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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

Ambulation Increases Decompression Sickness in Altitude Exposure

INTRODUCTION - Exercise accelerates inert gas elimination during oxygen breathing prior to decompression (prebreathe), but may also promote bubble formation and increase the risk of decompression sickness (DCS). The timing, pattern and intensity of exercise are likely critical to the net effect. The NASA Prebreathe Reduction Program (PRP) combined oxygen prebreathe and exercise preceding a 4.3 psi exposure in non-ambulatory subjects (a microgravity analog) to produce two protocols now used by astronauts preparing for extravehicular activity (CEVIS and ISLE). Additional work is required to investigate whether exercise normal to 1 G environments increases the risk of DCS over microgravity simulation. METHODS - The CEVIS protocol was replicated with one exception. Our subjects completed controlled ambulation (walking in place with fixed cadence and step height) during both preflight and at 4.3 psi instead of remaining non-ambulatory throughout. Decompression stress was graded with aural Doppler (Spencer 0-IV scale). Two-dimensional echocardiographic imaging was used to look for left heart gas emboli (the presence of which prompted test termination). Venous blood was collected at three points to correlate Doppler measures of decompression stress with microparticle (cell fragment) accumulation. Fisher Exact Tests compared test and control groups. Trial suspension would occur when DCS risk >15% or grade IV venous gas emboli (VGE) risk >20% (at 70% confidence). RESULTS - Eleven person-trials were completed (9 male, 2 female) when DCS prompted suspension. DCS was greater than in CEVIS trials (3/11 [27%] vs. 0/45 [0%], respectively, p=0.03). Statistical significance was not reached for peak grade IV VGE (2/11 [18%] vs. 3/45 [7%], p=0.149) or cumulative grade IV VGE observations per subject-trial (8/128 [6%] vs. 26/630 [4%], p=0.151). Microparticle data were collected for 5/11 trials (3 with DCS outcomes), with widely varying patterns that could not be resolved statistically. CONCLUSION - We did find that that ambulation increases decompression stress. Additional trials would improve the statistical power to assess differences in VGE and to evaluate the relationship between decompression stress and microparticles.

Conkin, Johnny↗
NASA NTRS2016

Ambulation During Periods of Supersaturation Increase Decompression Stress in Spacewalk Simulations

Musculoskeletal activity accelerates inert gas elimination during oxygen breathing prior to decompression (prebreathe), but may also promote bubble formation (nucleation) and increase the risk of decompression sickness (DCS). The timing, pattern and intensity of musculoskeletal activity and the level of tissue supersaturation are likely critical to the net effect. Understanding the relationships is important to evaluate exercise prebreathe protocols and quantify decompression risk in gravity and microgravity environments. The NASA Prebreathe Reduction Program (PRP) combined oxygen prebreathe and exercise preceding a low pressure (4.3 psia; altitude equivalent of 30,300 ft [9,235 m]) simulation exposure of non-ambulatory subjects (a microgravity analog) to produce two protocols now used by astronauts preparing for extravehicular activity. One protocol included both upright cycling and non-cycling exercise (CEVIS: 'cycle ergometer vibration isolation system') and one protocol relied on non-cycling exercise only (ISLE: 'in-suit light exercise'). CEVIS trial data serve as control data for the current study to investigate the influence of ambulation exercise in 1G environments on bubble formation and the subsequent risk of DCS.

Pollock, N. W.↗
NASA NTRS1981

The evolution of the lunar Nectaris multiring basin

The paper begins by discussing the pre-Nectaris crust, the formation of the basin, its age and its geophysics. The pre-mare basalt deposits are categorized into smooth plains deposits, cratered and patterned plains, knobby terrain, and massifs, and the structure, chemical composition, and probable origin of these are discussed. Alternative scenarios for the formation of the plains are that they consist of impact melt ejecta, ejecta overlying smoothed-out preexisting topographic material, or ejecta overlying extrusive deposits. The mare deposits are assessed in terms of their composition, basalt ages and thickness, and eruption styles. A probable age of 3.6 billion years for the basalts is given. The tectonics of mare ridges and fractures and floor-fractured craters are gone into. Post-mare cratering is also discussed. It is concluded that the morphology of multiring basins is strongly dependent on lithosphere thickness.

