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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 955 records · Page 53

PGM-Free ORR Catalysts Designed by Templating PANI-Type Polymers Containing Functional Groups with High Affinity to Iron

In this work, a coordination-chemistry approach was used to increase the content of nitrogen-coordinated iron moieties (Fe-N x ) in platinum group metal-free (PGM-free) catalysts for oxygen reduction reaction (ORR). The catalysts were derived from a series of polyaniline (PANI)-type precursors with N-containing functional side chains having high affinity to iron. The PGM-free ORR catalysts synthesized using such polymeric templates were characterized by scanning electron microscopy, X-ray diffractometry, and tested in an electrochemical cell and H 2 -air fuel cell for ORR activity. X-ray photoelectron spectroscopy (XPS) analysis showed that, in spite of similar nitrogen contents, catalysts obtained using PANI-type polymers containing side chains with high affinity to iron had higher Fe content than PANI-derived catalyst. These PGM-free catalysts showed improved ORR activity in an electrochemical cell and in H 2 -air fuel cell testing, compared to the PANI-derived catalyst. A correlation between the content of Fe-N x moieties and the fuel cell performance was observed in these PGM-free ORR catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

MgCl 2 : The Key Ingredient to Improve Chloride Containing Electrolytes for Rechargeable Magnesium-Ion Batteries

The effect of MgCl2 on a series of chloride containing magnesium electrolytes was investigated. In the presence of extra MgCl2, the electrochemical properties of Grignard reagents (RMgCl, R = Ph, Et, iPr) were significantly improved, and the advance of MgCl2 was further demonstrated in Mg-Mo6S8 rechargeable batteries with improved capacities and much smaller over-potentials. MgCl2 was then further proven to be powerful reagent to improve the performance of well-established strong Lewis acid derived magnesium electrolytes including the “all-phenyl” complex (APC) and alkoxide-based magnesium electrolytes. The results suggest that MgCl2 salt is a very important species to benefit all chloride containing electrolytes for rechargeable magnesium-ion batteries.

Magnesium ion batteries, electrolytes, chlorides↗

Decomposition of Phosphorus-Containing Additives at a Charged NMC Surface through Potentiostatic Holds

In this work, multiple phosphorus-containing compounds were evaluated as electrolyte additives for their reactivity at the cathode surface using LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC532) // Li 4 Ti 5 O 12 (LTO) cells with both cycling and high voltage potentiostatic holds. Additives surveyed include phosphite and phosphate derivatives with either trifluoroethyl, ethyl, or trimethylsilyl groups. With the same substituents, phosphite additives showed lower Coulombic efficiency (CE) and higher oxidation current during the potentiostatic hold. Regardless of substitution group, all phosphates showed slightly higher CE than the additive-free electrolyte (baseline), although no additive significantly decreases oxidation reactions over the course of the potentiostatic hold. Post-mortem X-ray photoelectron spectroscopy analysis of the cathodes indicates that the additive with trimethylsilyl group leads to significantly higher incidence of oxygen and phosphorus on the cathode surface for both phosphites and phosphates. Atomistic simulations indicate the susceptibility of these additives to electrochemical and chemical oxidation, showing chemical oxidation to be much more likely with the phosphite additives. Lastly, the identity of the ligands on the phosphorus-containing additive can dramatically affect both the decomposition current as well as cathode surface after the potentiostatic hold.

25 ENERGY STORAGE↗

Proactive Data Containers (PDC) v0.1

As extreme-scale era software, we are developing novel object- based data abstractions and storage mechanisms that take advantage of the deep storage hierarchy and enable proactive automated performance tuning. In order to achieve these goals, we have developed a fundamental new data abstraction, called Proactive Data Containers (PDC). A PDC is a container within a locus of storage (memory, NVRAM, disk, etc.) that stores science data in an object-oriented manner.

Byna, Suren↗

static-subid: Deterministic subordinate UID/GID assignment for unprivileged containers

static-subid calculates predictable subordinate UID and GID ranges for Linux users based on their UID, ensuring consistent ID mappings across multiple systems. Unlike shadow-utils' sequential allocation (which depends on creation order), static-subid uses a deterministic formula that guarantees the same user UID always receives the same subordinate ID range. Subordinate IDs enable user namespaces for unprivileged container runtimes (Podman, Docker rootless mode, LXC) by mapping container UIDs/GIDs to host subordinate IDs without requiring root privileges.

