Bulletin of the American Physical Society
Spring 2017 Meeting of the APS New England Section, held jointly with NanoWorcester
Volume 62, Number 5
Friday–Saturday, April 14–15, 2017; Worcester, Massachusetts
Session AA1: Poster Session |
Hide Abstracts |
Chair: Alan Wuosmoa, University of Connecticut Room: Campus Center Odeum |
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AA1.00001: Cross-Sectional Nanoscale Mapping of Poilycrystalline Silicon Solar Cell Performance Alexandra J. Longacre A challenge for approaching theoretical efficiency limits in polycrystalline Si solar cells is recombination at grain boundaries and back electrode contacts. This work employs conductive Atomic Force Microscopy to measure and map the topography and current pathways in cross sections of Si solar cells. Current is measured through the probe during in situ illumination up to 1 sun, providing nanoscale resolution of microstructural features and their photoconductive response. Applying such pcAFM reveals the distinct cell components (top electrode, front surface structuring, Si absorber, distinct facets, and back electrode). Performing these measurements as a function of bias further enables analysis of traditional photovoltaic performance metrics such as I SC and V OC . Back Surface Field (BSF) and Passivated Emitter and Rear Contact (PERC) solar cells are investigated. Ultimately this project aims to measure differences in the back contact properties as a function of processing and accelerated aging conditions to inform and ultimately improve solar cell lifetime predictions and efficiencies. [Preview Abstract] |
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AA1.00002: Nanoscale Cross Sectional Mapping of Ferroelectric Domains Zachary Thatcher Atomic Force Microscopy is typically employed for mapping the topography or properties of surfaces. In this work, cross sectional AFM is achieved to map functional properties through the depth of epitaxial and polycrystalline piezoelectric thin films. Direct DC biasing between a conducting probe and back electrode can orient local ferroelectric domains within these films. Subsequent or simultaneous imaging in Piezo Force Microscopy mode (PFM) then allows nanoscale mapping or dynamics of the domain distributions, respectively. Accordingly, both built-in as well as tip-induced domain patterns are recorded as a function of depth as well as film microstructure. This work literally provides a new perspective for ferroelectric switching processes and the influence of grain orientations on piezoelectricity. [Preview Abstract] |
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AA1.00003: Nanoscale Mapping of Polymer Dielectric Performance Thomas Moran We have studied electronic charge injection in polymeric dielectric coatings widely employed for power transmission applications. This is achieved with Electrostatic Force Microcopy (EFM), a variant of atomic force microscopy, specifically by tracking the magnitude of charge injection and dissipation as a function of time following direct biasing with a conducting AFM probe. Specimens include biaxially-oriented polypropylene (BOPP), a dielectric commonly used in radio frequency (RF) applications, with and without nanoclay sodium montmorillonite (MMT) coatings. With MMT, the magnitude of charge injection is reduced and charge dissipation is correspondingly faster than for conventional, uncoated BOPP specimens. For heterogeneous coatings such as a nanoclay, spatially quantifying the local charge magnitude and dissipation is especially critical, to enable improved performance of conventional polymer dielectrics and future multilayered systems. [Preview Abstract] |
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AA1.00004: Scanning microscopy study of the assembly and structure of filamentous virus M13 dispersed on graphite Carlos Cruz, Ibtihal Mutaen, Prashant Sharma We study the structure and surface binding of the filamentous virus M13 on graphite using AFM and STM in ambient conditions. A simple technique to isolate the virus is developed and the bias-dependent features of tunneling microscopy are studied to provide an estimate of the dielectric properties of a single M13 virus biomolecule. These measurements are used to interpret the topographic images of tunneling microscopy. [Preview Abstract] |
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AA1.00005: Surface Strain and Multiple Charge Density Wave States in TbTe$_{\mathrm{3}}$ Ling Fu, Aaron Kraft, Bishnu Sharma, Manoj Singh, Philip Walmsley, Ian Fisher, Michael Boyer We present our near-room temperature scanning tunneling microscopy (STM) measurements on TbTe$_{\mathrm{3}}$. Recent x-ray measurements and DFT calculations [1] indicate that anisotropic lattice strain energy is important in the establishment of a unidirectional CDW along the $c$-axis over the $a$-axis in the bulk below 336 K. In our STM measurements [2], we detect spatially separated perpendicular unidirectional CDWs established along both the $a-$ and $c-$crystal axes with no directional preference for the in-plane crystal axes ($a$ or $c)$. In addition we find regions where these two unidirectional orders coexist leading to observed bidirectional order. Our measurements indicate that the surface Te layer exposed on cleaving is only weakly coupled to the bulk and that strain variations across the surface drive the specific CDW order(s) observed. Our work suggests that similar mechanisms for CDW formation in the bulk are also involved at the surface.$\backslash $[1] Moore et al., PRB, 93, 024304, 2016.2] Fu et al., PRB, 94, 205101, 2016. [Preview Abstract] |
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AA1.00006: Investigation of the range of validity of the pairwise summation method applied to the calculation of the surface roughness correction to the van der Waals force Nancy Burnham, Andre Gusso Surface roughness is known to modify the van der Waals interaction between two surfaces. Here we use a nonperturbative approach of pairwise summation, the effective density method, in order to simplify such calculations. Our approach is compared with the multilayer effective medium model, whose range of validity is more understood. We find that pairwise summation can be used for roughness characterized by a correlation length of the order of an RMS amplitude when the amplitude is of the order of a few nanometers and only for insulating materials. The calculations can be applied to the stiction of micro- and nano-devices, the adherence of atomic-force microscope tips to surfaces, and in general, to the adhesion of insulators [1]. [1] A. Gusso and N.A. Burnham, Surface Science 651 (2016) 28-40 [Preview Abstract] |
