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All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Hydrogen Localization and Cluster Formation in α-Zr from First-Principles Investigations

We report alpha-zirconium (α-Zr) is a hydrogen atom host material used in nuclear energy and semiconducting applications due to Zr's excellent properties such as corrosion resistance, low thermal neutrons cross-section, and thermodynamically favorable interstitial sequestering of H atoms. Herein we use density functional theory simulations to systematically analyze the initial stages of H insertion in the Zr matrix, and determine optimal hydrogen localization, distribution, and clustering tendencies from a thermodynamics and kinetics perspective. Our results suggest that H occupation of tetrahedral sites is strongly favored, consistent with previous experimental and theoretical studies. Further, a cooperative effect in H localization is shown where H atoms favor clustering. The H pair is found to be the most stable by occupying tetrahedral sites with pairs at second nearest-neighbor positions (TTn2). Among the four H atom clusters, the most favorable configuration has two TTn2 pairs forming "box " or "zig-zag" shaped-cluster with the pairs separated by 3.03 or 3.25 Å, respectively. Nudged elastic band simulations suggest that the formation of TTn2 is facile and is limited by the small diffusion barrier of the monomer of less than 0.1 eV. Further, the formation routes for the 4H atom clusters are also presented. The current study can serve as a foundation to systematically model H atom clustering in metals and alloys.

36 MATERIALS SCIENCE↗
NASA NTRS2022

Research Report: Progress on Building a File Observatory for Secure Parser Development

Parsing untrusted data is notoriously challenging.Failure to handle maliciously crafted data correctly can (anddoes) lead to a wide range of vulnerabilities. The Languagetheoretic security (LangSec) philosophy seeks to obviate the needfor developers to apply ad hoc solutions by, instead, offeringformally correct and verifiable input handling throughout thesoftware development lifecycle. One of the key components indeveloping secure parsers is a broad coverage corpus that enablesdevelopers to understand the problem space for a given formatand to use, potentially, as seeds for fuzzing and other automatedtesting. In this paper, we offer an update on work reportedat the LangSec 2021 conference on the development of a fileobservatory to gather and enable analysis on a diverse collectionof files at scale. The initial focus of the observatory is on PortableDocument Format (PDF) files and file formats typically embeddedin PDFs. In this paper, we report on refactoring the ingestprocess, applying new analytic methods, and improving the User Interface.

Stonebraker, Ryan↗
NASA NTRS2012

A Massive, Cooling-Flow-Induced Starburst in the Core of a Highly Luminous Galaxy Cluster

In the cores of some galaxy clusters the hot intracluster plasma is dense enough that it should cool radiatively in the cluster s lifetime, leading to continuous "cooling flows" of gas sinking towards the cluster center, yet no such cooling flow has been observed. The low observed star formation rates and cool gas masses for these "cool core" clusters suggest that much of the cooling must be offset by astrophysical feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical, and infrared observations of the galaxy cluster SPT-CLJ2344-4243 at z = 0.596. These observations reveal an exceptionally luminous (L(sub 2-10 keV) = 8.2 10(exp 45) erg/s) galaxy cluster which hosts an extremely strong cooling flow (M(sub cool) = 3820 +/- 530 Stellar Mass/yr). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (740 +/- 160 Stellar Mass/ yr), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form via accretion of the intracluster medium, rather than the current picture of central galaxies assembling entirely via mergers.

