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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 1,783 records · Page 99
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Specific conductivity, pH, dissolved oxygen, water temperature and alkalinity in-situ data; Slate River floodplain, Crested Butte, CO; March 2021-October 2021

This data package includes a time-series of field measurements from March to October 2021 in groundwater and surface water from the Slate River floodplain in Crested Butte, CO, a focus field site for the SLAC Floodplain Hydro-Biogeochemistry SFA. The data was generated as part of the work targeting the overarching research question for the SLAC SFA: How do ubiquitous subsurface interfaces mediate molecular-scale biogeochemical processes and groundwater quality in floodplains and watersheds? The data package includes 5 data files, one for each measured variable: specific conductivity, pH, dissolved oxygen, water temperature and alkalinity. All measurements were recorded in the field immediately after water sampling. Groundwater samples were extracted from a network of installed rhizons (Rhizosphere Research Products, part no. 19.60.21F, 0.6 micrometer mesh size) and piezometer wells within the floodplain. In addition to the data files, there is a terminology file explaining the terms used, a file level metadata file, and a sensor file with metadata about the sensors used.All files are in csv format.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Ongoing Data Platform Development for High-Temperature Gas-cooled Reactor (HTGR) Thermal-Fluid Experiments Supported by Nuclear Energy University Program (NEUP) [Presentation Slides]

There are in total 30NEUP projects focusing on the thermal-fluid experiments related with High-Temperature Gas-cooled Reactor (HTGR) from FY2009 to FY2021, producing a large amount of high-quality validation data, however, these valuable data has been scattering everywhere and not been disseminated to the community well, and final reports are available only from OSTI webpage. This could potentially be a huge waste, not only for government budget but also for the HTGR research community. To improve access to this HTGR validation data and optimize the return on the significant investment made by DOE and supported by the Advanced Reactor Technologies (ART) Gas-Cooled Reactor (GCR) program, we conducted a survey to assess completed and ongoing HTGR NEUP projects with the aim to develop a public-access data platform that can be used to retrieve code validation data and guide future NEUP investments.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Functional renormalization group approach to the Yang-Lee edge singularity

Here, we determine the scaling properties of the Yang-Lee edge singularity as described by a one-component scalar field theory with imaginary cubic coupling, using the nonperturbative functional renormalization group in 3 ≤ d ≤ 6 Euclidean dimensions. We find very good agreement with high-temperature series data in d = 3 dimensions and compare our results to recent estimates of critical exponents obtained with the four-loop ϵ = 6 - d expansion and the conformal bootstrap. The relevance of operator insertions at the corresponding fixed point of the RG β functions is discussed and we estimate the error associated with O(∂ 4 ) truncations of the scale-dependent effective action.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Effects of structure and volcanic stratigraphy on groundwater and surface water flow: Hat Creek basin, California, USA

Abstract Hydrogeologic systems in the southern Cascade Range in California (USA) develop in volcanic rocks where morphology, stratigraphy, extensional structures, and attendant basin geometry play a central role in groundwater flow paths, groundwater/surface-water interactions, and spring discharge locations. High-volume springs (greater than 3 m 3 /s) flow from basin-filling (<800 ka) volcanic rocks in the Hat Creek and Fall River tributaries and contribute approximately half of the average annual flow of the Pit River, the largest tributary to Shasta Lake. A hydrogeologic conceptual framework is constructed for the Hat Creek basin combining new geologic mapping, water-well lithologic logs, a database of active faults, LiDAR mapping of faults and volcanic landforms, streamflow measurements and airborne thermal infrared remote sensing of stream temperature. These data are used to integrate the geologic structure and the volcanic and volcaniclastic stratigraphy to create a three-dimensional interpretation of the hydrogeology in the basin. Two large streamflow gains from focused groundwater discharge near Big Spring and north of Sugarloaf Peak result from geologic barriers that restrict lateral groundwater flow and force water into Hat Creek. The inferred groundwater-flow barriers divide the aquifer system into at least three leaky compartments. The two downstream compartments lose streamflow in the upstream reaches (immediately downstream of the groundwater-flow barriers) and gain in downstream reaches with the greatest inflows immediately upstream of the barriers.