Riehecky, Pat [Fermi National Accelerator Laborato↗

Thermal conductivity of crack-containing media: A numerical study

The present study aims to evaluate the effective thermal conduction behavior of crack-containing media through micromechanical modeling. Numerical analyses were performed using the finite element method, first using periodic arrays of elliptical pores and then reducing the elliptical minor axis to reach the crack limit. This parametric approach was seen to be able to capture the effect of discontinuity across the crack face in a straightforward manner. The overall thermal conductivity of the model structures, encompassing a range of crack densities and spatial distributions, was investigated. It was found that, for cracks with mixed orientations, the effective thermal conductivity is insensitive to the actual crack alignment and can be uniquely represented by the crack density. The mixed-orientation periodic crack configurations are also representative of random sizes, orientations, and spatial distributions of cracks, thus exhibiting a high degree of generality. The modeling analyses can also be used to determine simple empirical expressions for two- and three-dimensional media containing random cracks.

36 MATERIALS SCIENCE↗

The mitochondrial and chloroplast genomes of the haptophyte Chrysochromulina tobin contain unique repeat structures and gene profiles

Background: Haptophytes are widely and abundantly distributed in both marine and freshwater ecosystems. Few genomic analyses of representatives within this taxon have been reported, despite their early evolutionary origins and their prominent role in global carbon fixation. Results: The complete mitochondrial and chloroplast genome sequences of the haptophyte Chrysochromulina tobin (Prymnesiales) provide insight into the architecture and gene content of haptophyte organellar genomes. The mitochondrial genome (~34 kb) encodes 21 protein coding genes and contains a complex, 9 kb tandem repeat region. Similar to other haptophytes and rhodophytes, but not cryptophytes or stramenopiles, the mitochondrial genome has lost the nad7, nad9 and nad11 genes. The ~105 kb chloroplast genome encodes 112 protein coding genes, including ycf39 which has strong structural homology to NADP-binding nitrate transcriptional regulators; a divergent ‘CheY-like’ two-component response regulator (ycf55) and Tic/Toc (ycf60 and ycf80) membrane transporters. Notably, a zinc finger domain has been identified in the rpl36 ribosomal protein gene of all chloroplasts sequenced to date with the exception of haptophytes and cryptophytes - algae that have gained (via lateral gene transfer) an alternative rpl36 lacking the zinc finger motif. The two C. tobin chloroplast ribosomal RNA operon spacer regions differ in tRNA content. Additionally, each ribosomal operon contains multiple single nucleotide polymorphisms (SNPs) - a pattern observed in rhodophytes and cryptophytes, but few stramenopiles. Analysis of small (<200 bp) chloroplast encoded tandem and inverted repeats in C. tobin and 78 other algal chloroplast genomes show that repeat type, size and location are correlated with gene identity and taxonomic clade. Conclusion: The Chrysochromulina tobin organellar genomes provide new insight into organellar function and evolution. These are the first organellar genomes to be determined for the prymnesiales, a taxon that is present in both oceanic and freshwater systems and represents major primary photosynthetic producers and contributors to global ecosystem stability.

59 BASIC BIOLOGICAL SCIENCES↗

Methanosarcina acetivorans contains a functional ISC system for iron-sulfur cluster biogenesis

Abstract Background The production of methane by methanogens is dependent on numerous iron-sulfur (Fe-S) cluster proteins; yet, the machinery involved in Fe-S cluster biogenesis in methanogens remains largely unknown. Methanogen genomes encode uncharacterized homologs of the core components of the ISC (IscS and IscU) and SUF (SufBC) Fe-S cluster biogenesis systems found in bacteria and eukaryotes. Methanosarcina acetivorans contains three iscSU and two sufCB gene clusters. Here, we report genetic and biochemical characterization of M. acetivorans iscSU2 . Results Purified IscS2 exhibited pyridoxal 5′- phosphate-dependent release of sulfur from L-cysteine. Incubation of purified IscU2 with IscS2, cysteine, and iron (Fe 2+ ) resulted in the formation of [4Fe-4S] clusters in IscU2. IscU2 transferred a [4Fe-4S] cluster to purified M. acetivorans apo-aconitase. IscU2 also restored the aconitase activity in air-exposed M. acetivorans cell lysate. These biochemical results demonstrate that IscS2 is a cysteine desulfurase and that IscU2 is a Fe-S cluster scaffold. M. acetivorans strain DJL60 deleted of iscSU2 was generated to ascertain the in vivo importance of IscSU2. Strain DJL60 had Fe-S cluster content and growth similar to the parent strain but lower cysteine desulfurase activity. Strain DJL60 also had lower intracellular persulfide content compared to the parent strain when cysteine was an exogenous sulfur source, linking IscSU2 to sulfur metabolism. Conclusions This study establishes that M. acetivorans contains functional IscS and IscU, the core components of the ISC Fe-S cluster biogenesis system and provides the first evidence that ISC operates in methanogens.

