SEARCH · Search NASA
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Analysis of Al-26 and noble gases were conducted in a study of samples of two heavily weathered meteorites. The analyses were performed in accordance with procedures described by Cressy (1970) and by Herzog and Cressy (1974). The analytic data are presented in tables. Evidence is presented which implicates weathering as the most probable cause of the observed variation of Al-26 and the rare gas contents.
The Al-26 content of a group of stony meteorites with low levels of He-3 (implying outgassing caused by near approach to the sun) was analyzed in a test of the possible role of cosmic radiation in determining the radionuclide concentration of meteorites. The Al-26 contents of the meteorites with He-3 losses were found to be indistinguishable from the Al-26 contents of L- and H-chondrites. It is concluded that if the He-3 outgassing occurred near the sun, the flux of particles producing Al-26 must have been nearly normal, or the diffusion process must have taken place very rapidly.
Detailed experimental studies of the cyclic oxidation behavior of low-pressure plasma sprayed beta+gamma coasting on gamma-phase Ni-Cr-Al alloys have shown the correlation of weight change, oxide type, and Cr and Al concentration-distance profiles as a function of oxidation time. Of special interest was the transition to breakway oxidation due to the loss of the Al flux to the oxide and the failure of the coated alloy to form an Al2O3-rich oxide scale. The experimental results on beta+gamma/gamma coating systems were used as the basis of a numerical model (ternary, semi-infinite, finite-difference analysis) which accurately predicted changes in Cr and Al concentration-distance profiles. The model was used to study parameters critical to enhancing the life of coatings which fail by a combination of Al loss in forming the oxide scale and Al loss via interdiffusion with the substrate alloy. Comparisons of beta+gamma/gamma coating behavior are made to the oxidation of coated gamma+gamma-prime substrates, both ternary Ni-Cr-Al alloys and Mar-M 247-type alloys.
Despite the broad interest in Al-doped lithium lanthanum zirconium oxide (LLZO), the wide range of reported ionic conductivities suggests that the effect of processing parameters on the resulting phase purity and bulk conductivity is not well-understood. Here, in this work, we synthesized six separate series of LLZO with variations in Al concentration, Li excess, Li addition order, Li source, densification method, and mother powder to determine the effect on the composition, phase purity, density, and bulk conductivity. We found that a wider range of compositions (6.08–7.61 mol of Li and 0.06–0.23 mol of Al) than previously reported can result in cubic phase stability and that nearly all elements (Li, Al, Zr, and La) are lost to the MgO crucible during calcination and sintering. The manner in which different elements are lost is affected by the processing parameters. We observed that Al-doped LLZO shows great compositional flexibility in stabilizing the cubic phase, offering an explanation for the range of electrochemical performance metrics reported in the literature.
Previously computed rates of energy losses (Petrosian et al., 1967) ignored the presence of strong magnetic fields, hence the change brought in when such a field (about 10 to the 12th to 10 to the 13th power G) is included is studied. The results indicate that for T about 10 to the 8th power K and densities rho of about 10,000 g/cu cm, the presence of a strong H field decreases the energy losses by at the most a factor between 10 and 100 in the region up to rho = 1,000,000 g/cu cm. At higher densities the neutrino emissivities are almost identical.