Geology↗
DOE OSTI2014

Visualizations of coherent center domains in local Polyakov loops

Quantum Chromodynamics exhibits a hadronic confined phase at low to moderate temperatures and, at a critical temperature T{sub C}, undergoes a transition to a deconfined phase known as the quark–gluon plasma. The nature of this deconfinement phase transition is probed through visualizations of the Polyakov loop, a gauge independent order parameter. We produce visualizations that provide novel insights into the structure and evolution of center clusters. Using the HMC algorithm the percolation during the deconfinement transition is observed. Using 3D rendering of the phase and magnitude of the Polyakov loop, the fractal structure and correlations are examined. The evolution of the center clusters as the gauge fields thermalize from below the critical temperature to above it are also exposed. We observe deconfinement proceeding through a competition for the dominance of a particular center phase. We use stout-link smearing to remove small-scale noise in order to observe the large-scale evolution of the center clusters. A correlation between the magnitude of the Polyakov loop and the proximity of its phase to one of the center phases of SU(3) is evident in the visualizations. - Highlights: • We produce visualizations of center clusters in Polyakov loops. • The evolution of center clusters with HMC simulation time is examined. • Visualizations provide novel insights into the percolation of center clusters. • The magnitude and phase of the Polyakov loop are studied. • A correlation between the magnitude and center phase proximity is evident.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

At least 10% shorter C–H bonds in cryogenic protein crystal structures than in current AMBER forcefields

High resolution protein crystal structures resolved with X-ray diffraction data at cryogenic temperature are commonly used as experimental data to refine forcefields and evaluate protein folding simulations. However, it has been unclear hitherto whether the C–H bond lengths in cryogenic protein structures are significantly different from those defined in forcefields to affect protein folding simulations. This article reports the finding that the C–H bonds in high resolution cryogenic protein structures are 10–14% shorter than those defined in current AMBER forcefields, according to 3709 C–H bonds in the cryogenic protein structures with resolutions of 0.62–0.79 Å. Also, 20 all-atom, isothermal–isobaric, 0.5-μs molecular dynamics simulations showed that chignolin folded from a fully-extended backbone formation to the native β-hairpin conformation in the simulations using AMBER forcefield FF12SB at 300 K with an aggregated native state population including standard error of 10 ± 4%. However, the aggregated native state population with standard error reduced to 3 ± 2% in the same simulations except that C–H bonds were shortened by 10–14%. Furthermore, the aggregated native state populations with standard errors increased to 35 ± 3% and 26 ± 3% when using FF12MC, which is based on AMBER forcefield FF99, with and without the shortened C–H bonds, respectively. These results show that the 10–14% bond length differences can significantly affect protein folding simulations and suggest that re-parameterization of C–H bonds according to the cryogenic structures could improve the ability of a forcefield to fold proteins in molecular dynamics simulations. - Highlights: • Cryogenic crystal structures are commonly used in computational studies of proteins. • C–H bonds in the cryogenic structures are shorter than those defined in forcefields. • A survey of 3709 C–H bonds shows that the cryogenic bonds are 10–14% shorter. • The 10–14% differences affect molecular dynamics simulations of protein folding. • Shortening C–H bonds by 10–14% can improve protein folding simulations.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Strength and rupture geometry of un-irradiated C26M FeCrAl under LOCA burst testing conditions

