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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Research study on stabilization and control modern sampled-data control theory

The methods of continuous and discrete describing function analysis were applied to predicting the existence of self-sustained oscillations in the single-axis model of the large space telescope system with nonlinear control moment gyroscope friction characteristics. It is shown that the stability equations may be solved by a numerical-iterative technique using the describing function analysis, instead of the usual graphical methods. The numerical method is found to be effective in leading to a convergent solution rapidly, with an appropriate guess of the initial condition.

Kuo, B. C.↗
DOE OSTI2022

Broken-Symmetry Density Functional Theory Analysis of the Ω Intermediate in Radical S -Adenosyl- l -methionine Enzymes: Evidence for a Near-Attack Conformer over an Organometallic Species

Radical S-adenosyl-L-methionine (SAM) enzymes are found in all domains of life and catalyze a wide range of biochemical reactions. Recently, an organometallic intermediate, Ω, has been experimentally implicated in the 5'-deoxyadenosyl radical generation mechanism of the radical SAM superfamily. In this work, we employ broken-symmetry density functional theory to evaluate several structural models of Ω. The results show that the calculated hyperfine coupling constants (HFCCs) for the proposed organometallic structure of Ω are inconsistent with the experiment. In contrast, a near-attack conformer of SAM bound to the catalytic [4Fe–4S] cluster, in which the distance between the unique iron and SAM sulfur is ~3 Å, yields HFCCs that are all within 1 MHz of the experimental values. Furthermore, these results clarify the structure of the ubiquitous Ω intermediate and suggest a paradigm shift reversal regarding the mechanism of SAM cleavage by members of the radical SAM superfamily.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2012

Giovanni: The Bridge between Data and Science

NASA Giovanni (Goddard Interactive Online Visualization ANd aNalysis Infrastructure) is a web-based remote sensing and model data visualization and analysis system developed by the Goddard Earth Sciences Data and Information Services Center (GES DISC). This web-based tool facilitates data discovery, exploration and analysis of large amount of global and regional data sets, covering atmospheric dynamics, atmospheric chemistry, hydrology, oceanographic, and land surface. Data analysis functions include Lat-Lon map, time series, scatter plot, correlation map, difference, cross-section, vertical profile, and animation etc. Visualization options enable comparisons of multiple variables and easier refinement. Recently, new features have been developed, such as interactive scatter plots and maps. The performance is also being improved, in some cases by an order of magnitude for certain analysis functions with optimized software. We are working toward merging current Giovanni portals into a single omnibus portal with all variables in one (virtual) location to help users find a variable easily and enhance the intercomparison capability

Shen, Suhung↗
DOE OSTI2013

Genome sequence and functional genomic analysis of the oil-degrading bacterium Oleispira antarctica

Ubiquitous bacteria from the genus Oleispira drive oil degradation in the largest environment on Earth, the cold and deep sea. Here we report the genome sequence of Oleispira antarctica and show that compared with Alcanivorax borkumensis—the paradigm of mesophilic hydrocarbonoclastic bacteria—O. antarctica has a larger genome that has witnessed massive gene-transfer events. We identify an array of alkane monooxygenases, osmoprotectants, siderophores and micronutrient-scavenging pathways. We also show that at low temperatures, the main protein-folding machine Cpn60 functions as a single heptameric barrel that uses larger proteins as substrates compared with the classical double-barrel structure observed at higher temperatures. With 11 protein crystal structures, we further report the largest set of structures from one psychrotolerant organism. The most common structural feature is an increased content of surface-exposed negatively charged residues compared to their mesophilic counterparts. Our findings are relevant in the context of microbial cold-adaptation mechanisms and the development of strategies for oil-spill mitigation in cold environments.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

A comparative integrated transcript analysis and functional characterization of differential mechanisms for induction of liver hypertrophy in the rat