Jordan is located on an important spot along the Mediterranean and Black Sea Flyway. Hundreds of migratory bird species have been identified stopping over in Jordan during spring and autumn migratory seasons. Compared to mammals and economically important birds, the microbiomes of wild bird species are severely understudied. Gut microbial composition is a valuable source of information that reflects food preferences, foraging behavior, and the risk of pathogen transmission to humans and other animals. In this study, we assessed the microbiome composition of three species of migrating passerines (willow warblers, lesser whitethroats, and common reed warblers) captured during the spring migration stopover in Jordan in 2023. A total of 59 fecal samples were selected evenly from the three species and subjected to 16S sequencing and microbiome analysis. Our objectives were to determine the diversity of bacteria in these three species, assess the amount of intra- and inter-specific variation, and detect pathogenic genera and species that could pose health risks to humans, domestic animals, and wildlife. Bacteria mainly belonged to the phyla Proteobacteria (62%), Actinobacteriota (18%), Firmicutes (13%), Cyanobacteria (5%), and Bacteroidota (1%). The results reveal that lesser whitethroats had the greatest variation in bacterial genus richness, Shannon diversity, and microbial composition compared to willow warblers and common reed warblers. The three bird species harbored several pathogenic genera and species, including Campylobacter, Enterococcus, Escherichia-Shigella, Mycoplasma, Rickettsia, Clostridium perfringens, and Vibrio cholerae. We suggest further investigation to understand the relationship between migratory behavior and their gut microbiome. We advocate for the use of advanced molecular techniques to characterize the pathogens found in migratory birds that might have public and environmental health impacts in addition to economic loss.
The radial diffusion equation with synchrotron losses is solved by the Laplace-transform method for near equatorially mirroring relativistic electrons. The evolution of a power-law distribution function is found, and the characteristics of synchrotron burnoff are stated in terms of explicit parameters for an arbitrary diffusion coefficient of a specific form. The peaking of the 10.4-cm volume emissivity from Jupiter at an L shell of about 1.8 provides an estimate of the diffusion coefficient in the radiation belts; one value is suggested as the appropriate modification, for an equatorial field strength of 4.2 G, of the Birmingham et al. (1974) result. Nonsynchrotron losses are included phenomenologically; from the phase-space densities reported by McIlwain and Fillius (1975), the particle lifetime is estimated. Asymptotic forms for the distribution in the strong synchrotron loss regime are provided.
The data shared in here are X-ray computed tomography (XCT) scans of a hexagonal fuel nozzle in 3 sections with the Metrotom 800 system at the Manufacturing Demonstration Facility (MDF) at Oak Ridge National Laboratory. The data are used in the paper "Tomographic Sparse View Selection using the View Covariance Loss, by Lin et al. (doi:10.1109/TPAMI.2025.36000720), accepted to the international conference on computational imaging (ICCP 2025). Figures 4-7 in the paper describe the part/XCT scan. File name Descriptions: Bottom section: TCR- Single Channeled SRC L 2019-3-18 12-26-41.hdf5 Medium section: TCR- Single Channeled SRC M 2019-3-18 13-8-9.hdf5 Top section: TCR- Single Channeled SRC T 2019-3-18 13-45-39.hdf5 Each hdf5 file contains projection data, and all the relevant X-ray CT scan setting. The full list of included attributes: distance_unit: Units of all distances specified angle_unit : Units of the angles angles: Array of all angles used voxel_size_xy: Baseline recon (if any) has this voxel size in the in-plane direction voxel_size_z: Baseline recon (if any) has this voxel size in the cross-plane direction det_pixel_size_col: Size of the detector pixels in the column dimension det_pixel_size_row: Size of the detector pixels in the row dimension src_iso_dist: Source to iso-center distance iso_det_dist: Iso-center to detector distance det_angle: If the detector is rotated/tilted, this angle corresponds to that value det_row_offset: Center of rotation offset in the vertical direction det_col_offset: Center of rotation offset in the horizontal direction reconstruction: A baseline reconstruction stored as 3D array BHC params: Beam-hardening parameters - Van De Casteel Model - if it has been used to pre-process the projections We also provided a python script (hdf_io.py) that allows the user to read the relevant data from each hdf5 file.
It is shown here that the experimental results of Newman (1985) and Tan et al. (1986) regarding the loss of oxygen interstitials during 450 C annealing of Czochralski silicon are consistent with the recently proposed model of Borenstein, Peak, and Corbett (1986) for thermal donor formation. Calculations were carried out for TD cores corresponding to O2, O3, O4, and/or O5 clusters. A simple model which attempts to capture the essential physics of the interstitial depletion has been constructed, and is briefly described.
