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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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Ultrathin film crystallization of poly(ε-caprolactone) in blends containing styrene-isoprene block copolymers: The nano-rose morphology
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Origins of high strength and ductility combination in a Guinier-Preston zone containing Mg-Al-Ca-Mn alloy
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Impact of Sr-Containing Secondary Phases on Oxide Conductivity in Solid-Oxide Electrolyzer Cells
Solid-oxide electrolyzer cells (SOECs) based on a yttria-stabilized zirconia (YSZ) oxide electrolyte produce hydrogen from water with the assistance of excess thermal energy; however, Sr diffusion within the Gd-doped CeO 2 (GDC) barrier layer during processing or operation can lead to the formation of unwanted secondary phases such as SrO and SrZrO 3 . Here, to establish and compare the degree of impact of these phases on SOEC performance, we conduct first-principles calculations to study their bulk oxide conductivities and compare them to that of the YSZ electrolyte. We find that SrO has a low conductivity arising from the poor mobility and low concentration of mobile oxygen vacancies, and its presence in SOECs should therefore be avoided. SrZrO 3 also has a lower oxide conductivity than YSZ; however, this discrepancy is primarily due to lower vacancy concentrations rather than low mobility. We find that sufficient levels of Y-doping on the Zr site can increase oxygen vacancy concentrations in SrZrO 3 to achieve an oxide ionic conductivity on par with that of YSZ, thereby mitigating any potential deleterious effect on transport performance. Energy-dispersive X-ray spectroscopy confirms that Y is the most common minority element present in SrZrO 3 forming near the GDC–YSZ interface, alleviating concerns regarding the impact of SrZrO 3 on device performance. These results from our combined computational–experimental analysis can inform future engineering strategies designed to limit the detrimental effects of Sr-induced secondary phase formation on SOEC performance.
Naphthylbipyrrole-Containing Amethyrin Analogue: A New Ligand for the Uranyl (UO 2 2+ ) Cation
Using naphthobipyrrole as a functional building block, a new expanded porphyrin, naphtho-isoamethyrin, was prepared in 85% yield under acid catalyzed [4+2] MacDonald coupling conditions. Here, treatment of naphtho-isoamethyrin with the non- aqueous uranyl silylamide salt, [UO 2 [N(SiMe 3 ) 2 ] 2 ·2THF], yielded the corresponding uranyl complex. Upon metalation, naphtho-isoamethyrin undergoes a 2-electron oxidation to yield a formal 22 π-electron aromatic species, as inferred from 1H NMR and UV-vis spectroscopy, as well as cyclic voltammetry.
Quantitative Structure–Property Relationship (QSPR) Analysis of ZrO 2 -Containing Soda-Lime Borosilicate Glasses
Quantitative structure–property relationship (QSPR) analysis is a promising approach to correlate structural features with properties of glass materials that lack long-range order and usually have complex structures. By using carefully chosen descriptors based on structural models generated from molecular dynamics (MD) simulations, correlations with properties and insights on glass behaviors can be obtained. Zirconia can significantly alter glass properties including chemical durability, even in a small amount, and hence plays an important role in vitrification of nuclear waste where long-term chemical durability is desired. In this study, borosilicate glasses with the composition of xZrO 2 –(61 – x)SiO 2 –17B 2 O 3 –18Na 2 O–4CaO with x = 0, 1, 2, 4, 6, and 8 were simulated using classical MD simulations with the recently developed composition-dependent potentials. Short-range (e.g., bond distance and coordination numbers) and medium-range (e.g., Qn distribution, network connectivity, and ring-size distribution) structural features altered by ZrO 2 were obtained and analyzed. The use of a descriptor (Fnet descriptor) that combines short-range structural characteristics, from MD simulations, and the cation-oxygen single bond strength was found to provide excellent linear correlations with the density and initial dissolution rate of these glasses. Furthermore, the results show that by combining MD simulations and QSPR analysis the composition and structural effect on the properties of complex multicomponent glasses can be elucidated, thus suggesting that this is a promising approach for future glass research and new composition design.