McDonald, M.↗
DOE OSTI2024

Concepts for Actinide Recovery from TRISO Used Nuclear Fuel

The work described in this report has developed a preliminary conceptual flowsheet based on limited published literature for the head-end of a TRISO oxycarbide UNF reprocessing plant. The essential function of the head-end is to prepare the UNF for subsequent separation of actinides. The main steps of the conceptual TRISO UNF head-end reprocessing flowsheet are: 1. Fragmentation of the graphite moderator to expose the fuel particles. 2. Separation of fuel particles from fragmented graphite moderator by sieving and fluidization. 3. Fragmentation of the fuel particles to expose the fuel kernel. 4. Dissolution of the fuel kernel in nitric acid. Noteworthy at this step is the formation of organic acids (mainly oxalic and mellitic acids) from the carbon associated with the fuel and TRISO coatings. These acids can interfere with actinide separations and solvent extraction hydraulic performance and carbon dioxide gas generation. 5. Clarification of the dissolved fuel solution to separate the coating fragments. 6. Dissolver off-gas treatment with specific emphasis on managing generation of carbon dioxide gas containing carbon-14. The quantity of carbon dioxide is projected to be 100 to 1000 times greater than that arising from dissolving LWR UNF. Pre or post treatment of the exposed fuel kernels could be undertaken to mitigate the formation of organic acids but there still exists a significant off-gas treatment challenge. The literature on reprocessing uranium nitride UNF was reviewed but a flowsheet was not specifically developed since its scope and uncertainties are expected to be encompassed by the oxycarbide flowsheet. Overall, the predominant feature of processing TRISO UNF is carbon management to reduce waste volume and mitigate the formation of carbon dioxide and organic acids. This report recommends broad areas of research that will help to further define the head-end flowsheet.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2026

Catalytic Ambient Temperature Dinitrogen Conversion to a Bis(silyl)amine by Mononuclear Group 4 Aryloxide Complexes

The homogeneous conversion of ambient dinitrogen to amine products via the N2 reduction reaction (N2RR) remains a prized yet challenging feat for d-block complexes and is scarcely reported for f-block complexes. New, mononuclear TiIV and ZrIV aryloxide complexes Ti(DP)2 (1Ti), Zr(DP)2 (1Zr), and DP = [2-(OC6H2-2-tBu,4-Me)2CHPh] produce up to 51 eq. and up to 7.0 eq. of HN(SiMe3)2 per Ti/Zr, from N2, K0, weak acid, and chlorotrimethylsilane. Complex 1Ti exhibits more than double the activity toward N2-silylation of any previously reported Ti N2RR catalyst and can also catalyze the formation of up to 19 eq. of NH3, a new feature in early metal N2RR chemistry. The mononuclear 1Zr is the most active Zr catalyst for N2-silylation to date. [KSm(DP)2(THF)3] (1Sm), the mononuclear analogue of our previously reported dinuclear A-Sm complex, displays only stoichiometric N2-silylation due to its vulnerability to deleterious side reactions. DFT calculations confirm the catalysis can proceed via a monomeric Ti complex with a terminally bound, activated N2, agreeing with experimental 1H DOSY NMR measurements; the N-H bond is formed first, directing the catalyst selectivity. The isolable reduction product [K3(THF)Ti(DP)(DP-)(N2)] is also an active catalyst, and an intermediate in the calculated cycle.

Hernandez, Matthew↗
NASA NTRS1995

Large-Scale Structure of Magnetospheric Plasma

Recent investigations of magnetospheric plasma structure are summarized under the broad categories of empirical models, transport across boundaries, formation, and dynamics of the plasma sheet. This report reviews work in these areas during the period 1991 to 1993. Fully three-dimensional empirical models and simulations have become important contributors to our understanding of the magnetospheric system. Some new structural concepts have appeared in the literature: the 'entry boundary' and 'geo-pause', the plasma sheet 'region 1 vortices', the 'low-energy layer', the 'adia-baticity boundary' or 'wall region', and a region in the tail to which we refer as the 'injection port'. Traditional structural concepts have also been the subject of recent study, notably the plasmapause, the magnetopause, and the plasma sheet. Significant progress has been made in understanding the nature of plasma sheet formation and dynamics, but the acceleration of electrons to high energy remains somewhat mysterious.

