layers are spontaneously formed due to the diffusion-controlled growth process, leading to the greatly reduced surface nonradiative recombination, and enhanced carrier injection efficiency. The unique core-shell nanowire LEDs exhibit massively increased photoluminescence and electroluminescence intensities compared to conventional InGaN/GaN nanowire LEDs. Additionally, such core-shell LEDs emit strong white light with unprecedentedly high CRI of \textgreater 95, which are ideally suited for future smart lighting applications. [Preview Abstract] |
|
K1.00015: Growth and Characterization of ZnO Nanowires for Biological Sensing Applications Joshua M. Carlson, Kevin Mack-Fisher, Benjamin Roe, Tylor J. Peca, Kurt W. Kolasinski, Shawn H. Pfeil We present data on the growth of ZnO nanowires, which are under development as a less toxic alternative to quantum dots. Nanowires, grown via thermal oxidation of seed particles deposited by laser ablation, were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). AFM studies focused on the details of the growth processes that occur on sub-100 nm seed particles. There appear to be three main archetypes of wire decorated nanoparticles, they follow a general trend in the sizes of ``seed'' particles from which wires originate, as well as the width, length, and variety of their nanowires. We bin the seed particles into three classes by diameter, small (\textasciitilde 1 nm), medium (\textasciitilde 2.5-5 nm), and large (\textasciitilde 7-10 nm). Small seeds give rise to short nanowire spikes, \textasciitilde 0.5 nm in length, medium seeds give rise to intermediate length wires, 4-12 nm in length, and large seeds give rise to longer wires, 20-40 nm in length. This suggests that the size of the particle is qualitatively related to the ``upper ceiling'' on potential nanowire length. SEM studies focused on the details of growth processes that occur on 100 nm to 1 \textmu m seed particles. Large particles exhibits a remarkable growth regime in which nanowires completely consume the seed particle. [Preview Abstract] |
|
K1.00016: Zinc Tungstate Scintillators for Low Energy Electron Microscopy Derek Grove, Marian Tzolov, Nicholas Barbi, Owen Healy Zinc tungstate is a crystalline material that emits light as result of electron bombardment. We have deposited ZnWO$_{\mathrm{4\thinspace }}$films with electrical conductivity enough to prevent charging, photoluminescence quantum efficiency of 23{\%}, which are mechanically durable. This makes it a viable thin film coating for scintillators inside an SEM with the added benefit that it can deliver signal even at low energy of the electrons. Our theory is that zinc tungstate as a thin film on top of scintillators offers more benefits for low energy back scattered electron microscopy than ITO or Al, two materials that do not emit light in the presence of electron radiation. We have taken images at low accelerating voltages with two types scintillators, YAP with a thin film of zinc tungstate on top and YAG with ITO. The comparison shows much higher signal to noise ratio for the scintillator with zinc tungstate, and imaging with it at electron energies, where no image can be collected with the scintillator with ITO. The ability of the zinc tungstate film to prevent charging was confirmed with measurement of the electron emission vs. accelerating voltage. These curves are however, very sensitive to the surface properties of the sample. [Preview Abstract] |
|
K1.00017: Organic Solar Cells: Construction and Characterization Jake Keiper, Marian Tzolov An Organic Solar Cell is a type of photovoltaic cell that uses organic polymers for light absorption and charge transport. Organic Solar Cells have benefits such as being light weight, flexible, conforming to variety of surfaces, and potentially inexpensive and disposable. Production can vary by materials used and the structure of the devices. Different polymers are used in these cells to alter the band gap and utilize different parts of the solar spectrum. Structure varies in the sequence of the layers, such as the cells being regular or inverted cells. We will present results on regular cells with hole injection layers PEDOT and PlexCore. The interaction of the HIL with the solvent of the subsequent polymer blend solution was studied. We show that if this interaction is not prevented substantial electrical shorts form in the device severely deteriorating the photovoltaic performance. Methods of characterization include Current-Voltage characteristics and Impedance spectroscopy. We currently are using P3HT, PCPDTBT, and PCBM (C-60) for the active layer of the solar cells. Impedance spectroscopy has given us a great insight on the electrical processes in our devices and allows us to model the layers as realistic circuit components. This is useful when trying to improve our cells, as it allows us to target aspects of the production process. [Preview Abstract] |
|
K1.00018: Argon Adsorption in Three-Dimensional Ordered Mesoporous (3DOm) Carbons: Monte Carlo Molecular Simulation Study Max A. Maximov, Gennady Gor Templated nanoporous materials show excellent performance in many applications due to well-defined pore sizes and morphologies. 3DOm carbons are prepared using silica-nanospheres as a template, thus they have spherical pores interconnected by circular windows. Recent experiments show that 3DOm carbons work efficiently as a medium for storing methane in the pores in the form of hydrates. However, the basics of this process are not clear, and in particular it is not known how the pore morphology affect formation of hydrates. Moreover, even behavior of simpler fluids (nitrogen and argon) in 3DOm carbons, is not well understood. Adsorption of these two fluids is routinely used for characterization of nanoporous materials, and correct physical interpretation is required to extract the pore-size distribution from the experimental adsorption data. Here we present the Monte Carlo molecular simulation study of argon adsorption in 3DOm carbons. To represent 3DOm structure, we use two models: an ideal spherical pore, and a system of spherical pores, connected with the openings. Our simulations show that the openings between the pores are necessary for the analysis of experimental adsorption data. Our results also serve as a starting point for modeling hydrate formation in 3DOm carbons. [Preview Abstract] |
(Author Not Attending)
|
K1.00019: Synthesis and characterization of hierarchical structures based on CNT coated basalt fiber reinforced epoxy composites Garima Mittal, Kyong Yop Rhee Hierarchical structures open a new gateway of the opportunities to design the composites with advanced properties. Further, CNT is considered as an ideal reinforcing material due to its extremely high aspect ratio and extraordinary mechanical, thermal, and electrical properties. On contrary, the tendency of forming bundles restricts to attain optimum benefits of CNTs as a reinforcing material. In that case, making hierarchical structure by coating CNTs on the substrate provide a good solution. Therefore, in this study, CNTs were grown directly in basalt fiber through chemical vapor deposition process. The formed structures were characterized using HR-RAMAN, XRD, and FE-SEM. Later, to fabricate the composites, these hierarchical structures were reinforced into epoxy matrix using hand lay-up method. Further, thermal and tribological properties of these hierarchical composites were analyzed using thermogravimetric analysis and friction and wear tests. The outcomes indicated that the hierarchical composites exhibit superior properties as compared to the directly reinforced CNT based basalt-epoxy composites. [Preview Abstract] |
|
K1.00020: Third-order Nonlinearity of MoS$_{\mathrm{2}}$ and WS$_{\mathrm{2}}$ atomic Layers Tikaram Neupane, Sheng Yu, Bagher Tabibi, Felix Jaetae Seo The third-order optical nonlinearity of 2D transition metal dichalcogenide atomic layers is of great interest for the prospective applications in optical modulators and photonic devices. The third-order nonlinearity includes the nonlinear absorption and nonlinear refraction which can be characterized through either resonant or non-resonant excitation. The atomic layers for this presentation include tungsten disulfide (WS$_{\mathrm{2}})$ and molybdenum disulfide (MoS$_{\mathrm{2}})$ nanoflakes of 1-4 layers in deionized water. The excitation wavelength was 532 nm which was located above A and B exciton absorptions of MoS$_{\mathrm{2}}$ and between A and B exciton spectra of WS$_{\mathrm{2}}$. The excitation at 2.33 eV is resonant for A and B excitons of MoS$_{\mathrm{2}}$ and A exciton of WS$_{\mathrm{2}}$, and the non-resonant for B exciton of WS$_{\mathrm{2}}$. The nonlinear absorption coefficients for WS$_{\mathrm{2}}$ and MoS$_{\mathrm{2}}$ nanoflakes were analyzed to be \textasciitilde 6.7 x 10$^{\mathrm{4}}$ cm/GW and \textasciitilde -1.0x 10$^{\mathrm{5}}$ cm/GW with open Z-scan, respectively. The nonlinear refraction of WS$_{\mathrm{2}}$ and MoS$_{\mathrm{2}}$ were estimated to be \textasciitilde - 6.7 x 10$^{\mathrm{-10}}$ cm$^{\mathrm{2}}$/W and \textasciitilde -1.3 x 10$^{\mathrm{-10}}$ cm$^{\mathrm{2}}$/W, respectively, with peak-valley nonlinear transmittance trace. [Preview Abstract] |
|
K1.00021: Piezoelectricity of 2-Dimensional MoS$_{\mathrm{2}}$/WS$_{\mathrm{2}}$ Vertical Heterostructure Sheng Yu, Tikaram Neupane, Bagher Tabibi, Felix Jaetae Seo The two-dimensional atomic layers have a weak van der Waals coupling between layers, strong covalent in-plane bonds, large exciton binding energy, and reduced dielectric screening out-of-plane. The van der Waals heterostructure of p- and n-type atomic layers with different work functions has a type-II staggered gap alignment. The large band offsets of conduction band minima and valence band maxima between p- and n-type atomic layers results in significant electronic polarization and enormous piezoelectric energy conversion. Large elastic deformation and atomic polarization sensitivity to strain are excellent piezoelectric characteristics of heterostructure atomic layers. This presentation includes the piezoelectricity of MoS2 and WSe2 partial vertical heterostructure of AB and AA stacking as n- and p-type semiconductors with tensile strain along the transport direction. The output voltage of MoS2/WSe2 partial vertical AB stacking were 0.137 eV and 0.183 eV for the 4{\%} and 8{\%} tensile strain, respectively, to prove the piezoelectricity. The output voltage obviously depends on the stacking area, orientation, number of atomic layers, interlayer distance, and etc. [Preview Abstract] |