Whitford-Stark, J. L.↗
NASA NTRS2017

X-Ray Amorphous Phases in Terrestrial Analog Volcanic Sediments: Implications for Amorphous Phases in Gale Crater, Mars

X-ray diffraction (XRD) amorphous phases have been found as major components (approx.15-60 wt%) of all rock and soil samples measured by the CheMin XRD instrument in Gale Crater, Mars. The nature of these phases is not well understood and could be any combination of primary (e.g., glass) and secondary (e.g., allophane) phases. Amorphous phases form in abundance during surface weathering on Earth. Yet, these materials are poorly characterized, and it is not certain how properties like composition and structure change with formation environment. The presence of poorly crystalline phases can be inferred from XRD patterns by the appearance of a low angle rise (< or approx.10deg 2(theta)) or broad peaks in the background at low to moderate 2(theta) angles (amorphous humps). CheMin mineral abundances combined with bulk chemical composition measurements from the Alpha Particle X-ray Spectrometer (APXS) have been used to estimate the abundance and composition of the XRD amorphous materials in soil and rock samples on Mars. Here we apply a similar approach to a diverse suite of terrestrial samples - modern soils, glacial sediments, and paleosols - in order to determine how formation environment, climate, and diagenesis affect the abundance and composition of X-ray amorphous phases.

Smith, R. J.↗
DOE OSTI2024

Voltage and temperature effects on low cobalt lithium-ion battery cathode degradation

Degradation of low cobalt lithium-ion cathodes was tested using a full factorial combination of upper cut-off voltage (4.0 V and 4.3 V vs. Li/Li + ) and operating temperature (25 °C and 60 °C). Half-cell batteries were analyzed with electrochemical and microstructural characterization methods. Electrochemical performance was assessed with galvanostatic cycling, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) supported by distribution of relaxation times (DRT) analysis. Electrode microstructure was characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray absorption near edge structure (XANES) imaging. Higher cut-off voltage cycling shows presence of NiO x formation, a low diffusivity rock-salt phase, in both CV and XRD data. XRD patterns confirmed that the rock-salt phase was beginning to form at the low cut-off voltage at high temperature, but in much lower intensity than at the high cut-off voltage. Higher temperature accelerates degradation processes at both voltages. Degradation factors at high temperature include NiO x formation, cathode material dissolution, and electrolyte decomposition. SEM analysis suggests that supporting phases may isolate and disconnect active material particles reducing capacity retention and battery life cycle. DRT analysis and XANES imaging show that both high temperature samples revealed a NiO x phase based on an increased diffusive impedance and a visible shift in the XANES spectra. The low cut-off voltage, high temperature sample showed a split peak and shift to lower energies indicating early formation of the NiO x phase. The diffusive impedance, which hinders intercalation and deintercalation, is driven by the formation of the NiO x phase. While primarily driven by cut-off voltage, elevated temperature also contributes to this degradation mechanism.

electrochemical impedance spectroscopy↗
DOE OSTI2026

Recent efforts of vapour-phase strategies for EUV resist toward high- and hyper-NA extreme ultraviolet lithography

Extreme ultraviolet lithography (EUVL, λ = 13.5 nm) is critical for sub-1 nm technology nodes but remains constrained by inherent trade-offs among resolution, line-edge roughness (LER), and sensitivity. Stochastic effects originating from photon shot noise, low-energy secondary electron blur, and the random distribution of resist components further limit its advancement toward high numerical-aperture (NA, NA = 0.55) and hyper-NA (NA ≥0.75) EUVL. While the optimization of spin-on chemically amplified resists (CARs) continues, metal-oxide resists (MORs) have emerged as strong candidates for next-generation EUVL by incorporating metals with high EUV absorption coefficients, which enhances both resist sensitivity and etch resistance during pattern transfer. Besides spin-coating, recent advances in vapour-phase techniques, such as vapour-phase infiltration (VPI), chemical vapour deposition (CVD), and molecular atomic layer deposition (MALD), offer promising pathways to achieve new resist platforms, such as dry resists, that satisfy the stringent thickness and uniformity requirements of next-generation EUVL. These methods enable the direct incorporation of metal species into existing resist matrices or the formation of hybrid inorganic–organic resist platforms, thereby improving film uniformity, etch durability, and pattern fidelity while mitigating stochastic defects. This review highlights the latest advancements in vapour-phase-synthesized EUV resists, emphasizing material design, lithographic performance, and the underlying exposure mechanisms. Although still emerging, vapour-phase strategies are paving the way for an all-dry integration framework that could improve EUV patterning workflows and meet the demands of future technology nodes.

