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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Generation of Subauroral Longitudinally Extended Emissions Following Intensifications of the Poleward Boundary of the Substorm Bulge and Streamer Production

Observations showing the development of Subauroral Longitudinally Extended Emigerssions on a global scale are presented. It is demonstrated that they occur as a separation of an east-west arc-like band of luminosity that detaches away from the equatorward edge of the auroral distribution following episodes of auroral streamer production. They persist for time intervals on the order of ~30 min and devolve into patchy disjointed segments before they fade. Emissions are seen in both 557.7 nm OI and 391.4 nm N + 2 1NG lines, and 630.0 nm emissions are often observed equatorward. The 391.4 nm emissions are typically weaker and fade away more quickly than the 557.7 nm emissions, suggesting that an auroral precipitation source is initially present but is rapidly depleted as the forms age. All cases are associated with enhanced Subauroral Polarization Stream (SAPS) flows, and one event shows clear association with large-scale Giant Undulations (GUs) and the formation of spur-like forms that fold equatorward under the main oval. A model is proposed for the production of subauroral longitudinally extended forms in which nonlinear growth of SAPS-induced surface waves on the plasmapause results in a disruption of the boundary. It is suggested that hot plasma of plasma sheet origin becomes entrained in the plasmasphere to produce transient precipitation-associated auroral emissions that may decay into STEVE emissions and that cold dense plasma from the plasmasphere becomes entrained onto open drift paths to feed long-lived drainage plumes. This process may occur quasi periodically during intense substorms and storm-time conditions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Clonality, local population structure, and gametophyte sex ratios in cryptic species of the Sphagnum magellanicum complex

Sphagnum (peatmoss) comprises a moss (Bryophyta) clade with approximately 300-500 species. The genus has unparalleled ecological importance because Sphagnum-dominated peatlands store almost a third of the terrestrial carbon pool and peatmosses engineer the formation and microtopography of peatlands. Genomic resources for Sphagnum are being actively expanded, but many aspects of their biology are still poorly known. Among these are the degree to which Sphagnum species reproduce asexually, and the relative frequencies of male and female gametophytes in these haploid-dominant plants. Here, we assess clonality and gametophyte sex ratios and test hypotheses about the local-scale distribution of clones and sexes in four North American species of the S. magellanicum complex. These four species are difficult to distinguish morphologically and are very closely related. We also assess microbial communities associated with Sphagnum host plant clones and sexes at two sites. 405 samples of the four species, representing 57 populations, were subjected to RADseq. Analyses of population structure and clonality based on the molecular data utilized both phylogenetic and phenetic approaches. Multi-locus genotypes (genets) were identified using the RADseq data. Sexes of sampled ramets were determined using a molecular approach that utilized coverage of loci on the sex chromosomes after the method was validated using a sample of plants that expressed sex phenotypically. Sex ratios were estimated for each species, and populations within species. Differences in fitness between genets was estimated as the numbers of ramets each genet comprised. Degree of clonality (numbers of genets/numbers of ramets [samples]) within species, among sites, and between gametophyte sexes were estimated. Sex ratios were estimated for each species, and populations within species. Sphagnum-associated microbial communities were assessed at two sites in relation to Sphagnum clonality and sex. All four species appear to engage in a mixture of sexual and asexual (clonal) reproduction. A single ramet represents most genets but 2-8 ramets were detected for some genets. Only one genet is represented by ramets in multiple populations; all other genets are restricted to a single population. Within populations ramets of individual genets are spatially clustered, suggesting limited dispersal even within peatlands. Sex ratios are male-biased in S. diabolicum but female-biased in the other three species, although significantly so only in S. divinum. Neither species nor males/females differ in levels of clonal propagation. At St. Regis Lake (NY) and Franklin Bog (VT), microbial community composition is strongly differentiated between the sites, but differences between species, genets, and sexes were not detected. Within S. divinum, however, female gametophytes harbored 2-3 times the number oi of microbial taxa as males. These four Sphagnum species all exhibit a similar reproductive patterns that result from a mixture of sexual and asexual reproduction. The spatial patterns of clonally replicated ramets of genets suggest that these species fall between the so-called phalanx patterns where genets abut one another but do not extensively mix, because of limited ramet fragmentation, and the guerrilla patterns where extensive genet fragmentation and dispersal results in greater mixing of different genets. Although sex ratios in bryophytes are most often female-biased, both male and female biases occur in this complex of closely related species. The association of far greater microbial diversity for female gametophytes in S. divinum, which has a female-biased sex ratio, suggests additional research to determine if levels of microbial diversity are consistently correlated with differing patterns of sex ratio biases.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Numerical Analysis of Fuel Effects on Advanced Compression Ignition Using a Cooperative Fuel Research Engine Computational Fluid Dynamics Model