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AA1.00007: Effect of electric field on dielectric parameters of silver doped chalcogenide glassy alloy D Sharma, R K Shukla, A Kumar The effect of electric field on dielectric constant and dielectric loss of SeInAg chalcogenide glassy alloys is reported here. It is found that the glassy alloy shows a dynamic behavior with real and imaginary part of dielectric constants. The real part of dielectric constant shows the presence of one plateau at lower frequency from 500 Hz to 5 kHz, but then the second plateau appears as frequency increases from 5 kHz to 500 kHz. The imaginary part shows one peak for lower frequencies but two peaks for higher frequencies with an indication of having potential increased storage capacity of the material at higher frequencies with two peaks. Keywords: Electric field, dielectric constant, dielectric loss, glassy alloy, Storage, memory device, frequency. [Preview Abstract] |
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AA1.00008: Structure and properties of superhydrophobic nano-fibrous membranes of PVDF and PMMA-r- PFDMA Nelaka Govinna We are studying superhydrophobic nano-fibrous membranes for potential applications in oil-water separations. The membranes are blends comprising poly(vinylidene fluoride), PVDF, and a random co-polymer of poly(methyl methacrylate) and 1H,1H,2H,2H-perfluorodecyl methacrylate. PVDF imparts mechanical strength, while the copolymer, with highly fluorinated side groups, forms crystals that enhance membrane roughness and hydrophobicity. Composition was varied by controlling the PVDF content of the blends, including 100, 75, 50, 25, and 0 wt. \% PVDF. Nanofibers were obtained by electrospinning and their properties were studied using X-ray diffraction, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The blend’s crystallinity and degradation temperature both decreased as the copolymer content increased, as shown by X- ray and TGA respectively. Using fast scanning chip-based calorimetry, spin-cast thin films were heated and cooled at rates up to 2000 K/s and their crystallization kinetics were studied. Contact angle tests confirm that these electrospun nanofiber membranes are superhydrophobic. [Preview Abstract] |
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AA1.00009: Nacre's strategy to enhance mechanical and fracture properties. Sina Askarinejad, Nima Rahbar Enhanced mechanical and fracture properties of biological composites encourage researchers to focus on the problem-solving strategies of these naturally growing materials. Bone and nacre are prime examples of natural composites with high strength, stiffness and toughness. In addition to nano-scale features, nature has evolved complex and effective functionally graded interfaces. Particularly in nacre, organic-inorganic interface in which the proteins behave stiffer and stronger in proximity of minerals provide an impressive role in structural integrity and mechanical deformation of the natural composite. However, further research on the toughening mechanisms and the role of the interface properties is essential. In this study, a micromechanical analysis of the mechanical response of these composites is presented considering interface properties. The well-known shear-lag theory was employed on a simplified two-dimensional unit-cell of the multilayered composite. The results solve the important mysteries about nacre and emphasize on the role of organic-inorganic interface properties. [Preview Abstract] |
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AA1.00010: The chemo-microstructure-mechanical relationships for bitumne Xiaokong Yu, Nancy Burnham, Sergio Granados-Focil, Mingjiang Tao Previous studies suggest that bitumen's diverse microstructures are related to its physical and rheological properties; yet the chemical-mechanical relationships for bitumen have been very challenging to establish due to bitumen's complicated molecular interactions. This study aims to enable chemical optimization of bitumen that gives preferable mechanical properties. Two representative asphalt binders were chosen and derivative binders were prepared by remixing their asphaltene and maltene fractions at different ratios. For all binders, their microscopic morphology and mechanical contrast were evaluated using atomic force microscopy (AFM), and their bulk thermal and rheological properties were studied with differential scanning calorimetry and a dynamic shear rheometer, respectively. Bitumen's chemical composition affects its thermal and rheological properties through its characteristic microstructures. Phase segregation observed in AFM agrees with larges gaps among the multiple T$_{\mathrm{g}}$s, both of which are relevant to the aggregation behavior of the asphaltene fraction. [Preview Abstract] |
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AA1.00011: Surface modification of LiMn$_{\mathrm{2-x}}$Fe$_{\mathrm{x}}$O$_{\mathrm{4}}$ cathode materials with ZnO Amir Omidwar, Sam Chiovoloni, Rahul Singhal, Peter LeMaire We have successfully optimized the conditions for the synthesis of LiMn$_{\mathrm{2-x}}$Fe$_{\mathrm{x}}$O$_{\mathrm{4}}$ cathode materials for Li ion rechargeable batteries. We obtained the optimum calcinations temperatures for LiMn$_{\mathrm{2}}$O$_{\mathrm{4}}$, LiMn$_{\mathrm{1.75}}$Fe$_{\mathrm{0.25}}$O$_{\mathrm{4}}$, and LiMn$_{\mathrm{1.5}}$Fe$_{\mathrm{0.5}}$O$_{\mathrm{4}}$ as 850$^{\mathrm{o}}$C, 750$^{\mathrm{o}}$C, and 750$^{\mathrm{o}}$C, respectively. It has been reported in the literature that cycleability of LiMn$_{\mathrm{2}}$O$_{\mathrm{4\thinspace }}$cathode materials can be improved by surface modification of LiMn$_{\mathrm{2}}$O$_{\mathrm{4\thinspace }}$cathode materials with ZnO. In the present studies we have coated LiMn$_{\mathrm{2-x}}$Fe$_{\mathrm{x}}$O$_{\mathrm{4}}$ cathode materials with 2{\%} ZnO. The coating of ZnO onto LiMn$_{\mathrm{2-x}}$Fe$_{\mathrm{x}}$O$_{\mathrm{4\thinspace }}$were performed using zinc acetate as precursor materials. Appropriate quantity of zinc acetate was first dissolved in ethanol. Upon complete dissolution of zinc acetate in ethanol, required quantity of LiMn$_{\mathrm{2-x}}$Fe$_{\mathrm{x}}$O$_{\mathrm{4}}$ cathode material was poured in this solution, followed by continuous stirring for 4 hrs. The solution was then dried in an oven in air atmosphere. The physical characterization of the ZnO coated LiMn$_{\mathrm{2-x}}$Fe$_{\mathrm{x}}$O$_{\mathrm{4}}$ cathode materials were carried out using X-ray diffraction, differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). The detailed results of our investigation will be presented during the meeting. [Preview Abstract] |