|
K1.00022: Visible Transition in Localized Defect-mediated h-BN Monolayer Sheng Yu, Tikaram Neupane, Bagher Tabibi, Felix Jaetae Seo The studies of spin-resolved electronic bandstructure and electron density of states (DoS) for the defect-mediated hexagonal boron nitride (h-BN, E$_{\mathrm{B}}$\textasciitilde 5.2 eV) monolayer revealed the formation of energy states within the forbidden band and the electron spin-dependent optical transitions between the energy states in visible spectral region. The absorption and reflection coefficients of defect-mediated h-BN were analyzed by the density function theory (DFT). The localized point defects in h-BN included boron vacancy (V$_{\mathrm{B}})$, nitrogen vacancy (V$_{\mathrm{N}})$, boron replacing nitrogen (B$_{\mathrm{N}})$, nitrogen replacing boron (N$_{\mathrm{B}})$, carbon replacing boron (C$_{\mathrm{B}})$, carbon replacing nitrogen (C$_{\mathrm{N}})$, boron replacing nitrogen with boron vacancy (B$_{\mathrm{N}}$-V$_{\mathrm{B}})$ and nitrogen replacing boron with nitrogen vacancy (N$_{\mathrm{B}}$-V$_{\mathrm{N}})$. The prospective nonlocal correlation between electron spin and photon polarization in the defect-mediated h-BN will pave the application of quantum information processing with two-dimensional atomic layer solid-states. [Preview Abstract] |
|
K1.00023: The impact of sampling medium and environment on nanoparticle morphology Ogochukwu Enekwizu, Chao Chen, Yan Ma, Dmitry Zakharov, Alexei Khalizov Sampling on different substrates is commonly used in aerosol research. Our focus was on the transformations that can occur to the collected nanoparticles during storage, handling, and analysis. Collected samples were inspected by electron microscopy before and after exposure to various environments. The extent of sample alteration ranged from negligible to major, depending on the environment, substrate, and particle composition. We discuss the implications of our findings for cases where morphology and the mixing state of particles must be preserved and cases where particle transformations are desirable. [Preview Abstract] |
|
K1.00024: Suppressing Turbulence and Reducing Blood Viscosity to Prevent Heart Attacks and Strokes Kazi Tawhid-Al-Islam, Rongjia Tao, Enpeng Du, Hong Tang, Xiaojun Xu, Michael Autieri High viscosity and turbulence in blood flow greatly increase the risk of cardiac diseases. Turbulent blood flow makes the vasculature vulnerable to development of atherosclerotic plaque. In consequence, heavier workload on the heart results in high blood pressure, reduced oxygen function, heart murmur etc., which eventually may lead to heart attacks or ruptured blood vessels. Presently available medicines may reduce blood viscosity, however, only to worsen the turbulence because the Reynolds number goes up as the viscosity lowers. Here, we will report our \textbf{Magneto-Rheology} (MR) research that addresses both turbulence suppression and viscosity reduction simultaneously. When a strong magnetic field is applied along the blood flow direction, red blood cells are polarized, and aggregated into short chains, which lowers the viscosity significantly along the flow direction. And at the same time viscosity is increased in the directions perpendicular to the flow. We have observed that in an \textit{In-Vitro} system of blood flow, such anisotropic viscosity suppresses the turbulence. The preliminary results appear to be very promising, demonstrating this MR treatment reduces the blood pressure in real human subject. [Preview Abstract] |
|
K1.00025: Synthesis and structural characterization of geometrically frustrated double perovskites Connor Williams, Demetrios Papakostas, Jeremy P. Carlo In geometrically frustrated materials, magnetic order is inhibited by the arrangement of magnetic ions. Typically seen with triangular or tetrahedrally coordinated moments favoring antiparallel (antiferromagnetic) alignment, frustrated materials exhibit a variety of magnetic ground states due to the cancellation of normally dominant interactions, providing a window into exotic physics. Double perovskites of composition A$_{\mathrm{2}}$BB$\prime $O$_{\mathrm{6}}$, with 'rock-salt' order of magnetic B' ions, potentially exhibit frustration. Further, the chemical versatility of perovskites enables synthesis of compounds with divergent properties, with great potential to yield new insights into frustration physics. We report the solid-state synthesis and x-ray structural characterization of Ba$_{\mathrm{2}}$YbMoO$_{\mathrm{6}}$, Ba$_{\mathrm{2}}$YWO$_{\mathrm{6}}$, Ba$_{\mathrm{2}}$LuWO$_{\mathrm{6}}$, Ba$_{\mathrm{2}}$ScMoO$_{\mathrm{6,\thinspace }}$and Sr$_{\mathrm{2}}$ScMoO$_{\mathrm{6}}$. All but the latter crystallize in the ideal cubic \textit{Fm-3m} double perovskite structure, while Sr$_{\mathrm{2}}$ScMoO$_{\mathrm{6}}$ was refined in the tetragonal \textit{I4/m} space group, consistent with their respective Goldschmidt tolerance factors. [Preview Abstract] |
|
K1.00026: Synthesis and Magnetic Characterization of Double Perovskites Demetrios Papakostas, Connor Williams, Jeremy Carlo Geometric magnetic frustration occurs when magnetic ions are arranged spatially such that magnetic order is inhibited. Frustrated materials are of interest to the research community due to their rich magnetic phase diagrams, exhibiting exotic physics and sensitivity to parameters such as doping and structural distortion. We have performed SQUID susceptibility measurements on the following 4$d^{\mathrm{1}}$/5$d^{\mathrm{1}}$ (Mo$^{\mathrm{5+}}$/W$^{\mathrm{5+}})$ double perovskite compounds: Ba$_{\mathrm{2}}$YbMoO$_{\mathrm{6}}$, Ba$_{\mathrm{2}}$LuWO$_{\mathrm{6}}$, Ba$_{\mathrm{2}}$YWO$_{\mathrm{6}}$, Ba$_{\mathrm{2}}$ScMoO$_{\mathrm{6}}$, and Sr$_{\mathrm{2}}$ScMoO$_{\mathrm{6}}$. Double perovskites exhibit frustration in the presence of antiferromagnetic correlations. In our measurements, all five compounds exhibited Curie-Weiss behavior with large and negative Curie-Weiss temperatures indicative of antiferromagnetic correlations. No evidence of magnetic order was found to 2K, indicating high frustration indices as seen in spin-singlet candidates such as Ba$_{\mathrm{2}}$YMoO$_{\mathrm{6}}$ and Ba$_{\mathrm{2}}$LuMoO$_{\mathrm{6}}$. [Preview Abstract] |
|
K1.00027: Optimizing Sample Preparation for Soft Point Contact Spectroscopy of Iron Pnictude Crystals Caitlyn McConnell, Oberon Wackwitz, Despina Nakos, Luke Conover, Guotai Tan, Yu Song, Chenglin Zhang, Pengcheng Dai, Rui Zhang, Hu Ding, Roberto Ramos Point contact spectroscopy is a widely-used technique for measuring the energy gap of superconductors. Working with iron-based pnictides, particularly K-doped iron pnictide Ba(1-x)KxFe2As2, we have made electrical contact to crystal samples obtained from collaborators by applying a small amount of silver paint using a sharp-tipped wire. We have been moderately successful using this technique and report some results of measurements here. We report progress on ongoing efforts to optimize delivery of silver paint using a more controlled way that employs micro-pipettes. We also present details of how our conductance measurements are influenced by ``fritting'' which is a technique of tuning the point contact region through current impulses. All measurements were performed by undergraduate students. [Preview Abstract] |
|
K1.00028: Measuring the Superconducting Energy Gaps of Doped Iron Pnictide Superconductors Ba_(1-x) K_x Fe_2 A_2 using Soft Point Contact Spectroscopy Oberon Wackwitz, Luke Conover, Caitlyn McConnell, Guotai Tan, Yu Song, Chenglin Zhang, Pengcheng Dai, Roberto Ramos The iron-based superconductors or iron pnictides provide a new platform where the phenomenon of multi-band superconductivity can be studied. Multiple energy gaps in these samples can be measured, depending on the way the crystal has been grown and how the tunneling directions are accessed through fabrication and the way electrical contacts are made. These energy gaps are anisotropic relative to the crystal lattice, with some gaps primarily conducting parallel or perpendicular to the c-axis of the lattice. In this presentation, we report ongoing measurements of the energy gaps of K-doped iron pnictide Ba(1-x)KxFe2As2 superconductors, where x = 0.6, 0.5, and 0.33 near liquid helium temperatures. We report the observation of peaks and broad shoulders; some correlate well with existing data from literature while other new peaks are unexplained. These measurements have been performed fully by undergraduates. [Preview Abstract] |
|
K1.00029: Enhanced superconductivity in tin-based hyperbolic metamaterials William Zimmerman, Sabrina Searfoss, Christopher Jensen, Grace Yong, Vera Smolyaninova, Joseph Prestigiacomo, M. S. Osofsky, Igor Smolyaninov The search for superconductors with higher Tc is one of the most important problems in condensed matter physics. Recent experiments have demonstrated the enhancement of the critical temperature of a superconductor via the metamaterial approach [1, 2]. Electron-electron interaction in tin/dielectric epsilon near zero (ENZ) metamaterials was enhanced through dielectric response engineering. Here, we extended this approach to a hyperbolic configuration (tin/dielectric multilayers). We have also demonstrated that an aluminum/aluminum oxide hyperbolic metamaterial geometry is capable of Tc enhancement [1]. The dependence of Tc enhancement on metal volume fraction was studied. Polarization reflectometry was used to correlate anisotropy of dielectric function with superconducting properties. [1]. Vera N. Smolyaninova et.al, Scientific Reports 6, 34140 (2016) [2]. Vera N. Smolyaninova et.al, Scientific Reports 5, 15777 (2015). [Preview Abstract] |
|