Ferritic iron-chromium-aluminum (FeCrAl) alloys are an accident tolerant fuel candidate to replace the incumbent Zr-based claddings. Nuclear grade FeCrAl alloys are marked by superior high temperature mechanical behavior and exceptional steam oxidation resistance, both of which increase safety margins during accident scenarios. In the present study, the loss of coolant accident (LOCA) burst behaviors of three un-irradiated commercially fabricated cladding materials in a simulated LOCA environment were compared: (1) T35Y2, a 1 st generation nuclear grade FeCrAl, (2) C26M, a 2 nd generation nuclear grade FeCrAl, and (3) Zircaloy-2. Both FeCrAl alloys showed improved mechanical strength and steam oxidation resistance compared to Zircaloy-2. C26M claddings burst at significantly higher temperatures for all tested engineering hoop stresses, had limited ballooning, and demonstrated preferential fuel retention behavior in terms of burst opening area and length. High temperature tensile data for C26M is also presented. For both un-irradiated FeCrAl alloys, it was found that a distinct “threshold” burst stress signified the transition between small and large openings. Finally, higher threshold hoop stresses were associated with higher uniaxial strength for the FeCrAl alloys, indicating that tensile data, rather than creep data, could be useful for predicting rupture size and assessing fuel dispersal concerns.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Short Communication: Observation of Initial Burst Release of Fission Gas from High-Burnup UO 2 Nuclear Fuel During Thermal Transient

A system was developed and tested to provide a deeper understanding of the fission gas release kinetics from nuclear fuel during thermal transients. Pressure, temperature, spectral data, and optical images were simultaneously collected during resistive sample heating, and all released gases were collected in liquid nitrogen-cooled charcoal traps. Standup testing was performed with a high-burnup nuclear fuel segment from rod section with an average local burnup of 77 GWd/tU. During heating, the segment released approximately 6 ± 2% of generated fission gas inventory after ramp heating to 460°C. Here, heating ceased when the sample ejected from the holder, as observed by constant imaging.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2012

Electrical properties and scaling behaviour of rare earth based Ho{sub 2}CoZrO{sub 6} double perovskite ceramics

Graphical abstract: The X-ray diffraction analysis suggests that the compound crystallizes in monoclinic phase at room temperature with β = 108.51 ± 0.021° (a = 8.1858 ± 0.0023 Å, b = 5.2599 ± 0.0027 Å, c = 7.9874 ± 0.0031 Å) and cell volume = 324.17 Å{sup 3}. The SEM image indicates the uniformity of the grains in the samples. The grain size of the microstructure of HCZ is found to be ∼0.48 μm on average. Display Omitted Highlights: ► The conduction mechanism in HCZ may be due to hopping of small polaron. ► The material shows semiconducting behaviour. ► Conductivity obeys Jonscher's power law with high frequency dispersion. ► Both long-range and localized relaxation are present. -- Abstract: The Ho{sub 2}CoZrO{sub 6} (HCZ) double perovskite has been prepared in polycrystalline form by solid state reaction technique. The analysis of the X-ray powder diffraction pattern indicates that the crystal structure is monoclinic at room temperature with cell parameters a = 8.1858 ± 0.0023 Å, b = 5.2599 ± 0.0027 Å, c = 7.9874 ± 0.0031 Å and β = 108.51 ± 0.021°. The compound shows significant frequency dispersion in its dielectric properties. The Cole–Cole model is used to determine the polydispersive nature of dielectric relaxation. The scaling behaviour of dielectric loss and imaginary electric modulus suggest that the relaxation describe same mechanism at various temperatures. Impedance data presented in the Nyquist plot (Z″ versus Z′) are used to identify an equivalent circuit and to know the bulk and interface contributions. The complex impedance analysis of HCZ exhibits the appearance of both the grain and the grain-boundary contribution. The frequency dependent conductivity spectra follow the universal power law. The magnitude of the activation energy indicates that the carrier transport is due to the hopping conduction.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Recent Advances in the Understanding of the Influence of Electric and Magnetic Fields on Protein Crystal Growth

