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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Optical Ray-Tracing Performance Modeling of Quartz Half-Shell Tubes Aperture Cover for Falling Particle Receiver.
Abstract not provided.
Solid-state laser refrigeration of core-shell polystyrene microspheres
Microlaser designs based on the coupling of whispering gallery modes (WGMs) with the upconversion processes which take place within lanthanide-doped nanoparticles (UCNPs) have been demonstrated and shown to have many valuable qualities, such as high Q factors and low lasing thresholds. One obstacle that these microlaser designs still face is the challenges caused by photothermal heating of the gain medium, which could be solved through the design of a radiation balanced microlaser. In this work, WGM microresonators composed of 5 µm diameter polystyrene spheres are fabricated with a layer of Yb3+-doped NaYF4 UCNPs in order to test if the anti-Stokes cooling properties of the UCNPs can cool the microresonator and its environment under laser irradiation. We find via calibrated mean fluorescence spectroscopy that the UCNPs can cool their local environment by as much as 23 °C and significantly reduce the heating of the aqueous environment surrounding the microresonator, showing promise for inclusion in a design for a radiation balanced microlaser.
Assembly principles and structure of a 6.5-MDa bacterial microcompartment shell
Not Available
Collapse to the Center and Ambiguity in the Asymptotic Behavior of the Off-Shell Scattering Amplitude in Singular Three-Body Problems
Some examples of equations for the there-body problem where there is an oscillating high-momentum behavior are discussed. Specifically, these are (i) the equation in the fixed-center approximation; (ii) the unitarized equation in the fixed-center approximation; (iii) the Skornyakov–Ter-Martirosyan equation; and (iv) equations involving operators that are used in effective field theory—that is, those that are expandable in positive-power series in momentum. It is shown that, in such problems, there arises a situation analogous to a collapse to the center—that is, an infinite number of bound states. The energy of these states is unbounded from below. In this sense, the situation in the models being considered is close to a collapse to the center in the two-body problem.
Isoscalar and Isovector Giant Resonances in Closed Shells Nuclei and Bulk Properties of Nuclear Matter
Centroid energies, E CEN , of the isoscalar (T = 0) and isovector (T = 1) giant resonances of multipolarities L = 0 – 3 in 40,48 Ca, 68 Ni, 90 Zr, 116 Sn, 144 Sm and 208 Pb, were calculated within the fully self-consistent spherical Hartree-Fock (HF)-based random phase approximation (RPA) theory, using 33 different energy density functionals associated with Skyrme-type effective nucleon-nucleon interactions of the standard form commonly employed in the literature. Here, we also calculate the Pearson linear correlation coefficients between each E CEN and each bulk property of nuclear matter (NM), associated with the Skyrme interactions used in the calculations, and determine the sensitivity of E CEN to bulk properties of NM. By comparing the calculated values of E CEN to the experimental data, we constrain the values of the bulk NM properties. We find that interactions associated with the values of the NM effective mass, m* / m = 0.70 to 0.90, incompressibility coefficient, K NM = 210 to 240 MeV, and the enhancement coefficient of the energy weighted sum rule of the isovector giant dipole resonance, κ = 0.25 to 0.70, best reproduce the experimental data.
Anisotropic Jahn–Teller acceptors formed in GaAs by first-group elements with a filled d shell
A phenomenological model of double acceptors formed by Cu, Ag, and Au atoms in GaAs is presented. Experimentally observed phenomena related to the specific features of the spatial and electronic structure of these centers (the suppression of the Jahn–Teller effect by uniaxial pressure, softening of the crystal, recombination-induced reorientation of Jahn–Teller distortions of the center, the decrease in the stationary degree of alignment of center distortions by uniaxial pressure with an increase in the recombination rate of nonequilibrium electron–hole pairs through the center, the relaxation absorption of ultrasound, etc.) are described.
Highly Dispersed Carbon Supported PdNiMo Core with Pt Monolayer Shell Electrocatalysts for Oxygen Reduction Reaction
The development of low-cost, durable, and high-performance materials that could substitute for the current platinum-based electrocatalysts would accelerate the commercialization of polymer electrolyte membrane fuel cells as an alternative power source. We report herein a new fabrication approach of carbon-supported platinum monolayer (ML) on ternary palladium-nickelmolybdenum core electrocatalysts (Pt ML /PdNiMo/C) by a sonochemical method using ionic liquid (IL) as a dispersion medium. The sonolysis technique can control the size and distribution of the ternary-metal nanoparticles on different carbon supports without addition of any external reducing agents, surfactants or capping agents. Depositing Pt MLs using under-potential deposition method on the ternary PdNiMo nanoparticle cores could enhance activity and durability of the cathode during the oxygen reduction reaction of the fuel cell. Herein, we show that the described sonolysis method produces more reliable and cost-effective electrocatalysts that outperforms a commercial Pt-based catalyst.
Synthesis and Characterization of Core-Shell Nanocrystals of Co-Rich Cathodes
Not Available
FSU Effective Nuclear Shell Model Interactions
This effective nucleon-nucleon interactions matrix elements. https://github.com/alvolya/interaction_fsu
Shell Predictive Battery Life Models (SPBLM) [SWR-20-35]
Battery life models to predict the capacity fade and resistance growth of lithium-ion batteries from various manufacturers with different chemistries. The battery life model is trained on experimental test data, and accounts for calendar and cycling aging mechanisms as functions of cell environmental conditions and use. The battery life model is then used to predict capacity fade and resistance growth under any arbitrary aging scenario.
Oxygen Isotope Variability within Nautilus Shell Growth Bands
Not Available