Growing environmental concerns and demand for a better fuel economy are driving forces that motivate the research for more advanced engines. Multi-mode combustion strategies have gained attention for their potential to provide high thermal efficiency and low emissions for light-duty applications. These strategies target optimizing the engine performance by correlating different combustion modes to load operating conditions. The extension from boosted spark ignition (SI) mode at high loads to advanced compression ignition (ACI) mode at low loads can be achieved by increasing the compression ratio and utilizing intake air heating. Further, in order to enable an accurate control of intake charge condition for ACI mode and rapid mode-switches, it is essential to gain fundamental insights into the autoignition process. Within the scope of ACI, homogeneous charge compression ignition (HCCI) mode is of significant interest. It is known for its potential benefits, operation at low fuel consumption, low NOx, and particulate matter (PM) emissions. In the present work, a virtual Cooperative Fuel Research (CFR) engine model is used to analyze fuel effects on ACI combustion. In particular, the effect of fuel octane sensitivity (S) (at constant Research Octane Number (RON)) on autoignition propensity is assessed under beyond-RON (BRON) and beyond-MON (BMON) ACI conditions. The three-dimensional CFR engine computational fluid dynamics (CFD) model employs a finite-rate chemistry approach with a multi-zone binning strategy to capture autoignition. Two binary blends with Research Octane Number (RON) of 90 are chosen for this study: primary reference fuel (PRF) with S = 0 and toluene–heptane (TH) blend with S = 10.8, representing paraffinic and aromatic gasoline surrogates. Reduced mechanisms for these blends are generated from a detailed gasoline surrogate kinetic mechanism. Simulation results with the reduced mechanisms are validated against experimental data from an in-house CFR engine, with respect to in-cylinder pressure, heat release rate, and combustion phasing. Thereafter, the sensitivity of combustion behavior to ACI operating condition (BRON versus BMON), air-fuel ratio (λ = 2 and 3), and engine speed (600 and 900 rpm) is analyzed for both fuels. It is shown that the sensitivity of a fuel’s autoignition characteristics to λ and engine speed significantly differs at BRON and BMON conditions. Moreover, this sensitivity is found to vary among fuels, despite the same RON. It is also observed that the presence of low-temperature heat release (LTHR) under BRON condition leads to more sequential autoignition and longer combustion duration than BMON condition. Finally, the study indicates that the octane index (OI) fails to capture the trend in the variation of autoignition propensity with S under the BMON condition.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2022

Upward propagation of gigantic jets revealed by 3D radio and optical mapping

Occasionally, lightning will exit the top of a thunderstorm and connect to the lower edge of space, forming a gigantic jet. Here, we report on observations of a negative gigantic jet that transferred an extraordinary amount of charge between the troposphere and ionosphere (~300 C). It occurred in unusual circumstances, emerging from an area of weak convection. As the discharge ascended from the cloud top, tens of very high frequency (VHF) radio sources were detected from 22 to 45 km altitude, while simultaneous optical emissions (777.4 nm OI emitted from lightning leaders) remained near cloud top (15 to 20 km altitude). This implies that the high-altitude VHF sources were produced by streamers and the streamer discharge activity can extend all the way from near cloud top to the ionosphere. The simultaneous three-dimensional radio and optical data indicate that VHF lightning networks detect emissions from streamer corona rather than the leader channel, which has broad implications to lightning physics beyond that of gigantic jets.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Rethinking PCMI Failures Under Transient Conditions

