Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session AA06: V: Undergrad Research IIUndergrad Friendly
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Sponsoring Units: APS SPS Chair: Brad Conrad, AIP Room: Virtual Room 6 |
Monday, March 20, 2023 5:00AM - 5:12AM Author not Attending |
AA06.00001: The roles of eDNA and Alginate in biofilm mechanics and mechanical resistance to the immune system Isabella C Chavez Biofilm bacteria are embedded in a matrix of extracellular polymeric substances (EPS). Our goal is to understand the importance of different EPS types that Pseudomonas aeruginosa produce (specifically extracellular DNA (eDNA) and alginate) in the biofilm mechanics and how this relates to the success of neutrophils (phagocytic white blood cells) in engulfing biofilm bacteria. We apply neutrophils to biofilms treated with varying amounts of alginate lyase, which enzymatically breaks down alginate. We then use antibiotics to kill any bacteria in our samples that haven’t been engulfed by neutrophils. Then, we lyse neutrophils to release bacteria and count the number of bacteria remaining that were protected from antibiotics by being enclosed in neutrophils. We use the same process when assessing eDNA’s role, with DNase instead alginate lyase to break apart alginate structures. We also study the role of calcium ions at physiological concentrations; calcium ions can electrostatically crosslink alginate and eDNA, altering the mechanics of biofilms and their response to enzymatic treatments. |
Monday, March 20, 2023 5:12AM - 5:24AM |
AA06.00002: Characterizing the Viscoelasticity of Calcium-Alginate Hydrogels Via Multiple Particle Tracking Microrheology Hailey A Currie Pseudomonas aeruginosa is a biofilm-forming bacterium and an opportunistic human pathogen. These biofilms are highly adaptable and resistant to antimicrobial treatments, in part due to a heterogeneous intercellular matrix composition and superstructure. In recent work by others and ourselves, P. aeruginosa biofilms have been observed to incorporate substances, like collagen and calcium ions, that originate in the host environment. This can result in major alterations in the mechanical properties of the biofilm. In particular, another group has recently shown that calcium ions cross-link the matrix polymer alginate, creating a gel-like superstructure. In this work, I seek to use microrheology to characterize the viscoelastic properties of alginate hydrogels formed in the presence of biologically relevant concentrations of calcium ions as an in-vitro analog to alginate-dominant P. aeruginosa biofilms developing in a host environment containing calcium. Later, I intend to use microrheology to measure the effect of enzymatic treatment on such model "biofilms". The goal is to evaluate the efficacy of enzymes at disrupting the mechanics and microstructure of biofilms, and connect this to their possible roles in treating biofilm disease. |
Monday, March 20, 2023 5:24AM - 5:36AM |
AA06.00003: Structure of PLGA and Its Cardio-Protective Effect: Atomic Simulation and Machine Learning Jacob Groh, Levi McClurg, Jaehyun Lee, Michelle Chen, Howard H Chen Poly lactic-co-glycolic acid (PLGA) is a polymer consists of lactic acids and glycolic acids subunits. Being relatively inert, and able to break down in human body with no significant toxic effect to human body, PLGA has been FDA-approved and used in a wide range of medicine. However, the relation between its physio-chemical properties and biological properties remains unclear. In the case of doxorubicin, a drug that is commonly used in chemotherapy, while being very effective in fighting cancer, doxorubicin is also cardiotoxic leading to a tremendous risk of heart disease in cancer patients. We demonstrate here that PLGA in conjunction with doxorubicin mitigated cardiotoxicity effects in cultured cardiac cells increasing survival. To investigate the mechanism of PLGA’s cardio-protective effects we applied machine learning techniques including k-means clustering and random forest classification to unbiasedly identify the most important factors for PLGA’s enhancement on cell viability. Furthermore, we performed Quantum Expresso simulations to model the PLGA bond length, coordination numbers, density, etc. We analyzed the electronic and energetic distributions of PLGA to better understand the structure and function and to further optimize PLGA’s therapeutic potentials. |