K1.00030: PT restoration via increased loss and gain in the-symmetric Aubry-Andr\'{e} model Charles Liang, Derek Scott, Yogesh Joglekar In systems with ``balanced loss and gain,'' the~\textit{PT}~symmetry is broken by increasing the non-Hermiticity or the loss-gain strength. We show that finite lattices with oscillatory,~\textit{PT} -symmetric potentials exhibit unexpected~\textit{PT} -symmetry breaking and restoration. We obtain the~\textit{PT}~phase diagram as a function of potential periodicity, which also controls the location complex eigenvalues in the lattice spectrum. We show that the sum of~\textit{PT}~potentials with nearby periodicities leads to~\textit{PT} -symmetry restoration, where the system goes from a \textit{PT} -broken state to a~\textit{PT} -symmetric state as the average loss-gain strength is increased. We discuss the implications of this transition for the propagation of a light in an array of coupled waveguides. Reference [1] C. H. Liang, D. D. Scott, and Y. N. Joglekar, Phys. Rev. A \textbf{89}, 030102 (2014). [Preview Abstract] |
|
K1.00031: Electronic excitations in a one-dimensional J=$\frac{1}{2}$ antiferromagnet observed by Raman scattering Mai Ye, Jae-Wook Kim, Choong-Jae Won, Sang-Wook Cheong, Girsh Blumberg A major focus of experimental interest in low-dimensional iridium oxides has been to explore the interplay of quantum fluctuation, spin-orbit coupling and electron correlation effects. Ba$_5$CuIr$_3$O$_{12}$ serves as an ideal playground and contains weakly-interacting chains along which J=$\frac{1}{2}$ iridium ions are antiferromagnetically coupled. The intercept obtained by extrapolating high-temperature inverse static magnetic susceptibility is around -270\,K but no magnetic ordering occurs down to 4\,K\footnote{G. R. Blake et al., Chem. Mater. 10, 3536 (1998)}, indicating quanum fluctuation induced magnetic frustration. Here, we report polarized inelastic light-scattering spectrum of Ba$_5$CuIr$_3$O$_{12}$ as function of exciting laser energy and temperature. Low-energy magnetic response below 100\,meV only appears when the system is excited along the chain direction, corresponding to local antiferromagnetic correlations. On the other hand, the spectral lineshape of high-energy d-d electronic transitions at 570\,meV sheds light on the competition between localizing and itinerant tendency of electrons on iridium extended 5d orbits. [Preview Abstract] |
|
K1.00032: Variation in Ultrasound Attenuation in Relaxed and Contracted Muscle Tissue Thea Keppler, Michelle Milne The purpose of this study is to measure the attenuation of ultrasound in contracted and relaxed states in rat skeletal muscle. Ultrasonic waves are sound waves that have a frequency above twenty thousand Hertz (higher than the audible range). Attenuation, the loss of energy in a sound wave as it travels through a material, is an intrinsic property of that material. Therefore, it can be used to characterize tissues and has the potential to help physicians diagnose muscle abnormalities. Results indicate that ultrasonic waves attenuate at a higher rate in relaxed tissue versus contracted tissue. These results could have implications for ultrasound imaging of patients in the clinic. [Preview Abstract] |
|
K1.00033: How the Translocation Dynamics of DNA in an Oscillating Electric Field change with Frequency Thomas Longo, Rhys Duff, Zachary Dell, Ining Jou, Murugappan Muthukumar To make DNA sequencing more efficient and economical one proposed method has been to use nanopores. In nature, nanopores are the gateways that exist on a cell’s membrane, and are used by proteins which pass through them. By artificially creating these nanopores in a salt solution we can measure the current flow of the salt ions that pass through the nanopore, and if there is a strand of ssDNA in the nanopore, the current measured will change in accordance with the type of base that is in the constriction point, or the narrowest point, of the nanopore. In doing this, theoretically, we can completely sequence any strand of DNA that goes through the nanopore. However, there are two main problems with this method; the DNA translocates too quickly to measure accurately and nearby bases inside the constriction point influence the output current. My project seeks to better understand this process through molecular dynamics simulations. In my simulations, I will be testing whether applying an alternating current to the system will slow the translocation time of the ssDNA, and thereby, increase the accuracy of the sequencing process. In addition, I will be looking for the optimal frequency of the alternating current to maximize the length of the translocation time. [Preview Abstract] |
|
K1.00034: Translational and Rotational Diffusion of Bacteria Under the Influence of Direct Current Janet Peifer, Yong Wang Many bacteria, whose mobility is vital for their survival, naturally inhabit aqueous solutions. Therefore, it is of interest to investigate the movement and growth of bacteria in aqueous solutions. In this study, we focus on tracking and quantifying the motion of\textit{ E. coli} bacteria in LB medium. We first studied the diffusion of microspheres in water or a 50{\%} glycerol solution, in both of which the diffusion appeared to be Brownian. Then we observed the motion of live \textit{E. coli }bacteria in liquid LB medium, imitating the natural aqueous habitats of many bacterial species. Homemade MATLAB programs extracted the positions and orientations of live bacteria and their trajectories. We quantified the travel distances, translational step sizes, and rotational step sizes of the bacteria. Furthermore, we investigated the effect of electric current on the motion of \textit{E. coli} bacteria. Quantitative analyses showed that the bacteria were more likely to travel longer distances in the absence of electric current while retaining their translational step size and increasing their rotational step size in the presence of electric current. It was also observed that bacteria were drawn to the positive electrode and crowded densely in that area. [Preview Abstract] |
|
K1.00035: A Mean Field Model for Studying the Crowding Effect of TMAO in the Protein Hydration Shell Anthony Cooper, Luca Larini Studying the local dynamics of the water molecules closest to a protein has been a long-standing challenge. As the surface of a protein is not uniform, the solvent binds to a varying degree across different points along the surface. Additionally, other solutes may change the local properties of the hydrogen bond network, which in turn may stabilize or destabilize the protein itself. TMAO is a well-known crowding agent that is believed to stabilize a protein’s secondary structure not by direct contact with the backbone, but by an effect that is mediated by altering the hydrogen bond network of the water surrounding the protein. The exact nature of this effect is not fully understood. Here, we propose a mean field model that describes the interaction of TMAO with the water surrounding the protein and we will test our prediction through comparison with existing 2D IR spectroscopic data. Our mean field model correctly predicts the shift of the resonance frequency and the dependence on the concentration of solute while establishing a connection between the decay of the frequency-frequency correlation function and entropy of the system. [Preview Abstract] |
|
K1.00036: Observing Microtubules' Vibrational Properties in Micrometer Channels Karina Dsouza, Arooj Aslam, Camelia Prodan Taxol is a chemotherapy drug that discourages the spread of cancer by inhibiting microtubule (MT) catastrophe, forcing cancer cells to undergo apoptosis. Repeated use of Taxol, however, often yields Taxol-resistant cancer cells. It is possible that these cells have modified vibrational properties and edge modes that are interfering with Taxol's inhibition of MT catastrophe. The purpose of this research project is to flow MTs through progressively smaller channels (5.3 mm-\textasciitilde 270 $\mu $m) and lay the foundation for the isolation of an MT in a nanochannel -- which will allow for more controlled MT excitation and better observation of vibrational properties. [Preview Abstract] |
|
K1.00037: Modifying Amplitudes of Various Waves Using Novel Patterns Ayushi Sangoi, Camelia Prodan, Kyle Dobiszewski Certain novel patterns have various properties that can be applied to modifying acoustics among other things. This research project studies the effects of a novel pattern on the ability of waves to transfer through space. By understanding this relationship between the pattern and the movement of waves, we seek to help in sound-proofing rooms, noise reduction in industrial shipping and the navy, and hacking in air-gapped computers. Inspired by previous research regarding the transfer of water through such patterns and noise-dampening land art near Amsterdam's airport, we test the difference between the waves entering and leaving the patterns. The patterns are tested using various frequency stimuli. Certain frequencies were amplified by the novel pattern, while others were dampened almost to the point of being muted. The targeted frequencies shifted based on the spacing in the patterns themselves. This determines the role of the particular novel pattern in the transfer of waves. This helps support other research using microtubules in cancer research. The observations and discoveries of this research can have significant effects in the field of physics as well as life science and medicine. [Preview Abstract] |
|
K1.00038: Determining the Stoichiometry of Protein Complexes using V-Fusion and Single Molecule Imaging Maria Sirenko, Avtar Singh, Alexander Van Slyke, Alexander Song, Paul Kammermeier, Warren Zipfel The stoichiometry of subunits in protein complexes provides key insight into their molecular mechanisms but is often difficult to determine with existing methods.~Although stepwise photobleaching has been used, it is often applied in vitro or cellular expression is intentionally kept low; both of these situations may lead to artifacts. We demonstrate a novel single molecule imaging method using cellular fusion between expressing and non-expressing cells to dilute the concentration of protein complexes without affecting their integrity. After dilution, single protein complexes can be resolved and photobleach step counting provides protein stoichiometric information. We determine the stoichiometry of ADRB2 and EGFR before and after addition of ligand as well as upon exposure to inhibitors. [Preview Abstract] |
|
