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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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Electron probe microanalysis of irradiated FUTURIX-FTA U-Pu-Zr alloy with added minor actinides
Not Available
Microstructure and diffusion behavior of uranium fuel with minor additives
Fission product lanthanides in metallic fuels are known to cause adverse fuel-cladding chemical interaction (FCCI). Tin (Sn) and palladium (Pd) are being explored as the potential additives to reduce or mitigate lanthanide-induced FCCI by forming stable Sn-Ln and Pd-Ln compounds. The current study is an investigation of the fuel alloys, U–4Sn, U–4Sn-4Ln, U–4Pd, and U–4Pd-4Ln (wt. %), and their diffusion behaviors with Fe. Microstructural analysis was performed using scanning electron microscopy (SEM). Further, the binary phases in the UPd and USn alloys are identified as UPd 3 and suspected U 2 Sn, where U 2 Sn is unknown in the literature. The binary phases in the UPdLn alloy are identified as PdLn and Pd-rich Pd-Ln (Pd 4 Ln 3 and Pd 3 Ln 2 ), and in the USnLn alloy is SnLn. Diffusion of Fe with these binary phases is insignificant compared to the diffusion with U. The Ln-induced FCCI can be mitigated by the additives.
Effect of minor carbon additions on the high-temperature creep behavior of a single-crystal nickel-based superalloy
Different amounts of carbon were added to a single-crystal nickel-based superalloy. The microstructural evolution of these alloys before and after high-temperature creep tests was investigated by employing scanning electron microscopy and transmission electron microscopy. Upon increasing the carbon contents, the volume fraction and diameter of the carbides increased gradually: however, the creep lives of the alloys increased slightly at first and subsequently decreased. The formation of second-phase particles, such as the nano-sized M{sub 23}C{sub 6}, blocky and needle-shaped μ phase, was observed in the creep samples, which was closely related to the high-temperature creep behaviors. - Highlights: • Creep behaviors of alloys with different amounts of carbon were investigated. • The creep rupture lives increased and later decreased with more carbon. • Second-phase particles were responsible for the different creep behaviors.
Effects of friction stir processing and minor Sc addition on the microstructure, mechanical properties, and damping capacity of 7055 Al alloy
Highlights: • Good mechanical and damping properties were obtained in the 7055 after FSP and Sc addition. • The strengthening and damping mechanisms of FSP 7055(-Sc) were analyzed. • FSP and Sc addition were found to be strategy of preparing 7xxx alloys with well damping and mechanical properties. - Abstract: This study investigated the effects of friction stir processing (FSP) and addition of 0.25% (mass ratio) Sc on the microstructure, mechanical properties, and damping capacity of AA 7055 alloy. Microstructure analyses revealed that a low tool rotation rate of 300 rpm effectively inhibited the grain coarsening in the recrystallization of the alloy during FSP. Sc addition prevented the coarsening of grains and precipitated η phase and the annihilation of dislocations in the FSP AA 7055 alloy. After being subjected to FSP at 300 rpm, the AA 7055 alloy containing Sc exhibited good mechanical and damping properties, which were mainly attributed to the fine recrystallized grain structure, fine precipitated η phase, and large number of nano-sized Al{sub 3}(Sc, Zr) particles located at the grain boundaries and dislocations. This work provides an effective strategy for preparing commercial Al alloys with excellent damping capacity and mechanical properties.
A study of the effects of minor additives to Pb-Bi eutectic: Designing novel Pb-Bi-X liquid alloys for heat transfer applications
Not Available
Effect of Band Mismatch on Minority Carrier Transport in Heterojunction Solar Cells
Abstract not provided
The high risk HPV16 L2 minor capsid protein has multiple transport signals that mediate its nucleocytoplasmic traffic
In this study we examined the transport signals contributing to HPV16 L2 nucleocytoplasmic traffic using confocal microscopy analysis of enhanced green fluorescent protein-L2 (EGFP-L2) fusions expressed in HeLa cells. We confirmed that both nuclear localization signals (NLSs), the nNLS (1MRHKRSAKRTKR12) and cNLS (456RKRRKR461), previously characterized in vitro (Darshan et al., 2004), function independently in vivo. We discovered that a middle region rich in arginine residues (296SRRTGIRYSRIGNKQTLRTRS316) functions as a nuclear retention sequence (NRS), as mutagenesis of critical arginine residues within this NRS reduced the fraction of L2 in the nucleus despite the presence of both NLSs. Significantly, the infectivity of HPV16 pseudoviruses containing either RR297AA or RR297EE within the L2 NRS was strongly reduced both in HaCaT cells and in a murine challenge model. Experiments using Ratjadone A nuclear export inhibitor and mutation-localization analysis lead to the discovery of a leucine-rich nuclear export signal ({sub 462}LPYFFSDVSL) mediating 16L2 nuclear export. These data indicate that HPV16 L2 nucleocytoplasmic traffic is dependent on multiple functional transport signals.
Thermodynamic estimation of minor element distribution between immiscible liquids in Fe-Cu-based metal phase generated in melting treatment of municipal solid wastes
Graphical abstract: Display Omitted Highlights: Black-Right-Pointing-Pointer Two liquids separation of metal occurs in the melting of municipal solid waste. Black-Right-Pointing-Pointer The distribution of PGMs etc. between two liquid metal phases is studied. Black-Right-Pointing-Pointer Quite simple thermodynamic model is applied to predict the distribution ratio. Black-Right-Pointing-Pointer Au and Ag originated from WEEE are found to be concentrated into Cu-rich phase. - Abstract: Waste electrical and electronic equipment (WEEE) has become an important target in managing material cycles from the viewpoint of not only waste management and control of environmental pollution but also resource conservation. This study investigated the distribution tendency of trace elements in municipal solid waste (MSW) or incinerator ash, including valuable non-ferrous metals (Ni, Co, Cr, Mn, Mo, Ti, V, W, Zr), precious group metals (PGMs) originated from WEEE (Ag, Au, Pd, Pt), and others (Al, B, Pb, Si), between Fe-rich and Cu-rich metal phases by means of simple thermodynamic calculations. Most of the typical alloying elements for steel (Co, Cr, Mo, Nb, Ni, Si, Ti, V, and W) and Rh were preferentially distributed into the Fe-rich phase. PGMs, such as Au, Ag, and Pd, were enriched in the Cu-rich phase, whereas Pt was almost equally distributed into both phases. Since the primary metallurgical processing of Cu is followed by an electrolysis for refining, and since PGMs in crude copper have been industrially recovered from the resulting anode slime, our results indicated that Ag, Au, and Pd could be effectively recovered from MSW if the Cu-rich phase could be selectively collected.
Minor Impact of Ligand Shell Steric Profile on Colloidal Nanocarbon Catalysis
The catalytic activity of a colloidal nanoparticle is typically inhibited by the very capping agents that are required to maintain colloidal stability and catalyst dispersion. Yet, the relative importance of steric contributions to the observed attenuation in catalytic activity is poorly understood. In this work, we prepare colloidal graphitic carbon nanoparticles featuring covalent amide linkages to aliphatic surface capping agents of varying length. Using aerobic benzylamine oxidation as a test reaction, we find that the steric profile of the ligand shell plays a negligible role in suppressing catalytic activity relative to chemisorption interactions that alter the surface chemistry of the catalyst. The work indicates that heterostructured nanoparticles that provide distinct surface sites for ligand binding and substrate activation should allow for high colloidal stability and robust catalytic activity.