Under PCMI conditions, the cladding strain is driven by either pellet swelling during normal operation or pellet thermal expansion in transients. The loading in PCMI is displacement controlled because friction between the pellet and the cladding results in a strain compatibility at the pellet/cladding interface. Failure is known to occur under PCMI loading conditions during operation when normal power changes result in release of iodine (and other fission products) causing stress corrosion cracking where the crack-propagation rate is dependent upon the cladding stress but slow relative to strictly mechanical failures. Failures after normal power changes are often referred to as failure by pellet-cladding interaction or PCI to distinguish it from PCMI. Such failures are considered displacement-controlled failures, as noted above, and occur with limited plastic strain. This is different to what is typically thought of as PCMI failure under transient conditions, either Anticipated Operational Occurrences (AOOs) or Reactivity Insertion Accidents (RIAs), which is generally assumed to occur once the cladding reaches a mechanical strain limit. But there are two features in the typical PCMI failure in an RIA that are not consistent with the PCMI assumptions. The first is the ductile shear failure feature in cross section and the second is a large crack opening post failure (e.g., see OI-11 failure in NSRR program). The ductile feature is indicative of a plastic instability that requires very large local strains, and the large crack opening must be the result of a release of energy, both of which are not expected if stress in the cladding was only driven by thermal expansion in the pellet. It is concluded that there must be a mechanism (likely related to rod internal pressure) that eliminates strain compatibility between the pellet and cladding – allowing strain localization to occur in what are known as PCMI transient failures. In some sense, these PCMI failures may actually be early burst failures that occur when thermal expansion causes uniform strains greater than a defined limit and fission gas pressure eliminate the strain compatibility

Cantonwine, Paul↗
DOE OSTI2021

Room temperature plasma-etching and surface passivation of far-ultraviolet Al mirrors using electron beam generated plasmas

The development of optical systems operating in the far ultraviolet range (FUV, λ=100-200 nm) is limited by the efficiency of passivated aluminum (Al) mirrors. Although it is presently possible to obtain high-reflectivity FUV mirrors through physical vapor deposition, the process involves deposition with substrates at high temperatures, which is technically challenging for large optical elements. A novel passivation procedure for bare Al mirrors is reported. The treatment consisted of using a low-temperature electron-beam generated plasma produced in a gas mixture of Ar and SF6 to etch away the native oxide layer from the Al film, while simultaneously promoting the generation of a thin aluminum tri-fluoride (AlF3) layer on the Al surface. In the first section we analyze the effect of varying both ion energy and SF6 concentration on the FUV reflectance, thickness, composition, and surface morphology of the resulting AlF3 protective layers. In the second section, the reflectivity of samples is optimized at selected important FUV wavelengths for astronomical observations. Notably, samples attained state-of-the-art reflectances of 75% at 108.5 nm (He Lyman γ), 91% at 121.6 nm (H Lyman α), 90% at 130.4 nm (OI), and of 95% at 155.0 nm (C IV). The stability over time of these passivated mirrors is also investigated.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Materials Data on K5Au(IO)2 by Materials Project

K5Au(OI)2 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted linear geometry to two equivalent O2- and four equivalent I1- atoms. Both K–O bond lengths are 2.80 Å. There are a spread of K–I bond distances ranging from 3.58–3.87 Å. In the second K1+ site, K1+ is bonded in a distorted linear geometry to two equivalent O2- and four equivalent I1- atoms. There are one shorter (2.70 Å) and one longer (2.76 Å) K–O bond lengths. There are two shorter (3.60 Å) and two longer (3.74 Å) K–I bond lengths. In the third K1+ site, K1+ is bonded in a distorted linear geometry to two equivalent O2- and four equivalent I1- atoms. Both K–O bond lengths are 2.82 Å. All K–I bond lengths are 3.66 Å. Au1+ is bonded in a linear geometry to two equivalent O2- atoms. Both Au–O bond lengths are 2.06 Å. O2- is bonded to five K1+ and one Au1+ atom to form corner-sharing OK5Au octahedra. The corner-sharing octahedra tilt angles range from 0–12°. I1- is bonded in a 10-coordinate geometry to ten K1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb3Bi7Pb3(IO)10 by Materials Project