Moore, T. E.↗
NASA NTRSDate not supplied

Blast from the Past: ASDC Curation for NASA Suborbital Legacy Missions to Promote Data Discovery and Accessibility

NASA has an extensive history of conducting suborbital field campaigns to further advances in atmospheric sciences. Beginning with the Chemical Instrument Test and Evaluation (CITE) conducted in 1983-1984, NASA has completed many suborbital campaigns over the past three decades. Since the early 2010s, suborbital missions are typically assigned to a NASA Distributed Active Archive Center (DAAC) prior to the mission for long-term archival and distribution. Efforts are being made by NASA’s Earth Science Data and Information System (ESDIS) Project and the Airborne Data Management Group (ADMG) to assign legacy missions to DAACs for permanent archival and distribution, so that these valuable datasets remain to be available to the scientific community. NASA’s Atmospheric Science Data Center (ASDC) has been named the assigned DAAC for nearly 20 atmospheric composition legacy missions, including missions conducted as part of the Global Tropospheric Experiment (GTE) and expects to be named the assigned DAAC for more of these missions over the next few years. The primary goal of the ASDC is to provide access to the datasets as they are currently formatted to the broad user community and enhance their findability and accessibility. However, data reporting standards have evolved significantly since 1983 and the datasets span a wide variety of file formats, including text, Ames, GTE, and ICARTT (International Consortium for Atmospheric Research on Transport and Transformation), and the amount of metadata and relevant information included in the files also varies greatly and can not be readily extracted without subject matter knowledge. This has caused challenges for the ASDC’s suborbital metadata extraction pipeline in ensuring that accurate and necessary metadata is being provided for the missions by all the ASDC’s existing search mechanisms. To make the data more findable and accessible, the ASDC has begun researching ways to further enhance the datasets, including distributing value-added products (i.e. consistent file format such as ICARTT or netCDF), adding standard names from the ESDIS Standards Coordination Office (ESCO)-approved Atmospheric Composition Variable Standard Names Convention (ACVSNC), and creating outreach materials such as ArcGIS StoryMaps, User Guides, and Micro Articles, providing overviews of the missions and what type of data was collected during the missions. These efforts also help support NASA’s Open-Source Science by enhancing the FAIRness of the legacy data products. This presentation will review the ASDC’s ongoing efforts, progress made, and future plans for legacy missions.

Megan Buzanowicz↗
NASA NTRS2017

The Formation of Nucleobases from the UV Irradiation of Astrophysical Ice Analogs

Nucleobases are the fundamental information bearing components of both RNA and DNA. They are central to all known terrestrial life and they are generally conserved between species. Biological nucleobases can be divided into two groups based on the N-heterocyclic molecules pyrimidine (uracil, cytosine, and thymine) and purine (adenine and guanine) respectively. Do date, no experimental conditions have been determined that could produce both pyrimidines and purines together, abiotically, in a ter-restrial environment or an early terrestrial analog. Organic materials produced in extraterrestrial envi-ronments may have been delivered to the primitive earth by comets and meteorites and may have contrib-uted to the emergence of life. To date, some, but not all nucleobases have been detected in meteorites and their isotopic signatures may be consistent with an extraterrestrial origin. Earlier work in our lab demonstrated that it is possible to produce all of the pyrimidine group nucleobases from the UV-irradiation of pyrimidine in astrophysically relevant ice analogs. Here we report our most recent work, which studied the formation of the purine group nucleobases under similar conditions.