K1.00039: Distilling Muscle Actomyosin Interactions for Length Dependent Activation: Reducing a 15-State Model to 3 States Timothy Alcid, William Hunter Muscle proteins myosin and actin interact to produce force. These proteins align along filaments bundled together into sarcomeres. Actin contains sites where myosin heads attach to form crossbridges. Our basis was an existing crossbridge model (Caremani, 2015): 12 attached and 3 detached states cycle through ATP binding, hydrolysis and subsequent release of ADP and phosphate. A reduced, regulated computational model was created to have 1 detached and 2 attached kinetic states. Such reduction is critical because this actomyosin model will be part of complex, higher order models that include other aspects of muscle regulation. One detached state exists in an equilibrium mixture of 3 rapidly interacting structures, including the recently discovered super-relaxed structure. In this, the myosin head is held back against the filament backbone. When force is applied along the filament by the protein titin, these myosin heads release for interaction. Titin's role alters at different sarcomere lengths. Agreeing with data (Dobesh, 2002), the model can predict the probability of crossbridge formation and force production as sarcomere length changes. We anticipate this model (coupled with more data) will improve understanding of this length-dependent effect in actomyosin interactions. [Preview Abstract] |
|
K1.00040: Toward a Discrete Molecular Dynamics Coarse-Grained Lipid Bilayer Model for Studies of amyloid beta -Membrane Interactions Blake Antos, Dr. Brigita Urbanc Despite being the focus of intense study, the exact mechanism underlying Alzheimer’s disease is not well understood. Soluble, low molecular weight assemblies formed by amyloid beta-protein (Abeta), called oligomers, are hypothesized to trigger the Alzheimer’s disease pathology by causing synaptic failure that involves interactions between Abeta and the membrane. Several studies using a computational method called discrete molecular dynamics (DMD) combined with a coarse-grained protein model have demonstrated that many aspects of Abeta oligomer formation and structure can be captured and predicted by this efficient approach. Here, we aim to expand this DMD approach to include a model of a lipid bilayer to be combined with the protein model in an effort to examine Abeta -membrane interactions. We have developed a course-grained lipid model which can self-assemble into a membrane-like structure. Next, this lipid bilayer model will be characterized and the parameters of the model adjusted to achieve the correct cross-layer density and diffusion constant, and to capture multiple phases transitions observed in real membranes. Finally, we will investigate interactions of a lipid bilayer with Abeta oligomers which are expected to disrupt the lipid bilayer. This research will provide insights into the possible mechanisms underlying Abeta oligomer-mediated cytotoxicity. [Preview Abstract] |
|
K1.00041: Insulin Assembly at neutral pH: Comparison and Relevance to Abeta assembly Kaho Long, Thomas L. Williams, Brigita Urbanc Recent observations support a connection between Alzheimer’s disease (AD) and type 2 diabetes mellitus. These observations indicate that individuals with a disrupted insulin homeostasis of the body may have an increased risk of also developing AD later in life. This has lead us to begin an investigation into the role that insulin has on the ability of amyloid b-protein (Ab), specifically the 42 amino acid-long alloform Ab42, to disrupt membrane integrity. In this study we used a technique involving dye encapsulating large unilamellar vesicles, which is known as the calcein release assay. Using the calcein release assay we observed that the potency of Ab42 to disrupt the membrane integrity was inhibited by insulin in insulin concentration-dependent way. Our in vitro findings suggest a strong interaction between Ab42 and insulin, which may be of physiological relevance and may offer new therapeutic approaches against AD. [Preview Abstract] |
|
K1.00042: Insights into the Effect of Cross-Linking on Ab Oligomer Formation and Structure Shuting Zhang, Dillion M. Fox, Brigita Urbanc Amyloid beta-protein (Ab) is the main component of amyloid plaques thatrepresent one of the hallmarks of Alzheimer’s disease (AD). Ab forms lowmolecular weight (LMW) oligomers, which are hypothesized to trigger ADpathology. Because of their heterogeneous nature and relatively short life-times, Ab oligomers have not been crystallized to date and consequentlytheir structure has not been experimentally characterized. Covalent cross-linking of Ab oligomers combined with gel electrophoresis can be used tocharacterize oligomer size distributions of two predominant Ab alloforms,Ab40 and Ab42. A recent study reported formation of cross-linked Aboligomers that can form under physiological conditions in the presence ofcopper and hydrogen peroxide. Here, we use efficient discrete moleculardynamics (DMD) combined with the four-bead protein model and aminoacid-specific interactions (DMD4B-HYDRA approach) to examine the ef-fect of cross-linking on Ab oligomer formation. The results of our studydemonstrate that cross-linking via tyrosines facilitates self-assembly of bothalloforms, in particular that of Ab40, yet does not account for the formationof cross-linked Ab40 and Ab42 oligomers larger than trimers and tetramers,respectively. Cross-linking changes the secondary, tertiary, and quaternarystructure of Ab40 and Ab42 dimers and trimers by increasing the exposureof hydrophobic residues and facilitating formation of elongated oligomericshapes that differ from quasi-spherical globular structures observed in con- trol simulations. Our findings imply that amino acids other than tyrosineshave to be involved in cross-linking, the proposition that is currently underinvestigation. [Preview Abstract] |
|
K1.00043: Can Intercellular Functions be Potentially Cell Specific? Brandon Rosario, Marcos Hernandez, Mitra Shojania Feizabadi Microtubules are one of the intracellular elements that are involved in cell division, cellular transportation, and cellular morphology. One of the critical microtubule roles is the capture of replicated chromosomes during mitosis. Microtubules are intrinsically dynamic polymers that display non-equilibrium behavior known as dynamic instability. Under these dynamics microtubule ends stochastically switch between growing and shortening states. As reported, one of the biological significance of dynamic of microtubules can be related to the time it takes for them to find chromosomes as their target and consequently go through the cell division process. Microtubules' dynamics are well dependent on their structural composition. Our recently reported evidence show that some of the cancer microtubules express more stability in their dynamics as compared to brain microtubules. This slow dynamic of cancer microtubules can potentially be one of the factors that effects the cell division mechanism in cancer vs. brain cells by influencing the time it takes them to capture the chromosomes. This work discusses the experimental and theoretical results of our recent studies in these two groups of microtubules. [Preview Abstract] |
|
K1.00044: Study of the Contrast Agents Containing Metal Oxides and Lanthanide Element for Bioimaging Min Jae Shin, Richard Kyung The unique magnetic properties of the gadolinium ion allowed it to be used in a variety of ways, especially in MRI scanning. However, the use of some Gd(III) chelates in persons with renal disease was linked to a rare but severe complication, which may occur months after contrast has been injected. The common use of iodinated molecules as contrast agents has potential drawbacks, such as high dosage that lead to toxicity and lack of stability, motivating researchers to seek for alternatives that could yield more efficient results. Fluorescent functionalized fullerenes, metal oxide nanoparticles, such as titanium oxide and tantalum oxide have been on a rise as cost-efficient and biocompatible contrast agents in the medical world. In this paper, computational studies using program softwares and Density Functional Theory (DFT) for the functionalized molecules and metal oxides were used to determine whether fluorescent molecules are suitable contrast agents to use. The molecules were modeled and the safety and stability were checked quantitatively by analyzing the optimized energies of the molecules. [Preview Abstract] |
|
K1.00045: Wavelength tunable nanoparticle mediated release of polymersomes using ultrafast single pulse irradiation Abby Robinson, Gina DiSalvo, Julianne Griepenburg, Sean O'Malley, Daniel Bubb The self-assembly of amphiphilic di-block copolymers into polymeric vesicles, commonly known as polymersomes, is an area of high interest in research due to the potential~ applications in the field of drug delivery. Polymersomes are fully synthetic robust vesicles composed of a hydrophobic membrane and a hydrophilic core, providing the ability for stable dual-encapsulation of a variety of molecules. Methods have been developed for triggered encapsulant release using ultrafast, single-pulse irradiation with visible and near infrared light to provide a non-invasive method of achieving spatial and temporal control. We have shown that the incorporation of gold nanoparticles (AuNP) within the vesicle membrane provides wavelength specific vesicle rupture at 532 nm. The polymersome release profile can be tuned depending on the laser fluence, and the release wavelength can be changed by altering nanoparticle characteristics including shape, composition, and location. [Preview Abstract] |
|
K1.00046: High Speed Imaging to Measure Vibrational Modes of Microtubules Arooj Aslam, Karina Dsouza, Camelia Prodan, Emil Prodan The microtubule in the cell is built of smaller proteins called tubulin that self-assemble into a tube-like structure. Microtubules provide support for the cell, and are also a means for motor proteins to transport nutrients long distances around the cell. The microtubule also has a crucial role in coordinating various stages of cell division. Microtubules exhibit the ability to vary their length by a process called dynamic instability, and as microtubules outside the cell can also exhibit this property it is clear that the tubulin proteins themselves and how they are assembled dictate this function. The microtubule can be studied from a structural analysis standpoint. Using a high-speed camera to image fluorescently labeled microtubules actuated by thermal motion we can calculate the persistence length and the flexural rigidity of the microtubule. [Preview Abstract] |