59 BASIC BIOLOGICAL SCIENCES↗

Singularity: Scientific containers for mobility of compute

Here we present Singularity, software developed to bring containers and reproducibility to scientific computing. Using Singularity containers, developers can work in reproducible environments of their choosing and design, and these complete environments can easily be copied and executed on other platforms. Singularity is an open source initiative that harnesses the expertise of system and software engineers and researchers alike, and integrates seamlessly into common workflows for both of these groups. As its primary use case, Singularity brings mobility of computing to both users and HPC centers, providing a secure means to capture and distribute software and compute environments. This ability to create and deploy reproducible environments across these centers, a previously unmet need, makes Singularity a game changing development for computational science.

97 MATHEMATICS AND COMPUTING↗

Copper-containing layered oxide cathodes for sodium-ion batteries

Layered transition metal oxides are among the most promising cathode materials for sodium-ion batteries due to their high theoretical capacity, structural tunability, and cost-effectiveness. However, conventional Ni- and Co-based layered oxides are hindered by high raw material costs, limited elemental abundance, and phase instability during electrochemical cycling. Recently, copper has emerged as an attractive alternative transition metal, offering significant advantages in terms of redox activity, structural stabilization, voltage regulation, and rate performance. Unlike Ni and Co, Cu can facilitate unique redox mechanisms and enable more sustainable material design. This review systematically summarizes recent progress on Cu-containing layered sodium oxides, with emphasis on their structural characteristics, electrochemical behavior, and the critical roles that Cu plays within the host lattice. The insights provided herein aim to highlight the potential of Cu-substituted or Cu-containing layered oxides as a viable pathway toward high-performance and resource-accessible SIB cathodes for future energy storage applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Index tests for geosynthetic clay liners containing bentonite–polymer composites

The hydraulic conductivity of geosynthetic clay liners (GCLs) containing bentonite–polymer composites (BPCs) is controlled by a pore clogging mechanism related to the swelling of sodium bentonite (NaB) granules and formation of polymer gel in the pore space. Three index testing procedures that are influenced by bentonite swelling and rheology of the polymer gel were evaluated in this study for screening BPC GCLs for hydraulic conductivity: viscosity, liquid limit by fall-cone penetration and active water content. Experiments were conducted using polyacrylamide (PAM) polymer, dry-blended mixtures of PAM and NaB and a BPC from a commercially available GCL. These materials were contacted with inorganic solutions representing leachates from a range of waste containment scenarios. For the BPC that was evaluated, hydraulic conductivities less than 10 -10 m/s were obtained when the viscosity exceeded 220 mPa s and the active water content exceeded 300%. Hydraulic conductivities less than 10 -11 m/s were achieved for viscosity exceeding 350 mPa s, fall-cone liquid limit exceeding 190 and active water content exceeding 300%. Additional testing is needed to assess the generality of these index tests and the identified thresholds when applied to other BPC GCLs and other permeant liquids.

Engineering↗

Seaborgite, LiNa6K2(UO2)(SO4)5(SO3OH)(H2O), the First Uranyl Mineral Containing Lithium

