Bulletin of the American Physical Society
Joint Fall 2021 Meeting of the Texas Sections of APS, AAPT, and SPS
Volume 66, Number 10
Thursday–Saturday, October 21–23, 2021; Houston; Central Time
Session M04: Atomic, Molecular, and Optical Physics I |
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Chair: Tej Limbo, UHCL Room: STEM 2115 |
Friday, October 22, 2021 2:00PM - 2:12PM |
M04.00001: Silicon Nitride Protective Seal for Thermal Barrier Coating on Gas Turbine Engine Blades to Extend Longevity Elora Zucha, Said Bakkar, Ellen Steinmiller, Jacob Moldenhauer, Tim Hossain, Will Flanagan A sample representation of a gas turbine engine blade, consisting of a Nickel superalloy substrate with a deposited thermal barrier coating (TBC), was covered with silicon nitride, Si3N4, as a sacrificial layer using chemical vapor deposition (CVD). The silicon nitride layer was used to seal the yttria-stabilized zirconia (YSZ) surface of the TBC to mitigate calcium-magnesium-aluminum-silicon oxide (CMAS) attack. CMAS testing was carried out on the covered and uncovered surfaces by melting 0.1 g of the CMAS powder on the surface in a furnace at 1100 \textdegree C for 1 hour or under a torch at 1250 ${^\circ}$ for 10 minutes. The conformal surface reaction of the sealed layer confirmed no cracking or delamination at high temperatures. Scanning electron microscopy (SEM) micrographs confirmed that the surface of YSZ was successfully sealed. The new coating of silicon nitride was shown to be a viable technique to significantly reduce CMAS infiltration in porous thermal barrier coatings. [Preview Abstract] |
Friday, October 22, 2021 2:12PM - 2:24PM |
M04.00002: Optical properties of GaN/Er:GaN/GaN core-cladding planar waveguides Yaqiong Yan, Zhenyu Sun, Trey Smith, Weiping Zhao, Jing Li, Jingyu Lin, Hongxing Jiang Erbium doped GaN (Er:GaN) is a promising candidate as a gain medium for high energy lasers (HELs) operating at the “retina-safe” spectral region around 1.5 µm due to outstanding thermal, mechanical and optical properties of GaN host. Compared to YAG, GaN has a much higher thermal conductivity of $\kappa \quad \approx $ 253 W/m\textbullet K and a smaller thermal expansion coefficient of $\alpha \quad \approx $ 3.53 x 10$^{\mathrm{-6}}$ °C$^{\mathrm{-1}}$ and the potential to significantly outperform YAG based HELs. We report here the successful fabrication and optical characterization of GaN/Er:GaN/GaN core-cladding planar waveguides (PWGs). Optical confinement in the core layer has been investigated. The measured optical loss coefficients of Er:GaN PWGs at 1.54 µm have been measured and are respectively 1.0 cm$^{\mathrm{-1}}$ for the transverse electric (TE) and 1.2 cm$^{\mathrm{-1}}$ for the transverse magnetic (TM) modes. Based on the observed transition lines, a detailed energy levels diagram in Er:GaN has been constructed. Approaches to further reduce the optical loss and optimal configuration for resonantly pump GaN/Er:GaN/GaN PWGs for achieving amplification near 1.5 µm have been identified.~ [Preview Abstract] |
Friday, October 22, 2021 2:24PM - 2:36PM |
M04.00003: Molten Salt Reactors: A Paradigm Shift in Nuclear Energy Technologies Timothy Head Molten-salt cooled, liquid-fueled reactors have the potential to be the clean energy source of the future while also solving some of the world's most pressing problems. The Nuclear Energy eXperimental Testing Research Alliance (NEXTRA) consisting of team members from Abilene Christian University, Georgia Institute of Technology, Texas A{\&}M University, and University of Texas is working toward a molten salt research reactor design with planned construction permit submission to the Nuclear Regulatory Commission in 2022, and a plan to have the reactor built and go critical in 2025. The research and development program at ACU is furthering understanding of molten salt handling and measurement techniques while providing cross-disciplinary learning opportunities to students and faculty to solve the problems required to implement a new take on this old technology. [Preview Abstract] |
Friday, October 22, 2021 2:36PM - 2:48PM |