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AA1.00012: Improved Efficiency of Photoelectrochemical Water Oxidation using Tin Disulfide Photoanodes. Binod Giri Tin disulfide (SnS$_{\mathrm{2}})$ has gained a lot of attention from the scientific community due to its unique electrical and optical properties, which make it suitable for photocatalysis and solar energy conversion. It has a high absorption coefficient and can be used in photovoltaics as a single junction solar cell or in tandem with other materials such as silicon. When SnS$_{\mathrm{2}}$ thin films are used in tandem with silicon, the overall theoretical efficiency can surpass Shockley-Queisser limit of silicon. SnS$_{\mathrm{2}}$ is also a suitable material for photoelectrochemical (PEC) water oxidation because its conduction and valence band edges straddle redox potential of water. We report a scalable method of synthesizing thin films of tin disulfide nanoflakes in a two-step process. In the first step, pure SnS$_{\mathrm{2}}$ powder is synthesized using hydrothermal method. This powder is then evaporated in a vacuum environment and coated on conductive substrates. Although SnS$_{\mathrm{2\thinspace }}$has been fabricated before, this is the first project in which significant photocurrent has been recorded using SnS$_{\mathrm{2}}$ photoanode. We report photocurrents up to 2.6mA/cm$^{\mathrm{2}}$ achieved at 1.23 V vs RHE from a SnS$_{\mathrm{2}}$ photoanode when illuminated with a Xenon Lamp (300W, 100mW/cm$^{\mathrm{2}})$. [Preview Abstract] |
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AA1.00013: Conversion of CO2 into Useful Fuels using Cux/TiO2Photocatalysts Satish kumar Iyemperumal, Aaron N. Deskins Conversion of carbon dioxide, an abundant greenhouse gas, into useful fuels can help solve issues associated with both energy and the environment. Experiments have successfully shown activity for CO$_2$ conversion to products like methanol using Cu/TiO$_2$ photocatalysts. How this catalyst works and how it could be improved is an area of much research. We studied this catalyst using density functional theory (DFT) to obtain atomic level insights in the CO$_2$ reduction process on the catalyst surface. A key activation step in CO2 reduction is the formation of CO$_2$ anion species with a bent structure. We modeled small Cu$_x$ (x=1-4) clusters on a TiO$_2$-anatase surface. Our results show that Cu is able to activate CO$_2$ into a bent configuration that can be further reduced. Charge analysis indicates that CO$_2$ does indeed become negatively charged in a bent configuration, but not in a linear adsorption mode. We analyzed charge on Cu to assign its oxidation state, as well as calculating adsorbed CO vibrational modes, a common experimental method to assign oxidation state of supported metals. Our results identify how Cu clusters on TiO$_2$ surfaces may activate CO$_2$. Such knowledge is crucial towards refining and designing better catalysts for CO$_2$ reduction. [Preview Abstract] |
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AA1.00014: Carrier dynamics and the role of grain boundaries in polycrystalline PbS films Kateryna Kushnir, Kefan Chen, Pratap Rao, Lyubov Titova Polycrystalline lead sulfide (PbS) films are promising materials for use in highly ef?cient solar cells. We have used a time-resolved terahertz spectroscopy to study microscopic photoconductivity in thin polycrystalline PbS films. These films were synthesized using a chemical bath containing lead, sulfur precursors and reducing agent (hydroxylamine hydrochloride). The concentration of the hydroxylamine hydrochloride for all preparations have been varied from 0{\%} to 200{\%}. The deposition took place at room temperature. These sets of samples which were deposited, changed in a film morphology from 300 nm thick parse film composed of small crystallites to the densely packed 800 nm with large cubic grains. We find that while the lifetime of photoexcited carriers in all studied films is comparable to carrier lifetime in single crystalline silicon, grain boundaries significantly impede long-range conductivity even in dense films, suggesting that chemically modifying the surfaces of PbS grains is necessary to achieve efficient extraction of photoexcited carriers. [Preview Abstract] |
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AA1.00015: Thermodynamic Stability Analysis of Metal Organic Frameworks Yejin Kim, Richard Kyung Metal-Organic frameworks bear a huge potential for various developments in many different fields of science. This study seeks to study the stability and dynamics of different types of MOFs in various conditions, such as with different metal joints or linkers with different functional groups. In a more general sense, this research aims to contribute to the materialization of MOFs’ full usage in green energy and eco-friendly technologies. This research performs thermodynamic and stereo-chemical analysis of Metal Organic Frameworks. In this paper, Density Functional Theory (DFT), a computational chemistry, has been employed to figure out the stability and thermodynamics of different structures of MOFs, and to model the electron properties of the compound. With Avogadro and Chemcraft, programs that allow users to draw and estimate enthalpy for a compound, and Matlab which gives numerical estimate of electric potential between the capacitors, this research demonstrates the optimized geometry energy levels and fully determines the theoretical values of the structure’s atomic properties. [Preview Abstract] |