Abstract Seaborgite (IMA2019-087), LiNa6K2(UO2)(SO4)5(SO3OH)(H2O), is a new mineral species from the Blue Lizard mine, Red Canyon, San Juan County, Utah, U.S.A. It is a secondary phase found on gypsum in association with copiapite, ferrinatrite, ivsite, metavoltine, and römerite. Seaborgite occurs in sprays of light-yellow, long flattened prisms or blades, up to about 0.2 mm in length. Crystals are elongated on [100], flattened on {010}, and exhibit the forms {100}, {010}, {001}, and {101}. The mineral is transparent with vitreous luster and very pale-yellow streak. It exhibits bright lime-green fluorescence under a 405 nm laser. The Mohs hardness is ~2½. The mineral has brittle tenacity, curved or conchoidal fracture, and one good cleavage on {100}. The measured density is 2.97(2) g/cm3. The mineral is immediately soluble in H2O at room temperature. The mineral is optically biaxial (–), α = 1.505(2), β = 1.522(2), γ = 1.536(2) (white light); 2Vmeas = 85(1)°; moderate r < ν dispersion; orientation X ^ a ≈ 10°; pleochroic X colorless, Y and Z light green-yellow; X < Y ≈ Z. EPMA and LA-ICP-MS analyses of seaborgite undermeasured its Li, K, and Na. The empirical formula using Li, Na, and K based on the structure refinement is Li1.00Na5.81K2.19(UO2)(SO4)5(SO3OH)(H2O). Seaborgite is triclinic, P1, a = 5.4511(4), b = 14.4870(12), c = 15.8735(15) Å, α = 76.295(5), β = 81.439(6), γ = 85.511(6)°, V = 1203.07(18) Å3, and Z = 2. The structure (R1 = 0.0377 for 1935 I = 2σI) contains [(UO2)2(SO4)8]4– uranyl-sulfate clusters that are linked into a band by bridging LiO4 tetrahedra. The bands are linked through peripheral SO4 tetrahedra forming a thick heteropolyhedral layer. Channels within the layers contain a K site, while an additional K site, six Na sites, and an SO3OH group occupy the space between the heteropolyhedral layers.

Geochemistry & Geophysics↗

On the Alpha Radiation Damage to the O-Ring Seal of the SAVY-4000 Container

In this memo, the dose to an O-ring from the alpha decay of 238 PuO 2 is calculated. These calculations were made in order to assess possible radiation damage to the O-ring, which could lead to failure and loss of integrity of the seal created by the O-ring. The O-ring being discussed here provides the seal between the lid and bottom of a nuclear materials container. The container will be used for the storage and transport of a number of different radioactive materials. The analysis is made using 238 PuO 2 as it would create the greatest damage to the O-ring when considering the materials that may be stored in it. Contamination of the O-ring is not expected to occur. But in the event radioactive material comes in contact with the O-ring, these calculations provide an estimate of the radiation damage.

07 ISOTOPE AND RADIATION SOURCES↗

Systematic Method for Evaluating Extraction and Injection Flow Rates for 100-KR-4 and 100-HR-3 Groundwater Operable Unit Pump-and-Treat Interim Actions for Hydraulic Containment

This document describes a systematic method to develop flow rate recommendations for Pump-and-Treat (P&T) extraction and injection wells in 100-KR-4 and 100-HR-3 Groundwater Operable Units (OU) of the Hanford Site. Flow rate recommendations are developed as part of ongoing performance monitoring and remedy optimization of the P&T interim actions to develop hydraulic containment of the dissolved chromium plume in groundwater and protect the Columbia River from further discharges of groundwater from inland. This document details the methodology and data required to infer the influence of individual wells near the shoreline on hydraulic containment and river protection and develop flow rate recommendations to improve system performance and mitigate potential shortcomings of the system configuration in place.

54 ENVIRONMENTAL SCIENCES↗

Thermal aging modeling and validation on the Mo-containing Fe-Cr-Ni alloys

Thermodynamics of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys is critical knowledge to understand thermal aging effect on the phase stability of Mo-containing austenitic steels, which subsequently facilitates alloy design/improvement and degradation mitigation of these materials for reactor applications. Among the intermetallic phases, Chi (χ), Laves, and Sigma (σ) are often of concern because of their tendency to cause embrittlement of the materials. The focus of this study is thermal stability of the Chi and Laves phases as they were less studied compared to the Sigma phase. Coupled with thermodynamic modeling, thermal stability of intermetallic phases in Mo containing Fe-Cr-Ni alloys was investigated at 1000, 850 and 700°C for different annealing times. The morphologies, compositions and crystal structures of the precipitates of the intermetallic phases were carefully examined by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and transmission electron microscopy. Three key findings resulted from this study. First, the Chi phase is stable at high temperature, and with decreasing temperature it transforms into the Laves phase that is stable at low temperature. Secondly, Cr, Mo, Ni are soluble in both the Chi and Laves phases, with the solubility of Mo playing a major role in the relative stability of the intermetallic phases. Thirdly, in situ transformation from Chi phase to Laves phase was directly observed, which increased the local strain field, generated dislocations in the intermetallic phases, and altered the precipitate phase orientation relationship with the austenitic matrix. The thermodynamic models that were developed and validated were then applied to evaluating the effect of Mo on the thermal stability of intermetallic phases in type 316 and NF709 stainless steels.

