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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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Design studies using MCNP6® for an oil well logging prototype tool and a test facility
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Facile synthesis of thiophene/selenophene-fused acene and their optoelectronic properties
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A Facile, One-Step Synthesis for Core–Shell Perovskite Materials via Molten Salt
Core–shell La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF)–La 0.8 Sr 0.2 MnO 3 (LSM) heterostructure crystalline materials have been synthesized in a simple, one-step feeding method via a KNO 3 molten salt solvent. Two-phase perovskite composites can be synthesized in times as short as 10 minutes and is demonstrated for the first time in a molten salt. Further, a combination of X-ray diffraction and S/TEM energy dispersive X-ray spectroscopy has been utilized to confirm the formation of an LSM shell on LSCF cores in all samples when adjusting dwell time, core size, weight ratio between core and shell precursors, and weight ratio of powder to salt. Specifically, decreasing the LSCF core size increases core–shell yield. Smaller cores introduce a greater density of facets on the crystal surface and provide more favorable sites for LSM heterogeneous nucleation.
Facile Oxidation of Ce(III) to Ce(IV) Using Cu(I) Salts
The synthesis, luminescence, and electrochemical properties of the Ce(III) compound, [(C 5 Me 5 )2(2,6- i Pr 2 C 6 H 3 O)Ce(THF)], 1, were investigated. Based on the electrochemical data, treatment of 1 with CuX (X = Cl, Br, I) results in the formation of the corresponding Ce(IV) complexes, [(C 5 Me 5 ) 2 (2,6- i Pr 2 C 6 H 3 O)Ce(X)]. Each complex has been characterized using NMR, IR, and UV−vis spectroscopy as well as structurally determined using X-ray crystallography. Additionally, the treatment of [(C 5 Me 5 ) 2 (2,6- i Pr 2 C 6 H 3 O)Ce(Br)] with AgF results in the formation of the putative [(C 5 Me 5 ) 2 (2,6- i Pr 2 C 6 H 3 O)Ce(F)]. Furthermore, the electronic structure of these Ce(IV)−X complexes was investigated by bond analyses and the Ce(IV)−F moiety using quantum chemistry NMR calculations.
Facile Directed Assembly of Hollow Polymer Nanocapsules within Spontaneously Formed Catanionic Surfactant Vesicles
Surfactant vesicles containing monomers in the interior of the bilayer were used to template hollow polymer nanocapsules. This study investigated the formation of surfactant/monomer assemblies by two loading methods, concurrent loading and diffusion loading. The assembly process and the resulting aggregates were investigated with dynamic light scattering, small angle neutron scattering, and small-angle X-ray scattering. Acrylic monomers formed vesicles with a mixture of cationic and anionic surfactants in a broad range of surfactant ratios. Regions with predominant formation of vesicles were broader for compositions containing acrylic monomers compared with blank surfactants. This observation supports the stabilization of the vesicular structure by acrylic monomers. Diffusion loading produced monomer-loaded vesicles unless vesicles were composed from surfactants at the ratios close to the boundary of a vesicular phase region on a phase diagram. Both concurrent-loaded and diffusion-loaded surfactant/monomer vesicles produced hollow polymer nanocapsules upon the polymerization of monomers in the bilayer followed by removal of surfactant scaffolds.
Rapid, facile synthesis of conjugated polymer zwitterions in ionic liquids
Ionic liquids (ILs) were utilized for the rapid air-stable Suzuki polymerization of polar zwitterionic thiophene monomers, precluding the need for volatile organic solvents, phosphine ligands and phase transfer catalysts typically used in conjugated polymer synthesis.
Moderate supercritical synthesis as a facile route to mixed-valent uranium( iv , v ) and ( v , vi ) silicates
The synthesis of five new U( iv , v ) and U( v , vi ) silicates points toward moderate supercritical synthesis as a new route to the stabilization of mixed-valent uranium compounds.
Facile one-pot synthesis of PdM (M = Ag, Ni, Cu, Y) nanowires for use in mixed matrix membranes for efficient hydrogen separation
A general synthesis method is demonstrated for producing PdM (M= Ag, Cu, Ni, and Y) nanowire networks. As a prototypical application, these nanowires are incorporated into polybenzimidazole to create mixed matrix membranes for H 2 /CO 2 separation.