The main goal of the present work was to better understand the molecular mechanisms underlying liver hypertrophy (LH), a recurrent finding observed following acute or repeated drug administration to animals, using transcriptomic technologies together with the results from conventional toxicology methods. Administration of 5 terminated proprietary drug candidates from participating companies involved in the EU Innomed PredTox Project or the reference hepatotoxicant troglitazone to rats for up to a 14-day duration induced LH as the main liver phenotypic toxicity outcome. The integrated analysis of transcriptomic liver expression data across studies turned out to be the most informative approach for the generation of mechanistic models of LH. In response to a xenobiotic stimulus, a marked increase in the expression of xenobiotic metabolizing enzymes (XME) was observed in a subset of 4 studies. Accumulation of these newly-synthesized proteins within the smooth endoplasmic reticulum (SER) would suggest proliferation of this organelle, which most likely is the main molecular process underlying the LH observed in XME studies. In another subset of 2 studies (including troglitazone), a marked up-regulation of genes involved in peroxisomal fatty acid {beta}-oxidation was noted, associated with induction of genes involved in peroxisome proliferation. Therefore, an increase in peroxisome abundance would be the main mechanism underlying LH noted in this second study subset. Together, the use of transcript profiling provides a means to generate putative mechanistic models underlying the pathogenesis of liver hypertrophy, to distinguish between subtle variations in subcellular organelle proliferation and creates opportunities for improved mechanism-based risk assessment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Quantifying local exciton, charge resonance, and multiexciton character in correlated wave functions of multichromophoric systems

A new method for quantifying the contributions of local excitation, charge resonance, and multiexciton configurations in correlated wave functions of multichromophoric systems is presented. The approach relies on fragment-localized orbitals and employs spin correlators. Its utility is illustrated by calculations on model clusters of hydrogen, ethylene, and tetracene molecules using adiabatic restricted-active-space configuration interaction wave functions. In addition to the wave function analysis, this approach provides a basis for a simple state-specific energy correction accounting for insufficient description of electron correlation. The decomposition scheme also allows one to compute energies of the diabatic states of the local excitonic, charge-resonance, and multi-excitonic character. The new method provides insight into electronic structure of multichromophoric systems and delivers valuable reference data for validating excitonic models.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1992

Identification of aerodynamic models for maneuvering aircraft

The method based on Fourier functional analysis and indicial formulation for aerodynamic modeling as proposed by Chin and Lan is extensively examined and improved for the purpose of general applications to realistic airplane configurations. Improvement is made to automate the calculation of model coefficients, and to evaluate more accurately the indicial integral. Test data of large angle-of-attack ranges for two different models, a 70 deg. delta wing and an F-18 model, are used to further verify the applicability of Fourier functional analysis and validate the indicial formulation. The results show that the general expression for harmonic motions throughout a range of k is capable of accurately modeling the nonlinear responses with large phase lag except in the region where an inconsistent hysteresis behavior from one frequency to the other occurs. The results by the indicial formulation indicate that more accurate results can be obtained when the motion starts from a low angle of attack where hysteresis effect is not important.

Lan, C. Edward↗
DOE OSTI2021

Identification of LiH and nanocrystalline LiF in the solid–electrolyte interphase of lithium metal anodes

A comprehensive understanding of the solid–electrolyte interphase (SEI) composition is crucial to developing high-energy batteries based on lithium metal anodes. A particularly contentious issue concerns the presence of LiH in the SEI. In this work, we report on the use of synchrotron-based X-ray diffraction and pair distribution function analysis to identify and differentiate two elusive components, LiH and LiF, in the SEI of lithium metal anodes. LiH is identified as a component of the SEI in high abundance, and the possibility of its misidentification as LiF in the literature is discussed. LiF in the SEI is found to have different structural features from LiF in the bulk phase, including a larger lattice parameter and a smaller grain size (<3 nm). These characteristics favour Li + transport and explain why an ionic insulator, like LiF, has been found to be a favoured component for the SEI. Finally, pair distribution function analysis reveals key amorphous components in the SEI.

