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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Investigation of solid plume simulation criteria to produce flight plume effects on multibody configuration in wind tunnel tests

An investigation to determine the sensitivity of the space shuttle base and forebody aerodynamics to the size and shape of various solid plume simulators was conducted. Families of cones of varying angle and base diameter, at various axial positions behind a Space Shuttle launch vehicle model, were wind tunnel tested. This parametric evaluation yielded base pressure and force coefficient data which indicated that solid plume simulators are an inexpensive, quick method of approximating the effect of engine exhaust plumes on the base and forebody aerodynamics of future, complex multibody launch vehicles.

Frost, A. L.↗
DOE OSTI2024

Advanced Characterization of Solid-State Battery Materials Using Neutron Scattering Techniques

Advanced batteries require advanced characterization techniques, and neutron scattering is one of the most powerful experimental methods available for studying next-generation battery materials. Neutron scattering offers a non-destructive method to probe the complex structural and chemical processes occurring in batteries during operation in truly in situ/in operando measurements with a high sensitivity to battery-relevant elements such as lithium. Neutrons have energies comparable to the energies of excitations in materials and wavelengths comparable to atomic distances in the solid state, thus giving access to study structural and dynamical properties of materials on an atomic scale. In this review, a broad overview of selected neutron scattering techniques is presented to illustrate how neutron scattering can be used to gain invaluable information of solid-state battery materials, with a focus on in situ/in operando methods. These techniques span multiple decades of length and time scales to uncover the complex processes taking place fundamentally on the atomic scale and to determine how these processes impact the macroscale properties and performance of functional battery systems. This review serves the solid-state battery research community by examining how the unique capabilities of neutron scattering can be applied to answer critical and unresolved questions of materials research in this field. A thorough and broad perspective is provided with numerous practical examples showing these techniques in action for battery research.

25 ENERGY STORAGE↗
DOE OSTI2021

Are Contact Angle Measurements Useful for Oxide-Coated Liquid Metals?

This work establishes that static contact angles for gallium-based liquid metals have no utility despite the continued and common use of such angles in the literature. In the presence of oxygen, these metals rapidly form a thin (~1–3 nm) surface oxide “skin” that adheres to many surfaces and mechanically impedes its flow. This property is problematic for contact angle measurements, which presume the ability of liquids to flow freely to adopt shapes that minimize the interfacial energy. We show here that advancing angles for a metal are always high (>140°)—even on substrates to which it adheres—because the solid native oxide must rupture in tension to advance the contact line. The advancing angle for the metal depends subtly on the substrate surface chemistry but does not vary strongly with hydrophobicity of the substrate. During receding measurements, the metal droplet initially sags as the liquid withdraws from the “sac” formed by the skin and thus the contact area with the substrate initially increases despite its volumetric recession. Furthermore, the oxide pins at the perimeter of the deflated “sac” on all the surfaces are tested, except for certain rough surfaces. With additional withdrawal of the liquid metal, the pinned angle gets smaller until eventually the oxide “sac” collapses. Thus, static contact angles can be manipulated mechanically from 0° to >140° due to hysteresis and are therefore uninformative. We also provide recommendations and best practices for wetting experiments, which may find use in applications that use these alloys such as soft electronics, composites, and microfluidics.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Evolution of the Cellulose Microfibril through Gamma-Valerolactone-Assisted Co-Solvent and Enzymatic Hydrolysis

Biomass recalcitrance during deconstruction remains a key bottleneck to affordable biomass processing technologies. A clear connection between the cell wall structure and biomass deconstruction is necessary to understand how lignocellulosic material is broken down to valuable monomeric components. Here, we monitor changes in the cellulose microfibril domains of poplar, sorghum, and switchgrass throughout gamma-valerolactone (GVL)–water co-solvent pretreatment and enzymatic hydrolysis using solid-state 13 C cross-polarization magic angle spinning nuclear magnetic resonance spectroscopy (CP/MAS 13 C-NMR) and wide-angle X-ray scattering (WAXS). Spectral fitting of NMR peaks corresponding to different cellulose microenvironments at the C 4 carbon center suggests that a mildly acidic GVL–water co-solvent pretreatment of poplar leads to nearly full removal of xylan–cellulose linkages, which primes the cellulose for enzymatic attack. The spectral fitting also suggests that the pretreatment causes significant depletion of the inaccessible fibril surface domains with an increase in more thermally stable crystalline resonances (I β ). WAXS confirmed a decrease in the lattice spacing between (200) crystalline planes with increasing co-solvent pretreatment severity. These results are interpreted as an opening of bound microfibril surfaces previously inaccessible to the co-solvent system, which leaves behind a more thermally stable, crystalline domain that is potentially prone to relaxation and recrystallization. Full conversion of residual GVL-pretreated biomass was achieved after the GVL co-solvent pretreatment at 140 °C using a commercial enzyme cocktail, CTec2, which contains different cellulases and other enzymes. Spectral fitting of enzymatically hydrolyzed samples by a single engineered cellulase, CelR, suggests that the residual cellulose recalcitrance is mainly due to the inability of CelR to digest the I β crystalline domain present in pretreated samples. This work helps to provide new information regarding the structure of the cell wall and recalcitrance throughout GVL–water mild acidolysis and CelR enzymatic biomass deconstruction by tracking the evolution of structural domains within the cellulose microfibril. This work further directs recommendations for improving the conversion and sugar yields in future studies. Finally, our findings inform inquiry into larger questions of cellulose recalcitrance through GVL pretreatment and CelR enzymatic hydrolysis and give insight into subsequent required steps for full cellulose conversion with attention to the most recalcitrant cellulose structures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