This public dataset contains openly-documented, machine readable digital research data corresponding to figures published in C. Rodriguez Sanchez et al., “ Impurity Dynamics and Radiative Losses During Local Helicity Injection Startup in the Pegasus-III Spherical Tokamak,” accepted for publication in Physics of Plasmas .
Results are reported from acoustic transmission-loss measurements on 13 curved Al and composite aircraft-type panels (height 0.81 m, arc length 1.32 m, and curvature radius 2.29 m) without and with integral damping of various types. The fabrication of the panels and the test procedures are described and illustrated with photographs, and the results are presented in graphs. It is found that the loss of a curved panel exceeds the mass-law-predicted loss for a flat panel of the same material and thickness at frequencies below the ring frequency. At higher frequencies, the curved-panel loss is lower than the mass-law loss, being proportional to 20 time the log of thickness. Integral damping is found to be effective both below and above the ring frequency, but different mechanisms are responsible in each case.
Observations with the International Ultraviolet Explorer (IUE) have made possible a comparison between chromospheric radiative loss rates in the Mg II h and k lines and the Ca II H and K lines. Observations made by Stencel et al. (1980) confirm the findings of Linsky et al. (1979) that the chromospheric radiative loss rates in h and k and H and K are about equal for supergiants, but the h and k loss rate is greater than the H and K loss rate in giants. It is pointed out that this may result from physical differences between the lower chromospheres of giants and supergiants. The present investigation has the objective to explore the possibility of determining relative chromospheric radiative loss rates in F and G dwarf stars with low-resolution IUE spectra. It is found that this is possible. Cluster stars were selected to provide two temperature sequences at two slightly different metal abundances.
Quantum coherence in superconducting circuits has increased steadily over the last decades because of a growing understanding of the various loss mechanisms. Recently, tantalum (Ta) emerged as a promising material to address microscopic sources of loss found on niobium (Nb) or aluminum (Al) surfaces. However, the effects of film and interface microstructure on low-temperature microwave loss are still not well understood. Here, in this study, we present a systematic study of the structural and electrical properties of Ta and Nb films sputtered on c-plane sapphire at varying growth temperatures. As growth temperature was increased, our results show that the onset of epitaxial growth of α -phase Ta correlates with lower Ta surface roughness, higher critical temperature, and higher residual resistivity ratio, but surprisingly also correlates with a significant increase in loss at microwave frequency. Notably, this high level of loss is not observed in Nb films prepared in the same way and having very similar structure. By experimentally controlling the surface on which the Ta film is nucleated, we determine that the source of loss was only present in samples having an epitaxial Ta/sapphire interface and show that it was apparently mitigated by either growing a thin, epitaxial Nb interlayer between the Ta film and the substrate or by intentionally treating, and effectively damaging, the sapphire surface with an in situ argon plasma before Ta growth. In addition to elucidating this interfacial microwave loss, this work provides adequate process details to aid reproducible growth of low-loss Ta films across fabrication facilities.
A pack diffusion process has been developed which permits the introduction of nearly 6 wt % Al into solid solution in the near surface region of TDNiCr (Ni-20 wt % Cr-2 vol % ThO2) and Ni-20Cr. Alumina scales, adherent under cyclic heating and cooling conditions, were produced on TDNiCr-5.86Al upon exposure to an environment of 1330 N/sq m (10 torr) or 101,000 N/sq m (760 torr) air at temperatures of 1093 and 1204 C. While the same oxidation kinetics were observed in isothermal tests for Ni-14.6Cr-5.86Al as were obtained for the TDNiCr-5.86Al, the dispersion-strengthened alloy exhibited superior oxide scale adhesion during cyclic testing. At 1204 C, continuous weight gains were observed under all test conditions for TDNiCr-5.86Al, in contrast to the weight loss with time which occurred several hours after exposure of TDNiCr to an oxidizing environment. TDNiCr with an initial aluminum surface concentration of 4.95 wt % has nearly comparable oxidation resistance to the TDNiCr-5.86Al alloy.
