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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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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Sr(SnAs)2 by Materials Project

Sr(SnAs)2 crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three Sr(SnAs)2 sheets oriented in the (0, 0, 1) direction. Sr2+ is bonded to six equivalent As3- atoms to form edge-sharing SrAs6 octahedra. All Sr–As bond lengths are 3.17 Å. Sn2+ is bonded in a distorted trigonal non-coplanar geometry to three equivalent As3- atoms. All Sn–As bond lengths are 2.83 Å. As3- is bonded to three equivalent Sr2+ and three equivalent Sn2+ atoms to form a mixture of edge and corner-sharing AsSr3Sn3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(SnAs)2 by Materials Project

Na(SnAs)2 crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three Na(SnAs)2 sheets oriented in the (0, 0, 1) direction. Na1+ is bonded to six equivalent As3- atoms to form edge-sharing NaAs6 octahedra. All Na–As bond lengths are 3.14 Å. Sn+2.50+ is bonded in a distorted T-shaped geometry to three equivalent As3- atoms. All Sn–As bond lengths are 2.72 Å. As3- is bonded to three equivalent Na1+ and three equivalent Sn+2.50+ atoms to form a mixture of corner and edge-sharing AsNa3Sn3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnAs by Materials Project

SnAs is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Sn3+ is bonded to six equivalent As3- atoms to form a mixture of corner and edge-sharing SnAs6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Sn–As bond lengths are 2.90 Å. As3- is bonded to six equivalent Sn3+ atoms to form a mixture of corner and edge-sharing AsSn6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Spectral evidence of solar neighborhood analogs in CALIFA galaxies

We introduce a novel nonparametric method to find solar neighborhood analogs (SNAs) in extragalactic integral field spectroscopic surveys. The main ansatz is that the physical properties of the solar neighborhood (SN) should be encoded in its optical stellar spectrum. We assume that our best estimate of such a spectrum is the one extracted from the analysis performed by the Code for Stellar properties Heuristic Assignment (CoSHA) from the MaStar stellar library. It follows that finding SNAs in other galaxies consist in matching, in a χ 2 sense, the SN reference spectrum across the optical extent of the observed galaxies. We applied this procedure to a selection of CALIFA galaxies, by requiring a close to face-on projection, relative isolation, and non-active galactic nucleus. We explore how the local and global properties of the SNAs (stellar age, metallicity, dust extinction, mass-to-light ratio, stellar surface mass density, star-formation density, and galactocentric distance) and their corresponding host galaxies (morphological type, total stellar mass, star-formation rate, and effective radius) compared with those of the SN and the Milky Way (MW). We find that SNAs are located preferentially in S(B)a–S(B)c galaxies, in a ring-like structure, which radii seem to scale with the galaxy size. Despite the known sources of systematics and errors, most properties present a considerable agreement with the literature on the SN. We conclude that the solar neighborhood is relatively common in our sample of SNAs. Our results warrant a systematic exploration of correlations among the physical properties of the SNAs and their host galaxies. We reckon that our method should inform current models of the galactic habitable zone in our MW and other galaxies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

A first-in-human phase 0 clinical study of RNA interference–based spherical nucleic acids in patients with recurrent glioblastoma

Glioblastoma (GBM) is one of the most difficult cancers to effectively treat, in part because of the lack of precision therapies and limited therapeutic access to intracranial tumor sites due to the presence of the blood-brain and blood-tumor barriers. We have developed a precision medicine approach for GBM treatment that involves the use of brain-penetrant RNA interference–based spherical nucleic acids (SNAs), which consist of gold nanoparticle cores covalently conjugated with radially oriented and densely packed small interfering RNA (siRNA) oligonucleotides. On the basis of previous preclinical evaluation, we conducted toxicology and toxicokinetic studies in nonhuman primates and a single-arm, open-label phase 0 first-in-human trial ( NCT03020017 ) to determine safety, pharmacokinetics, intratumoral accumulation and gene-suppressive activity of systemically administered SNAs carrying siRNA specific for the GBM oncogene Bcl2Like12 (Bcl2L12). Patients with recurrent GBM were treated with intravenous administration of siBcl2L12-SNAs (drug moniker: NU-0129), at a dose corresponding to 1/50th of the no-observed-adverse-event level, followed by tumor resection. Safety assessment revealed no grade 4 or 5 treatment–related toxicities. Inductively coupled plasma mass spectrometry, x-ray fluorescence microscopy, and silver staining of resected GBM tissue demonstrated that intravenously administered SNAs reached patient tumors, with gold enrichment observed in the tumor-associated endothelium, macrophages, and tumor cells. NU-0129 uptake into glioma cells correlated with a reduction in tumor-associated Bcl2L12 protein expression, as indicated by comparison of matched primary tumor and NU-0129–treated recurrent tumor. Our results establish SNA nanoconjugates as a potential brain-penetrant precision medicine approach for the systemic treatment of GBM.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Materials Data on SnAs3 by Materials Project

SnAs(As)2 is alpha Niobium phosphide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two As sheets oriented in the (0, 0, 1) direction and two SnAs sheets oriented in the (0, 0, 1) direction. In each As sheet, As+1.33- is bonded in a square co-planar geometry to four equivalent As+1.33- atoms. All As–As bond lengths are 2.80 Å. In each SnAs sheet, Sn4+ is bonded in a square co-planar geometry to four equivalent As+1.33- atoms. All Sn–As bond lengths are 2.80 Å. As+1.33- is bonded in a square co-planar geometry to four equivalent Sn4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Observation of surface ferromagnons in the axion-insulating phase of the antiferromagnetic topological insulator EuSn 2⁢ As 2

We report the study of spin dynamics of Eu 2+ in the antiferromagnetic axion topological insulator EuSn 2 ⁢As 2 by means of antiferromagnetic resonance at 9.34 GHz. Below the Néel temperature (𝑇 N ), two types of resonance modes, the conventional bulk antiferromagnetic resonance and additional surface ferromagnetic resonance, are observed. The latter turns out to be characteristic of the axion-insulating phase. Above 𝑇 N , we prove the existence of a Kosterlitz-Thouless scenario that is relevant for the spin relaxation in the Eu 2+ layers. The absence of Korringa relaxation indicates the strong confinement of the conduction electrons at the Fermi level to the SnAs layers.

Antiferromagnets↗
NASA NTRS2014

External Dependencies-Driven Architecture Discovery and Analysis of Implemented Systems

A method for architecture discovery and analysis of implemented systems (AIS) is disclosed. The premise of the method is that architecture decisions are inspired and influenced by the external entities that the software system makes use of. Examples of such external entities are COTS components, frameworks, and ultimately even the programming language itself and its libraries. Traces of these architecture decisions can thus be found in the implemented software and is manifested in the way software systems use such external entities. While this fact is often ignored in contemporary reverse engineering methods, the AIS method actively leverages and makes use of the dependencies to external entities as a starting point for the architecture discovery. The AIS method is demonstrated using the NASA's Space Network Access System (SNAS). The results show that, with abundant evidence, the method offers reusable and repeatable guidelines for discovering the architecture and locating potential risks (e.g. low testability, decreased performance) that are hidden deep in the implementation. The analysis is conducted by using external dependencies to identify, classify and review a minimal set of key source code files. Given the benefits of analyzing external dependencies as a way to discover architectures, it is argued that external dependencies deserve to be treated as first-class citizens during reverse engineering. The current structure of a knowledge base of external entities and analysis questions with strategies for getting answers is also discussed.

Ganesan, Dharmalingam↗