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11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CeTh by Materials Project

ThCe crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Th sites. In the first Th site, Th is bonded to six equivalent Th and six Ce atoms to form ThCe6Th6 cuboctahedra that share corners with twelve ThCe6Th6 cuboctahedra, edges with twelve ThCe6Th6 cuboctahedra, edges with twelve CeCe6Th6 cuboctahedra, faces with six equivalent ThCe6Th6 cuboctahedra, and faces with twelve CeCe6Th6 cuboctahedra. All Th–Th bond lengths are 3.45 Å. All Th–Ce bond lengths are 3.46 Å. In the second Th site, Th is bonded to ten equivalent Th and six Ce atoms to form ThCe6Th10 cuboctahedra that share corners with ten CeCe6Th6 cuboctahedra, corners with twelve ThCe6Th6 cuboctahedra, edges with eight CeCe6Th6 cuboctahedra, edges with sixteen ThCe6Th6 cuboctahedra, faces with sixteen equivalent ThCe6Th10 cuboctahedra, and faces with eighteen CeCe6Th6 cuboctahedra. There are a spread of Th–Th bond distances ranging from 3.45–6.90 Å. All Th–Ce bond lengths are 3.46 Å. There are three inequivalent Ce sites. In the first Ce site, Ce is bonded to six equivalent Th and six equivalent Ce atoms to form CeCe6Th6 cuboctahedra that share corners with twelve CeCe6Th6 cuboctahedra, edges with twelve equivalent ThCe6Th6 cuboctahedra, edges with twelve CeCe6Th6 cuboctahedra, faces with six equivalent CeCe6Th6 cuboctahedra, and faces with twelve equivalent ThCe6Th6 cuboctahedra. All Ce–Ce bond lengths are 3.45 Å. In the second Ce site, Ce is bonded to six Th and six equivalent Ce atoms to form CeCe6Th6 cuboctahedra that share corners with five equivalent ThCe6Th10 cuboctahedra, corners with twelve CeCe6Th6 cuboctahedra, edges with ten ThCe6Th6 cuboctahedra, edges with twelve CeCe6Th6 cuboctahedra, faces with six equivalent CeCe6Th6 cuboctahedra, and faces with fifteen ThCe6Th6 cuboctahedra. All Ce–Th bond lengths are 3.46 Å. All Ce–Ce bond lengths are 3.45 Å. In the third Ce site, Ce is bonded to six Th and six equivalent Ce atoms to form CeCe6Th6 cuboctahedra that share corners with five equivalent ThCe6Th10 cuboctahedra, corners with twelve CeCe6Th6 cuboctahedra, edges with ten ThCe6Th6 cuboctahedra, edges with twelve CeCe6Th6 cuboctahedra, faces with six equivalent CeCe6Th6 cuboctahedra, and faces with fifteen ThCe6Th6 cuboctahedra. All Ce–Ce bond lengths are 3.45 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Enhanced terrestrial Fe(II) mobilization identified through a novel mechanism of microbially driven cave formation in Fe(III)-rich rocks

Most cave formation requires mass separation from a host rock in a process that operates outward from permeable pathways to create the cave void. Given the poor solubility of Fe(III) phases, such processes are insufficient to account for the significant iron formation caves (IFCs) seen in Brazilian banded iron formations (BIF) and associated rock. Here in this study we demonstrate that microbially-mediated reductive Fe(III) dissolution is solubilizing the poorly soluble Fe(III) phases to soluble Fe(II) in the anoxic zone behind cave walls. The resultant Fe(III)-depleted material (termed sub muros) is unable to maintain the structural integrity of the walls and repeated rounds of wall collapse lead to formation of the cave void in an active, measurable process. This mechanism may move significant quantities of Fe(II) into ground water and may help to explain the mechanism of BIF dissolution and REE enrichment in the generation of canga. The role of Fe(III) reducing microorganism and mass separation behind the walls (outward-in, rather than inward-out) is not only a novel mechanism of speleogenesis, but it also may identify a previously overlooked source of continental Fe that may have contributed to Archaean BIF formation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Genomic and morphological characterization of Knufia obscura isolated from the Mars 2020 spacecraft assembly facility

