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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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From Ta 2 S 5 Wires to Ta 2 O 5 and Ta 2 O 5– x S x
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Iodine capture with mechanically robust heat-treated Ag-Al-Si-O xerogel sorbents
Silver-loaded heat-treated aluminosilicate xerogels (Ag-HTX) were evaluated as sorbents for iodine [I2(g)] capture. The heat treatment step was performed to help increase the mechanical integrity of the gels. The synthesized xerogels were characterized using powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, gravimetric iodine loading, nanoindentation, and dynamic mechanical analysis. The structural and chemical analyses of Ag-HTX showed uniform distribution of Ag throughout the gel network after Ag-exchange. After I2(g) capture, the AgI crystallites were observed in the sorbent verifying chemisorption as the iodine capture mechanism. Iodine loading of this xerogel was 0.43 g g-1 at 150°C over 1 d and 0.52 g g-1 at 22°C over 33 d. The specific surface area of Ag-HTX was 202 m2 g-1 and decreased to 87 m2 g-1 after iodine loading. The hardness of the heat-treated xerogel was 160 times higher than heat-treated aerogel of the same composition. The heat-treatment process increased the modulus value to 40.77 MPa from 6.99 MPa of as-made xerogel, demonstrating the need for this added step in the synthesis process. These results show that Ag-HTX is a promising sorbent for I2(g) capture with good loading capacity and mechanical stability.
Thermal Equations of State of Corundum and Rh[subscript 2]O[subscript 3] (II)-Type Al[subscript 2]O[
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Navigating the Noise: Bringing Clarity to ML Parameterization Design With O $\boldsymbol{\mathcal{O}}$(100) Ensembles
Abstract Machine‐learning (ML) parameterizations of subgrid processes (here of turbulence, convection, and radiation) may one day replace conventional parameterizations by emulating high‐resolution physics without the cost of explicit simulation. However, uncertainty about the relationship between offline and online performance (i.e., when integrated with a large‐scale general circulation model) hinders their development. Much of this uncertainty stems from limited sampling of the noisy, emergent effects of upstream ML design decisions on downstream online hybrid simulation. Our work rectifies the sampling issue via the construction of a semi‐automated, end‐to‐end pipeline for size ensembles of hybrid simulations, revealing important nuances in how systematic reductions in offline error manifest in changes to online error and online stability. For example, removing dropout and switching from a Mean Squared Error to a Mean Absolute Error loss both reduce offline error, but they have opposite effects on online error and online stability. Other design decisions, like incorporating memory, converting moisture input from specific humidity to relative humidity, using batch normalization, and training on multiple climates do not come with any such compromises. Finally, we show that ensemble sizes of may be necessary to reliably detect causally relevant differences online. By enabling rapid online experimentation at scale, we can empirically settle debates regarding subgrid ML parameterization design that would have otherwise remained unresolved in the noise.
Spin canting across core/shell Fe[subscript 3]O[subscript 4]/Mn[subscript x]Fe[subscript 3;#8722;x]O[subscript 4] nanoparticles
Abstract not provided
Isotopic Effect on Electrochemical CO2 Reduction Activity and Selectivity in H2O- and D2O-based Electrolytes over Palladium
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Biomimetic O[subscript 2] adsorption in an iron metal-organic framework for air separation
Abstract not provided
Lithium vanadium oxide (Li 1.1 V 3 O 8 ) thick porous electrodes with high rate capacity: utilization and evolution upon extended cycling elucidated via operando energy dispersive X-ray diffraction and continuum simulation
The phase distribution of lithiated LVO in thick (~500 μm) porous electrodes (TPEs) designed to facilitate both ion and electron transport was determined using synchrotron-based operando energy dispersive X-ray diffraction (EDXRD). Probing 3 positions in the TPE while cycling at a 1C rate revealed a homogeneous phase transition across the thickness of the electrode at the 1st and 95th cycles. Additionally, continuum modelling indicated uniform lithiation across the TPE in agreement with the EDXRD results and ascribed decreasing accessible active material to be the cause of loss in delivered capacity between the 1st and 95th cycles. The model was supported by the observation of significant particle fracture by SEM consistent with loss of electrical contact. Overall, the combination of operando EDXRD, continuum modeling, and ex situ measurements enabled a deeper understanding of lithium vanadium oxide transport properties under high rate extended cycling within a thick highly porous electrode architecture.
Evaluation of sputtered nickel oxide, cobalt oxide and nickel–cobalt oxide on n-type silicon photoanodes for solar-driven O 2 (g) evolution from water
Thin films of nickel oxide (NiO x ), cobalt oxide (CoO x ) and nickel–cobalt oxide (NiCoO x ) produced integrated, protected Si (111) photoanodes integrated, protected Si photoanodes that did not require deposition of a separate heterogeneous electrocatalyst for water oxidation.
Free-standing bilayered vanadium oxide films synthesized by liquid exfoliation of chemically preintercalated δ-Li x V 2 O 5 · n H 2 O
A free-standing film composed of bilayered vanadium oxide nanoflakes is for the first time synthesized using a new low-energy process.
Tailoring defects and nanocrystal transformation for optimal heating power in bimagnetic Co y Fe 1− y O@Co x Fe 3− x O 4 particles
Synchrotron X-ray scattering reveals that atomic-scale defect control manipulated by chemical substitution optimizes nanomagnetism and enables hyperthermia heating in core-shell iron-oxide nanocrystals.
Encapsulation of the vanadium substituted Keggin polyoxometalates [α-PVW 11 O 40 ] 4− and [α-PV 2 W 10 O 40 ] 5− in HKUST-1
Solid state UV-vis reflectance spectra reveal the distinct electronic structure of POM@MOF materials obtained by synthetic encapsulation of mono- and di-vanadium substituted Keggin polyoxotungstates in HKUST-1.
Strain transfer in porous multiferroic composites of CoFe 2 O 4 and PbZr x Ti 1- x O 3
This manuscript examines the mechanism of strain-coupling in a multiferroic composite of mesoporous cobalt ferrite (CFO), conformally filled with lead zirconate titanate (PZT). We find that when the composites are electrically poled, remanent strain from the piezoelectric PZT layer can be transferred to the magnetostrictive CFO layer. X-ray diffraction shows that this strain transfer is greatest in the most porous samples, in agreement with magnetometry measurements, which show the greatest change in sample saturation magnetization in the most porous samples. In conclusion, strain analysis shows that porosity both accommodates greater lattice strain and mitigates the effects of substrate clamping in thin film strain-coupled composites.
Machine learning improves predictions of agricultural nitrous oxide (N 2 O) emissions from intensively managed cropping systems
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