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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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NASA NTRS1976

Origin of organic compounds on the primitive earth and in meteorites

The paper examines the role and relative contributions of different forms of energy to the synthesis of amino acids and other organic compounds on the primitive earth and in the solar nebula. Attention is directed mainly to the activation steps and formation of reactive intermediate compounds. Electric discharges appear to be not only the most efficient energy for amino acid synthesis but also yield a mixture of amino acids that is qualitatively and quantitatively the same as that found in the Murchison carbonaceous chondrite. Ultraviolet light is likely to have played a major role in prebiotic synthesis. The reaction of CO plus H2 plus NH3 on the surface of a Fischer-Tropsch catalyst produces reactive intermediates which lead to amino acids and other organic compounds in a much less efficient way than electric discharges.

Miller, S. L.↗

NASA NTRS1987

Solitary waves in the resonant phenomenon between a surface gravity wave packet and an internal gravity wave

A two-layer inviscid incompressible fluid system of intermediate depth is considered. A multiple-scales perturbation technique is applied to the basic equations and boundary conditions for a two-layer fluid system to derive a system of weakly nonlinear partial integrodifferential equations governing the resonant interaction between a surface gravity wave packet and an internal gravity wave at an intermediate depth, providing a bridge between the existing shallow and deep fluid theories. The convolution integral term in these equations accounts for the dispersion in the lower-layer fluid. An iterative fast Fourier transform scheme is developed to find solitary wave solutions to this system of equations. The overtaking collision of two pairs of solitary waves, simulated using a spectral method, is found to be inelastic. It is found that the amplitude of the solitary waves changes slightly after the collision. The phase shifts these solitary waves undergo was calculated numerically.

Sepulveda, Nicasio↗

DOE OSTI2023

Applying the core-satellite species concept: Characteristics of rare and common riverine dissolved organic matter

Introduction: Dissolved organic matter (DOM) composition varies over space and time, with a multitude of factors driving the presence or absence of each compound found in the complex DOM mixture. Compounds ubiquitously present across a wide range of river systems (hereafter termed core compounds) may differ in chemical composition and reactivity from compounds present in only a few settings (hereafter termed satellite compounds). Here, we investigated the spatial patterns in DOM molecular formulae presence (occupancy) in surface water and sediments across 97 river corridors at a continental scale using the “Worldwide Hydrobiogeochemical Observation Network for Dynamic River Systems—WHONDRS” research consortium. Methods: We used a novel data-driven approach to identify core and satellite compounds and compared their molecular properties identified with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Results: In this work, we found that core compounds clustered around intermediate hydrogen/carbon and oxygen/carbon ratios across both sediment and surface water samples, whereas the satellite compounds varied widely in their elemental composition. Within surface water samples, core compounds were dominated by lignin-like formulae, whereas protein-like formulae dominated the core pool in sediment samples. In contrast, satellite molecular formulae were more evenly distributed between compound classes in both sediment and water molecules. Core compounds found in both sediment and water exhibited lower molecular mass, lower oxidation state, and a higher degree of aromaticity, and were inferred to be more persistent than global satellite compounds. Higher putative biochemical transformations were found in core than satellite compounds, suggesting that the core pool was more processed. Discussion: The observed differences in chemical properties of core and satellite compounds point to potential differences in their sources and contribution to DOM processing in river corridors. Overall, our work points to the potential of data-driven approaches separating rare and common compounds to reduce some of the complexity inherent in studying riverine DOM.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2025

Impact of Hydroxyl Functionalization and Unsaturation on Linear Poly(ethylene- co -vinyl alcohol)

Functionalization of C═C in unsaturated polyolefins by hydroboration/oxidation successfully generates linear poly(ethylene-co-vinyl alcohol) (LEVOH) polymers. This postpolymerization modification expands upon previously reported chemistry to control the extent of functionalization through reagent stoichiometry. Partial functionalization (24–92% of C═C) of polycyclooctene produces materials with both C═C in the backbone and pendant OH and subsequent hydrogenation generate a LEVOH. We explore the thermal, structural, surface, and adhesive properties of these LEVOH and the partially unsaturated intermediate and find they are impacted by both the extent of OH incorporation and saturation. The presence of C═C significantly reduces the melting temperature and crystallinity while increasing surface polarity and adhesive strength compared with saturated polymers at equivalent functionalization. Furthermore, this investigation demonstrates linear analogs of EVOH with a wide range of properties tuned by extent of hydroxylation and presence of unsaturation.