M04.00004: A Study On Machine Learning In Muon Tomography Clive Binu, Sadman Ahmed Shanto, Gabriel Chiselenco, Victor Bradely, Samuel Cano, Mohammed Moosajee, Cristobal Moreno, Madison Howard, Katrina Webb Machine learning (ML) has been used in almost all aspects of our lives, but Muon Tomography has been rather slow embracing the full capabilities offered by ML. In this paper, we report on the implementation of ML concepts to depth reconstruction by two neural networks (NN) models. The first NN is the image classification model which is used to classify the tomograms to in- and out-of-focus. The training dataset has around 20 thousand tomograms and is used to obtain the best in-focus image. The second model is the object detection model coupled with k-means clustering for shape extraction. The dataset used in this training is unique and has to be annotated. By using k-means clustering, the shape of the detected objects in the tomograms is extracted to generate the 3D reconstruction. The image classification showed an accuracy of 84\% and the object detection model resulted in 80\% accuracy. [Preview Abstract] |
Friday, October 22, 2021 2:48PM - 3:00PM |
M04.00005: Muon Tomography to Map Queen Maeve's Cairn Victor Bradley, Samuel Cano, Alan Chavez, Muhammed Moosajee, Cristobal Moreno, Katrina Webb Queen Maeve’s cairn in northwestern Ireland, a large man-made stone Neolithic mound, is one of the largest unexcavated cairns in Europe. As such, there is strong motivation to non-invasively map its internal structure. We are developing a muon telescope specifically for this purpose. Muons are partially absorbed by the stone and soil in the cairn but pass through voids less impeded, granting us a view inside the structure. Monte-Carlo simulations are used to create a comparative baseline to real-world data, as well as various machine learning approaches to enhance the detector performance. [Preview Abstract] |
Friday, October 22, 2021 3:00PM - 3:12PM |
M04.00006: Interference of two laser beams on a glass surface Rishi Bharadwaj, Cristian Bahrim The analysis of the reflectance of a laser beam by a glass surface within 20 degrees of the Brewster angle indicates that we can effectively lock the probe laser's energy into the vibrations of the electric dipoles located on the surface, when this probe is assisted by a second stronger coupling laser beam oriented perpendicularly to the same spot of the surface. In the interaction area between the two lasers, about 2mm wide, the analysis of the light beam of the probe laser reflected by the surface, indicates that the vibration of the surface dipoles is inhibited by the larger vibrational frequency of the coupling laser. Our experimental signal clearly shows a typical pattern with evenly spaced fringes of interference located near the Brewster angle minimum of the parallel component of reflectance. In such a case, the Brewster minimum gets wider, into a Brewster region of width about 1 degree. [Preview Abstract] |
Friday, October 22, 2021 3:12PM - 3:24PM |
M04.00007: Studies of Efficiency in a Regenerative Braking System Alexander Bahrim, Gleb Tcheslavski, Cristian Bahrim A regenerative braking system (or RBS) is an energy recovery mechanism, typically associated to slowing down a moving vehicle or object by converting its~rotational energy into electric power that can be either used immediately or stored. We built an RBS by connecting the shaft of a motor with a steel flywheel and a turbine generator. This motor-flywheel-generator (MFG) system is used to study the efficiency in energy conversion from the rotational energy of the flywheel into electrical energy stored by a large capacitor (or battery). The paper will present the building steps of an RBS, including the design of a circuit convertor of AC power from the turbine, into DC power stored by capacitor, and the efficiency in energy conversion for various rotations per minute (RPM) regulated by a computer driven ClearPath motor. Our system reached 30{\%} efficiency at 1,000 RPM, and through the extrapolation of our data, it indicates an astonishing 51{\%} efficiency at 2,000 RPM, which corresponds to real-world applications. [Preview Abstract] |
Friday, October 22, 2021 3:24PM - 3:36PM |