Rb3Pb3Bi7(OI)10 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded in a 7-coordinate geometry to two O2- and five I1- atoms. There are one shorter (3.01 Å) and one longer (3.03 Å) Rb–O bond lengths. There are a spread of Rb–I bond distances ranging from 3.54–3.86 Å. In the second Rb1+ site, Rb1+ is bonded in a 2-coordinate geometry to two O2- and three I1- atoms. There are one shorter (2.91 Å) and one longer (3.08 Å) Rb–O bond lengths. There are a spread of Rb–I bond distances ranging from 3.59–4.05 Å. In the third Rb1+ site, Rb1+ is bonded in a distorted single-bond geometry to one O2- and four I1- atoms. The Rb–O bond length is 2.74 Å. There are a spread of Rb–I bond distances ranging from 3.76–4.22 Å. There are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a single-bond geometry to one O2- and two I1- atoms. The Pb–O bond length is 2.27 Å. There are one shorter (3.26 Å) and one longer (3.57 Å) Pb–I bond lengths. In the second Pb2+ site, Pb2+ is bonded in a distorted single-bond geometry to one O2- and three I1- atoms. The Pb–O bond length is 2.19 Å. There are a spread of Pb–I bond distances ranging from 3.10–3.56 Å. In the third Pb2+ site, Pb2+ is bonded in a 2-coordinate geometry to two O2- and three I1- atoms. There are one shorter (2.31 Å) and one longer (2.38 Å) Pb–O bond lengths. There are a spread of Pb–I bond distances ranging from 3.19–3.75 Å. There are seven inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a 3-coordinate geometry to three O2- and two I1- atoms. There are two shorter (2.17 Å) and one longer (2.19 Å) Bi–O bond lengths. There are one shorter (3.34 Å) and one longer (3.75 Å) Bi–I bond lengths. In the second Bi3+ site, Bi3+ is bonded in a 3-coordinate geometry to three O2- and two I1- atoms. There are a spread of Bi–O bond distances ranging from 2.16–2.19 Å. There are one shorter (3.34 Å) and one longer (3.39 Å) Bi–I bond lengths. In the third Bi3+ site, Bi3+ is bonded in a 4-coordinate geometry to three O2- and two equivalent I1- atoms. There are a spread of Bi–O bond distances ranging from 2.22–2.52 Å. There are one shorter (3.35 Å) and one longer (3.66 Å) Bi–I bond lengths. In the fourth Bi3+ site, Bi3+ is bonded in a 2-coordinate geometry to two O2- and two I1- atoms. There are one shorter (2.06 Å) and one longer (2.18 Å) Bi–O bond lengths. There are one shorter (3.05 Å) and one longer (3.52 Å) Bi–I bond lengths. In the fifth Bi3+ site, Bi3+ is bonded in a distorted L-shaped geometry to two O2- and one I1- atom. There are one shorter (2.06 Å) and one longer (2.13 Å) Bi–O bond lengths. The Bi–I bond length is 3.49 Å. In the sixth Bi3+ site, Bi3+ is bonded in a distorted water-like geometry to two O2- and two I1- atoms. There are one shorter (2.07 Å) and one longer (2.12 Å) Bi–O bond lengths. There are one shorter (3.07 Å) and one longer (3.57 Å) Bi–I bond lengths. In the seventh Bi3+ site, Bi3+ is bonded in a distorted L-shaped geometry to two O2- and one I1- atom. There are one shorter (2.07 Å) and one longer (2.15 Å) Bi–O bond lengths. The Bi–I bond length is 3.17 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to three Bi3+ and one I1- atom. The O–I bond length is 3.59 Å. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Bi3+ and one I1- atom. The O–I bond length is 3.36 Å. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Rb1+, one Pb2+, and one Bi3+ atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to two Bi3+ and one I1- atom. The O–I bond length is 3.23 Å. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Pb2+ and one Bi3+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Rb1+, two Bi3+, and one I1- atom. The O–I bond length is 3.57 Å. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Rb1+, one Pb2+, and one Bi3+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Rb1+ and one I1- atom. The O–I bond length is 1.95 Å. In the ninth O2- site, O2- is bonded in a distorted water-like geometry to two Bi3+ and one I1- atom. The O–I bond length is 3.87 Å. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Pb2+ and two Bi3+ atoms. There are ten inequivalent I1- sites. In the first I1- site, I1- is bonded in a distorted single-bond geometry to one Bi3+ atom. In the second I1- site, I1- is bonded in a 2-coordinate geometry to two Bi3+ atoms. In the third I1- site, I1- is bonded in a 4-coordinate geometry to one Rb1+, one Pb2+, and two Bi3+ atoms. In the fourth I1- site, I1- is bonded in a 5-coordinate geometry to one Pb2+, four Bi3+, and two O2- atoms. In the fifth I1- site, I1- is bonded in a 3-coordinate geometry to two equivalent Rb1+ and one Pb2+ atom. In the sixth I1- site, I1- is bonded in a 3-coordinate geometry to one Rb1+, one Bi3+, and one O2- atom. In the seventh I1- site, I1- is bonded in a 6-coordinate geometry to three Rb1+, one Pb2+, one Bi3+, and one O2- atom. In the eighth I1- site, I1- is bonded in a 5-coordinate geometry to three Rb1+ and two Pb2+ atoms. In the ninth I1- site, I1- is bonded in a 1-coordinate geometry to one O2- atom. In the tenth I1- site, I1- is bonded in a 6-coordinate geometry to two Rb1+, two equivalent Pb2+, one Bi3+, and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(IO)2 by Materials Project