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AA1.00016: Hyperbolic Metamaterials Used in the SPP Dong Ju Lee, Richard Kyung Metamaterials are man-made combinations of two different media. By combining these media, and their properties such as permittivity and index of refraction, and creating a multilayered structure where each layer is thinner than the wavelength of the light propagating through it, new properties are born. The uniqueness about metamaterials is the ability to contain light waves that are greater in size than the entire structure. COMSOL was used for the SPP Problems and virtually constructed metamaterials of specific dimensions and indices of refraction. Then photons passing through the metamaterials were simulated. If the material successfully contains a standing wave within a metamaterial that is much smaller than the wave itself, it shows the size efficiency of using metamaterials in modern appliances. The relations, Reflection Coefficient vs. Angle and the Reflection Coefficient vs. Efficient Index showed the reflectivity of the light that has been propagated through the prism in two period metamaterials were different each other. To find the accurate incident angle and the effective index, we found the point at which the reflectivity (the y-axis) reaches 0. This suggests that the light has not been reflected; instead, it is traveling directly parallel to the media inside. [Preview Abstract] |
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AA1.00017: Nano Particles and Fullerene Derivatives Used in Reduction of ROS in Cancer Treatment YongWoo Lim, Richard Kyung Certain reactive oxygen species in the human body can cause oxidative stress to biological cells due to the process of uncontrolled radical reactions. Methods of using fullerenes to control reactions were researched to determine whether or not fullerenes are apt for cancer treatments. Gamess, Avogadro and Chemcraft molecule simulators were used to measure the optimized energy and electrostatic forces acting on the fullerenes when they are attached with hydroxyl, carboxyl groups and other functional groups; and through this, analysis of the thermodynamic stability was conducted. Experimental results also proved that C60 were the most effective in reducing oxygen radicals because chemiluminescence times were the shortest out of all the test subjects. Through the simulation of several different fullerenes, those with lower enthalpies with chemical stability that is suitable for medical use were found. Although fullerene such as C40 had decreasing enthalpies when combined with hydroxyl and carboxyl groups, it had higher enthalpies ranging from 24,000 to 27,000 kilojoules per mole. Fullerene such as one of C82 isomers was more viable as it had a significantly lower range of 11,000 to 17,000 kilojoules per mole even though its enthalpies increased when combined with other groups. [Preview Abstract] |
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AA1.00018: Functional characterization of the human zinc transporter, hZIP4, in the zinc-deficient \textit{S. cerevisiae} strain ZHY3 Yuting Liu, Elizabeth Bafaro, Robert Dempski Zinc deficiency is a significant nutritional problem in humans. As zinc cannot passively diffuse across cell membranes, it must be transported into cells and intracellular compartments by transporter proteins. The Human Zinc-regulated, Iron-regulated transporter-like Protein (hZIP) gene family has been recognized in humans to be involved in metal uptake and transport. The hZIP4 protein was initially discovered as mutations in this protein results in \textit{acrodermatitis entreropathica} (AE), a zinc deficiency disease. Here, we have used heterologous expression of hZIP4 in \textit{S. cerevisiae} to examine the functionality of this protein. Analysis of our experimental results demonstrate that hZIP4 is functional in \textit{S. cerevisiae}, an important first step in investigating the molecular mechanism of hZIP4. [Preview Abstract] |
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AA1.00019: Vimentin effects on mechanosensitivity of cells Minh Tri Ho Thanh, Will Linthicum, Sakthikumar Ambady, Qi Wen Vimentin is a type III intermediate filament protein that is used widely as a marker of the epithelial cancer. Yet, the role of vimentin in tumor formation and metastasis has not been studied in depth until recently. In this research, we would like to study the effect of knocking down vimentin expression on cell mechanosensitivity, which is critical for the development and metastasis of cancer. Control and vimentin knockdown (vim-) fibroblasts cultured on PAA gels with stiffness values ranging 2-20kPa. Using traction force microscopy, this study reveals that vim- fibroblasts are less responsive to the change in stiffness of the environment, demonstrated through lower rate of change in cell spreading area, degree of polarization, traction force, traction stress, and contractile moment. Furthermore, lower strain energy and surface tension in vim- fibroblasts might suggests that force transmission is impaired when vimentin expression is reduced. [Preview Abstract] |
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AA1.00020: The Role of Vimentin in Regulating Cellular Response to Substrate Properties Will Linthicum, Qi Wen Mechanical stiffness and nanotopography of extracellular matrix can regulate cellular behavior. Studying the mechanisms that allow cells to sense these physical properties of the microenvironment aids in the understanding of critical medical questions such as cancer cell metastasis and immunological responses to tissue engineered constructs. We aim to unveil the role of vimentin, a cytoskeletal protein, in mediating the cellular sensitivity to changes in substrate stiffness and nanotopography, as vimentin has been established as a biomarker for cancer and a regulator of cell morphology. Using Atomic Force Microscopy, we measured the cell stiffness of fibroblasts as a function of substrate nanotopography and stiffness. We found that decreasing the level of vimentin expression in 3T3 fibroblasts led to decreased ability to sense variations in substrate stiffness. In the future, we will characterize the effects of vimentin knockdown on cellular sensitivity to substrate nanotopography. Moreover, to test the hypothesis that vimentin modulate ability of cells to sense their microenvironment through its regulative effects on integrin-based adhesions, we will study the vimentin regulated cell-substrate adhesions on the single molecule level using single cell force spectroscopy. [Preview Abstract] |