|
K1.00047: Self-Assembling Beta-Sheet Peptides for Targeting Amyloid Aggregates Biplab Sarkar, Salam Hashmi, Ghiday Lamptey, Henry Cabral, Peter Nguyen, Vivek Kumar Alzheimer's is the most common form of dementia that affects over 5 million people in the US. Current treatments offer a means to slow disease progression rather than reverse its effects. Two prime suspects linked with disease progression are neurofibrillary tangles and amyloid-beta plaques. Our research explores methods in which amyloid-beta plaques can be tagged in vivo for macrophage recruitment, phagocytosis, and consequent immune destruction. We propose the use of multi-domain peptides (MDP) due to their functional properties. By using an MDP with the base structure K$_{\mathrm{2}}$(SL)$_{\mathrm{6}}$K$_{\mathrm{2}}$, modified with an amyloid-beta nucleation site can promote hybridization with amyloid-beta plaques in vivo. After our MDP has been developed and tested for macrophage recruitment, we can investigate hybridization potential with amyloid-beta in vitro and in vivo. With successful hybridization of our modified MDP fibers and amyloid-beta plaques, we can then test the immune destruction of these hybrid fibers by macrophage phagocytosis. Successful plaque reduction in vivo may enable reversal of symptoms and improvement in cognitive capabilities for patients. [Preview Abstract] |
|
K1.00048: Towards two-dimensional quantum gases of strongly dipolar molecules Aden Lam, Niccolo Bigagli, Claire Warner, Sebastian Will In recent years, ultracold atoms have been very successful in investigating strongly interacting quantum many-body systems. The experimental toolkit of atomic physics provides precise control of the interactions via external fields. Exploiting this control, ultracold atoms can be bound into deeply bound molecules that possess useful internal degrees of freedom. In particular, heteronuclear molecules in the rovibrational ground state with tunable dipolar interactions make the study of quantum systems with strong long-range interactions accessible and constitute an attractive system for quantum simulation. At Columbia, we are working towards a two-dimensional (2D) system of ultracold dipolar molecules to study novel phases in 2D quantum systems with long-range interactions. In a regime where repulsive dipolar interactions dominate, the emergence of a self-organised crystal phase is predicted. Upon reducing the interaction strength, a quantum phase transition into a dipolar superfluid is expected, as well as the possible appearance of a supersolid. In the setup under construction, we will use homogeneous electric fields - created by in-vacuum electrodes - to control the dipolar interactions. In addition, we will be able to observe the 2D quantum phases via high resolution imaging. [Preview Abstract] |
|
K1.00049: Critical temperature and condensate fraction of ${}^{87}$Rb Bose-Einstein condensation Peter Zhou The momentum distribution of an ultracold gas of ${}^{87}$Rb atoms was observed using absorption imaging after a time-of-flight (TOF) expansion. Measurements were made for ${}^{87}$Rb atoms confined in an optical lattice of varying potential depths and for atoms without an optical lattice. The density profiles extracted from the TOF absorption imaging were analyzed to determine the temperature dependence of the condensate fraction and the critical temperature marking the onset of Bose-Einstein condensation (BEC). The Bragg scattering of light from the ${}^{87}$Rb atoms was used to probe the transition to a Bose-Einstein condensate at the critical temperature. [Preview Abstract] |
|
K1.00050: Vortex beams of far-infrared synchrotron radiation for spectroscopy of quantum materials at MET, NSLS-II BNL Tomasz Cyrulik, Taras Stanislavchuk, Andrei Sirenko, Tao Zhou, G. L. Carr We present a design of an optics system for conversion between conventional circularly or linearly polarized coherent synchrotron radiation into a vortex beam with a non-zero orbital angular momentum (OAM). The modified optical setup will be operational in a broad-band spectral range from 20 cm$^{\mathrm{-1}}$ up to 4000 cm$^{\mathrm{-1}}$ using Si and ZnSe axicone retarders producing OAM with $l=+$/-1. Beams with higher order of the OAM $l=+$/-1, $+$/-2, $+$/-3, $+$/-4 and $+$/-5 will be achieved with a motorized phase-shifting spiral mirror. Quantum materials will be studied using vortex beams at the MET beamline of NSLS-II, Brookhaven National Lab at low temperatures and in strong magnetic fields. This work is supported by NJIT-SEED Grant. [Preview Abstract] |
|
K1.00051: Intracavity Optogalvanic Spectroscopy System for Radiocarbon Analysis Gustavo Arias, Mark DeGuzman, Sharon Evangelina, Alessandra Panuccio, Joshua Thompson, Daniel Murnick An improved intracavity optogalvanic spectroscopy (ICOGS) system (Daniel E.Murnick, Ozgur Dogru and Erhan Ilkmen, \textit{Analytical Chemistry}, \textbf{80}, 4820-4824 (2008)) for $^{\mathrm{14}}$C analysis is under development. A new discharge excitation and monitoring circuit with extremely stable voltage and current characteristics provides long term system stability and reproducibility. To ensure quality data, many dependent parameters are optimized including: gas pressure, gas flow, and a CO$_{\mathrm{2}}$ sample injection protocol. Control measurements are carried out using CO$_{\mathrm{2}}$ free air and 1{\%} CO$_{\mathrm{2}}$ in air standards. The ICOGS signal consists of the $^{\mathrm{14}}$CO$_{\mathrm{2}}$ contribution plus backgrounds from both the standard air and the dominant stable carbon isotopes. We have developed a mathematical vector deconvolution model in order to quantify precisely the $^{\mathrm{14}}$CO$_{\mathrm{2}}$ component of the ICOGS signal. ~We determine each component via vector decomposition to calculate the laser induced change in discharge impedance due to the presence of $^{\mathrm{14}}$CO$_{\mathrm{2}}$. Our objective is to develop a calibration curve in order to obtain accurate measurements for small unknown samples of CO$_{\mathrm{2}}$. Such measurements will be useful in many fields, such as radioactive tracing in biology and medicine and monitoring the concentration of radiocarbon in the atmosphere. ~ [Preview Abstract] |
|
K1.00052: Squeezing Light with Atoms: Generation of Non-Classical Light via Four-Wave Mixing Nathan Super, Haley Bauser, Irina Novikova The goal of the project is to produce a pair of polarization-entangled light fields using four-wave mixing in hot Rubidium vapor. In this process, interaction of atoms with near-resonant strong control optical field results in strong amplification of a weak probe optical field and in generation of a quantum correlated conjugate Stokes optical field. To establish the quantum correlation between the Stokes and probe fields, we measured the differential intensity noise between the Stokes and probe fields. If it falls below the quantum noise limit, then two-mode intensity squeezing has been achieved, as a first step toward realization of the polarization Bell states. [Preview Abstract] |
|
K1.00053: Suppression of Four-Wave Mixing in Hot Rubidium Vapor Using Ladder Scheme Raman Absorption Nikunjkumar Prajapati We experimentally investigate the effectiveness of four-wave mixing suppression in a double-lambda interaction scheme by introducing an additional ladder-type two-photon Raman absorption resonance for one of the optical fields. We propose several possible interaction configurations involving either one or two isotopes of Rb and experimentally demonstrate the possibility of efficient four-wave mixing suppression in both EIT and far-detuned Raman cases. [Preview Abstract] |
|
K1.00054: Efficient processing of Lattice Light Sheet Microscopy data for visualization Migle Surblyte, Akshay Naik, Roman Voronov Fluorescent imaging of live cells is complicated by the effects of phototoxicity and photobleaching. Lattice Light Sheet Microscopy (LLSM) is a breakthrough technology by 2014 Nobel Laureate Eric Betzig that has opened up a new era of fluorescent imaging by minimizing these effects 100-fold. However, this method produces large amounts of data, which forces users to process data on clusters for most visualizations. The problem is exacerbated by the fact that most supercomputers do not support commercial visualization software due to high costs. Therefore, there is a need for an open source solution that can process and visualize the large data efficiently. To address this need, we have a created a program which automates the LLSM imaging, writes its results to the non-proprietary HDF5 data format, and then renders the images using Python scripts and the parallelized visualization software, VisIt. Our code supports time series, multiple color channels, and data cropping. Additionally, volume stitching is accomplished via image registration with Fiji. The resulting code is utilizable on most national supercomputers, allowing for virtually limitless sample sizes and duration of visualizations. [Preview Abstract] |
|
K1.00055: Remote characterization of flying mosquitoes using an infrared Lidar system Adrien Genoud, Roman Basistyy, Gregory Williams, Benjamin Thomas More than one million people die every year due to mosquito-borne diseases. As of now, most study of mosquito population is done through trapping methods that are tedious to set up, costly and present scientific biases. Lack of reliable data on the spatial distribution and population dynamics of key mosquito species has become a major obstacle to the development of predictive spatial models for risk of exposure to key vectors. This project describes an innovative technique for the remote sensing of mosquito population. Based on an infrared continuous wave Lidar, the presented technique aims at the remote characterization of flying mosquitoes. By retrieving the insect's wing beat frequency, this new entomological Lidar can count and differentiate male from female of the Aedes Albopictus, Aedes Aegypti and Culex Genus with an accuracy of at least 94 percent. This study also evaluates the relevance of wing beat frequency alone as a predictor variable for mosquito species classification. The ability to collect extensive data with automatic characterization will enable entomological studies to better understand population dynamics and behavior, migration patterns and circadian rhythm as well as evaluate the impact of new and existing mosquito control methodologies. [Preview Abstract] |