Astrophysical Ice↗
NASA NTRS2012

In Situ Carbon and Sulfur Isotope Analysis of Archean Organic Matter and Pyrite

Stable isotopic compositions of biologically important elements (e.g., C and S) in sedimentary rocks are valuable biosignatures to the extent that they indicate the presence and variable expression of microbial metabolisms in space and time. Strong interactions between the carbon and sulfur cycles (e.g., via organic matter remineralization during microbial sulfate reduction) make coordinated, in situ C and S isotope analysis by secondary ion mass spectrometry (SIMS) a particularly powerful tool. In rocks ranging in age from 2.7-2.5 Ga, expansions in the ranges of delta C-13 of organic matter and delta S-34 of pyrite likely reflect the increasing influence of oxygenic photosynthesis in the surface ocean (as well as methane and sulfur metabolisms in deeper waters), whereas the large range of mass independent sulfur isotope fractionation (Delta S-33) suggests that the atmosphere remained anoxic until approx 2.4 Gyr ago. We report in situ delta C-13 measurements of organic matter in the approx 2.7-2.6 Ga Carawine Dolomite, Marra Mamba Iron Formation, and Jeerinah, Wittenoom, and Tumbiana Formations, as well as the approx 2.5 Ga Mount McRae Shale. We also report in situ delta S-24 and Delta S-33 measurements of pyrite associated with organic matter in a subset of these samples. In a single square cm sample of the Tumbiana Formation with bulk delta C-13(sub org) of -49.7% (VPDB), two distinct kerogen types have delta C-13 values, measured in situ, consistent with oxygenic photosynthesis (-33%) and methane metabolism (-52%). In a sample from the ABDP-9 core, radiobitumen associated with a uraniferous mineral grain is C-13-enriched by 8% (-26.8%0) relative to average in situ kerogen (-34.9%0) and similar in delta C-13 to solvent extractable hydrocarbons from the Mount McRae Shale (avg delta C-13 = -27.1 %). Average reproducibility for delta C-13 was 0.4% (2 SD) using a 6 micron spot and 0.8% using a 3 micron spot. In situ sulfur isotope analyses of 33 authigenic pyrite grains in 3 samples of the ABDP-9 core using a 10 micron spot (2 SD reproducibility = 0.4% for delta S-34 and -0.1% for Delta S-33) show a range of 28.1 % in delta S-34 (-10.3 to 17.8%) and 13.3%0 in Delta S-33 (-3.8 to 9.5%), whereas the range from 132 bulk analyses across 84 m of core is 19.4% for delta S-34 and 11.5% for Delta S-33. Coordinated, in situ carbon and sulfur isotope analyses in one ABDP-9 sample are shown. In situ values from this kerogen-pyrite association are within 0.1% of the bulk value in the case of delta C-13 and higher by several permil in the case of delta S-34 and Delta S-33. Coordinated in situ carbon and sulfur isotope analyses in rocks deposited during key intervals of environmental change (e.g., the Great Oxidation Event) can refine our understanding of the mode and tempo of change. In Earth's oldest sedimentary rocks, and in extraterrestrial samples, these coordinated in situ analyses may reveal biosignatures in the form of isotopic correlations at the scale of individual microorganisms and their microhabitats.

Williford, K. H.↗
DOE OSTI2025

Synthesis challenges, thermodynamic stability, and growth kinetics of La–Si–P ternary compounds

Although many new compounds have been recently predicted with the help of machine learning, the successful experimental synthesis of these compounds remains challenging. Computational insights about the thermodynamic stability and phase formation kinetics among the ground state and competing metastable phases are highly desirable to rationalize and attempt to overcome synthesis challenges experimentally. In this work, we explore synthetic challenges within ternary La–Si–P compounds through feedback between experimental and computational studies. We discuss the experimental challenges in forming three computationally predicted ternary phases (La 2 SiP, La 5 SiP 3 , and La 2 SiP 3 ). To understand the synthetic challenges, we performed molecular dynamics (MD) simulations using an accurate and efficient artificial neural network machine learning (ANN-ML) interatomic potential. We study the phase stability and formation kinetics of these ternary phases in relation to the reported and synthesized La 2 SiP 4 phase. While the growth of the La 2 SiP 4 phase can be reproduced by our MD simulation, our results indicate that the rapid formation of a Si-substituted LaP crystalline phase is a major barrier to the synthesis of the predicted La 2 SiP, La 5 SiP 3 , and La 2 SiP 3 ternary compounds, agreeing well with experimental observations. Our simulations also suggest that there is a narrow temperature window in which the La 2 SiP 3 phase can be grown from the solid–liquid interface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Computed Tomography Scanning and Petrophysical Measurements of the Wellington KGS 2-32 Core

This report describes the use of the computed tomography facilities and the Multi-Sensor Core Logger at the National Energy Technology Laboratory in Morgantown, West Virginia to characterize core from the Wellington KGS 2-32 well (API 15-191-22770). Core from the well was obtained as part of the Small-Scale Field Test Demonstrating Carbon Dioxide Sequestration in Arbuckle Saline Aquifer and by CO 2 -Enhanced Oil Recovery at Wellington Field, Sumner County, Kansas (DE-FE0006821). The primary impetus of this work was to capture a detailed a digital representation of the core from the Wellington KGS 2-32 well (Sumner County, Kansas). The collaboration between the U.S. Department of Energy’s (DOE) NETL and the Kansas Geological Survey (KGS) at the University of Kansas enables other research entities to access information about this potential carbon storage location and formations. The resultant datasets are presented in this report and can be accessed from NETL's Energy Data eXchange (EDX) online system using the following link: https://edx.netl.doe.gov/dataset/wellington2-32-core.