Monday, March 20, 2023 5:36AM - 5:48AM |
AA06.00004: Millikelvin Characterization of Electronic Components for Cryoelectronic Circuits Dmitri Krymski, Pragya R Shrestha, Yanxue Hong, Nikki Ebadollahi, Runze Li, Joshua Pomeroy Discrete electronic components such as resistors, transistors, and capacitors are measured at millikelvin temperatures and compared to their room temperature values for use in designing basic electronic circuits at cryogenic temperatures. Electronic circuits designed within the cryogenic environment offer a pathway to reduce parasitic noise — however, operating parameters of discrete components used in the circuits should be known for the designed circuit to work as expected at cryogenic temperatures. To investigate the temperature-dependent characteristics and obtain the operating parameters, the components were attached to a mounted printed-circuit-board within the mixing chamber of a dilution refrigerator and were measured at room temperature, 4 K, and 10 mK. For a series of resistors ranging from 100 Ω to 1 MΩ, resistances were found to change by a factor of 0.96 to 1.27 at cryogenic temperatures. Transistors showed a volt-scale shift in threshold voltage and improved transconductance with decreasing temperature. Capacitors were found to be less consistent in their temperature-dependance characteristics. |
Monday, March 20, 2023 5:48AM - 6:00AM |
AA06.00005: Performance Assessment of NASA Mission Proposal to Characterize Exoplanet Atmospheres with Space-based High-Resolution IR Spectrometer Chaucer Langbert The search for life beyond our Solar System requires the remote detection of molecules in exoplanet atmospheres. One goal of the James Webb Space Telescope (JWST) is to detect particular molecules in the atmospheres of transiting exoplanets with the help of longer wavelength coverage and improved sensitivity. Higher spectral resolution in the infrared region beyond that of JWST could reveal a greater wealth of information about key molecules in these atmospheres. We use of a model of HD 209458b's transmission and eclipse spectra to simulate observations for a proposed infrared spectrometer with ten times the resolution of JWST. The spectrometer would be launched into space and could make these measurements. We explore its parameters and noise tolerances in order to support a satellite mission containing the suggested infrared spectrometer. We show that even signal-to-noise ratios of 100 can lead to statistically-significant measurements of exoplanet atmospheres. This work serves as a preliminary set of guidelines that will be crucial for making robust observations of exoplanet atmospheres with a space-based high-resolution infrared spectrometer. |
Monday, March 20, 2023 6:00AM - 6:12AM |
AA06.00006: Using a Monte Carlo Event Generator to Model String Resonances in Proton-Proton Collisions Kenny Moc, Douglas M Gingrich, Jack H Lindon String effects may be detectable at low-energy scale in specific models of string theory. In such cases, proton-proton collisions at the LHC could produce string resonances that would differ from our theory of quantum chromodynamics, which governs the interactions between quarks and gluons. We could detect these resonances by analyzing particle jets generated by the quarks and gluons. We form simulations of these collisions using a Monte Carlo event generator with string resonances and with pure QCD. Our objective is to aid in the search for particles beyond the standard model. |
Monday, March 20, 2023 6:12AM - 6:24AM |
AA06.00007: The physical structure of Spacetime Aman Yadav Constructed an equation in the context of Einstein’s general relativity by employing the conjunction of wave function’s derivatives and Schrodinger's equation, confirming its validity by reducing the parameters to Planck’s scale. The results we get from our fabricated equation is somehow providing a satisfactory solution in terms of its structure and dimensional aspect which corresponds to Einstein’s field equation. The equation considers both mass and mass-less particles and determines their wavelengths and potential energy respectively. We have also discussed the behavior of the equation when it is reduced to Planck’s unit which leads to the accumulation of Newtonian values. I will propose a physical description of spacetime structure using our aquired equation and furthermore, define the origin of gravity. |
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