Carbohydrate-Containing Conjugated Polymers: Solvent-Resistant Materials for Greener Organic Electronics
Organic semiconducting polymers are exciting materials for electronic applications because of their good mechanical and optoelectronic properties. A major advantage of organic semiconductors is their solution processability. This allows access to a variety of simple and cost-effective device fabrication methods compared to the expensive, high-temperature processing methods required for silicon-based electronics. However, these materials often have low solubility, which limits their processing to toxic halogenated solvents. Also, their limited solubility often leads to interfacial mixing during device fabrication. Herein, this work explores the incorporation of environmentally friendly carbohydrate side chains in conjugated polymers to enhance processability in eco-friendly solvents. Moreover, a mild postprocessing treatment was designed to enable solvent resistance. Isoindigo-based polymers with varied ratios of acetyl-protected galactose side chains were synthesized to improve solubility in o-anisole in the protected state, while inducing solvent resistance through intramolecular hydrogen bonding in the deprotected state. Solvent resistance was confirmed both visually upon submersion in various solvents and using UV–visible spectroscopy. Importantly, the mild basic treatment to achieve solvent resistance has no negative impact on the electronic performance of these materials in organic field-effect transistors, even after subsequent submersion in various solvents, making them a valuable platform for the production of green processable multilayer electronics.
Gas-Phase Dimerization of Ethylene under Mild Conditions Catalyzed by MOF Materials Containing (bpy)Ni II Complexes
NU-1000-(bpy)Ni II , a highly porous MOF material possessing well-defined (bpy)Ni II moieties, was prepared through solvent-assisted ligand incorporation (SALI). Treatment with Et 2 AlCl affords a single-site catalyst with excellent catalytic activity for ethylene dimerization (intrinsic activity for butenes that is up to an order of magnitude higher than the corresponding (bpy)NiCl 2 homogeneous analogue) and stability (can be reused at least three times). The high porosity of this catalyst results in outstanding levels of activity at ambient temperature in gas-phase ethylene dimerization reactions, both under batch and continuous flow conditions.
Structure of a Dinuclear Iron Cluster-Containing [beta]-Hydroxylase Active in Antibiotic Biosynthesis
Abstract not provided
Investigation of High-Pressure and Temperature Behavior of Surfactant-Containing Periodic Mesostructured Silicas
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CuPYDC metalloligands and postsynthetic rearrangement/metalation as routes to bimetallic uranyl containing hybrid materials: Syntheses, structures, and fluorescence
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Structural Origin of Overcharge-induced Thermal Instability of Ni-containing Layered-cathodes for High-energy-density Lithium Batteries
Using a combination of time-resolved X-ray diffraction (XRD), in situ transmission electron microscopy (TEM), and first principles calculations, we explore the structural origin of the overcharge induced thermal instability of two cathode materials, LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} and LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2}, which exhibit significant difference in thermal stabilities. Detailed TEM analysis reveals, for the first time, a complex core-shell-surface structure of the particles in both materials that was not previously detected by XRD. Structural comparison indicates that the overcharged Li{sub x}Ni{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} (x < 0.15) particles consist of a rhombohedral core, a spinel shell, and a rock-salt structure at the surface, while the overcharged LixNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} consists of a similar core-shell-surface structure but a very different CdI{sub 2}-type surface structure. The thermal instability of LixNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} can be attributed to the release of oxygen because of the rapid growth of the rock-salt-type structure on the surface during heating. In contrast, the CdI{sub 2}-type surface structure of the overcharged LixNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} particles delays the oxygen-release reaction to a much higher temperature resulting in better stability. These results gave deep insight into the relationship between the local structural changes and the thermal stability of cathode materials, which is vital to the development of new cathode materials for the next generation of lithium-ion batteries.
Synthesis and Characterization of a Plasmonic-Semiconductor Composite Containing Rationally Designed, Optically Tunable Gold Nanorod Dimers and Anatase TiO2
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Time resolved assembly of chiral uranyl peroxo cage clusters containing belts of polyhedra
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Synthesis, Structure, and Reactivity of Iridium(III) Complexes Containing a 4,6-Dimethyl-1,3-benzenediphenylimine Pincer Ligand
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