Sr(OI)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Sr sites. In the first Sr site, Sr is bonded in a 9-coordinate geometry to four O and four I atoms. There are a spread of Sr–O bond distances ranging from 2.50–2.53 Å. There are a spread of Sr–I bond distances ranging from 3.43–3.71 Å. In the second Sr site, Sr is bonded in a 9-coordinate geometry to four O and five I atoms. There are a spread of Sr–O bond distances ranging from 2.51–2.53 Å. There are a spread of Sr–I bond distances ranging from 3.47–3.83 Å. In the third Sr site, Sr is bonded in a 9-coordinate geometry to four O and four I atoms. There are a spread of Sr–O bond distances ranging from 2.51–2.53 Å. There are a spread of Sr–I bond distances ranging from 3.43–3.70 Å. In the fourth Sr site, Sr is bonded in a 9-coordinate geometry to four O and five I atoms. There are a spread of Sr–O bond distances ranging from 2.50–2.53 Å. There are a spread of Sr–I bond distances ranging from 3.46–3.85 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. The O–O bond length is 1.38 Å. In the second O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. The O–O bond length is 1.37 Å. In the third O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. The O–O bond length is 1.38 Å. In the fourth O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. The O–O bond length is 1.37 Å. In the fifth O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. In the sixth O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. In the seventh O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. In the eighth O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. There are eight inequivalent I sites. In the first I site, I is bonded in a distorted water-like geometry to two Sr and one I atom. The I–I bond length is 3.31 Å. In the second I site, I is bonded in a 2-coordinate geometry to three Sr and one I atom. The I–I bond length is 3.27 Å. In the third I site, I is bonded in a distorted water-like geometry to two Sr and one I atom. The I–I bond length is 3.28 Å. In the fourth I site, I is bonded in a 2-coordinate geometry to three Sr and one I atom. The I–I bond length is 3.30 Å. In the fifth I site, I is bonded in a distorted rectangular see-saw-like geometry to two Sr and two I atoms. The I–I bond length is 2.88 Å. In the sixth I site, I is bonded in a 4-coordinate geometry to two Sr and two I atoms. The I–I bond length is 2.88 Å. In the seventh I site, I is bonded in a distorted rectangular see-saw-like geometry to two Sr and two I atoms. In the eighth I site, I is bonded in a 4-coordinate geometry to two Sr and two I atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(IO)2 by Materials Project