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AA1.00021: Ultrasonic Backscatter coefficient, Attenuation Coefficients and Speed of Sound measurement estimates using Human Colon Cancer Cells. Judene Thomas Ultrasound is increasingly being used in therapeutic applications, however, little is known about the direct effects of various ultrasonic frequencies on cells. We aim to demonstrate the efficacy of ultrasonic measurements and the effect of frequency variations on cancer cells. The attenuation, speed of sound and backscatter coefficients of human colon cancer cell lines were measured using an emitting and receiving transducer, a sine-wave function generator as well as an amplifier. The sample was placed between transducers, each connected to a function generator and amplifier, and the time when the signal is received was recorded with and without the sample. A backscatter experiment at five varying frequencies using a single element focused transducer connected to a pulsar receiver and an oscilloscope was then performed. When the sample was aligned with the transducer a signal was recorded at 9 points and the coefficient calculated using Matlab. Different settings of frequency in an ultrasonic treatment protocol can lead to different impacts on proliferation, morphology, differentiation and may be used to stimulate or inhibit the growth of individual cell types, potentially leading to ground breaking therapies for various types of cancers and other diseases. [Preview Abstract] |
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AA1.00022: Modeling and characterizing cell growth in moss Steven Vandal, Kyle Lemoi, Xinxin Ding, Supriya Agrawal, Luis Vidali, Erkan Tuzel The moss Physcomitrella patens is an excellent model organism due to its simple development, complete well-annotated genome sequence, and powerful genetics. In this work, we developed a coarse-grained model of moss growth which can be used to characterize the plant's early development composed of protonemal cells. To understand the morphology of the developing plants, we measured various metrics including their area, solidity, eccentricity, circularity, and fractal dimension. We then created a model of moss growth based on L-systems that recapitulates experimental results. We quantified the age of individual plants by their morphological characteristics using the plastochron index, and compared our results to those obtained by classifying the plants by time. The model can be used to detect changes in the moss plant shape through comparison to wild-type plants in metric-space, and will provide further insight into characterization of different mutant phenotypes with altered plant development. [Preview Abstract] |
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AA1.00023: Studio Physics in a Seven-Week Term with Transportable Labs in a Shared Space Sophia Leitzman, Joseph DePaolo-Boisvert, Jeanne Hubelbank, Nancy Burnham By applying a studio-style learning approach to an Introductory Mechanics course, students' learning and understanding of the material should be greatly enhanced. ~What makes the installation of studio physics at Worcester Polytechnic Institute (WPI) unique is a studio space that will be shared with other departments and the school following a seven-week class schedule - a relatively short period of time for this method of learning. ~During the pilot course, techniques such as miniature lectures, problem solving, group laboratory experiments, and clicker questions were all utilized. ~Labs were tested not only for effectiveness at demonstrating concepts but also for ease of assembly and transportability. ~The Mechanics Baseline Test was administered at the beginning and end of the course to measure normalized gain. ~The results was an average class normalized gain of 0.18 and ranged from -0.11 to 0.64. ~Additionally, small amounts of qualitative student feedback were continuously collected over the duration of the pilot course while larger feedback reports were collected at the middle and end of the term. ~If the results from this pilot course are promising, studio physics has the potential to become an option for all students at WPI. [Preview Abstract] |
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AA1.00024: In-class use of clickers and clicker tests improve learning and enable instant feedback and retests via automated grading Snehalata Kadam, Nancy Burnham, Erin DeSilva An audience response system (``clickers'') was gradually incorporated into introductory physics courses at Worcester Polytechnic Institute during the years 2011-14. Clickers were used in lectures, as a means of preparing for labs, and for collection of exam data and grading. Average student grades were 13.5{\%} greater, as measured by comparing exam results with a previous year. Student acceptance of clickers was high, ranging from 66{\%} to 95{\%}, and grading time for exams was markedly reduced, from a full day to a few hours for approximately 150 students. The streamlined grading allowed for a second test on the same material for the students who failed the first one. These improvements have the immediate effects of engagement, learning, and efficiency, and ideally, they will also provide an environment in which more students will succeed in college and their careers. [Preview Abstract] |
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AA1.00025: Atomic Force Microscopy Education Nancy Burnham, Andrew Pic, Valerie Moore Atomic force microscopy is a crucial part of nanoscience. Despite the simplicity of its design, a simple cantilever with a sharp tip, learning and teaching AFM can be difficult. Five levels of AFM education were identified from existing education infrastructure: demonstrations, single or several laboratories within another course, term or semester based courses devoted to AFM, personalized hands-on instruction, and short courses. Information was gathered from a survey as well as interviews given to figures in AFM education. Advice, general practices, and a list of resources were compiled into a website, presentation, a project report, which was in turn accepted as a chapter in a book [1]. These are intended to become a resource to help educators approach and design their own AFM educational experience. [1] A.C. Pic, V.A. Moore, N.A. Burnham, Atomic Force Microscopy Education, in \textit{Global Perspectives of Nanoscience and Engineering Education}, pp. 131-169 (2016), Eds. K. Winkelmann and B. Bhushan [Preview Abstract] |
