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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Singlet magnetism in intermetallic UGa 2 unveiled by inelastic x-ray scattering

Using high resolution tender x-ray resonant inelastic scattering and hard x-ray nonresonant inelastic scattering beyond the dipole limit we were able to detect electronic excitations in intermetallic UGa 2 that are highly atomic in nature. Analysis of the spectral lineshape reveals that the local 5⁢ƒ 2 configuration characterizes the correlated nature of this ferromagnet. The orientation and directional dependence of the spectra indicate that the ground state is made of the Γ 1 singlet and/or Γ 6 doublet symmetry. With the ordered moment in the ab plane, we infer that the magnetism originates from the higher lying Γ 6 doublet being mixed with the Γ 1 singlet due to intersite exchange, qualifying UGa 2 to be a true quantum magnet. The ability to observe atomic excitations is crucial to resolve the ongoing debate about the degree of localization versus itineracy in U intermetallics.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on UGa by Materials Project

U(Ga) crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. U is bonded to six equivalent U and six equivalent Ga atoms to form UU6Ga6 cuboctahedra that share corners with eighteen equivalent UU6Ga6 cuboctahedra, edges with six equivalent UU6Ga6 cuboctahedra, edges with twelve equivalent GaU6Ga6 cuboctahedra, faces with eight equivalent UU6Ga6 cuboctahedra, and faces with twelve equivalent GaU6Ga6 cuboctahedra. All U–U bond lengths are 2.93 Å. All U–Ga bond lengths are 3.13 Å. Ga is bonded to six equivalent U and six equivalent Ga atoms to form GaU6Ga6 cuboctahedra that share corners with eighteen equivalent GaU6Ga6 cuboctahedra, edges with six equivalent GaU6Ga6 cuboctahedra, edges with twelve equivalent UU6Ga6 cuboctahedra, faces with eight equivalent GaU6Ga6 cuboctahedra, and faces with twelve equivalent UU6Ga6 cuboctahedra. All Ga–Ga bond lengths are 2.93 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Low cost, flexible, and distribution level universal grid analyser platform: designs and implementations

This study presents the designs and implementations of a distribution level open-universal grid analyser (Open-UGA) platform. The proposed Open-UGA platform consists of distribution-level phasor measurement units (PMUs), a standard signal generator, a router, and a server. Firstly, an overall introduction for the software, hardware, and server architectures of the Open-UGA platform is given. To give a detailed design, the software, hardware, server block diagrams, flowcharts, and printed circuit board photo of the Open-UGA platform are presented in detail. Then, four different types of distribution level PMU algorithms are introduced and implemented in the Open-UGA platform to verify the flexibility and reconfigurability. The flowcharts and functionalities of these four UGAs with different PMU algorithms are given as example implementations. Lastly, a performance comparison is conducted with both quantitative and illustrative results.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2022

Precise ROCOF estimation algorithm for low inertia power grids

The precise estimation of Rate Of Change Of Frequencies (ROCOFs) in a generation trip event can be helpful on power system inertia estimation, fast system response, and accurate event capturing. However, the ROCOF estimations from the existing Synchronized Measurement Devices (SMDs) are usually simply calculated by the finite difference between two adjacent frequency measurement points. The ineluctable noises, disturbances, and spikes from real-world frequency measurements can bring large dynamics to the ROCOF estimation and thus can result in an inaccurate estimation of the initial ROCOF. This issue becomes more serious when the target power grid has low inertia, and a large amount of distributed energy sources are deployed. To address this issue, a precise ROCOF estimation algorithm is designed based on least square method with flexible window size. In addition, a median filter is also designed and applied on the frequency measurements before using the proposed algorithm. The window size and thresholds in the proposed algorithm are determined with historical event data analysis. The proposed algorithm is deployed in a low cost, flexible, and distribution level universal grid analyzer (UGA) platform. In conclusion, multiple experiments are conducted in both a laboratory and the Hawaiian Islands to verify the effectiveness of the proposed algorithm.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2024

Engineered mRNA–ribosome fusions for facile biosynthesis of selenoproteins

Ribosomes are often used in synthetic biology as a tool to produce desired proteins with enhanced properties or entirely new functions. However, repurposing ribosomes for producing designer proteins is challenging due to the limited number of engineering solutions available to alter the natural activity of these enzymes. In this study, we advance ribosome engineering by describing a novel strategy based on functional fusions of ribosomal RNA (rRNA) with messenger RNA (mRNA). Specifically, we create an mRNA–ribosome fusion called RiboU, where the 16S rRNA is covalently attached to selenocysteine insertion sequence (SECIS), a regulatory RNA element found in mRNAs encoding selenoproteins. When SECIS sequences are present in natural mRNAs, they instruct ribosomes to decode UGA codons as selenocysteine (Sec, U) codons instead of interpreting them as stop codons. This enables ribosomes to insert Sec into the growing polypeptide chain at the appropriate site. Our work demonstrates that the SECIS sequence maintains its functionality even when inserted into the ribosome structure. As a result, the engineered ribosomes RiboU interpret UAG codons as Sec codons, allowing easy and site-specific insertion of Sec in a protein of interest with no further modification to the natural machinery of protein synthesis. To validate this approach, we use RiboU ribosomes to produce three functional target selenoproteins in Escherichia coli by site-specifically inserting Sec into the proteins’ active sites. Overall, our work demonstrates the feasibility of creating functional mRNA–rRNA fusions as a strategy for ribosome engineering, providing a novel tool for producing Sec-containing proteins in live bacterial cells.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