Crystal structure↗

DOE OSTI2023

Mechanistic Insights into Nonoxidative Ethanol Dehydrogenation on NiCu Single-Atom Alloys

Ethanol dehydrogenation presents a promising pathway towards the production of acetaldehyde, a valuable building block in chemicals production. Under non-oxidative conditions, the reaction is facilitated by supported Cu nanoparticles which afford reasonable activity and high selectivity. The stability issues associated with Cu nanoparticle sintering can be addressed by the addition of small amounts of Ni, which further boost reactivity while retaining selectivity. Despite the promise of NiCu single-atom alloys for non-oxidative ethanol dehydrogenation, little is known about the role of each component and the pathway of this mechanistically complex process. Herein, kinetic investigations from reactor tests identify C-H bond scission as the rate limiting step, while 1-hydroxyethyl is detected as the intermediate via IR spectroscopy. Temperature program desorption studies are employed to examine the effect of Ni coverage and to demonstrate that Ni atoms activate ethanol selectively at lower temperatures, resulting in higher acetaldehyde yield than pure Cu. Temperature program desorption experiments also reveal the spillover of intermediates from the Ni atom to neighboring Cu sites as a relevant step in the reaction pathway. Density functional theory calculations are used to investigate the 2 reaction energetics and to confirm that C-H bond scission is the initial reaction step, while a clear effect of H 2 partial pressure on the reaction pathway is realized. Further, counter to the expected behavior that all reaction steps take place on the Ni atoms, our degree of rate control analysis reveals that a mechanism involving spillover of the 1-hydroxyethyl intermediate from the Ni atom to the Cu surface, where it will dehydrogenate further, is more likely. Furthermore, our combined kinetic, spectroscopic, and theoretical approach sheds light on this complex reaction mechanism and represents a promising method for the understanding and designing of highly active, selective, and stable single-atom alloys for other multistep catalytic processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Towards atom-level understanding of metal oxide catalysts for the oxygen evolution reaction with machine learning

Abstract Green hydrogen production is crucial for a sustainable future, but current catalysts for the oxygen evolution reaction (OER) suffer from slow kinetics, despite many efforts to produce optimal designs, particularly through the calculation of descriptors for activity. In this study, we develop a dataset of density functional theory calculations of bulk and surface perovskite oxides, and adsorption energies of OER intermediates, which includes compositions up to quaternary and facets up to (555). We demonstrate that per-site properties of perovskite oxides such as Bader charge or band center can be tuned through element substitution and faceting, and develop a machine learning model that accurately predicts these properties directly from the local chemical environment. We leverage these per-site properties to identify promising perovskites with high theoretical OER activity. The identified design principles and promising materials provide a roadmap for closing the gap between current artificial catalysts and biological enzymes such as photosystem II.

Chemistry↗

NASA NTRS1974

Radiometric diameters and albedos of 40 asteroids

The radiometric method of measuring the albedos and sizes of small airless objects was applied to forty asteroids. The largest asteroids were revealed to be 1 Ceres, 2 Pallas, 4 Vesta, 10 Hygiea, and 511 Davida. The highest albedo belonged to 4 Vesta. The darkest asteroids were 19 Fortuna, 324 Bamberga, and 747 Winchester. A comparison of the derived diameters and albedos with photometrically measured colors reveals three distinct classes of objects. The largest group is those with red color and albedos in the lunar range. The second group, which includes most of the largest objects, is characterized by more neutral color and lower albedo. The third class has one member, 4 Vesta, an object of high albedo and intermediate color. Objects in the first group have surfaces composed presumably of silicate minerals. The second and third groups may be similar in composition to the carbonaceous chondrites and the basaltic achondrite meteorites, respectively.