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AA1.00026: Innovating Nanoparticle Safety: Storage, Handling, and Disposal Processes Finn O'Brien, Katherine Moore, Ivanna Stuart, Andrew Lewis, Nancy Burnham Uncertainty concerning nanoparticle safety measures stem from a scarcity of readily accessible, practical, and application-specific information. This constitutes a hazard for the workplace and the environment. We investigated nano-safety questions and interviewed researchers across Switzerland. We created a set of printable, customizable posters with clear guidelines, and a list of recommend~equipment~to make a laboratory nanoparticle ready, which we both made available online. Through these solutions, we aim to improve the implementation of safe nanoparticle practices and save researchers time and frustration.~ [Preview Abstract] |
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AA1.00027: Recognizing and Engineering Routes Around the Cognitive Obstacles Encountered by Non-majors in Introductory Calculus-based Physics - Part 2 Norma Chase Given the broad cross section of humanity appearing for a first college level physics course (including highly intelligent non-visual thinkers), how is the lecturer to proceed? How is the Physics Community to proceed in devising curricular standards which will shape the cognitive development of the next generation of medical doctors (and other healthcare providers), biologists and chemists, engineers, and other citizens seeking (and in need of) a solid general education? How do we also avoid terrorizing and demoralizing less experienced students, while (at the same time) challenging students who have considerable experience (and find delight in) in solving long complicated problems? In Part 1 of this paper, the author discussed methods for recognizing and engineering routes around some of the many cognitive obstacles encountered by non-majors. This paper extends the previous, discussing additional routes around cognitive obstacles, including the ultimate obstacle -- student incredulity that multi-step reasoning is ``really necessary''. [Preview Abstract] |
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AA1.00028: Mentoring Partnerships in Undergraduate Physics and Astronomy Education Andria Schwortz, Andrea Burrows Relationships are the root of being able to teach well, regardless of the context. In this project, the researchers draw parallels between two studies into collegiate STEM learning where mentoring of students proved beneficial to the participants. The first study used an action research approach to partner a researcher with the community of a collegiate studio physics electricity and magnetism course. Mentoring partnerships between students and their teaching assistant via student/TA conferences resulted in improvements to the student/TA relationship, though students were reluctant to voice their opinions. The second study took a quantitative approach to determine participant learning after a three-phase astronomy dataset activity. Female undergraduates exhibited lower levels of learning than male undergraduates, or either male or female science educators. Implications included the need for further investigation into the challenges faced by female undergraduate students in both physics and astronomy. Connections are made across these two studies, and possible causes and future strategies to create stronger partnerships with students are discussed. [Preview Abstract] |
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AA1.00029: How Fear of Nuclear Power is Warming Our Planet Paul H Carr The world is presently decommissioning nuclear reactors faster than the increase in the deployment of wind and solar (1). Solar energy is only available 26{\%} of the time and wind 33{\%}. Nuclear is 24/7. To make up for the net nuclear decrease, we are increasing our burning of fossil fuels, raising carbon dioxide emissions, and warming our planet. This is particularly true in Germany. $\backslash $pard Bill Gates is presently funding next generation TerraPower's nuclear pilot plant being built in China. This traveling wave reactor converts depleted uranium, a byproduct of the nuclear-fission process, into usable fuel. Thorium molten salt molten salt nuclear reactors (MSR), demonstrated at Oak Ridge National Laboratory 1965-1970, consume nearly 100{\%} of their fuel, compared with 3{\%} for older reactors with solid uranium fuel (2). MSRs eliminate the need for Yucca Mountain storage by consuming nuclear waste. Thorium fluoride molten fuel for MSRs is of no weapons value. REFERENCES (1) Michael Shellenberger YouTube 2016 TED Talk. (2) David A. Cornell. ``Fracking and the Future of Fuel.''\textit{Physics Today, pgs 10 -11. }February 2017. [Preview Abstract] |
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AA1.00030: Seasonal Variation in Angular Irradiance from Atmospherically Scattered Sunlight James Kulowiec, Jalal Butt, Nimmi Sharma The aerosol phase function is a measure of the efficiency with which aerosols scatter light into each angle. Different types of aerosol classes (dust, marine, etc.) display different phase functions. This study investigated aerosol phase functions derived from radiometer measurements taken by the Aerosol Robotic Network (AERONET) at Mauna Loa Observatory (MLO) in Hawaii. Data from different wavelengths were splined and converted to derive a phase function at the NdYAG laser wavelength of 532 nm. The investigation included statistical analyses, finding the average angular scattering at each angle over dates encompassing multiple years, the standard deviation, and average for each seasonal period. Phase functions are needed for conversion of bistatic laser radar measurements to total aerosol extinction, and results from this study will be used in laser radar atmospheric profiling. Also satellite measurements of aerosol phase functions for different aerosol classes were compared to the derived AERONET phase functions each season to investigate whether different types of aerosols were present over MLO at different times of year. [Preview Abstract] |
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AA1.00031: Free-Tropospheric Aerosol Detection at Mauna Loa Observatory Using Bi-Static Lidar Chris Oville, Jalal Butt, James Kulowiec, Nimmi Sharma Because of their increased longevity and spatial range, aerosols which become entrained above the planetary boundary layer are thought to have important effects on weather patterns and climate. The study of this phenomenon requires sound determination of atmospheric modeling parameters -- namely baseline aerosol levels in areas which are geographically isolated from anthropologic aerosol generation. Due to its location and the proximity of available instrumentation, Mauna Loa Observatory is an ideal setting for this and as such was the site of choice for this investigation in which a CLidar system -- a CCD-camera based bi-static Lidar -- was used to measure aerosol levels in the atmosphere. Several years of data were analyzed with a focus on free-tropospheric altitudes, and yearly and seasonal trends were evaluated for significant patterns. [Preview Abstract] |