Following the suggestion of Willson et al. (1987) that A- and F-type main-sequence stars might undergo significant mass loss due to pulsationally driven winds, upper limits to the ionized mass loss from A and F dwarfs have been obtained using VLA observations. These stringent upper limits show that the level of ionized mass loss would have at most only a small effect on stellar evolution. Radiative-equilibrium atmospheric and wind models for early A dwarfs indicate that it is highly likely that a wind flowing from such stars would be significantly ionized. In addition, late A and early F dwarfs exhibit chromospheric emission indicative of significant nonradiative heating. The present mass-loss limits are thus representative of the total mass-loss rates for these stars. It is concluded that A and F dwarfs are not losing sufficient mass to cause A dwarfs to evolve into G dwarfs.
Abstract This article presents an industry-relevant method for quantifying cellulose in mixed substrate samples. We built upon the cellulosic glucan measurement proposed by Sluiter et al. (2021) to investigate significant cellulose loss under cold caustic conditions, which has hindered the establishment of an industrially relevant method. To overcome this issue, we used dimethyl sulfoxide (DMSO) as an alternative solvent, which avoids mercerization reactions (Budtova and Navard 2015) but may leave some resistant starch in the sample. Treatment via an enzyme mixture removed starch and conformed to US Environmental Protection Agency (EPA) guidance on cellulose measurement by establishing quantitative de-starching via nuclear magnetic resonance (EPA 2022). The selective removal of yeast beta-glucan was accomplished using a commercially available Zymolyase. Our results demonstrated excellent reproducibility, with coefficients of variance of 7.14% or less, when measuring cellulose in low cellulose content samples. The method was tested on relevant lab and plant samples, showing an average 0.9% ethanol derived from the conversion of cellulose when cellulase was added to the process and zero response when no cellulase was added. These findings indicate that a cellulose method using DMSO and pullulanase provides a complete and accurate view of cellulose content, composition, and conversion in industrial fermentation processes.
The diffusion theory of inner belt protons is extended to lower energies for comparison with the data of Hovestadt et al. The effects of Coulomb energy loss, nuclear inelastic scattering, and the secular decrease of the earth's magnetic field are included. The Farley and Walt solar cycle averaged atmosphere and a neutron source based on the most recent measurements are used. It is found that diffusion theory can account for the observed flux of low-energy protons provided that the diffusion coefficient increases at smaller values of the first invariant. This result is interpreted as additional evidence for the importance of electrostatic field fluctuations in causing radial diffusion.
Alpha particle confinement is crucial for sustaining burning plasmas and designing future reactor concepts. Along with classical/prompt losses, various magnetohydrodynamic instabilities can lead to wave-particle interactions which can transport alpha particles outward from the plasma. This can result in a reduction in plasma heating/performance, and, at worst, damage in-vessel components. Joint European Torus’s recent deuterium–tritium campaigns in 2021–2023 have produced numerous alpha particle loss measurements with its scintillator probe and Faraday cup array fast ion loss detectors as discussed in Bonofiglo et al (2024 Nucl. Fusion 64 096038). This paper will report on integrated energetic particle transport modeling in support of those measurements. The modeling is accomplished with the TRANSP and ORBIT-kick codes with the use of recently developed reduced models which calculate mode structure, amplitude, and the evolving dynamics. When possible, constraints and comparisons to experiment are conducted. Case studies are performed on a variety of magnetohydrodynamic activity, including: fishbones, tearing modes (TMs), and sawtooth crashes. Additionally, a special case of an alpha-driven toroidal Alfvén eigenmode is briefly discussed, where modeling showed marginally weak alpha losses and was unable to support experimental observations. Coupled effects between a TM and toroidal field ripple are presented and were unable to replicate the observations in lost particle pitch but did duplicate the localized flattening of the measured neutron profile. Additional modeling results compare the magnitude of losses and energy/velocity-space sensitivities against experimental observations/measurements for each scenario. This work corroborates numeric alpha transport modeling while also identifying model deficiencies. While this report details alpha transport, it also presents open issues for discussion in assessing the validity of our numerical models towards burning plasmas.