M04.00008: Mechanism of Surface-Enhanced Raman Scattering on Multilayer Ti$_{\mathbf{3}}$\textbf{C}$_{\mathbf{2}}$\textbf{T}$_{\mathbf{X}}$\textbf{ Nanosheets} Tej Limbu, Basant Chitara, Martha Garcia Cervantes, Yu Zhou, Shengxi Huang, Yongan Tang, Fei Yan MXenes have attracted great attention~as~flat substrates~for surface-enhanced Raman scattering (SERS) applications. However, the underlying SERS mechanism has not been a focus of any investigation. Herein, we report the first systematic experimental study on the SERS activity of Ti$_{3}$C$_{2}$T$_{X\, }$nanosheets with thickness ranging from 5 to 120 nm, using methylene blue (MB) as a probe molecule. We found that SERS intensity increases with the MXene nanosheet thickness. The thickness-dependence of the Raman enhancement can be accounted for by the adsorption and intercalation of MB molecules into the interlayer spacing of Ti$_{3}$C$_{2}$T$_{X}$. Furthermore, by combining experimental observations and numerical calculation, we confirm that the charge transfer mechanism is dominantly responsible for Raman enhancement on Ti$_{3}$C$_{2}$T$_{X}$. Additionally, we report an observation of resonance coupling of charge transfer and molecular transition as a contributing factor to the higher EF obtained with a 633 nm laser excitation. Taken together, these findings have significant implications for cost and performance optimization in designing MXene-based SERS substrates for next-generation chemical and biological sensing platforms. [Preview Abstract] |
Friday, October 22, 2021 3:36PM - 3:48PM |
M04.00009: Magnetic 3D Printing Filament Development and Printing Methods Daniel Luna, Camila Belduque, Harrison Thramann, Subash Panta, Liam Omer, Tanjina Ahmed, Jitendra Tate, Wilhelmus Geerts Due to its innumerable amount of uses and applications, 3D printing technology has grabbed the attention of scientists and engineers around the world. This has led to the development of many types of filaments to suit specific applications. In this case, magnetic filaments have been created using strontium ferrite and NdFeB particles embedded in nylon. A particular interest has been placed on magnetic field assisted additive manufacturing (MFAAM) to aid in particle alignment, yielding a stronger magnetic moment in the printed product. Prints were made with different sized printing nozzles to determine how magnetic properties were affected, which were measured using a Vibrating Sample Magnetometer (VSM). A common issue with the printing process of a magnetic filament is the particles getting clogged in a nozzle if it is too small. Fortunately, the results show that when printed within an applied magnetic field, the samples that were created using a larger nozzle exhibited stronger magnetic characteristics, and are much less prone to clogging. This is significant because it overcomes a major obstacle in the 3D printing of magnetic filaments, greatly increasing ease of use. [Preview Abstract] |
Friday, October 22, 2021 3:48PM - 4:00PM |
M04.00010: Tailoring The Spin Dependent Electronic Transport of Low Dimensional Materials Aydin Mammadov, Serkan Caliskan Density Functional Theory combined with Non Equilibrium Green's Function Formalism is employed to examine graphene-like structures containing either transition metals (TMs) or defects. After the structural optimization, first principles calculations are performed to exhibit spin polarized electronic structure and transport properties of these materials. It is revealed that structural defects can induce spin polarization which can further be enhanced through TMs. They can be utilized to manipulate the spin dependent behavior and achieve half metallic property which plays a crucial role for the envisaged spintronic devices. [Preview Abstract] |
Friday, October 22, 2021 4:00PM - 4:12PM |
M04.00011: Development of Multi-functional 2D Layered Double Hydroxides (LDHs). Ashtami Jayakumar, Lilly Schaffer, Maggie Paulose, Chandra Mohan, Oomman Varghese Layered double hydroxides (LDHs) are interesting two-dimensional (2D) clay nanomaterials that possess exceptional functionalities appropriate for a range of applications including electrocatalysis, photocatalysis, drug delivery, immune therapy and bone tissue engineering. LDHs [[M$_{1-x}^{2+}$M$_{x}^{3+}$(OH)$_{2}$]$^{x+}$[A$_{x/n}$]$^{n-}$~mH$_{2}$O] are sensitive towards the fabrication conditions and elemental combinations. One of the major hurdles in LDH development is to control tendency to grow into platelets of larger size and to exist in wide size distribution. We have successfully controlled the growth dynamics of LDHs by tuning the nucleation and hydrothermal growth conditions and fabricated the hexagonal platelet structured LDHs with narrow size distribution. The fabricated LDHs of different compositions showed significant potential as electrocatalysts for hydrogen generation via water splitting and/or for immunotherapy applications. In this presentation, we discuss the performance of different LDHs in these applications and the influence of growth conditions in controlling the size distribution and morphology. [Preview Abstract] |
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