36 MATERIALS SCIENCE↗
NASA NTRS1993

Constraints on chemical evolution models from QSOALS abundances

Models of the formation and early chemical evolution of our Galaxy are guided and constrained by our knowledge of abundances in globular cluster stars and halo field stars. The abundance patterns identified in halo and disk stars should be discernible in absorption lines of gas clouds in forming galaxies which are accidentally lying in front of background QSO's. Conversely, the ensemble of QSO absorption line systems (QSOALS) at each redshift may suggest a detailed model for the formation of our Galaxy that is testable using abundance patterns in halo stars.

Lauroesch, J. T.↗
DOE OSTI2024

Reversible Electron-Beam Patterning of Colloidal Nanoparticles at Fluid Interfaces

The directed self-assembly of colloidal nanoparticles (NPs) using external fields guides the formation of sophisticated hierarchical materials but becomes less effective with decreasing particle size. As an alternative, electron-beam-driven assembly offers a potential avenue for targeted nanoscale manipulation, yet remains poorly controlled due to the variety and complexity of beam interaction mechanisms. Here, we investigate the beam–particle interaction of silica NPs pinned to the fluid–vacuum interface of ionic liquid droplets. In these experiments, scanning electron microscopy of the droplet surface resolves NP trajectories over space and time while simultaneously driving their reorganization. With this platform, we demonstrate the ability to direct particle transport and create transient, reversible colloidal patterns on the droplet surface. By tuning the beam voltage, we achieve precise control over both the strength and sign of the beam–particle interaction, with low voltages repelling particles and high voltages attracting them. This response stems from the formation of well-defined solvent flow fields generated from trace radiolysis of the ionic liquid, as determined through statistical analysis of single-particle trajectories under varying solvent composition. Altogether, electron-beam-guided assembly introduces a versatile strategy for nanoscale colloidal manipulation, offering new possibilities for the design of dynamic, reconfigurable systems with applications in adaptive photonics and catalysis.

36 MATERIALS SCIENCE↗
NASA NTRS1979

Frost streaks in the south polar cap of Mars

Viking Orbiter images of the annual south polar cap on Mars exhibit elongated bright features that are associated with craters and resemble wind streaks observed elsewhere on Mars. The study focuses on the well-documented frost streaks. The discussion covers the morphology of frost streaks, occurrence, seasonal behavior, thickness of frost in streak deposits, wind patterns inferred from frost streaks and other eolian features in the south polar region, formation of frost streaks, and other locales of preferential frost accumulation. The form and seasonal behavior of the bright elongated albedo markings which extend from the rims of many craters in the south polar cap suggest that they are accumulations of CO2 frost in the lee of craters. The frost streaks appear in the fall, increasing in length but not changing in direction during fall and winter. The frost streaks indicate a prograde circulation pattern of near-surface winds around the pole. Other details are also presented.

Thomas, P.↗
NASA NTRS1997

Ultrasonic Nondestructive Evaluation Techniques Applied to the Quantitative Characterization of Textile Composite Materials

In this Progress Report, we describe our further development of advanced ultrasonic nondestructive evaluation methods applied to the characterization of anisotropic materials. We present images obtained from experimental measurements of ultrasonic diffraction patterns transmitted through water only and transmitted through water and a thin woven composite. All images of diffraction patterns have been included on the accompanying CD-ROM in the JPEG format and Adobe TM Portable Document Format (PDF), in addition to the inclusion of hardcopies of the images contained in this report. In our previous semi-annual Progress Report (NAG 1-1848, December, 1996), we proposed a simple model to simulate the effect of a thin woven composite on an insonifying ultrasonic pressure field. This initial approach provided an avenue to begin development of a robust measurement method for nondestructive evaluation of anisotropic materials. In this Progress Report, we extend that work by performing experimental measurements on a single layer of a five-harness biaxial woven composite to investigate how a thin, yet architecturally complex, material interacts with the insonifying ultrasonic field. In Section 2 of this Progress Report we describe the experimental arrangement and methods for data acquisition of the ultrasonic diffraction patterns upon transmission through a thin woven composite. We also briefly describe the thin composite specimen investigated. Section 3 details the analysis of the experimental data followed by the experimental results in Section 4. Finally, a discussion of the observations and conclusions is found in Section 5.

