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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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At least 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

In Situ TEM Study of Radiation Resistance of Metallic Glass–Metal Core–Shell Nanocubes

Radiation damage can cause significantly more surface damage in metallic nanostructures than bulk materials. Structural changes from displacement damage compromise the performance of nanostructures in radiation environments such as nuclear reactors and outer space, or used in radiation therapy for biomedical treatments. As such, it is important to develop strategies to prevent this from occurring if nanostructures are to be incorporated into these applications. In this work, in situ transmission electron microscope ion irradiation was used to investigate whether a metallic glass (MG) coating mitigates sputtering and morphological changes in metallic nanostructures. Dislocation-free Au nanocubes and Au nanocubes coated with a Ni–B MG were bombarded with 2.8 MeV Au 4+ ions. The formation of internal defects in bare Au nanocubes was observed at a fluence of 7.5 × 10 11 ions/cm 2 (0.008 dpa), and morphological changes such as surface roughening, rounding of corners, and formation of nanofilaments began at 4 × 10 12 ions/cm 2 (0.04 dpa). In contrast, the Ni–B MG-coated Au nanocubes (Au@NiB) showed minimal morphological changes at a fluence of 1.9 × 10 13 ions/cm 2 (0.2 dpa). Finally, the MG coating maintains its amorphous nature under all irradiation conditions investigated.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Primary biomolecular adsorption energetics of core–shell nanocomplexes: Implications for biological interactions

Molecular organization at the nano-bio interface governing the colloidal stability, reactivity, immune recognition, and drug delivery performance of nanoparticles remains difficult to predict. Quantifying the primary hydration energetics of biomolecule-coated nanomaterials can determine those interactions and provide a basis for engineered nanocarriers with tailored behavior in biological systems. Here, we measured the thermodynamics of water adsorption on patchy dry magnetite (Fe 3 O 4 ) nanoparticles coated with three model biomolecules, bovine serum albumin, potato starch, and lauric acid and compared these properties to the hydration energetics of the corresponding free dry biomolecules. The results demonstrate how the surface functionalization alters the hydrophilicity, the accessible hydrophilic surface, and the interaction potential of the nanocomplex surface with biological media. The protein coating increases the interaction potential of the surface of the nanocomplex. The weaker interaction potential of the polysaccharide coating and the relatively large hydrophilic surface area allow dynamic and reversible binding, while the fatty acid rearranges into a partial bilayer with very strong hydrophilicity. The findings establish the hydration enthalpy as a quantitative basis to determine and interpret nanoparticle interactions with proteins, membranes, and biological fluids, and provide a thermodynamic foundation for designing nanocarriers with predictable biological reactivity.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Structure of Cl 38 and the quest for a comprehensive shell model interaction

The higher-spin structure of 38 Cl ($N=21$) was investigated following the 26 Mg( 14 C, $pn$) reaction at 30 and 37 MeV beam energies. The outgoing protons were detected in an $E-ΔE$ Si telescope placed at 0° close to the target with a Ta beam stopper between the target and telescope. Multiple $γ$ rays were detected in time coincidence with the protons using an enhanced version of the FSU $γ$-detection array. The level scheme was extended up to 8420 keV with a likely spin of 10 $ℏ$. A new multishell interaction was developed guided by the experimental information. This FSU interaction was built by fitting to the energies of 270 experimental states from 13 C to 51 Ti. Calculations using the FSU interaction reproduce observed properties of 38 Cl rather well, including the spectroscopic factors. The interaction has been successfully used to interpret the 1p1h and 2p2h configurations in some nearby nuclei as well.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Resonances of A = 4T = 1 isospin triplet states within the ab initio no-core Gamow shell model

Here, the A = 4 nuclei, i.e., 4 H, 4 He, and 4 Li , establish an interesting isospin T = 1 isobaric system. 4 H and 4 Li are unbound broad resonances, whereas 4 He is deeply bound in its ground state but unbound in all its excited states. The present situation is that experiments so far have not given consistent data on the resonances. Few-body calculations have well studied the scatterings of the 4N systems. In the present work, we provide many-body calculations of the broad resonance structures, in an ab initio framework with modern realistic interactions. It occurs that, indeed, 4 H, 4 Li, and excited 4 He are broad resonances, which is in accordance with experimental observations. The calculations also show that the first 1 - excited state almost degenerates with the 2 - ground state in the pair of mirror isobars of 4 H and 4 Li, which may suggest that the experimental data on energy and width are the mixture of the ground state and the first excited state. The T = 1 isospin triplet formed with an excited state of 4 He and ground states of 4 H and 4 Li is studied, focusing on the effect of isospin symmetry breaking.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Stability of Panels of a Thermoelastic Shell Heated at the Edge by a Mobile Point Source

The thermostability of thin-walled structures is considered by means of a thermoelasticity problem in a three-dimensional quasi-static formulation. Finite-element models of panels in the form of a circular cylinder and a plate reinforced by ribs are constructed. Numerical solutions are obtained for the stability loss of thermoelastic thin-walled reinforced structures with intense edge heating by a mobile heat source.

42 ENGINEERING↗
DOE OSTI2018

Nanodiamond‐Palladium Core–Shell Organohybrid Synthesis: A Mild Vapor‐Phase Procedure Enabling Nanolayering Metal onto Functionalized sp 3 ‐Carbon

Abstract A novel approach for the bottom‐up construction of hybrid organic–inorganic nanocomposites with an intimate arrangement between sp 3 ‐carbon 3D molecular‐size nanodiamonds (diamondoids) and a coated palladium surface as nanolayer is reported. The construction process is conducted stepwisely from the gas phase, using first controlled vapor‐phase self‐assembly of tailor‐made functionalized diamantane derivatives, followed by low‐temperature (45 °C) chemical vapor deposition of an organometallic complex in a reducing H 2 atmosphere over the self‐assembled diamondoid scaffold. The use of self‐assemblies of primary diamantane phosphine and phosphine oxide, which are produced with high structural uniformity and reproducibility, yields new hybrid diamondoid‐palladium materials incorporating PdOPHdiamantane bonding motifs. Additional investigations provide evidence for a very challenging issue in the intimate construction of sp 3 ‐C/metal scaffolds. Scanning electron microscopy and transmission electron microscopy microscopies combined with X‐ray photoelectron spectroscopy surface analysis and EDX bulk analysis confirm the formation of diamondoid‐palladium organohybrids with unique surface layering. The vapor phase‐controlled mild synthetic process allows excellent control over nanocomposite formation and morphology from molecular‐level modifications. As such, this bottom‐up composite building process bridges scales from the molecular (functionalized diamondoids) over nanoscopic (self‐assemblies) to microscopic regime (hybrids), in the challenging association of transition metals with an electronically saturated sp 3 ‐carbon organic host material.

Gunawan, Maria A.↗