|
K1.00056: Theoretical Determined Terahertz Attenuation in Snow and Sleet Dylan Renaud, John Federici Market demand for high-bandwidth wireless communication options in outdoor settings has pushed wireless communication systems towards higher frequency regimes. However, attenuation of wireless signals due to environmental factors such as atmospheric gases and particulates generally scales with increasing frequency, thereby limiting the functionality of such systems. Low-frequency THz radiation (.1 - 1 THz) has been identified as a suitable carrier range due to its reduced attenuation relative to higher frequencies and significant available bandwidth. Still, little is known about the attenuation of THz radiation in the presence of weather conditions such as snow and sleet. In this study, the attenuation of THz radiation by snow aggregates and sleet is investigated using the Mie approach for the scattering of electromagnetic radiation. Differences in attenuation spectra between rain, sleet, and dry snow are identified and the difficulty of measuring THz attenuation by dry snow aggregates is considered. In addition, it is suggested that water vapour may be the leading attenuator for instances of dry snowfall. Finally, the potential for THz radiation to be used in aircraft ice sensing systems is explored by analyzing THz backscattering calculations for various ice-crystal sizes. [Preview Abstract] |
|
K1.00057: A Novel Low-Pass Filter to Enhance Bio-image Quality Using Numerical and Computational Simulations Edward Choi, Andrew Kyung For some bio-images obtained from tomography techniques for obtaining clear images, the imaging process involves more work than simple quantitative image analysis. Previous research, which suggests image quality enhancement via preprocessing, watershed segmentation, and morphological image processing, had minimal impact on image resolution. This study examines bio-image processes to propose a more effective algorithm for processing a bio-image. In this project, normal MRI image of a brain using raw frequency data is presented. Also a new low pass filters are introduced to assess different enhancement strategies, with the end goal of achieving improvement of image quality in a pixel scale. This enhancement process requires computational and mathematical techniques. This techniques are applied and tested to the bio-image obtained from diffuse optical tomography (DOT), which is an emerging medical imaging in which tissue is illuminated by near-infrared light from an array of sources. As an enhancement procedure, the application of transformations using unit impulse function, Gaussian function, and a proposed low-pass filter(LPF) is introduced in this paper. With the transformation and filtering technique, this paper determines a new algorithm that enhances bio-image quality. [Preview Abstract] |
|
K1.00058: Structure Function Relationship in the Variation of Colloidal Behavior of reduced Graphene Oxides and Their Fate in Aqueous Environments Samar Azizighannad, Somenath Mitra Graphene Oxides (GO) contain different oxygen containing groups such as hydroxyl, carboxyl which make them highly hydrophilic or hydrophobic. Cytotoxicity toward bacteria through both membrane and oxidative stress has been demonstrated for GO and reduced graphene oxide (r-GO). While a hydrophobic r-GO can be expected to settle out of aqueous media into solid phases such as river sediments, hydrophilic r-GO will stay dispersed. As a result, the understanding of aqueous behavior of GO and r-GO in aqueous media is of great importance. This paper presents a study of different Go and r-Go and demonstrates that show that solubility decrease with removal of oxygen containing groups and can vary from 7.4 \textmu g/ml to nearly insoluble while the hydrophobicity as measured by a hydrophobicity index can increase from -3.89{\%} to 5.2{\%}. Colloidal behavior can also vary quite dramatically where the critical coagulation concentration (CCC) can range from 28 to 15 in presence of 0.5 mmole/l NaCl. The data presented here shows that the fate of GO and r-GO in water, and their fate in water depends upon their structure, which were characterized by SEM, TEM, Raman and TGA. [Preview Abstract] |
|
K1.00059: The Investigation of Surface Modification Techniques for Ozone Generators William P. Davis, Daniel E. Guerrero and Jose L. Lopez Department of Physics Seton Hall University, 400 South Orange Avenue South Orange, NJ 07079 USA William Davis Ozone is produced on an industrial scale normally through a dielectric barrier discharge (DBD) plasma reactor, where a high energy electric field propagates between to electrodes separated by a dielectric, with a mixture of pure Oxygen gas (O$_{\mathrm{2}})$ and Nitrogen admixture(N$_{\mathrm{2}})$ flowing through the gap between the electrodes. Nitrogen itself plays an important role in the concentration of ozone produced from these plasma reactors. While it is known that N$_{\mathrm{2}}$ is used as a third body collider, another important yet poorly understood function comes from the nitrogen being added to the feed gas into the reactor. Previous studies indicate that when the N$_{\mathrm{2}}$ feed gas is shut off, the ozone concentrations in the gas effluent proceeds to drop gradually over time, indicating that the nitrogen itself is having an effect on the ozone production This experiment aims to investigate, why nitrogen effects the production of ozone, and to investigate if there is any way to produce this effect on different metals including stainless steel, using a nitrogen plasma treatment, to see if they are similar or better results when used as electrodes in a DBD plasma reactor. It will also characterize each electrode based on different parameters including but not limited to Ozone production, SEM and FTIR. [Preview Abstract] |
|
K1.00060: Calculation of elastic properties of argon confined in nanopores of various morphologies using grand canonical Monte Carlo Christopher Dobrzanski, Gennady Gor Fluids confined in nanopores exhibit thermo-physical properties that differ from the properties of the same fluids in bulk. Among these properties are the isothermal compressibility or elastic modulus. The modulus of a fluid in nanopores can be extracted from ultrasonic experiments or calculated from molecular simulations. Using grand canonical Monte Carlo simulations, we calculated the modulus for liquid argon at its normal boiling point 87.3 K adsorbed in silica pores of various sizes and morphologies. For both spherical and cylindrical pores above 2 nm, we obtained a logarithmic dependence of fluid modulus on the vapor pressure. Calculation of the modulus of the fluid in spherical pores at saturation displayed a linear function of the reciprocal pore size. The calculation for cylindrical pores shows a similar trend, however, it is hard to make quantitative conclusions from the highly scattered resulting data. With the development of effective medium theories for decoupling properties of nanoporous media and the fluids confined within them, our results set the basis for analysis of the experimentally-measured elastic properties of fluid-saturated nanoporous materials and can enable probing pore size through ultrasonic measurements. [Preview Abstract] |
|
K1.00061: Thermodynamic Analysis of Surface Functionalized Fullerenes in Treating Acne Vulgaris Se Ri Lee Acne vulgaris is a common skin disease with a multifactorial pathogenesis, including follicular hyperproliferation, sebaceous hyperplasia, commensal bacteria, and inflammation. Recent research has attributed oxidative stress to be a possible cause of this disease, spurring studies assessing the use of fullerene derivatives as antioxidant agents in treating acne. The purpose of this project is to study the potential use of fullerene derivatives in acne therapy. Hydrophilic functional groups were added to fullerene molecules due to the hydrophobic nature of fullerenes. A computational chemical software measured the optimized geometries and chemical properties of the modeled structures by using theoretical values and considering the molecules’ atomic properties. The efficiency of these molecules was determined by assessing their thermodynamic stability, and surface functionalization was studied to determine its effects on the modification of the biocompatibility of the material itself. The stereochemistry of PVP-F(Polyvinylpyrrolidone Fullerene) and N-methyl pyrrolidine fullerene(NMP-F) molecules were studied to assess their chemical properties including thermodynamic stability. [Preview Abstract] |
|
K1.00062: Magnetic Field Assisted Milli-scale Robotic Assembly Machine: An Approach to Massively Parallel Robotic Automation Systems Yan Liu, Nuggehalli Ravindra Using large numbers of micro robots to heterogeneously integrate small pieces to build advanced structures has long been a vision in manufacturing automation. In this paper, a new type of machine, Magnetic Field Assisted Milli-scale Robotic Assembly machine is described. The machine prototype consists of a 16x16 array of electromagnets. We have successfully demonstrated using the machine to manipulate up to 9 milli-scale robots simultaneously. Moreover, we have demonstrated pick-and-place 2 LEDs simultaneously by operating two micro robots. The design and modeling of the micro robot are also discussed. [Preview Abstract] |
|
K1.00063: Influence of Passivation Layers on Optical Properties of Black Silicon Sita Rajyalaxmi Marthi, Asahel Banobre, N M Ravindra Crystalline Silicon (c-Si) is the most abundant and widely used semiconductor. Si is a semiconductor with indirect bandgap. The average reflectance of c-Si is about 30{\%} in the visible range of wavelengths. Standard Si solar cells are not entirely useful in the infrared spectrum region. In order to make Si useful in a wide spectral range, the surface of Si is modified to reduce the reflectance of c-Si. The silicon thus modified is called Black Silicon (BSi). In the present study, we present the influence of passivation on the optical properties of BSi. The optical properties of passivation layers such as SiO$_{\mathrm{2}}$, Si$_{\mathrm{3}}$N$_{\mathrm{4}}$ and Al$_{\mathrm{2}}$O$_{\mathrm{3}}$, on BSi are examined in the wavelength range of 0.4 to 2.4 $\mu $m. [Preview Abstract] |