Sr(OI)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Sr sites. In the first Sr site, Sr is bonded to four O and three I atoms to form distorted edge-sharing SrI3O4 pentagonal bipyramids. There are a spread of Sr–O bond distances ranging from 2.47–2.50 Å. There are a spread of Sr–I bond distances ranging from 3.35–3.51 Å. In the second Sr site, Sr is bonded in a 2-coordinate geometry to four O and five I atoms. There are a spread of Sr–O bond distances ranging from 2.48–2.72 Å. There are a spread of Sr–I bond distances ranging from 3.40–4.02 Å. In the third Sr site, Sr is bonded in a 2-coordinate geometry to four O and four I atoms. There are a spread of Sr–O bond distances ranging from 2.48–2.70 Å. There are a spread of Sr–I bond distances ranging from 3.43–3.65 Å. In the fourth Sr site, Sr is bonded in a 4-coordinate geometry to four O and four I atoms. There are a spread of Sr–O bond distances ranging from 2.46–2.52 Å. There are a spread of Sr–I bond distances ranging from 3.31–3.94 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. The O–O bond length is 1.38 Å. In the second O site, O is bonded in a T-shaped geometry to two equivalent Sr and one O atom. The O–O bond length is 1.40 Å. In the third O site, O is bonded in a distorted T-shaped geometry to two equivalent Sr and one O atom. The O–O bond length is 1.42 Å. In the fourth O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. The O–O bond length is 1.37 Å. In the fifth O site, O is bonded in a 3-coordinate geometry to two equivalent Sr and one O atom. In the sixth O site, O is bonded in a 4-coordinate geometry to two equivalent Sr, one O, and one I atom. The O–I bond length is 2.36 Å. In the seventh O site, O is bonded in a 4-coordinate geometry to two equivalent Sr, one O, and one I atom. The O–I bond length is 2.34 Å. In the eighth O site, O is bonded in a distorted T-shaped geometry to two equivalent Sr and one O atom. There are eight inequivalent I sites. In the first I site, I is bonded in a 4-coordinate geometry to three Sr and one I atom. The I–I bond length is 3.34 Å. In the second I site, I is bonded in a distorted single-bond geometry to one Sr, one O, and one I atom. The I–I bond length is 3.17 Å. In the third I site, I is bonded in a distorted single-bond geometry to one Sr, one O, and one I atom. In the fourth I site, I is bonded in a 2-coordinate geometry to three Sr and one I atom. In the fifth I site, I is bonded in a distorted bent 120 degrees geometry to two Sr and one I atom. The I–I bond length is 3.29 Å. In the sixth I site, I is bonded in a 2-coordinate geometry to two Sr and one I atom. The I–I bond length is 3.29 Å. In the seventh I site, I is bonded in a 2-coordinate geometry to two Sr and one I atom. In the eighth I site, I is bonded in a distorted bent 120 degrees geometry to two Sr and one I atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Approach to Startup Inventory for Viable Commercial Power Plant

Summary • FPP realization within the next 10-15 years will require dedicated efforts to improve DIR, burn fraction, fueling efficiency, and/or processing times. • Modest improvements from either the fuel cycle side or plasma physics side should be possible with considered allocation of R&D funding. • Current gaps in particular include blanket extraction at scale, improved efficiency in isotope separation and detritiation, and maximizing DIR efficiency. • Total costs for FPP construction and commissioning depend heavily on site regulation, so decreases in required SI and OI can lead to large decreases in capital outlay. • Some subsystems in the fuel cycle are required from a environmental management perspective but are both energetically expensive and time consuming, particularly water detritiation. • Low inventories but high capital and operational costs mean a centralized water detritiation plant could greatly improve likelihood of deployment of multiple FPPs on the same time scale.

MALONE, COLLIN↗
DOE OSTI2023

Genomic and Phenotypic Characterization of Shiga Toxin-Producing Escherichia albertii Strains Isolated from Wild Birds in a Major Agricultural Region in California

Escherichia albertii is an emerging foodborne pathogen. To better understand the pathogenesis and health risk of this pathogen, comparative genomics and phenotypic characterization were applied to assess the pathogenicity potential of E. albertii strains isolated from wild birds in a major agricultural region in California. Shiga toxin genes stx2f were present in all avian strains. Pangenome analyses of 20 complete genomes revealed a total of 11,249 genes, of which nearly 80% were accessory genes. Both core gene-based phylogenetic and accessory gene-based relatedness analyses consistently grouped the three stx2f-positive clinical strains with the five avian strains carrying ST7971. Among the three Stx2f-converting prophage integration sites identified, ssrA was the most common one. Besides the locus of enterocyte effacement and type three secretion system, the high pathogenicity island, OI-122, and type six secretion systems were identified. Substantial strain variation in virulence gene repertoire, Shiga toxin production, and cytotoxicity were revealed. Six avian strains exhibited significantly higher cytotoxicity than that of stx2f-positive E. coli, and three of them exhibited a comparable level of cytotoxicity with that of enterohemorrhagic E. coli outbreak strains, suggesting that wild birds could serve as a reservoir of E. albertii strains with great potential to cause severe diseases in humans.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Catalytic conversion of post-consumer recycled high-density polyethylene oil over Zn-impregnated ZSM-5 catalysts