36 MATERIALS SCIENCE↗
DOE OSTI2023

A density functional theory analysis of the adsorption and surface chemistry of inorganic iodine species on graphitea

In the event of a nuclear accident, fission products may be released into the environment. The release of 131 I is of particular concern to human health. Iodine can be captured using a number of materials and frequently, this is accomplished with activated carbon impregnated with organic bases. Previous studies have used DFT and the graphite (0001) surface as a surrogate for adsorption, those studies focus on the species I • , I 2 , and CH 3 I. In this work we perform an ab initio study of the adsorption onto the surface of a graphite sheet of I 2 , CH 3 I, and inorganic acidic iodine species (HI, HOI, HIO 2 , and HIO 3 ), which were selected to examine the possible effect of oxidation state on adsorption. The PBE exchange-correlation functional with D3 dispersion was employed. It was found that for molecular iodine, the iodine atoms tended to either situate above the center of a hexagonal site on the graphite or directly atop a carbon atom with the lighter components resting closer to the graphite. For each species the relative binding energies spanned the range of 21–33 kJ mol -1 and graphite-iodine distance was in the range of 3.52–3.93 Å. In all cases we found no significant charge transfer between the iodine species and the graphite, thus we conclude that all the iodine species studied undergo strong physisorption to the graphite.

Ritzmann, Andrew M.↗
DOE OSTI2015

Structural comparison of four different antibodies interacting with human papillomavirus 16 and mechanisms of neutralization

Cryo-electron microscopy (cryo-EM) was used to solve the structures of human papillomavirus type 16 (HPV16) complexed with fragments of antibody (Fab) from three different neutralizing monoclonals (mAbs): H16.1A, H16.14J, and H263.A2. The structure-function analysis revealed predominantly monovalent binding of each Fab with capsid interactions that involved multiple loops from symmetry related copies of the major capsid protein. The residues identified in each Fab-virus interface map to a conformational groove on the surface of the capsomer. In addition to the known involvement of the FG and HI loops, the DE loop was also found to constitute the core of each epitope. Surprisingly, the epitope mapping also identified minor contributions by EF and BC loops. Complementary immunological assays included mAb and Fab neutralization. The specific binding characteristics of mAbs correlated with different neutralizing behaviors in pre- and post-attachment neutralization assays. - Highlights: • We present HPV16-Fab complexes from neutralizing mAbs: H16.1A, H16.14J, and H263.A2. • The structure-function analysis revealed predominantly monovalent binding of each mAb. • Capsid–Fab interactions involved multiple loops from symmetry related L1 proteins. • Besides the known FG and HI loops, epitope mapping also identified DE, EF, and BC loops. • Neutralizing assays complement the structures to show multiple neutralization mechanisms.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Atomic Structure of Au 329 (SR) 84 Faradaurate Plasmonic Nanomolecules

To design novel nanomaterials, it is important to precisely control the composition, determine the atomic structure, and manipulate the structure to tune the materials property. Here we present a comprehensive characterization of the material whose composition is Au329(SR)84 precisely, therefore referred to as a nanomolecule. The size homogeneity was shown by electron microscopy, solution X-ray scattering, and mass spectrometry. We proposed its atomic structure to contain the Au260 core using experiments and modeling of a total-scattering-based atomic-pair distribution functional analysis. HAADF- STEM images shows fcc-like 2.0 ± 0.1 nm diameter nanomolecules.

Kumara, Chanaka↗
DOE OSTI2016

Diverse mechanisms of metaeffector activity in an intracellular bacterial pathogen, Legionella pneumophila