|
K1.00064: P-Si Based Microbolometer Asahel Banobre, Sita Rajyalaxmi Marthi, N. M. Ravindra Uncooled microbolometers are widely used in thermal detection in the fields of defense, surveillance, automotive and other related industries. The motivation for this study is the consideration of p-doped silicon as an alternative candidate to replace the standard infrared detector thermosensing materials. Its low cost and easy integration with the actual silicon planar lithography microfabrication techniques are some of the primary drivers for this investigation. Simulation of the radiative properties of a multilayer structure, comprising of p-Si as the sensing element, in the infrared spectral range of 2.5-14 microns, utilizing Multi-Rad-software based on a matrix method of representing the optical properties, at room temperature, is presented. [Preview Abstract] |
|
K1.00065: HAWC+/SOFIA Instrumental Polarization Calibration Joseph M. Michail, David T. Chuss, Javad Siah, C. Darren Dowell, John E. Vaillancourt HAWC+ is a new far-infrared polarimeter for the NASA/DLR SOFIA (Stratospheric Observatory for Infrared Astronomy) telescope. HAWC+ has the capability to measure the polarization of astronomical sources with unprecedented sensitivity and angular resolution in four bands from 50-250 microns. Using data obtained during commissioning flights, we implemented a calibration strategy that separates the astronomical polarization signal from the induced instrumental polarization. The result of this analysis is a map of the instrumental polarization as a function of position in the instrument's focal plane in each band. The results show consistency between bands, as well as with other methods used to determine preliminary instrumental polarization values. [Preview Abstract] |
|
K1.00066: Development of a Microwave Calibrator for Cosmological Measurements Vincent Mutolo, David Chuss, Martin DeGeorge, David Greene, Karwan Rostem, David Stilwell, Edward Wollack We are developing a calibrator for an instrument to measure the Cosmic Microwave Background (CMB). The calibrator must fill an approximately 1 meter aperture and have a reflectivity below a few parts in 10,000,000 over a broad spectrum from millimeter-wave radiation through the far-infrared. The geometry of the calibrator is an array of cones that utilizes the high-absorptivity loaded-dielectric in concert with a geometry that maximizes radiative coupling. We are optimizing the geometric taper of the cones to reach the reflectance specification while maintaining manufacturability. The cones are made of an epoxy and stainless steel mixture that provide a highly-absorptive dielectric that is capable of being cast into the desired profile. We are also refining the manufacturing process to reach the challenging physical design specifications. [Preview Abstract] |
|
K1.00067: Targeted Search for Milky Way Satellites Using HSC Bethlee Lindor, Adrian Price-Whelan We present the results from a targeted search for new Milky Way (MW) satellites based on survey data from the Hyper-Suprime Cam (HSC) Subaru Strategic Program. HSC has deep photometry which enables the discovery of ultra faint dwarf galaxies in the galactic halo. We choose this region because the galactic halo contains stars that are tracers of old metal-poor stellar populations similar to those seen in the known dwarf galaxies around the MW: RR Lyrae, K Giants, and Blue Horizontal Branch stars. We locate these types of stars in the HSC footprint, and use their accurate heliodistances to determine whether they are satellite galaxies. This is done by discovering spatial overdensities of resolved stellar sources against foreground stars and background galaxies around our tracer star. Our method has yet to yield detections of MW satellites, but remains promising for the upcoming LSST survey. Knowing where the MW dwarf might be and knowing its distance from target stars will allow LSST to provide a great wealth of information for the open question of Dark Matter and Dark Energy. Still, future work on this project would be to analyze more HSC data upon release or to quantify at what limits we can say that there are no galaxies around the searched regions. [Preview Abstract] |
|
K1.00068: Studying dark matter substructure with gravitational lensing Sean Brennan, Charles Keeton The Cold Dark Matter (CDM) paradigm does a remarkably good job of reproducing the large scale structure of the universe, but it predicts more small-scale structure than seems to be observed. In particular, CDM predicts that a galaxy like the Milky Way should have thousands of dark matter "subhalos", but only a few dozen dwarf galaxies are observed. Gravitational lensing provides an opportunity to search for dark matter subhalos, because they affect the distortions that occur when the gravity of a foreground galaxy bends light from a background source. Some gravitational lens systems exhibit features that cannot be explained by a smooth mass distribution, but are well fit by a model that includes a mass clump representing a dark matter subhalo. Some groups use these single-clump models to claim the detection of individual dark matter subhalos, measure their properties, and then constrain the abundance of dark matter substructure. In our work, we consider whether it is valid to use single-clump lens models to draw conclusions about CDM. We create realistic mock lenses with populations of dark matter subhalos, fit them with single-clump models, and assess whether the models yield reliable measurements of the subhalo properties. [Preview Abstract] |
|
K1.00069: An Investigation of Five Mass Transferring Binary Systems Kate Jamison, Emily Geist, Matthew Beaky An eclipsing binary is a type of variable star whose changes in brightness are caused by periodic eclipses of the two stars in the system. A mass transfer eclipsing binary consists of two stars in close proximity where one star is transferring mass to the other, causing a change in the orbital period. They provide a stringent test of astrophysical theories of stellar evolution. We used the 31-inch Lowell telescope at Lowell Observatory in Flagstaff, Arizona to observe the eclipsing binary system V0579 Lyr, and the 16-inch Meade LX200GPS telescope with a SBIG ST-8XME CCD camera at Juniata College to capture images of four more eclipsing binaries: KN Vul, V0406 Lyr, V2240 Cyg, and MS Her. The images were analyzed to create a light curve, which is a graph of magnitude vs. phase. From the light curve, a model that includes size, temperature, shape, inclination angle, and various other physical parameters was made for each eclipsing binary system. [Preview Abstract] |
|
K1.00070: Effect of Large Masses on Particle-Particle Interactions Tommie Day, Erin De Pree Interactions between particles are governed by the Lagrangian which depends on the trace of the metric of local spacetime. Particle-particle interactions near massive objects will depend on the mass, angular momentum, and charge of the object. We explore and compare interactions in flat spacetime with those in a Schwarzschild metric for spin-0 and spin-1/2 particles through computational simulation. [Preview Abstract] |
|
K1.00071: Resonant frequencies of a Schwarzschild black hole with a global monopole in $f(R)$ gravity Horacio Vieira, Joao Gracca, Valdir Bezerra We obtain an exact solution for both angular and radial parts of the covariant Klein-Gordon equation for a massive scalar field in a Schwarzschild black hole with a global monopole in $f(R)$ gravity. This solution is given in terms of the general Heun function. We investigated some processes associated with scalar fields in the background under consideration, in special, the existence of resonant frequencies. From this analytic solution, corresponding to the radial part, we obtained the resonant frequencies which are a complex number and its imaginary component tells us how quickly the oscillation will die away. [Preview Abstract] |
|
K1.00072: Multi-point observations of magnetospheric responses to interplanetary shocks. Mayowa Adewuyi, Hyomin Kim, Andrew Gerrard, Louis Lanzerotti, Michael Hartinger We report on observations of magnetospheric responses due to interplanetary shocks associated with sudden changes in solar wind flow pressure. Such solar wind transient events are statistically surveyed using solar wind data and their magnetospheric and ionospheric responses are investigated using field and particle data from various spacecraft (Cluster, THEMIS, Van Allen Probes, and MMS) and ground instrument data. Our statistical study presents spatial distributions of ULF wave generation mechanisms and propagation, and ring current particle dynamics in association with compression and/or expansion of the magnetosphere caused by interplanetary shocks. Inner-magnetospheric responses are a particular focus in our study to understand how far the transient phenomena in the solar wind propagate in the magnetosphere and what controls the spatial distributions of the responses. [Preview Abstract] |
|
K1.00073: Ionogram Scaling with Neural Networks and SAMI3 Model Comparison Noah Walsh, Kate Zawdie, Douglas Drob, Leslie Smith We improved the automation of the scaling process of converting raw ionogram soundings into usable data using machine learning techniques and neural networks, and analyzing scaled data and comparing it to our ionosphere model. We gathered data from multiple ionosonde sites across the United States, Peru and the Pacific using ionosondes. An ionosonde is a chirp-sounder that sends radio wave pulses into the ionosphere and records the reflected, refracted, and scattered radio waves. This 16 channel raw sounding data is cleaned and processed into an ionogram, and then scaled into a usable format, such as Standard Archiving Output (SAO) format. We used SAMI3, a global, three-dimensional, physics based model of the ionosphere which models the plasma and chemical evolution of multiple ion species, to understand the evolution of the peak electron density and peak height of the F2 layer. Our analysis will be used to improve the SAMI3 model. This research was performed at the U.S. Naval Research Laboratory. [Preview Abstract] |