Members of the family Trichomeriaceae, belonging to the Chaetothyriales order and the Ascomycota phylum, are known for their capability to inhabit hostile environments characterized by extreme temperatures, oligotrophic conditions, drought, or presence of toxic compounds. The genus Knufia encompasses many polyextremophilic species. In this report, the genomic and morphological features of the strain FJI-L2-BK-P2 presented, which was isolated from the Mars 2020 mission spacecraft assembly facility located at the Jet Propulsion Laboratory in Pasadena, California. The identification is based on sequence alignment for marker genes, multi-locus sequence analysis, and whole genome sequence phylogeny. The morphological features were studied using a diverse range of microscopic techniques (bright field, phase contrast, differential interference contrast and scanning electron microscopy). The phylogenetic marker genes of the strain FJI-L2-BK-P2 exhibited highest similarities with type strain of Knufia obscura (CBS 148926 T ) that was isolated from the gas tank of a car in Italy. To validate the species identity, whole genomes of both strains (FJI-L2-BK-P2 and CBS 148926 T ) were sequenced, annotated, and strain FJI-L2-BK-P2 was confirmed as K. obscura. The morphological analysis and description of the genomic characteristics of K. obscura FJI-L2-BK-P2 may contribute to refining the taxonomy of Knufia species. Key morphological features are reported in this K. obscura strain, resembling microsclerotia and chlamydospore-like propagules. These features known to be characteristic features in black fungi which could potentially facilitate their adaptation to harsh environments.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Description and Genome Characterization of Three Novel Fungal Strains Isolated from Mars 2020 Mission-Associated Spacecraft Assembly Facility Surfaces—Recommendations for Two New Genera and One Species

National Aeronautics and Space Administration’s (NASA) spacecraft assembly facilities are monitored for the presence of any bacteria or fungi that might conceivably survive a transfer to an extraterrestrial environment. Fungi present a broad and diverse range of phenotypic and functional traits to adapt to extreme conditions, hence the detection of fungi and subsequent eradication of them are needed to prevent forward contamination for future NASA missions. During the construction and assembly for the Mars 2020 mission, three fungal strains with unique morphological and phylogenetic properties were isolated from spacecraft assembly facilities. The reconstruction of phylogenetic trees based on several gene loci (ITS, LSU, SSU, RPB, TUB, TEF1) using multi-locus sequence typing (MLST) and whole genome sequencing (WGS) analyses supported the hypothesis that these were novel species. Here we report the genus or species-level classification of these three novel strains via a polyphasic approach using phylogenetic analysis, colony and cell morphology, and comparative analysis of WGS. The strain FJI-L9-BK-P1 isolated from the Jet Propulsion Laboratory Spacecraft Assembly Facility (JPL-SAF) exhibited a putative phylogenetic relationship with the strain Aaosphaeria arxii CBS175.79 but showed distinct morphology and microscopic features. Another JPL-SAF strain, FJII-L3-CM-DR1, was phylogenetically distinct from members of the family Trichomeriaceae and exhibited morphologically different features from the genera Lithohypha and Strelitziana. The strain FKI-L1-BK-DR1 isolated from the Kennedy Space Center facility was identified as a member of Dothideomycetes incertae sedis and is closely related to the family Kirschsteiniotheliaceae according to a phylogenetic analysis. The polyphasic taxonomic approach supported the recommendation for establishing two novel genera and one novel species. The names Aaosphaeria pasadenensis (FJI-L9-BK-P1 = NRRL 64424 = DSM 114621), Pasadenomyces melaninifex (FJII-L3-CM-DR1 = NRRL 64433 = DSM 114623), and Floridaphiala radiotolerans (FKI-L1-BK-DR1 = NRRL 64434 = DSM 114624) are proposed as type species. Furthermore, resistance to ultraviolet-C and presence of specific biosynthetic gene cluster(s) coding for metabolically active compounds are unique to these strains.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2024

Susceptibility of extremophiles to far-UVC light for bioburden reduction in spacecraft assembly facilities

The prevention and reduction of microbial species entering and leaving Earth's biosphere is a critical aspect of planetary protection research. While various decontamination methods exist and are currently utilized for planetary protection purposes, the use of far-UVC light (200–230 nm) as a means for microbial reduction remains underexplored. Unlike conventional germicidal ultraviolet at 254 nm, which can pose a health risk to humans even with small exposure doses, far-UVC light poses minimal health hazard making it a suitable candidate for implementation in occupied areas of spacecraft assembly facilities. This study investigates the efficacy of far-UVC 222-nm light to inactivate bacteria using microbial species which are relevant to planetary protection either in vegetative cell or spore form. All the tested vegetative cells demonstrated susceptibility to 222-nm exposure, although susceptibility varied among the tested species. Notably, Deinococcus radiodurans, a species highly tolerant to extreme environmental conditions, exhibited the most resistance to far-UVC exposure with a dose of 112 mJ/cm 2 required for a 1-log reduction in survival. While spore susceptibility was similar across the species tested, Bacillus pumilus spores were the most resistant of the tested spores when analyzed with a bi-exponential cell killing model (D 90 of 6.8 mJ/cm 2 ). Overall, these results demonstrate the efficacy of far-UVC light for reducing microbial bioburden to help ensure the success and safety of future space exploration missions.

Ultraviolet light↗