Miller, James G.↗
NASA NTRS2011

Seafloor Control on Sea Ice

The seafloor has a profound role in Arctic sea ice formation and seasonal evolution. Ocean bathymetry controls the distribution and mixing of warm and cold waters, which may originate from different sources, thereby dictating the pattern of sea ice on the ocean surface. Sea ice dynamics, forced by surface winds, are also guided by seafloor features in preferential directions. Here, satellite mapping of sea ice together with buoy measurements are used to reveal the bathymetric control on sea ice growth and dynamics. Bathymetric effects on sea ice formation are clearly observed in the conformation between sea ice patterns and bathymetric characteristics in the peripheral seas. Beyond local features, bathymetric control appears over extensive ice-prone regions across the Arctic Ocean. The large-scale conformation between bathymetry and patterns of different synoptic sea ice classes, including seasonal and perennial sea ice, is identified. An implication of the bathymetric influence is that the maximum extent of the total sea ice cover is relatively stable, as observed by scatterometer data in the decade of the 2000s, while the minimum ice extent has decreased drastically. Because of the geologic control, the sea ice cover can expand only as far as it reaches the seashore, the continental shelf break, or other pronounced bathymetric features in the peripheral seas. Since the seafloor does not change significantly for decades or centuries, sea ice patterns can be recurrent around certain bathymetric features, which, once identified, may help improve short-term forecast and seasonal outlook of the sea ice cover. Moreover, the seafloor can indirectly influence cloud cover by its control on sea ice distribution, which differentially modulates the latent heat flux through ice covered and open water areas.

Nghiem, S. V.↗
NASA NTRS1997

An Experimental Study of Swirling Flows as Applied to Annular Combustors

This thesis presents an experimental study of swirling flows with direct applications to gas turbine combustors. Two separate flowfields were investigated: a round, swirling jet and a non-combusting annular combustor model. These studies were intended to allow both a further understanding of the behavior of general swirling flow characteristics, such as the recirculation zone, as well as to provide a base for the development of computational models. In order to determine the characteristics of swirling flows the concentration fields of a round, swirling jet were analyzed for varying amount of swirl. The experimental method used was a light scattering concentration measurement technique known as marker nephelometry. Results indicated the formation of a zone of recirculating fluid for swirl ratios (rotational speed x jet radius over mass average axial velocity) above a certain critical value. The size of this recirculation zone, as well as the spread angle of the jet, was found to increase with increase in the amount of applied swirl. The annular combustor model flowfield simulated the cold-flow characteristics of typical current annular combustors: swirl, recirculation, primary air cross jets and high levels of turbulence. The measurements in the combustor model made by the Laser Doppler Velocimetry technique, allowed the evaluation of the mean and rms velocities in the three coordinate directions, one Reynold's shear stress component and the turbulence kinetic energy: The primary cross jets were found to have a very strong effect on both the mean and turbulence flowfields. These cross jets, along with a large step change in area and wall jet inlet flow pattern, reduced the overall swirl in the test section to negligible levels. The formation of the strong recirculation zone is due mainly to the cross jets and the large step change in area. The cross jets were also found to drive a four-celled vortex-type motion (parallel to the combustor longitudinal axis) near the cross jet injection plane.

Seal, Michael Damian, II↗
DOE OSTI2026

Lignin structural changes and high p -coumaroylation in incipient lignification in moso bamboo

Lignification is a crucial process for strengthening plant tissues, facilitating water transport, and providing defense against pathogens. In the Poaceae family, p-hydroxycinnamic acids are commonly incorporated into lignin, with acylation by p-coumarate (pCA) occurring during lignification. In this study, we performed DFRC and 2D HSQC-NMR analyses to investigate changes in lignin substructures and the degree of lignin pCA-acylation throughout bamboo stem development. Furthermore, immunohistochemical analysis was conducted to elucidate the spatial distribution of lignin substructures within different cell types. Our results revealed that, in young tissues, β–O–4-linked lignin units are predominantly derived from monolignol-pCA conjugates, specifically coniferyl- and sinapyl-pCA. Both lignin structure and the pattern of pCA acylation varied depending on the stage of cell wall formation and the cell type, particularly between vascular fiber cells and parenchyma cells. Based on our results, moso bamboo culms exhibit a distinctive feature during incipient lignification, in which monolignols are predominantly acylated with pCA. As a result, this feature has not been reported in other grasses, suggesting that extensive p-coumaroylation of monolignols plays an important role in the rapid elongation of bamboo culms.