Contrasting physics in wire array z pinch sources of 1-20 keV emission on the Z facility
Imploding wire arrays on the 20 MA Z generator have recently provided some of the most powerful and energetic laboratory sources of multi-keV photons, including ∼375 kJ of Al K-shell emission (hν ∼ 1–2 keV), ∼80 kJ of stainless steel K-shell emission (hν ∼ 5–9 keV) and a kJ-level of Mo K-shell emission (hν ∼ 17 keV). While the global implosion dynamics of these different wire arrays are very similar, the physical process that dominates the emission from these x-ray sources fall into three broad categories. Al wire arrays produce a column of plasma with densities up to ∼3 × 10{sup 21} ions/cm{sup 3}, where opacity inhibits the escape of K-shell photons. Significant structure from instabilities can reduce the density and increase the surface area, therefore increase the K-shell emission. In contrast, stainless steel wire arrays operate in a regime where achieving a high pinch temperature (achieved by thermalizing a high implosion kinetic energy) is critical and, while opacity is present, it has less impact on the pinch emissivity. At higher photon energies, line emission associated with inner shell ionization due to energetic electrons becomes important.
Comment on “A novel and facile decay path of Criegee intermediates by intramolecular insertion reactions via roaming transition states” [J. Chem. Phys. 142 , 124312 (2015)]
In a recent article, Nguyen et al. report the discovery of a new decomposition pathway for small Criegee intermediates. Prior to this publication, the lowest known pathway for decomposition of Criegee intermediates involved ring closure to form a dioxirane followed by ring opening to make a methylenebisoxy biradical, which can then isomerize or decompose via a variety of pathways. The new pathway reported by Nguyen et al. involves the partial cleavage of the OO bond of the Criegee intermediate forming nascent H 2 CO and O( 1 D) fragments. The O( 1 D) fragment then orbits around the H 2 CO fragment in a manner reminiscent of roaming radical reactions and eventually inserts into one of the CH bonds of the H 2 CO fragment leading directly to formic acid. The authors report saddle point geometries for this pathway determined at a number of different levels of theory in which the distance between the oxygen atom and the formaldehyde varies from 2.0 Å to 3.5 Å depending on the level of theory. Density functional theory (DFT) calculations are found to give more compact, planar saddle point structures while coupled cluster, CCSD(T), and complete active space self consistent field, CASSCF, optimizations lead to looser saddle point structures in which the O atom orbits above the plane of the H 2 CO fragment.
Observation of hohlraum-wall motion with spectrally selective x-ray imaging at the National Ignition Facility
The high fuel capsule compression required for indirect drive inertial confinement fusion requires careful control of the X-ray drive symmetry throughout the laser pulse. When the outer cone beams strike the hohlraum wall, the plasma ablated off the hohlraum wall expands into the hohlraum and can alter both the outer and inner cone beam propagations and hence the X-ray drive symmetry especially at the final stage of the drive pulse. To quantitatively understand the wall motion, we developed a new experimental technique which visualizes the expansion and stagnation of the hohlraum wall plasma. Details of the experiment and the technique of spectrally selective x-ray imaging are discussed.
Charge Breeding of Radioactive Isotopes at the CARIBU Facility
An Electron Beam Ion Source Charge Breeder (EBIS-CB) has been developed at Argonne National Laboratory as part of the californium rare ion breeder upgrade. For the past year, the EBIS-CB has been undergoing commissioning as part of the ATLAS accelerator complex. It has delivered both stable and radioactive beams with A/Q < 6, breeding times < 30 ms, low background contamination, and charge breeding efficiencies > 18% into a single charge state. The operation of this device, challenges during the commissioning phase, and future improvements will be discussed. Published by AIP Publishing.
Uncertainty analysis of Response Functions and y-Backgrounds on Tion and t0 Measurements from Cherenkov Neutron Detectors at the National Ignition Facility (NIF) a)
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A NIST facility for resonant soft x-ray scattering measuring nano-scale soft matter structure at NSLS-II
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