47 OTHER INSTRUMENTATION↗
NASA NTRS2003

Preliminary Assessment Of The Burning Dynamics Of Jp8 Droplets In Microgravity

In this report we present new data for fuel droplet combustion in microgravity to examine the influence of ambient gas and fuel composition on flame structure and sooting dynamics for droplets with initial diameters in the range of 0.4mm to 0.5mm. The fuels are JP8 (a kerosene derivative) and nonane. The ambient gas is air and a mixture of 30% oxygen and 70% helium, the latter having been examined for burning under conditions where soot formation is minimal. Some data at elevated pressures are also reported. The burning process shows a nonlinear D2 progression which is independent of soot formation as burning in a helium inert showed the same nonlinear trend. Flames were proportionally farther from the droplet surface in helium than they were in air. A nondimensional parameter is presented that consolidates the three standoff distances for the droplet, flame and soot shell diameters within the initial diameter ranges examined.

Bae, J. H.↗
DOE OSTI2026

Ionic Precursors Transformed Into Vinyl Acetate Synthesis Catalyst via Reaction-Driven Restructuring

Conventional preparation of supported bimetallic catalysts relies on solution-mediated metal salt immobilization and pre-formation of alloy nanoparticles before reaction. Here, we report a fundamentally different synthesis strategy of using a physical mixture of salt precursors to generate an active catalyst during reaction. The catalytic structure is generated in situ from Pd3(OAc)6, Au(OH)3, and KOAc through H2 treatment and reaction-driven restructuring under vinyl acetate monomer (VAM) synthesis conditions. Ascertained from in situ X-ray diffraction and operando infrared spectroscopy analyses, reduction treatment produces segregated Pd and Au domains, and subsequent exposure to a VAM reaction mixture triggers dynamic extraction of Pd from the metal surface. This latter process, mediated by acetate-assisted redox cycles, facilitates Pd migration toward Au domains to form a near-surface localized Pd50Au50 alloy phase. Monometallic Pd domains serve as a reservoir of Pd to the alloy phase, leading to and sustaining a more Pd-enriched active surface and a higher population of accessible Pd sites, compared to a conventionally prepared K-PdAu/SiO2 catalyst. Consequently, this leads to a twofold increase in the VAM formation rate, demonstrating highly active bimetallic catalysts can be generated through the gas-phase treatment of physically mixed ionic precursors.

Cha, Byeong Jun [Rice University]↗
DOE OSTI2023

SPRUCE Peat Mercury, Methylmercury and Sulfur Concentrations from Experimental Plot Cores, 2012

This data set reports the results of analyses of peat core samples for total mercury and methylmercury, as well as carbon, nitrogen and sulfur. Samples were collected as part of a larger sampling campaign from the SPRUCE experimental study plots located in the S1-Bog. From 2012-08-13 to 2012-10-15, a team of SPRUCE investigators and collaborators collected core samples of peat in the SPRUCE experimental plots. The goal was to characterize the biological, physical, and chemical characteristics of peat, and how those characteristics changed throughout the depth profile of the bog, prior to the initialization of the SPRUCE experimental warming and CO2 treatments. Cores were collected from 16 experimental plots; peat cores were collected from the hummock and hollow surfaces to depths of 300 cm in 10 cm, 25, and 50 cm increments (Pierce et al, 2022). Three replicate cores were collected from both hummock and hollow locations in each plot. The coring locations within each plot were mapped. This dataset contains one file in comma separated (*.csv) format. User Note: The coring descriptions and some reported data are the same as in the related data set, Iverson et al. (2014). Samples for mercury and carbon, nitrogen and sulfur analyses by the University of Minnesota were collected as part of this sampling campaign.

54 ENVIRONMENTAL SCIENCES↗