Here, in this contribution we use nonconventional methods that help to increase the success rate of a protein crystal growth, and consequently of structural projects using X-ray diffraction techniques. In order to achieve this purpose, this contribution presents new approaches involving more sophisticated techniques of protein crystallization, not just for growing protein crystals of different sizes by using electric fields, but also for controlling crystal size and orientation. Also, this latter was possible through the use of magnetic fields that allow to obtain protein crystals suitable for both high-resolution X-ray and neutron diffraction crystallography where big crystals are required. This contribution discusses some pros, cons and realities of the role of electromagnetic fields in protein crystallization research, and their effect on protein crystal contacts. Additionally, we discuss the importance of room and low temperatures during data collection. Finally, we also discuss the effect of applying a rather strong magnetic field of 16.5 T, for shorts and long periods of time, on protein crystal growth, and on the 3D structure of two model proteins.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Honeycomb-like S = 5/2 Spin–Lattices in Manganese(II) Vanadates

We synthesized new complex manganese vanadate materials as high-quality single crystals in multi-millimeter lengths using a high-temperature, high-pressure hydrothermal method. We grew one compound, Mn 5 (VO 4 ) 2 (OH) 4 , from Mn 2 O 3 and V 2 O 5 in 3 M CsOH at 580 °C and 1.5 kbar. Changing the mineralizer to 1 M CsOH/3MCsCl leads to the formation of another product, Mn 6 O(VO 4 ) 2 (OH). Both compounds were structurally characterized by single-crystal X-ray diffraction (Mn 5 (VO 4 ) 2 (OH) 4 : C2/m, Z = 2, a = 9.6568(9) Å, b = 9.5627(9) Å, c = 5.4139(6) Å, β = 98.529(8)°; Mn 6 O(VO 4 ) 2 (OH): P21/m, Z = 2, a = 8.9363(12) Å, b = 6.4678(8) Å, c = 10.4478(13) Å, β = 99.798(3)°), revealing interesting low-dimensional transition-metal features. Mn 5 (VO 4 ) 2 (OH) 4 possesses complex honeycomb-type Mn–O layers, built from edge-sharing [MnO 6 ] octahedra in the bc plane, with bridging vanadate groups connecting these layers along the a-axis. Mn 6 O(VO 4 ) 2 (OH) presents a more complicated structure with both octahedral [MnO 6 ] and trigonal bipyramidal [MnO 5 ] units. A different pattern of planar honeycomb sheets are formed by edge-shared [MnO6] octahedra, and these sublattices are connected through edge-shared dimers of [MnO 5 ] trigonal bipyramids to form corrugated sheets. Vanadate groups again condense the sheets into a three-dimensional framework. Infrared and Raman spectroscopies indicated the presence of OH groups and displayed characteristic Raman scattering due to vanadate groups. Furthermore, temperature-dependent magnetic studies indicated Curie–Weiss behavior above 100 K with significant anti-ferromagnetic coupling for both compounds, with further complex magnetic behavior at lower temperatures. The data indicate canted anti-ferromagnetic order below 57 K in Mn 5 (VO 4 ) 2 (OH) 4 and below 45 K in Mn 6 O(VO 4 ) 2 (OH). Members of another class of compounds, K 2 M 3 (VO 4 ) 2 (OH) 2 (M = Mn, Co), also containing a honeycomb-type sublattice, were also synthesized to allow a comparison of the structural features across all three structure types and to demonstrate extension to other transition metals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Tetragonal BaCoO 3 : A Co 4+ Ferromagnetic Mott Insulator

