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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

A bird of two hemispheres: an examination of Swainson’s hawk (Buteo swainsoni) ecology across a landscape of increasing wind energy development

The purpose of this study was to expand knowledge on the life history of Swainson’s hawks (Buteo swainsoni), including aspects of breeding, juvenile periods, migration, and risks posed by the wind energy industry. Data presented in this dissertation was collected in northern Texas (Armstrong, Carson, Hale, Hockley, Lubbock, Potter, Randall, and Swisher counties) from 2012 to 2018 and from satellite transmitters attached to hawks from 2012 to 2021. Information has been formatted to facilitate future publication of results and is presented here in discrete chapters grouping similar categories of information; some redundancy exists among chapters, but the bulk of each chapter contains unique analyses, results, and conclusions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Examining Bioethanol-Producing Ultrastructures with Electron Microscopy and Molecular Dynamics

A longstanding goal in the biofuel sector is to increase the efficiency of the circularization of the use of materials (1). One such instance is the degradation of plant material, such as cellulose, and converting it to biofuel via bacterial digestion (2). The bifunctional aldehyde-alcohol dehydrogenase (AdhE) from the anaerobic thermophile C. thermocellum seems to be vital for the production and cellular tolerance of bioethanol; however, it lacks the efficiency to produce ethanol at industry standards (3). Therefore, to understand how C. thermocellum AdhE functions, we used cryo-electron microscopy (cryo-EM) to obtain a 3.2 A structure of the AdhE complex. When compared to previously published structures from E. coli (4-6), we identified potential regions that control the native conformation of the ultrastructure, as well as located channels that isolate the intermediate aldehyde from the cellular milieu. This high-resolution structure, in combination with molecular dynamics simulations, provides insight into one example of substrate channeling and establishes a basis for future mutagenesis studies.

AdhE↗
DOE OSTI2022

Comparison of zirconium redistribution in BISON EBR-II models using FIPD and IMIS databases with experimental Post Irradiation Examination

The BISON code framework is utilized to model and analyze zirconium redistribution within UPuZr metallic fuels. The simulation results are compared against past experimental metallography data to validate the BISON code models. Various BISON models are implemented and compared to properly reflect the Zr present in past data.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

A New Search for Low-mass Dark Matter and an Examination and Reduction of the Uncertainty due to the Photoelectric Absorption Cross Section using a Cryogenic Silicon Detector with Single-charge Sensitivity

Many astrophysical observations point to the abundant existence of dark matter (DM) in the universe composed of particles beyond the Standard Model. However despite numerous experiments using different techniques, DM particles have yet to be directly observed. The Super Cryogenic Dark Matter Search (SuperCDMS) SNOLAB experiment will employ silicon and germanium crystal detectors operated at temperatures as low as 15~mK to probe DM interactions using phonon and ionization signals. Recently, R\&D; facilities have developed gram-sized high-voltage eV-scale (HVeV) silicon detectors that achieve single-electron-hole-pair resolution. By probing effective DM-electron interactions, these devices can be used for searches of low-mass DM candidates.This dissertation presents a DM search experiment known as HVeV Run~2 that employs a second-generation HVeV detector operated in an above-ground laboratory at Northwestern University (IL, USA). Energy spectra are obtained from a blind analysis with 0.39 and 1.2\,g-days of exposure with the detector biased at 60 and 100\,V, respectively. The 0.93~gram detector achieves a 3\,eV phonon energy resolution, corresponding to a world-leading charge resolution of 3\,\% of a single electron-hole pair for a detector bias of 100\,V. With charge carrier trapping and impact ionization effects incorporated into the DM signal models, the resulting exclusion limits are reported for inelastic DM-electron scattering for DM masses from 0.5--$10^{4}$\,MeV$/c^{2}$; in the mass range from 1.2--50\,eV$/c^{2}$ the limits for dark photon and axion-like particle absorption are reported.Several DM search experiments, including HVeV Run~2, are sensitive to low-mass DM candidates that rely on the temperature-dependent photoelectric absorption cross section of silicon. However discrepancies in the underlying literature data result in dominating systematic uncertainties on the DM exclusion limits. In order to reduce these systematic uncertainties, this dissertation presents a novel method of making a direct, low-temperature measurement of the photoelectric absorption cross section of silicon at energies near the band gap (1.2--2.8\,eV).

Wilson, Matthew James↗