Morrison, D.↗

NASA NTRS1982

Uniform semiclassical quantization of regular and chaotic classical dynamics on the Henon-Heiles surface

Qualitative arguments are adduced which indicate that the apparently chaotic dynamics on the Henon-Heiles (1964) surface display sufficient regularity on a short to intermediate (but not long) time scale to allow the use of standard EBK quantization techniques. This takes advantage of the remnants of manifold structure implied. A complete uniform semiclassical quantization is performed using the time independent technique of the Birkhoff-Gustavson normal form, which was recently introduced in the context of semiclassical quantization by Swimm and Delos (1977, 1979).

Jaffe, C.↗

NASA NTRS1986

Compensation for Primary Reflector Wavefront Error

The object of the invention is to compensate for errors in a large telescope primary reflector by making certain compensating deviations in a smaller, auxiliary reflector of the telescope. At least one intermediate element forms an image of the primary surface onto the secondary surface, so each point on the secondary surface corresponds to a point on the primary surface. The secondary surface is formed with a deviation from an ideal secondary surface, with the piston distance of each point on the actual secondary surface equal to the piston distance of a corresponding piston on the actual primary surface from the ideal primary surface. It is found that this results in electromagnetic (e.g., light) rays which strike a deviating area of the actual primary surface being brought to the same focus as if the actual primary surface did not have a diviation from an ideal primary surface.

Meinel, A. B.↗

NASA NTRS1991

A conformal oxidation-resistant, plasma-polymerized coating

A comparative study was made of the surface recession (etching) of thin films of plasma polymerized tetrafluoro ethylene (PPTFE), polytetrafluoro ethylene (PTFE), and ion-beam sputter deposited polytetrafluoro ethylene (SPTFE) exposed to ground-state atomic oxygen downstream from a nonequilibrium radio-frequency O2 plasma. At 22 C, the etch rates for PTFE, SPTFE, and PPTFE were in the ratio of 8.7:1.8:1.0. A thin, conformal coating of PPTFE (etch rate of 0.3 nm/h at 22 C) was found to protect an underlying cast film of a reactive polymer, cis-1,4 polybutadiene, against ground-state atomic oxygen attack for the time required to fully etch away the PPTFE coating. From ESCA analysis, PTFE exhibited only minor surface oxidation (uptake of 0.5 atom percent O) upon etching, its F/C ratio decreasing slightly from 2.00 to 1.97; PPTFE exhibited considerable surface oxidation (uptake of 5.9 atom percent O) intermediate between those of PTFE and PPTFE, with a decrease in F/C ratio from 1.73 to 1.67. A plasma-polymerized fluorocarbon coating such as PPTFE might be useful for space applications to protect polymers that are vulnerable to oxidation or degradation by oxygen atoms.

Golub, Morton A.↗

NASA NTRS1992

Modelling of IR emission of interstellar clouds. I - Emission of isolated clouds and dust abundance variations

A model for the IR emission and extinction properties of small dust particles is used here to compute the IR emissions in the IRAS photometric bands for a set of isolated, spherical, and nonhomogeneous clouds heated by the local interstellar radiation field. It is predicted that the IR limb brightening (LB) in the IRAS photometric bands caused by selective absorption of UV photons of different energies in the cloud generally happens for central extinctions over 4 mag at 12 microns and greater than 10 mag at 100 microns and intermediate extinctions for the other IRAS bands. The surface brightness in the four IRAS bands is limited to about 0.4, 0.6, 3, and 10 MJy/sr at 12, 25, 60, and 100 microns respectively when no strong density discontinuity is present at the cloud edge.