|
K1.00074: Investigation of Ionospheric Radio Propagation Using Amateur Radio Data Sources Joshua Katz, Nathaniel Frissell, Ethan Miller, Matthew Cooper, Joshua Vega, Mary West Amateur radio operators are hobbyists who routinely communicate using high frequency (HF, 3-30 MHz) radio links that travel over-the-horizon due to ionospheric refraction. These hobbyists have created global-scale systems that automatically monitor and log these communications to centralized database systems, thereby creating a large data set that can be mined for radio propagation, space weather, and space physics studies. In this data set there are interesting relations between the signal to noise ratios logged by the amateurs and the distances between the transmitters and receivers. These relations may be used to identify locations where the ionospheric waveguide has sufficiently refracted a radio signal back to Earth's surface. We show comparisons of the structures that appear in the amateur radio data set to existing ionospheric metrics and traditional sounding techniques. [Preview Abstract] |
|
K1.00075: High-resolution Observation of Moving Magnetic Features in Active Regions Qin Li, Na Deng, Ju Jing, Haimin Wang Moving magnetic features (MMFs) are small photospheric magnetic elements that emerge and move outward toward the boundary of moat regions mostly during a sunspot decaying phase, in a serpent wave-like magnetic topology. Studies of MMFs and their classification (e.g., unipolar or bipolar types) strongly rely on the high spatiotemporal-resolution observation of photospheric magnetic field. In this work, we present a detailed observation of a sunspot evolution in NOAA active region (AR) 12565, using exceptionally high resolution H$\alpha$ images from the 1.6m New Solar telescope (NST) at Big Bear Solar Observatory (BBSO) and the UV images from the Interface Region Imaging Spectrograph (IRIS). The spectropolarimetric measurements of photospheric magnetic field are obtained from the NST Near InfraRed Imaging Spectropolarimeter (NIRIS) at Fe I 1.56 $\mu$m line. We investigate the horizontal motion of the classified MMFs and discuss the clustering patterns of the geometry and motion of the MMFs. We estimate the rate of flux generation by appearance of MMFs and the role MMFs play in sunspot decaying phase. We also study the interaction between the MMFs and the existing magnetic field features and its response to Ellerman bombs and IRIS bombs respectively at higher layers. [Preview Abstract] |
|
K1.00076: Spectral Analysis Flare Ribbons by NST and IRIS Nengyi Huang, Yan Xu, Jing Ju, Haimin Wang As one of the most powerful phenomena of solar activities, flares have long been observed and studied extensively. Taking advantages of observing capabilities of modern solar telescopes and focal-plane instruments such as the Interface Region Imaging Spectrograph (IRIS) and the 1.6 m New Solar Telescope (NST) at Big Bear Solar observatory (BBSO), we are able to obtain high resolution imaging spectroscopic data in UV, visible and near-infrared (NIR) wavelengths. Here we present the spectral analysis of an M6.5 flare (SOL2015-06-22T18:23) which was well covered by the joint observation of IRIS and NST. In the visible wavelengths H-alpha and TiO, we can separate the flare ribbon into a very narrow leading front and faint trailing component, of which the former is characterized by the intense emission and significant Doppler signals. In the IRIS UV spectra, the ribbon front shows distinct properties, such as the line broadening, Doppler shifts and central reversal pattern, which are consistent with the visible observations. These characteristics suggest that the ribbon front to be the precipitation site of energetic electron beams. [Preview Abstract] |
|
K1.00077: Evolution of photospheric flow and magnetic fields associated with the 2015 June 22 m6.5 flare Jiasheng Wang, Chang Liu, Na Deng, Haimin Wang The evolution of photospheric flow and magnetic fields before and after flares can provide important information regarding the flare triggering and back reaction processes. However, such studies on the flow field are rare due to the paucity of high-resolution observations covering the entire flaring period. Here we study the structural evolution of penumbra and shear flows associated with the 2015 June 22 M6.5 flare in NOAA AR 12371, using high-resolution imaging observation in the TiO band taken by the 1.6\textasciitilde m Goode Solar Telescope at Big Bear Solar Observatory, with the aid of the DAVE method for flow tracking. The accompanied photospheric vector magnetic field changes are also analyzed using data from the Helioseismic and Magnetic Imager. As a result, we found, for a penumbral segment in the negative field adjacent to the magnetic polarity inversion line (PIL), an enhancement of penumbral flows (up to an unusually high value of \textasciitilde 2 km/s) and extension of penumbral fibrils after the first peak of the flare hard X-ray (HXR) emission. We also found a shear flow region at the PIL, which is co-spatial with a precursor brightening kernel and exhibits a gradual increase of shear flow velocity (up to \textasciitilde 0.68 km/s) after the flare. The enhancing penumbral and shear flow regions are also accompanied by an increase of horizontal field and decrease of magnetic inclination angle. These results are discussed in the context of the theory of back reaction of coronal restructuring on the photosphere as a result of flare energy release. [Preview Abstract] |
|
K1.00078: Simulating Amateur Radio During the August 21, 2017 Total Solar Eclipse J.S. Vega, N.A. Frissell, J.D. Katz, J.D. Huba As the shadow of a total solar eclipse passes across the Earth it causes a temporary change in the shadowed portion of the ionosphere. This change affects the propagation of radio waves and radio communications, especially in the MF and HF frequency ranges (0.3-3 MHz and 3-30 MHz, respectively). Such was the case during the August 21, 2017 total solar eclipse that traveled across the contiguous United States from Oregon to South Carolina. During the eclipse, the Ham Radio Science Citizen Investigation (HamSCI) project conducted a nation-wide experiment called the Solar Eclipse QSO Party (SEQP) in order to crowd-source data from the vast number of amateur ``ham'' radio operators to show how the eclipse affected radio propagation. We present the results generated from a simulation of the SEQP as well as a comparison between the simulated results and actual results. The simulation program uses the SAMI3 ionospheric model developed by the U.S. Naval Research Laboratory which, in addition to a ``normal'' model, includes a special ``eclipse'' model specifically created for the August 21, 2017 eclipse. The program also uses the PHaRLAP ionospheric raytracing toolkit to compute the path of individual rays from transmitters to receivers. [Preview Abstract] |
|
K1.00079: Local Helioseismology and Modeling of Impulsive Events John Stefan, Alexander Kosovichev Helioseismology investigates the Sun's interior through oscillation observations, and is composed of both local and global studies. Global helioseismology focuses on global mode oscillations of the Sun, which can be observed by effects on the surface. Local helioseismology focuses on the effects of these oscillations to the background state of the Sun, including time-dependent characteristics which help us understand the structure and processes of the solar interior. We propose a model to simulate the effects of impulsive events (so-called sunquakes) on pressure and density, as well as helioseismic waves that travel through the Sun's interior. We are able to decompose the governing equations into one dimension, and then reconstruct solutions in 3D using spherical harmonics. Since the bulk of computation is spent on solving the differential equations, performing these calculations in 1D greatly reduces computational cost. Additionally, we employ non-reflecting boundary conditions at the solar surface to more accurately describe how acoustic waves travel in the Sun. By comparing simulations to data obtained from the Solar Dynamics Observatory (SDO), etc., we hope to identify the source height (or depth) of sunquakes and perhaps even the mechanism of excitation. [Preview Abstract] |
|
K1.00080: Statistical Analysis of Chromospheric Evaporations in Solar Flares Viacheslav Sadykov, Alexander Kosovichev, Graham Kerr Chromospheric evaporation is one of the key processes of solar flares. Properties of chromospheric evaporation are thought to be closely connected to the energy release rates and energy transport mechanisms. In this work, we present a study of flare events simultaneously observed by IRIS and RHESSI, focusing on spatio-temporal characteristics of the flare dynamics. Event selection is performed using the Interactive Multi-Instrument Database of Solar Flares (IMIDSF) recently developed by the Center for Computational Heliophysics at NJIT. The selection of IRIS observations was restricted to the fast-scanning regimes (coarse or sparse-raster modes with $\ge $4 slit positions, $\ge $6`` spatial coverage, and $\le $60 sec loop time). We have chosen 11 events, and estimated the spatially-resolved Doppler shifts of the transition region (CII 1334.5{\AA}) and hot coronal (FeXXI 1354.1{\AA}) lines reflecting the dynamics of the chromospheric evaporation and condensation. We also estimated parameters of the beam heating from RHESSI data assuming the thick-target beam heating model. The correlations of the derived line profile properties and hard X-ray characteristics are presented and compared with characteristics of the synthetic spectra calculated from the RADYN radiative hydrodynamic flare models. [Preview Abstract] |
|
K1.00081: Easier to Break from Inside a Neutrosophic Dynamical Complex System than from Outside Florentin Smarandache, Andrusa R. Vatuiu We define a neutrosophic mathematical model using a system of ordinary differential equations and we use the neutrosophic probability in order to approximate the process of breaking from inside a neutrosophic complex dynamic system. It shows that for breaking from inside it is needed a smaller force than for breaking from outside the neutrosophic complex dynamic system. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700