Abstract Pathogens deliver complex arsenals of translocated effector proteins to host cells during infection, but the extent to which these proteins are regulated once inside the eukaryotic cell remains poorly defined. Among all bacterial pathogens, Legionella pneumophila maintains the largest known set of translocated substrates, delivering over 300 proteins to the host cell via its Type IVB , Icm/Dot translocation system. Backed by a few notable examples of effector–effector regulation in L. pneumophila , we sought to define the extent of this phenomenon through a systematic analysis of effector–effector functional interaction. We used Saccharomyces cerevisiae , an established proxy for the eukaryotic host, to query > 108,000 pairwise genetic interactions between two compatible expression libraries of ~330 L. pneumophila‐ translocated substrates. While capturing all known examples of effector–effector suppression, we identify fourteen novel translocated substrates that suppress the activity of other bacterial effectors and one pair with synergistic activities. In at least nine instances, this regulation is direct—a hallmark of an emerging class of proteins called metaeffectors, or “effectors of effectors”. Through detailed structural and functional analysis, we show that metaeffector activity derives from a diverse range of mechanisms, shapes evolution, and can be used to reveal important aspects of each cognate effector's function. Metaeffectors, along with other, indirect, forms of effector–effector modulation, may be a common feature of many intracellular pathogens—with unrealized potential to inform our understanding of how pathogens regulate their interactions with the host cell.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Pressure Induced Liquid-to-Liquid Transition in Zr-based Supercooled Melts and Pressure Quenched Glasses

Through high-energy x-ray diffraction and atomic pair density function analysis we find that Zr-based metallic alloy, heated to the supercooled liquid state under hydrostatic pressure and then quenched to room temperature, exhibits a distinct glassy structure. The PDF indicates that the Zr-Zr distances in this glass are significantly reduced compared to those quenched without pressure. Annealing at the glass transition temperature at ambient pressure reverses structural changes and the initial glassy state is recovered. This result suggests that pressure causes a liquid-to-liquid phase transition in this metallic alloy supercooled melt. Such a pressure induced transition is known for covalent liquids, but has not been observed for metallic liquids. The High Pressure Quenched glasses are stable in ambient conditions after decompression.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Metric freeness and projectivity for classical and quantum normed modules

In functional analysis, there are several diverse approaches to the notion of projective module. We show that a certain general categorical scheme contains all basic versions as special cases. In this scheme, the notion of free object comes to the foreground, and, in the best categories, projective objects are precisely retracts of free ones. We are especially interested in the so-called metric version of projectivity and characterize the metrically free classical and quantum (= operator) normed modules. Informally speaking, so-called extremal projectivity, which was known earlier, is interpreted as a kind of 'asymptotical metric projectivity'. In addition, we answer the following specific question in the geometry of normed spaces: what is the structure of metrically projective modules in the simplest case of normed spaces? We prove that metrically projective normed spaces are precisely the subspaces of l{sub 1}(M) (where M is a set) that are denoted by l{sub 1}{sup 0}(M) and consist of finitely supported functions. Thus, in this case, projectivity coincides with freeness. Bibliography: 28 titles.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

Functional insights of novel Bathyarchaeia reveal metabolic versatility in their role in peatlands of the Peruvian Amazon

ABSTRACT The decomposition of soil organic carbon within tropical peatlands is influenced by the functional composition of the microbial community. In this study, building upon our previous work, we recovered a total of 28 metagenome-assembled genomes (MAGs) classified as Bathyarchaeia from the tropical peatlands of the Pastaza-Marañón Foreland Basin (PMFB) in the Amazon. Using phylogenomic analyses, we identified nine genus-level clades to have representatives from the PMFB, with four forming a putative novel family (“CandidatusPaludivitaceae”) endemic to peatlands. We focus on theCa. Paludivitaceae MAGs due to the novelty of this group and the limited understanding of their role within tropical peatlands. Functional analysis of these MAGs reveals that this putative family comprises facultative anaerobes, possessing the genetic potential for oxygen, sulfide, or nitrogen oxidation. This metabolic versatility can be coupled to the fermentation of acetoin, propanol, or proline. The other clades outsideCa. Paludivitaceae are putatively capable of acetogenesis andde novoamino acid biosynthesis and encode a high amount of Fe 3+ transporters. Crucially, theCa. Paludivitaceae are predicted to be carboxydotrophic, capable of utilizing CO for energy generation or biomass production. Through this metabolism, they could detoxify the environment from CO, a byproduct of methanogenesis, or produce methanogenic substrates like CO 2 and H 2 . Overall, our results show the complex metabolism and various lineages of Bathyarchaeia within tropical peatlands pointing to the need to further evaluate their role in these ecosystems. IMPORTANCE With the expansion of theCandidatusPaludivitaceae family by the assembly of 28 new metagenome assembled genomes, this study provides novel insights into their metabolic diversity and ecological significance in peatland ecosystems. From a comprehensive phylogenic and functional analysis, we have elucidated their putative unique facultative anaerobic capabilities and CO detoxification potential. This research highlights their crucial role in carbon cycling and greenhouse gas regulation. These findings are essential for resolving the microbial processes affecting peat soil stability, offering new perspectives on the ecological roles of previously underexplored and underrepresented archaeal populations.