Bernard, J. P.↗

NASA NTRS1993

Fluidic scale model multi-plane thrust vector control test results

An experimental investigation has been conducted at the NASA Langley 16-Foot Transonic Tunnel Static Test Facility to determine the concept feasibility of using fluidics to achieve multiplane thrust vector control in a 2D convergent-divergent (2D-CD) fixed aperture nozzle. Pitch thrust vector control is achieved by injection of flow through a slot in the divergent flap into the primary nozzle flow stream. Yaw vector control results from secondary air delivered tangentially to vertical Coanda flaps. These flaps are offset laterally and aligned parallel to the primary nozzle side walls. All tests were conducted at static (no external flow) conditions. Flow visualization was conducted using a paint flow technique and Focus Schlieren. Significant levels of pitch deflection angles (19 deg) were achieved at low pressure ratios and practical levels (14 deg) resulted at typical intermediate power settings. The ability of the Coanda surface blowing concept to produce yaw deflection was limited to NPR not greater than 4.

Chiarelli, Charles↗

NASA NTRS1995

Langley Research Center - Soluble Imide (LaRC-SI)

This report is about experimenting and developing uses for the new thermal plastic developed by Dr. Robert Bryant called the 'Langley Research Center - Soluble Imide' (LaRC-SI). The three developments are: the use of the LaRC-SI as a dielectric for thin film sensors, as an adhesive to place diamonds on surfaces to increase thermal conductivity, and as an intermediate layer to allow the placement of metal on aluminum nitride. The LaRC-SI was developed by Dr. Robert G. Bryant, a chemical engineer at NASA Langley Research Center. The unique properties of this material is that it is an amorphous thermoplastic. This means that it can be reformed at elevated temperature and pressures. It can be applied in the form of a spray, spin, dip coating, paint, or spread with a doctors blade. The LaRC-SI has excellent adhesive and dielectric properties. It can also be recycled. Potential applications for this material are resin for mechanical parts such as gears, bearings and valves, advanced composites like carbon fiber, high strength adhesives, thin film circuits, and as a dielectric film for placing electrical components on conductive materials.

Stang, David↗

DOE OSTI2023

Mechanistic Insights into the Catalytic Condensation of Methyl Ketones on MgO Surfaces

Ketone coupling via aldol condensation is one of the promising routes to produce cyclic and value-added precursors for renewable hydrocarbon biofuels. A first-principles-based microkinetic modeling is performed to evaluate the surface-mediated reaction mechanisms and the role of water molecules in the observed activities for 2-pentanone and 3-pentanone aldol condensation on dehydroxylated MgO(111) surface and hydroxylated terminated surface[OH-MgO(111)]. Here, we have identified the enhancement of the surface OH group to MgO(111) surface catalytic activity by destabilizing the binding strength of reaction intermediates and reducing the energy barriers of rate-determining steps(proton transfer and dehydration steps). The 2-pentanone has one elementary step less in the complete reaction mechanism of aldol condensation and preferable energy barrier for proton transfer and dehydration steps, revealing 2-pentanone as terminal ketone is more reactive than 3-pentanone as central ketone. The water molecules dominated the OH-MgO( 111) surface after further addition of water, leading to the reduction of turnover frequency of the aldol condensation dimer product as the loss of aldol condensation reaction intermediates in competitive adsorption with water molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1976

Hybrid-mode thermionic converter

Converter's collector electrode has uniform low work-function surface and operates at sufficiently low temperature to produce negligible electron emission. Emitter electrode has main region which has intermediate work-function and auxiliary region which has relatively high work-function surface.