We report the stabilization of the metastable body-centered tetragonal (BCT) phase of BaCoO 3 (BCT-BaCoO 3 ) under high-pressure (15 GPa) and hightemperature (1200 °C) conditions using a mixture precursor. This double perovskite adopts the EuTiO 3 -type structure (space group I4/mcm), as confirmed by powder Xray diffraction and high-resolution STEM. X-ray photoelectron spectroscopy indicates a predominant Co 4+ oxidation state without detectable oxygen vacancies. Magnetization and heat capacity measurements reveal ferromagnetic ordering at T C ∼ 107 K, attributable to the BCT-BaCoO 3 phase. Above this temperature, the mixed-phase sample exhibits Curie−Weiss paramagnetism, a low-spin to high-spin crossover upon cooling, and a possible intermediate-spin state at elevated temperatures. Resistivity data indicates insulating behavior with weak magnetoresistance. DFT and DFT + DMFT calculations suggest that the insulating state originates from an orbitally selective transition sensitive to the nominal valence of the Co-d shell. The metastable BCT-BaCoO 3 phase cannot be retained in pure form at ambient pressure but can be stabilized by embedding it in a disordered mixture, offering a potential route to discover and preserve other high-pressure phases under ambient conditions.

Magnetic properties↗
DOE OSTI2017

Laser ablation of sub-10 nm silver nanoparticles

Laser ablation of silver nanoparticles (NPs) was studied with laser post-ionization (LPI) time-of-flight mass spectrometry (TOF MS). Silver NPs containing ~15 000 Ag atoms (4 nm radius) were deposited by soft landing (energy 3 eV/atom) onto indium tin oxide (ITO)/glass substrates. Laser ablation was performed using frequency-doubled Ti:sapphire nanosecond pulsed laser irradiation at three different wavelengths (371, 401, and 421 nm), whereas for post-ionization, pulses from an F 2 laser were used. Laser fluences and time delay dependencies of Ag and In signals were obtained. Using these data, the temperature of the desorption source as well as its time duration were calculated. It was found that the peak temperature of NPs was above their melting point and they cooled down slowly, with temperature decay time of several hundreds of nanoseconds. This anomalous behavior was explained based on a model where the semiconducting ITO substrate is initially transparent to the desorption laser radiation but starts to adsorb it due to the temperature increase arising from heat exchange with NPs. Poor heat conduction in the ITO film creates conditions for long-lived hot spots on the surface and initiates further optical damage of the substrate. No difference in the ablation process due to plasmon resonance was detected, likely due to thermal expansion and melting of NPs during laser irradiation, which then broadens the plasmon absorption band enough to cover all wavelengths used. Here, these results clearly demonstrate that the process of NP interaction with laser radiation is governed not only by initial optical and thermophysical parameters of NPs and the surrounding media, but also by their alteration due to temperature increases during the irradiation process.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Probing Ligand Exchange in the P450 Enzyme CYP121 from Mycobacterium tuberculosis : Dynamic Equilibrium of the Distal Heme Ligand as a Function of pH and Temperature

CYP121 is a cytochrome P450 enzyme from Mycobacterium tuberculosis that catalyzes the formation of a C–C bond between the aromatic groups of its cyclodityrosine substrate (cYY). The crystal structure of CYP121 in complex with cYY reveals that the solvent-derived ligand remains bound to the ferric ion in the enzyme–substrate complex. Whereas in the generally accepted P450 mechanism, binding of the primary substrate in the active-site triggers the release of the solvent-derived ligand, priming the metal center for reduction and subsequent O 2 binding. In this work we employed sodium cyanide to probe the metal–ligand exchange of the enzyme and the enzyme–substrate complex. The cyano adducts were characterized by UV–vis, EPR, and ENDOR spectroscopies and X-ray crystallography. A 100-fold increase in the affinity of cyanide binding to the enzyme–substrate complex over the ligand-free enzyme was observed. The crystal structure of the [CYP121(cYY)CN] ternary complex showed a rearrangement of the substrate in the active-site, when compared to the structure of the binary [CYP121(cYY)] complex. Transient kinetic studies showed that cYY binding resulted in a lower second-order rate constant ( k on (CN) ) but a much more stable cyanide adduct with 3 orders of magnitude slower k off (CN) rate. A dynamic equilibrium between multiple high- and low-spin species for both the enzyme and enzyme–substrate complex was also observed, which is sensitive to changes in both pH and temperature. Our data reveal the chemical and physical properties of the solvent-derived ligand of the enzyme, which will help to understand the initial steps of the catalytic mechanism.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Magnetotransport of Sm 2 Ir 2 O 7 across the pressure-induced quantum-critical phase boundary