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AA1.00032: Stationary-bike bike generator Jordon Penor The design of a stationary-bike bike generator and a system to store the energy generated is presented. Modifications to the stationary bike include a front wheel substitution, a mechanical assembly to accommodate a belt, pulley and motor, a rechargeable deep cycle battery, and a readout display of voltage, current, and guidance for the rider. The design uses a motor attached to the top of the system storing the energy to generate electric current. The system is designed to recharge batteries at the proper voltage and current to avoid damage. The system is intended as a prototype for a college class in Bolivia to develop a series of bike generators to provide power on days when their power is not reliable. [Preview Abstract] |
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AA1.00033: Binary gas mixture in a high speed channel Dr. Sahadev Pradhan The viscous, compressible flow in a 2D wall-bounded channel, with bottom wall moving in? the positive $x-$direction, simulated using the direct simulation Monte Carlo (DSMC) method,? has been used as a test bed for examining different aspects of flow phenomenon and separation performance of a binary gas mixture at Mach number \textit{Ma }$=$\textit{ (U\textunderscore w / }$\backslash $\textit{sqrt(}$\gamma $\textit{ k\textunderscore B T\textunderscore w /m)?) }in the range\textit{0.1 \textless Ma \textless 30}, and Knudsen number \textit{Kn }$=$\textit{ 1/(}$\backslash $\textit{sqrt(2) }$\pi $\textit{ d\textasciicircum 2 n\textunderscore d H)}in the range? \textit{.1 \textless Kn \textless 10}. The generalized? analytical model is formulated which includes the fifth order differential equation for the? boundary layer at the channel wall in terms of master potential ($\chi )$, which is derived? from the equations of motion in a 2D rectangular $(x - y)$coordinate. The starting point? of the analytical model is the Navier-Stokes, mass, momentum and energy conservation? equations in the $(x - y)$coordinate, where $x$and $y$are the streamwise? and wall-normal directions, respectively. The linearization approximation is used ((Pradhan {\&} Kumaran\textit{, J. Fluid Mech -}); (Kumaran {\&} Pradhan, \textit{J. Fluid Mech -})), where the equations of motion are truncated at linear order in the velocity and pressure perturbations to the base flow, which is anisothermal compressible Couette flow. Additional assumptions in the? analytical model include high aspect ratio \textit{(L \textgreater \textgreater H)}, constant temperature in the base state (isothermal condition), and low? Reynolds number (laminar flow). The analytical solutionsare compared with direct simulation Monte Carlo (DSMC) simulations and found good agreement (with a difference of less than 10{\%}), provided the boundary conditions are accurately incorporated in the analytical solution. [Preview Abstract] |
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AA1.00034: Composite reinforced metallic cylinder for high speed rotation Dr. Sahadev Pradhan The objective of the present study is to design and development of the composite reinforced thin metallic cylinder to increase the peripheral speed significantly and thereby improve the separation performance in a centrifugal gas separation processes through proper optimization of the internal parameters. According to Dirac equation (Cohen (1951)), the maximum separative work for a centrifugal gas separation process increase with 4th power of the peripheral speed. Therefore, it has been intended to reinforce the metallic cylinder with composites (carbon fibers: T-700 and T- 1000 grade with suitable epoxy resin) to increase the stiffness and hoop stress so that the peripheral speed can be increased significantly, and thereby enhance the separative output. Here, we have developed the mathematical model to investigate the elastic stresses of a laminated cylinder subjected to mechanical, thermal and thermo-mechanical loading. A detailed analysis is carried out to underline the basic hypothesis of each formulation. Further, we evaluate the steady state creep response of the rotating cylinder and analyze the stresses and strain rates in the cylinder. [Preview Abstract] |
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AA1.00035: DSMC Simulations of High Mach Number Taylor-Couette Flow Dr. Sahadev Pradhan The main focus of this work is to characterise the Taylor-Couette flow of an ideal gas between two coaxial cylinders at Mach number \textit{Ma }$=$\textit{ (U\textunderscore w / }$\backslash $\textit{sqrt\textbraceleft kb T\textunderscore w / m\textbraceright )}in the range 0.01 \textless Ma \textless , and Knudsen number \textit{Kn }$=$\textit{ (1 / (}$\backslash $\textit{sqrt\textbraceleft 2\textbraceright }$\backslash $\textit{pi d\textasciicircum 2 n\textunderscore d (r\textunderscore 2 - r\textunderscore 1))) }in the range 0.001 \textless Kn \textless , using two-dimensional (2D) direct simulation Monte Carlo (DSMC) simulations. Here, \textit{r\textunderscore 1}and \textit{r\textunderscore 2}are the radius of inner and outer cylinder respectively, \textit{U\textunderscore w}is the circumferential wall velocity of the inner cylinder, \textit{T\textunderscore w}is the isothermal wall temperature, \textit{n\textunderscore d}is the number density of the gas molecules, $m$and $d$ are the molecular mass and diameter, and \textit{kb}is the Boltzmann constant. The cylindrical surfaces are specified as being diffusely reflecting with the thermal accommodation coefficient equal to one. In the present analysis of high Mach number compressible Taylor-Couette flow using DSMC method, wall slip in the temperature and the velocities are found to be significant. Slip occurs because the temperature/velocity of the molecules incident on the wall could be very different from that of the wall, even though the temperature/velocity of the reflected molecules is equal to that of the wall. Due to the high surface speed of the inner cylinder, significant heating of the gas is taking place. The gas temperature increases until the heat transfer to the surface equals the work done in moving the surface. The highest temperature is obtained near the moving surface of the inner cylinder at a radius of about (1.26 r\textunderscore 1). [Preview Abstract] |