A Porous Crystalline Nitrone‐Linked Covalent Organic Framework**

Abstract Herein, we report the synthesis of a nitrone‐linked covalent organic framework, COF‐115, by combining N , N′ , N′ , N ′′′‐(ethene‐1, 1, 2, 2‐tetrayltetrakis(benzene‐4, 1‐diyl))tetrakis(hydroxylamine) and terephthaladehyde via a polycondensation reaction. The formation of the nitrone functionality was confirmed by solid‐state 13 C multi cross‐polarization magic angle spinning NMR spectroscopy of the 13 C‐isotope‐labeled COF‐115 and Fourier‐transform infrared spectroscopy. The permanent porosity of COF‐115 was evaluated through low‐pressure N 2 , CO 2 , and H 2 sorption experiments. Water vapor and carbon dioxide sorption analysis of COF‐115 and the isoreticular imine‐linked COF indicated a superior potential of N ‐oxide‐based porous materials for atmospheric water harvesting and CO 2 capture applications. Density functional theory calculations provided valuable insights into the difference between the adsorption properties of these COFs. Lastly, photoinduced rearrangement of COF‐115 to the associated amide‐linked material was successfully demonstrated.

Kurandina, Daria↗
DOE OSTI2023

Dynamic Oscillation and Motion of Oil‐in‐Water Emulsion Droplets

Abstract The interplay of interfacial tensions on droplets results in a range of self‐powered motions that mimic those of living systems and serve as a tunable model to understand their complex non‐equilibrium behavior. Spontaneous shape deformations and oscillations are crucial features observed in nature but difficult to incorporate in synthetic artificial systems. Here, we report sessile oil‐in‐water emulsions that exhibit rapid oscillating behavior. The oscillations depend on the nature and concentration of the surfactant, the chemical composition of the oil, and the wettability of the solid substrate. The rapid changes in the contact angle per oscillation are observed using side‐view optical microscopy. We propose that the changes in the interfacial tension of the oil droplets is due to the partitioning of the surfactant into the oil phase and the movement of self‐emulsified oil out of the parent droplets giving rise to the rhythmic variation in droplet contact‐line. The ability to control and understand droplet oscillation can help model similar oscillations in out‐of‐equilibrium systems in nature and reproduce biomimetic behavior in artificial systems for various applications, such as microfluidic lab‐on‐a‐chip and adaptive materials.

Krishna Mani, Sanjana↗
DOE OSTI2023

Dynamic Oscillation and Motion of Oil‐in‐Water Emulsion Droplets

The interplay of interfacial tensions on droplets results in a range of self‐powered motions that mimic those of living systems and serve as a tunable model to understand their complex non‐equilibrium behavior. Spontaneous shape deformations and oscillations are crucial features observed in nature but difficult to incorporate in synthetic artificial systems. Here, we report sessile oil‐in‐water emulsions that exhibit rapid oscillating behavior. The oscillations depend on the nature and concentration of the surfactant, the chemical composition of the oil, and the wettability of the solid substrate. The rapid changes in the contact angle per oscillation are observed using side‐view optical microscopy. We propose that the changes in the interfacial tension of the oil droplets is due to the partitioning of the surfactant into the oil phase and the movement of self‐emulsified oil out of the parent droplets giving rise to the rhythmic variation in droplet contact‐line. The ability to control and understand droplet oscillation can help model similar oscillations in out‐of‐equilibrium systems in nature and reproduce biomimetic behavior in artificial systems for various applications, such as microfluidic lab‐on‐a‐chip and adaptive materials.

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

Engineered selective biotoxin‐binding hydrogels for toxin sequestration

The development of synthetic selective membranes that separate materials of similar sizes, charges, and/or polarities remains a difficult challenge, and looking towards biology provides inspiration for new designs. In this work, a series of cholera toxin binding peptides (CTBPs) are identified, spanning a range of binding inhibitions, and integrated into chemically cross-linked cholera toxin binding gels (CTBGs) via thiol-Michael polycondensation reactions. All gels demonstrate rheological profiles consistent with elastic solids. The CTBGs are probed via small-angle neutron scattering and exhibit a correlation length, ξ, smaller than most proteins (1.3–2.5 nm). Thus, an effective entropic mesh is formed to block non-targeted proteins. However, the CTBGs have a dynamic mesh size, Ξ, that is larger than cholera toxin (CT) to allow the transport of target proteins. The CTBGs with the highest binding inhibitions both show high selectivity and permeation of CT, rejecting all other tested proteins. In total, two new highly selective CTBGs are synthesized and validated for use in cholera toxin remediation. Together, this platform demonstrates the wide applicability of selectively-diffusive materials for difficult separations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Structure of Lung-Mimetic Multilamellar Bodies with Lipid Compositions Relevant in Pneumonia