Rare-earth pyrochlore iridates host two interlocking magnetic sublattices of corner-sharing tetrahedra and can harbour a unique combination of frustrated moments, exotic excitations and highly correlated electrons. They are also the first systems predicted to display both topological Weyl semimetal and axion insulator phases. We have measured the transport and magnetotransport properties of single-crystal Sm 2 Ir 2 O 7 up to and beyond the pressure-induced quantum critical point for all-in-all-out (AIAO) Ir order at p c = 63 kbar previously identified by resonant X-ray scattering and close to which Weyl semimetallic behavior has been previously predicted. Our findings overturn the accepted expectation that the suppression of AIAO order should lead to metallic conduction persisting down to zero temperature. Instead, the resistivity-minimum temperature, which tracks the decrease in the AIAO ordering temperature for pressures up to 30 kbar, begins to increase under further application of pressure, pointing to the presence of a second as-yet unidentified mechanism leading to non-metallic behavior. The magnetotransport does track the suppression of Ir magnetism, however, with a strong hysteresis observed only within the AIAO phase boundary, similar to that found for Ho 2 Ir 2 O 7 and attributed to plastic deformation of Ir domains. Around pc we find the emergence of a new type of electronic phase, characterized by a negative magnetoresistance with small hysteresis at the lowest temperatures, and hysteresis-free positive magnetoresistance above approximately 5K. The temperature dependence of our low-temperature transport data are found to be best described by a model consistent with a Weyl semimetal across the entire pressure range.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Machine learning prediction of connectivity, biodiversity and resilience in the Coral Triangle

Abstract Even optimistic climate scenarios predict catastrophic consequences for coral reef ecosystems by 2100. Understanding how reef connectivity, biodiversity and resilience are shaped by climate variability would improve chances to establish sustainable management practices. In this regard, ecoregionalization and connectivity are pivotal to designating effective marine protected areas. Here, machine learning algorithms and physical intuition are applied to sea surface temperature anomaly data over a twenty-four-year period to extract ecoregions and assess connectivity and bleaching recovery potential in the Coral Triangle and surrounding oceans. Furthermore, the impacts of the El Niño Southern Oscillation (ENSO) on biodiversity and resilience are quantified. We find that resilience is higher for reefs north of the Equator and that the extraordinary biodiversity of the Coral Triangle is dynamic in time and space, and benefits from ENSO. The large-scale exchange of genetic material is enhanced between the Indian Ocean and the Coral Triangle during La Niña years, and between the Coral Triangle and the central Pacific in neutral conditions. Through machine learning the outstanding biodiversity of the Coral Triangle, its evolution and the increase of species richness are contextualized through geological times, while offering new hope for monitoring its future.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Thermodynamics of technetium: Reconciling theory and experiment using density functional perturbation analysis

The structure, lattice dynamics and thermodynamic properties of bulk technetium were investigated within the framework of density functional theory. The phonon density of states spectrum computed with density functional perturbation theory closely matches inelastic coherent neutron scattering measurements. The thermal properties of technetium were derived from phonon frequencies calculated within the quasi-harmonic approximation (QHA), which introduces a volume dependence of phonon frequencies as a part of the anharmonic effect. As a result, the predicted thermal expansion and isobaric heat capacity of technetium are in excellent agreement with available experimental data for temperatures up to ~1600 K.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Thermoelectric transport of semiconductor full-Heusler VFe 2 Al

Seebeck coefficient of VFe 2 Al over a wide range of doping levels can be explained only with a small band-gap ( E g ) range of 0.02–0.04 eV. This E g value is also consistent with high-temperature resistivity data of nominally stoichiometric VFe 2 Al.

Anand, Shashwat↗