Microbiology↗
DOE OSTI2018

Infrastructure development for radioactive materials at the NSLS-II

The X-ray Powder Diffraction (XPD) Beamline at the National Synchrotron Light Source-II is a multipurpose instrument designed for high-resolution, high-energy X-ray scattering techniques. In this article, the capabilities, opportunities and recent developments in the characterization of radioactive materials at XPD are described. The overarching goal of this work is to provide researchers access to advanced synchrotron techniques suited to the structural characterization of materials for advanced nuclear energy systems. XPD is a new beamline providing high photon flux for X-ray Diffraction, Pair Distribution Function analysis and Small Angle X-ray Scattering. The infrastructure and software described here extend the existing capabilities at XPD to accommodate radioactive materials. Such techniques will contribute crucial information to the characterization and quantification of advanced materials for nuclear energy applications. We describe the automated radioactive sample collection capabilities and recent X-ray Diffraction and Small Angle X-ray Scattering results from neutron irradiated reactor pressure vessel steels and oxide dispersion strengthened steels.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

FERMI LARGE AREA TELESCOPE DETECTION OF GRAVITATIONAL LENS DELAYED γ-RAY FLARES FROM BLAZAR B0218+357

Using data from the Fermi Large Area Telescope (LAT), we report the first clear γ-ray measurement of a delay between flares from the gravitationally lensed images of a blazar. The delay was detected in B0218+357, a known double-image lensed system, during a period of enhanced γ-ray activity with peak fluxes consistently observed to reach >20-50 × its previous average flux. An auto-correlation function analysis identified a delay in the γ-ray data of 11.46 ± 0.16 days (1σ) that is ∼1 day greater than previous radio measurements. Considering that it is beyond the capabilities of the LAT to spatially resolve the two images, we nevertheless decomposed individual sequences of superposing γ-ray flares/delayed emissions. In three such ∼8-10 day-long sequences within a ∼4 month span, considering confusion due to overlapping flaring emission and flux measurement uncertainties, we found flux ratios consistent with ∼1, thus systematically smaller than those from radio observations. During the first, best-defined flare, the delayed emission was detailed with a Fermi pointing, and we observed flux doubling timescales of ∼3-6 hr implying as well extremely compact γ-ray emitting regions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Strain engineered pyrochlore at high pressure

Strain engineering is a promising method for next-generation materials processing techniques. Here, we use mechanical milling and annealing followed by compression in diamond anvil cell to tailor the intrinsic and extrinsic strain in pyrochlore, Dy 2 Ti 2 O 7 and Dy 2 Zr 2 O 7 . Raman spectroscopy, X-ray pair distribution function analysis, and X-ray diffraction were used to characterize atomic order over short-, medium-, and long-range spatial scales, respectively, under ambient conditions. Raman spectroscopy and X-ray diffraction were further employed to interrogate the material in situ at high pressure. High-pressure behavior is found to depend on the species and concentration of defects in the sample at ambient conditions. Overall, we show that defects can be engineered to lower the phase transformation onset pressure by ~50% in the ordered pyrochlore Dy 2 Zr 2 O 7 , and lower the phase transformation completion pressure by ~20% in the disordered pyrochlore Dy 2 Zr 2 O 7 . These improvements are achieved without significantly sacrificing mechanical integrity, as characterized by bulk modulus.

36 MATERIALS SCIENCE↗