U-gas +Cool GTL™ - A New Integrated Process for Direct Biomass Conversion to Liquid Fuels

The U-Gas gasification technology, marketed by Sungas, is a proven fluid bed gasification technology for biomass conversion. U-Gas has been tested on a wide variety of biomass feeds including wood and waste streams. The U-Gas Technology has successfully converted wood for more than 20 years in a gasification plant in Skive Denmark at the 150t/d size. GTI has also recently developed the Cool GTL process for converting biogas to high quality gasoline, jet, and diesel fuels. The technoeconomics and LCA for the combination of the two technologies results an integrated optimized process, which will be discussed. The Cool GTL process is still in development and the development should be complete by 2023. Cool GTL converts high CO2 content feeds to synthesis gas with a 2-2.4/1 H2/CO ratio suitable for fuels synthesis. The process is based on a novel, highly stabile CO2/steam reforming catalyst. The 2.0-2.4/1 H2/CO synthesis gas ratio is always achieved, independently of feed CO2 content, by adjusting the amount of water added according to the amount of CO2 in the feed. The reformer catalyst has been tested for 500 hours and shows no measurable deactivation. The product from the reformer then goes directly to a low temperature slurry bed Fischer Tropsch reactor with an integrated finishing hydroisomerization reactor which makes hydrocarbon liquids from the synthesis gas. With this configuration no wax is produced. The technoeconomics and carbon intensity for the integration of UGas and the Cool GTL processes will be compared to other biomass conversion approaches. The use of electrolysis to boost H2 in the feed and increase liquid production will also be analyzed as a potential process improvement with sensitivities to the cost of electricity and the use of renewable electricity.

09 BIOMASS FUELS↗
DOE OSTI2025

Investigating the Impact of Absorbed Surface Impurities (CO, CO 2 , CH 4 , and H 2 O) on Getter Rate Performance

This report provides an overview of engineering and experimental efforts to establish a new capability for measuring H2 uptake rates for Tritium Producing Abosrber Rod (TPBAR) getter materials. This new system was used to gain a better understanding of the impact of contaminant species (CO 2 , CO, CH 4 , and H 2 O) on getter performance under relevant hydrogen uptake conditions (350 °C, 20 torr). Herein, we successfully established a high-resolution gravimetric sorption (HRGS) system in a flow through configuration that can measure sample mass changes with high resolution (1 µg or 10 µg) over long experiment times (days), high temperature, and varying pressures. We coupled this capability with an in-line universal gas analyzer (UGA) system to characterize potential surface chemistry side reactions occurring after contaminant gas exposure. The major findings of this study suggest that methane and CO have the most detrimental effects on getter H 2 uptake performance showing large changes in rate after exposure compared to CO 2 and water. The effect of these contaminant species did not influence getter sample capacity (~ 1.8 wt% H 2 ). After CO and methane exposure, changes in getter rate were accompanied by observable Ni-surface defects and pinholes via SEM imaging suggesting possible Ni- layer corrosion. Additionally, the increase in C and O signal in the zircaloy layer, observed via EDX, point to C and O species transport through the getter sample resulting in the formation of carbides and oxide species. Thus, co-exposure studies where mixed gases or water vapor are introduced together will be important to further understand what mechanisms are contributing to Ni-layer corrosion and changes in getter performance.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Genome Analysis of a Verrucomicrobial Endosymbiont With a Tiny Genome Discovered in an Antarctic Lake

Organic Lake in Antarctica is a marine-derived, cold (–13°C), stratified (oxic-anoxic), hypersaline (>200 gl –1 ) system with unusual chemistry (very high levels of dimethylsulfide) that supports the growth of phylogenetically and metabolically diverse microorganisms. Symbionts are not well characterized in Antarctica. However, unicellular eukaryotes are often present in Antarctic lakes and theoretically could harbor endosymbionts. Here, we describe Candidatus Organicella extenuata, a member of the Verrucomicrobia with a highly reduced genome, recovered as a metagenome-assembled genome with genetic code 4 (UGA-to-Trp recoding) from Organic Lake. It is closely related to Candidatus Pinguicocccus supinus (163,218 bp, 205 genes), a newly described cytoplasmic endosymbiont of the freshwater ciliate Euplotes vanleeuwenhoeki (Serra et al., 2020). At 158,228 bp (encoding 194 genes), the genome of Ca. Organicella extenuata is among the smallest known bacterial genomes and similar to the genome of Ca. Pinguicoccus supinus (163,218 bp, 205 genes). Ca. Organicella extenuata retains a capacity for replication, transcription, translation, and protein-folding while lacking any capacity for the biosynthesis of amino acids or vitamins. Notably, the endosymbiont retains a capacity for fatty acid synthesis (type II) and iron–sulfur (Fe-S) cluster assembly. Metagenomic analysis of 150 new metagenomes from Organic Lake and more than 70 other Antarctic aquatic locations revealed a strong correlation in abundance between Ca. Organicella extenuata and a novel ciliate of the genus Euplotes. Like Ca. Pinguicoccus supinus, we infer that Ca. Organicella extenuata is an endosymbiont of Euplotes and hypothesize that both Ca. Organicella extenuata and Ca. Pinguicocccus supinus provide fatty acids and Fe-S clusters to their Euplotes host as the foundation of a mutualistic symbiosis. The discovery of Ca. Organicella extenuata as possessing genetic code 4 illustrates that in addition to identifying endosymbionts by sequencing known symbiotic communities and searching metagenome data using reference endosymbiont genomes, the potential exists to identify novel endosymbionts by searching for unusual coding parameters.

59 BASIC BIOLOGICAL SCIENCES↗