Rasor, N. S.↗

DOE OSTI2022

Step-by-step state-selective tracking of fragmentation dynamics of water dications by momentum imaging

Abstract The double photoionization of a molecule by one photon ejects two electrons and typically creates an unstable dication. Observing the subsequent fragmentation products in coincidence can reveal a surprisingly detailed picture of the dynamics. Determining the time evolution and quantum mechanical states involved leads to deeper understanding of molecular dynamics. Here in a combined experimental and theoretical study, we unambiguously separate the sequential breakup via D + + OD + intermediates, from other processes leading to the same D + + D + + O final products of double ionization of water by a single photon. Moreover, we experimentally identify, separate, and follow step by step, two pathways involving the b 1 Σ + and a 1 Δ electronic states of the intermediate OD + ion. Our classical trajectory calculations on the relevant potential energy surfaces reproduce well the measured data and, combined with the experiment, enable the determination of the internal energy and angular momentum distribution of the OD + intermediate.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2023

Mineral surface-catalyzed oxidation of Mn(II) by bromate: Implications for the occurrence of Mn oxides on Mars

The occurrence of manganese (Mn) oxides on Mars is believed to be an indicator of an O 2 -rich paleoenvironment of Mars because Mn oxides often form through the oxidation of Mn(II) by O 2 on the surface of Earth. An alternative formation pathway was recently proposed, in which Mn(II) is oxidized by bromate (BrO 3 - ), a common oxidant in contemporary Martian regolith. However, the oxidation of Mn(II) by bromate in solution is kinetically controlled and slow unless using very high concentrations (100 mM) of reactants that may be irrelevant to the conditions of Mars. We conducted laboratory simulations to determine whether iron (Fe) oxides (hematite and goethite) and a phyllosilicate (montmorillonite), abundant minerals on the surface of Mars, could catalyze the oxidation of Mn(II) by bromate. Hematite and goethite, but not montmorillonite, dramatically accelerated the oxidation with a low concentration (1 mM) of Mn(II) and bromate under various solution conditions. Further, the reaction system was autocatalytic with Fe oxides initiating the oxidation of Mn(II) at the early stage and the subsequent catalysis mainly provided by the Mn oxide products. In contrast to producing Mn(IV)O 2 only during the homogeneous oxidation of Mn(II) by bromate in solutions, the heterogeneous mineral-surface catalyzed oxidation resulted in a mixture of Mn(III)OOH and Mn(IV)O 2 phases. Mn(III)OOH was an intermediate product and can be further oxidized by bromate to Mn(IV)O 2 . The occurrence and accumulation of the intermediate product MnOOH can be attributed to its rapid formation due to surface-enhanced nucleation and growth on Fe oxide surfaces and to its higher resistance to oxidation by bromate than Mn(III) ions or clusters. Overall, mineralsurface catalyzed oxidation of Mn(II) by bromate is favorable from both thermodynamic and kinetic perspectives, and can be a major pathway for the occurrence of Mn oxides on Mars where microorganisms are lacking to catalyze the reaction. Our study further improves our understanding of the thermodynamic and kinetic controls on Mn(II) oxidation.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2024

Revealing Local and Directional Aspects of Catalytic Active Sites by the Nuclear and Surface Electrostatic Potential

This work examines the prospects of using the electrostatic potential, V(r), as a descriptor in heterogeneous catalysis. In particular, the subatomic spatial resolution of the property allows for analysis of both directionality and confinement effects in surface adsorption. This feature of V(r) is used to identify adsorption sites, orientations, and energetics for metal surfaces, particles, and nanoclusters upon interactions with catalytically relevant intermediates. The use of V(r) in assessing the 3D nature of catalytic sites in low-temperature and electrocatalysis is highlighted, and future directions in catalysis design are discussed. Ultimately, we provide a critical analysis of the use of V(r) in the predictions of local adsorption susceptibilities, and we address its limitations. The link between V(r) and other established descriptors in catalysis are motivated via physical relations and theoretical derivations; close ties are established between V(r) and the d-band center (ε d ), as well as the surface site stability (BE M ). In conclusion, by comparing the performance of V(r) evaluated on isodensity contours, i.e., the surface electrostatic potential, to that of V(r) evaluated at the nucleus of an atom, we investigate the application space for a directional and an atom-localized version of the V(r) descriptor for catalyst design.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