36 MATERIALS SCIENCE↗

Defense Waste Processing Facility (DWPF) Viscosity Model: Revisions for Processing High TiO 2 Containing Glasses

Radioactive high-level waste (HLW) at the Savannah River Site (SRS) has successfully been vitrified into borosilicate glass in the Defense Waste Processing Facility (DWPF) since 1996. Vitrification requires stringent product/process (P/P) constraints since the glass cannot be reworked once it is poured into ten foot tall by two foot diameter canisters. A unique “feed forward” statistical process control (SPC) was developed for this control rather than statistical quality control (SQC). In SPC, the feed composition to the DWPF melter is controlled prior to vitrification. In SQC, the glass product would be sampled after it is vitrified. Individual glass property-composition models form the basis for the “feed forward” SPC. The models transform constraints on the melt and glass properties into constraints on the feed composition going to the melter in order to guarantee, at the 95% confidence level, that the feed will be processable and that the durability of the resulting waste form will be acceptable to a geologic repository. The DWPF SPC system is known as the Product Composition Control System (PCCS). The DWPF will soon be receiving wastes from the Salt Waste Processing Facility (SWPF) containing increased concentrations of TiO 2 , Na 2 O, and Cs 2 O . The SWPF is being built to pretreat the high-curie fraction of the salt waste to be removed from the HLW tanks in the F- and H-Area Tank Farms at the SRS. In order to process TiO 2 concentrations >2.0 wt% in the DWPF, new viscosity data were developed over the range of 1.90 to 6.09 wt% TiO 2 and evaluated against the 2005 viscosity model. An alternate viscosity model is also derived for potential future use, should the DWPF ever need to process other titanate-containing ion exchange materials. The ultimate limit on the amount of TiO 2 that can be accommodated from SWPF will be determined by the three PCCS models, the waste composition of a given sludge batch, the waste loading of the sludge batch, and the frit used for vitrification.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Pipe Overpack Container Fire Testing: Phase I & II

The Pipe Overpack Container (POC) was developed at Rocky Flats to transport plutonium residues with higher levels of plutonium than standard transuranic (TRU) waste to the Waste Isolation Pilot Plant (WIPP) for disposal. In 1996 Sandia National Laboratories (SNL) conducted a series of tests to determine the degree of protection POCs provided during storage accident events. One of these tests exposed four of the POCs to a 30-minute engulfing pool fire, resulting in one of the 7A drum overpacks generating sufficient internal pressure to pop off its lid and expose the top of the pipe container (PC) to the fire environment. The initial contents of the POCs were inert materials, which would not generate large internal pressure within the PC if heated. However, POCs are now being used to store combustible TRU waste at Department of Energy (DOE) sites. At the request of DOE’s Office of Environmental Management (EM) and National Nuclear Security Administration (NNSA), starting in 2015 SNL conducted a new series of fire tests to examine whether PCs with combustibles would reach a temperature that would result in (1) decomposition of inner contents and (2) subsequent generation of sufficient gas to cause the PC to over-pressurize and release its inner content. Tests conducted during 2015 and 2016, and described herein, were done in two phases. The goal of the first phase was to see if the PC would reach high enough temperatures to decompose typical combustible materials inside the PC. The goal of the second test phase was to determine under what heating loads (i.e., incident heat fluxes) the 7A drum lid pops off from the POC drum. This report will describe the various tests conducted in phase I and II, present preliminary results from these tests, and discuss implications for the POCs.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

SAVY 4000 Container Filter Design Life and Extension Implementation

The SAVY 4000 is a general purpose, reusable container for the storage of solid nuclear material inside a nuclear facility. The canister has a permitted loading for material with a thermal output not to exceed 25 watts. This wattage limit applies to all containers, regardless of their size.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