The catalytic conversion of post-consumer recycled high-density polyethylene (PCR-HDPE) pyrolysis oil was investigated using modified ZSM-5 zeolites, prepared under different conditions. The PCR-HDPE oil, obtained through pyrolysis at 500 °C followed by distillation at 165 °C, contained a naphtha fraction hydrocarbons suitable for catalytic upgrading. H/ZSM-5 converts PCR-HDPE naphtha fraction oil primarily into BTX, along with light paraffins and olefins. Introducing mesoporosity led to increased propylene yield at the expense of BTX. Zn impregnation onto H/ZSM-5 and H-meso/ZSM-5 enhanced BTX yield by up to 13 %. However, Zn-meso/ZSM-5 exhibited a lower BTX yield than Zn/ZSM-5 with the same Zn loadings, especially after additional steam treatment at 700 °C. Spent catalysts revealed no noticeable increase in metal contaminants such as calcium and aluminum that were present in the PCR-HDPE. Here, the Zn/ZSM-5 catalyst was stable for more than 50 h time on stream and showed promising potential for upgrading PCR-HDPE naphtha fraction oils.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

An Activity-Based Sensing Approach to Monitor Nanomaterial-Promoted Changes in Labile Metal Pools in Living Systems

Metal-based nanoparticles are a promising class of materials for diagnosis and treatment of cancer and other diseases. However, mechanisms of action of these nanomedicines remain insufficiently understood due in large part to our limited understanding of the dynamic equilibria between solid metal nanoparticles and labile metal ions generated from these nanoparticles within complex biological milieus. Here, we apply activitybased sensing to directly identify and investigate the fate of labile copper pools with metal and oxidation state-specificity generated by anticancer copper nanomedicines. We found that treatment of cells with copper-releasing nanoparticles alter labile Cu(I)/Cu(II) ratios through an increase in labile Cu(II), while overall labile copper levels decrease. Labile copper release triggers compensatory responses in two major antioxidant pathways, glutathione (GSH) and nuclear factor erythroid 2-related factor 2 (NRF2), as well as in metal homeostasis to limit copper availability via regulation of copper export (ATP7B) and copper import (CTR1) proteins. These findings establish the value of activity-based sensing as a generalizable approach for labile metal imaging to help decipher molecular mechanisms of bioactive metal nanoparticles and guide the development of more effective nanomedicine diagnostics and therapies to target metal-dependent disease vulnerabilities.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Development, characterisation, and deployment of the SNO+ liquid scintillator

A liquid scintillator consisting of linear alkylbenzene as the solvent and 2,5-diphenyloxazole as the fluor was developed for the SNO+ experiment. This mixture was chosen as it is compatible with acrylic and has a competitive light yield to pre-existing liquid scintillators while conferring other advantages including longer attenuation lengths, superior safety characteristics, chemical simplicity, ease of handling, and logistical availability. Its properties have been extensively characterized and are presented here. This liquid scintillator is now used in several neutrino physics experiments in addition to SNO+.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Subaru/HSC deep optical imaging of infrared sources in the AKARI North Ecliptic Pole-Wide field

In this work, we present a five-broad-band (grizy) photometric catalogue of Subaru/Hyper Suprime-Cam (HSC) optical imaging observations at around the North Ecliptic Pole (NEP) where the AKARI infrared (IR) satellite conducted a large survey (NEP-Wide survey). The observations cover almost all the NEP-Wide survey field down to the depth of 28.1, 26.8, 26.3, 25.5, and 25.0 mag (5σ) at grizy, respectively. The five-band HSC catalogue contains about 2.6 million objects, and 70 959 AKARI NEP-Wide counterpart sources are identified in the catalogue. We added existing supplementary catalogues from the u band to the far-IR band, and estimated photo-z for the AKARI-HSC sources. We achieved σΔz/(1 + zs) = 0.06 and an outlier rate of 13.4 per cent at z = 0.2–1.5. Using the spectral energy distribution (SED) template fitting, we classified the AKARI-HSC galaxies into four categories, namely quiescent, star-forming, Type1 active galactic nucleus (AGN), and Type2 AGN, in each redshift bin. Then, at z > 1, the mean SED of star-forming galaxies in mid-IR (3–10 μm) range is significantly different from that of spiral galaxies in the nearby Universe, indicating that many of star-forming galaxies at z > 1 contain a heat source capable of heating dust to temperatures that radiate thermal emission in the mid-IR range. Furthermore, we estimated the number fraction of AGNs (fAGN) in each bin of redshift and IR luminosity (L IR ), and examined the dependence of redshift and L IR . In log(L IR /L ⊙ ) = 11.0–14.0, the fAGN shows a significant increase with increasing redshift, regardless of the LIR bins. In contrast, the fAGN shows a slight increase against L IR at z < 1 and no increase with increasing L IR at z > 1.

79 ASTRONOMY AND ASTROPHYSICS↗