Munekata, Noriaki [Kyoto University (Japan); Unive↗
DOE OSTI2025

Strain release through hydrogen bond–mediated layer twisting

Strain engineering, enabling the precise control over structure and functional properties, is a key strategy for the design of advanced materials. However, the mechanisms governing strain evolution and release at the nanoscale remain largely unexplored. In this study, we leverage in situ heating transmission electron microscopy and synchrotron x-ray spectroscopy to investigate the strain relaxation pathways of boehmite (γ-AlOOH) at 575 kelvin by revealing real-time structural dynamics. Through tracking the moiré pattern evolution, we identify distinct strain release mechanisms, including layer twisting, defect formation, and domain restructuring. Our neural network potential calculations reveal that energy fluctuations at small twist angles are dominated by an interference-like interaction modulation of hydrogen bonds between boehmite interlayers, with metastable twisted structures corresponding to local minima of the potential energy landscape. This work establishes a previously unidentified paradigm of two-dimensional layer twisting mediated by hydrogen bonding, offering insights into strain-driven transformation mechanisms, and thus may have broad implications for strain in material and earth sciences.

36 MATERIALS SCIENCE↗
NASA NTRS1973

Utilizing ERTS-1 imagery for tectonic analysis through study of the Bighorn Mountains region

The author has identified the following significant results. Comparisons of imagery of three seasons, late summer-fall, winter, and spring indicate that for this region fall imagery is the best for overall geologic analysis. Winter scenes with light to moderate snow cover provide excellent topographic detail owing to snow enhancement, lower sun angle, and clarity of the atmosphere. Spring imagery has considerable reduction of tonal contrast owing to the low reflecting heavy green grass cover which subdues lithologic effects; heavy snow cover in the uplands masks topography. Mapping of geologic formations is impractical in most cases. Separation into tonal units can provide some general clues on structure. A given tonal unit can include parts of several geologic formations and different stratigraphic units can have the same tonal signature. Drainage patterns and anomalies provide the most consistent clues for detecting folds, monoclines, and homoclines. Vegetation only locally reflects lithology and structure. False color infrared 9 x 9 transparencies are the most valuable single imagery. Where these can be supplemented by U-2 color infrared for more detailed work, a tremendous amount of information is available. Adequately field checking such a large area just in one scene is the major logistic problem even in a fairly well known region.

Hoppin, R. A.↗
NASA NTRS1974

Application of remote sensing techniques in land-use planning: Flood-plain delineation

The delineation of areas subject to inundation by means of remotely-sensed data acquisition represents a considerable saving in personnel time. Repeated input from aerial sensor sources provides the planner with a potent tool for the formation of a data base and for the monitoring of land use patterns over a period of time. The primary output of this project was a set of base map overlays at a scale of 1:62,500 delineating areas which require special regulations when proposed for land use involving human habitation or certain classes of storage. A secondary product of the study was county-wide maps of watershed configurations and of soil hydrologic groups. Further research is anticipated to extend the mapping of watershed areas outside the political boundaries of Cochise County, which will provide data for subsequent rainfall-runoff relationship studies in the area. All of the data provided will be incorporated into the Cochise County composite computer mapping project now operational. Results of this project have improved the pool of information available to the planning staff of Cochise County.

Altenstadter, J.↗
NASA NTRS1986

Multicolor photometry of field galaxies to B = 24

The redshifts and colors of nearly 10,000 galaxies at galactic latitudes SA57 and SA68 were determined by photometric scans which included UV and near-IR bands, covering 0.5 sq deg of sky. Slopes were calculated for UV, IR, red and blue counts of galaxies with respect to the brightness detected. It was found that galaxies of magnitudes over 20 show increasingly greater UV excess, which may be indicative of star formation regions. Future applications of the data generated for examining galaxy clustering patterns and evolutionary scenarios are discussed.

Koo, David C.↗
NASA NTRS1994

Wind Streaks on Venus: Clues to Atmospheric Circulation

Magellan images reveal surface features on Venus attributed to wind processes. Sand dunes, wind-sculpted hills, and more than 5830 wind streaks have been identified. The streaks serve as local "wind vanes," representing wind direction at the time of streak formation and allowing the first global mapping of near-surface wind patterns on Venus. Wind streaks are oriented both toward the equator and toward the west. When streaks associated with local transient events, such as impact cratering, are deleted, the westward component is mostly lost but the equatorward component remains. This pattern is consistent with a Hadley circulation of the lower atmosphere.

Greeley, Ronald↗