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AA1.00036: DSMC simulations of leading edge flat-plate boundary layer flows at high Mach number Dr. Sahadev Pradhan The flow over a 2D leading-edge flat plate is studied at Mach number \textit{Ma }$= (U_{inf}/ \backslash $\textit{sqrt\textbraceleft k}$_{B}T_{inf}$\textit{/ m\textbraceright ) }in the range \textit{\textless Ma \textless 10}, and at Reynolds number number \textit{Re }$= (L_{T} U_{inf}$\textit{ rho}$_{inf\thinspace }$\textit{)/ mu}$_{inf\thinspace }$ equal to 10$^{\mathrm{\thinspace \thinspace }}$using two-dimensional (2D) direct simulation Monte Carlo (DSMC) simulations to understand the flow phenomena of the leading-edge flat plate boundary layer at high Mach number. Here, $L_{T}$is the characteristic dimension, $U_{inf}$and $T_{inf}$are the free stream velocity and temperature, \textit{rho}$_{inf}$ is the free stream density, $m$is the molecular mass, \textit{mu}$_{inf\thinspace }$is the molecular viscosity based on the free stream temperature $T_{inf},$and $k_{B}$is the Boltzmann constant. The variation of streamwise velocity, temperature, number-density, and mean free path along the wall normal direction away from the plate surface is studied. The qualitative nature of the streamwise velocity at high Mach number is similar to those in the incompressible limit (parabolic profile). However, there are important differences. The amplitudes of the streamwise velocity increase as the Mach number increases and turned into a more flatter profile near the wall. There is significant velocity and temperature slip ((Pradhan and Kumaran, J. Fluid Mech-2011); (Kumaran and Pradhan, J. Fluid Mech-2014)) at the surface of the plate, and the slip increases as the Mach number is increased. It is interesting to note that for the highest Mach numbers considered here, the streamwise velocity at the wall exceeds the sound speed, and the flow is supersonic throughout the flow domain. [Preview Abstract] |
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AA1.00037: NbH4 of 716068141 to Tessellations Lukas Widjaja, SE Adopts for Nano-Education through 3.77 - 4.29 billion years before of first livign Lifes /"KOMPAS"/, M-4, h 8 we have "cell void" of Poisson-Voronoi tessellations of INSOLVENCIES AVOIDANCES to "1/f [Voro]-noi-[SE] to theirselves cross-section ti Yakov Michael Epstein:"Crowding Stress & Human Behavior ComplexitySciences accordances to "dynamics of de Azcarraga & Lukierski N=2 massive superparticle". We also intended to appreciates nannofossil-nannoplankton denotes of hydrocarbon-carbohydrate bioinspires fro Wortel oilwell nearby Oyong oilfields, September 24, 2007 to Fractal Signals" from Greogy W. Wornell in-Officio of Georg Earl Windsor's first quotes of The Republic of INDONESIA spalled/"knocked-Out " realms since 1970 Anefalos secondary particle to the Pop[e] Econophysics/-nomies of Inept Secondantee ;"J.O[DR-HC Jakob Oetama] knocked out by HE. Mr. Jusuf WIDODO cq Litbang "KOMPAS" seminarian establishments. [Preview Abstract] |
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AA1.00038: Insolvency Risk of [Inflation]-ary Universe WH- Maksoed Accompanies \textit{``reforma'' }of OECD 2$^{\mathrm{nd}}$ Forum for Asian Insolvency Reform [FAIR ], 2002 we have Hugonnier, \textit{et.al: }\textbf{`Bank capital, liquid reserves {\&} insolvency Risk'' }of Dirjen PPR KeMenKeu RI appreciations from PPRC/PasukanPemukul Reaksi Cepat and Andrei Linde: \textbf{``Inflationary of cosmology [Universe ?] after Planck 2013''- }2014 Her Majestie Fraulein Nitia Anisa, SE invited through \textless meetings.aps.org/Meeting/FWS16/Session/G1?showAbstract\textgreater of they were Planck blackbody radiation 7 thermionic emission that show discontinuous change. As well broadway type adopt for \textbf{``Aura Biru''}- 2009 herewith provided \underline {https://anticorruptionsociety.com/oppt-one-peoples-public-trust} Gramedia-BAKRIE Oil {\&} Gas Recoveries, the Pop[E]-conophyiscs/mies INEPT secondants [cq HE. Mr. H. TUK SETYOHADI ] purposes to HE. Mr. Dr-HC JAKOB OETAMA/HE. Mr. Lukas WIDJAYA,SE [Preview Abstract] |
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AA1.00039: Bio-Inspired Materials to Astranomics WH- Maksoed,SSi Inclusively Prometheus : "forethought" denotes, follows with "me fuse.." retrieves from Roy E. Bergstroem:"Thanks to the new more powerful, highly efficient Allied [Fractal-G. Wornell ]Signal 731-40 engines, the SpX offers a range of 3690 miles, 600 miles greater than the Hawker 800". The SpX can fly nonstop from NewYork to Los Angeles of speed of .82 Mach & offers the most advanced digital avionics that will be available on future larger business Jets like Challenger, Falcon 2000 & AstraGalaxy, John Rawls:"Justice As Fairness"- 1971 engages... Compares I. Panas:"Super-atom representation of HTS" to three kinds of elementary particles: lepton, quarks & gauge bosons for "global warming" accomplishes carbon emission provided Jaco F. Schutte: "the particle swarm optimalization algorithm [Preview Abstract] |
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AA1.00040: Condensed-Matter Systems & Thermopower/Thermionic CeRu4Sb12 Widastra Hidajatullah,SSi Occasionally, the quoted "...used to modelvarious condensed-matter systems with quenched disorder includes vortex phase.."-ChenZeng &LEATH, Physica C, 332 (2000) reminds "Borse-Einstein condensated matter waves, as well as acoustic waves cited whereas for W.A. Little:"Possibility of synthetizing an organic superconductors", PhysRev 134, 61- June 15, 1964 are metal-organic core-shell of TIPSb/triisopropylantimony accompanied with;"Another promising particle geometry are metallic-nanoshells [Xu, 2004 & Talley, et.al-2005 ]which can show large field-enhancements due to reduced plasmon linewidths at near-infrared frequencies"- Stefan A Maier:"Plasmonic: fundamentals & Aplications", Springer, 165 e.g. variouses "near-field communications". For anyon superconductors includes FQHE bosonic formulation if related to peptide-computing & E Tuedoes, et. al in predicting isomorphic residue replacement for protein design [Tuedoes, et.al- IntlJoPeptideProteinRes, v 36- 1990 ]allows us to calculate optical, conductivity, resistivity & thermopower of CeRu4Sb12 with her crystal Force & molecular conformation cited from. [Preview Abstract] |
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