The hierarchical assembly of lipids, as modulated by composition and environment, plays a significant role in the function of biological membranes and a myriad of diseases. Elevated concentrations of calcium ions and cardiolipin (CL), an anionic tetra-alkyl lipid found in mitochondria and some bacterial cell membranes, have been implicated in pneumonia recently. However, their impact on the physicochemical properties of lipid assemblies in lungs and how it impairs alveoli function is still unknown. We use small- and wide-angle X-ray scattering (S/WAXS) and solid-state nuclear magnetic resonance (ssNMR) to probe the structure and dynamics of lung-mimetic multilamellar bodies (MLBs) in the presence of Ca 2+ and CL. We conjecture that CL overexpressed in the hypophase of alveoli strongly affects the structure of lung-lipid bilayers and their stacking in the MLBs. Specifically, S/WAXS data revealed that CL induces significant shrinkage of the water-layer separating the concentric bilayers in multilamellar aggregates. ssNMR measurements indicate that this interbilayer tightening is due to undulation repulsion damping as CL renders the glycerol backbone of the membranes significantly more static. In addition to MLB dehydration, CL promotes intrabilayer phase separation into saturated-rich and unsaturated-rich lipid domains that couple across multiple layers. Expectedly, addition of Ca 2+ screens the electrostatic repulsion between negatively charged lung membranes. Furthermore, when CL is present, addition of Ca 2+ results in an apparent interbilayer expansion likely due to local structural defects. Combining S/WAXS and ssNMR on systems with compositions pertinent to healthy and unhealthy lung membranes, we propose how alteration of the physiochemical properties of MLBs can critically impact the breathing cycle.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Scattering Neutrons along the Polyelectrolyte Complex/Coacervate Continuum

The coil size of narrow molecular weight distribution deuterated poly(styrenesulfonate), PSS, within a polyelectrolyte complex doped with KBr was tracked across the continuum from solid to coacervate to solution using small-angle neutron scattering. Here, while PSS alone in solution exhibited the familiar and pronounced “polyelectrolyte effect” of coil shrinkage with increasing [KBr], the radius of gyration R g of the PSS in the complex remained surprisingly constant up to 1.4 M KBr, which is close to the transition between complex and coacervate behavior. Thereafter, R g decreased with increasing KBr, remaining slightly larger than R g for PSS in KBr alone. Upturns in the scattering at low angle, seen for complexes in lower [KBr], are consistent with porosity, observed macroscopically as whitening of the bulk complex—a universal property of polyelectrolyte complexes. Reasons for this porosity, imaged by scanning electron microscopy, are discussed. At high q ranges, a correlation peak between deuterated coils of PSS was observed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Measurement and Analysis of the Microphysical Properties of Arctic Precipitation Showing Frequent Occurrence of Riming

Detailed ground-based observations of snow are scarce in remote regions, such as the Arctic. Here, Multi-Angle Snowflake Camera measurements of over 55,000 solid hydrometeors—obtained during a two-year period from August 2016 to August 2018 at Oliktok Point, Alaska—are analyzed and compared to similar measurements from an earlier experiment at Alta, Utah. In general, distributions of hydrometeor fall speed, fall orientation, aspect ratio, flatness, and complexity (i.e., riming degree) were observed to be very similar between the two locations, except that Arctic hydrometeors tended to be smaller. In total, the slope parameter defining a negative exponential of the size distribution was approximately 50% steeper in the Arctic as at Alta. Sixty-six percent of particles were observed to be rimed or moderately rimed with some suggestion that riming is favored by weak boundary layer stability. On average, the fall speed of rimed particles was not notably different from aggregates. However, graupel density and fall speed increase as cloud temperatures approach the melting point.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1975

Airloads investigation of an 0.030-scale model of the space shuttle vehicle 140A/B launch configuration (model 47-OTS) in the arc 11-foot unitary plan wind tunnel for Mach range 0.6 to 1.4 (IA14A), Volume 2

Results of tests conducted on an 0.030-scale launch configuration model of the space shuttle vehicle 140A/B in the NASA/ARC 11-foot unitary plan wind tunnel are presented. Aerodynamic loads data were obtained at Mach numbers from 0.6 to 1.4. Surface pressure distributions were obtained simultaneously with six-component stability and control force data on the complete launch configuration. The configuration consisted of the orbiter, an external tank, two solid rocket boosters, and associated intercomponent attach hardware. Angles of attack and sideslip from -10 degrees to +10 degrees were investigated.

Gillins, R. L.↗
NASA NTRS1975

Airloads investigation of an 0.030-scale model of the space shuttle vehicle 140A/B launch configuration (model 47-OTS) in the arc 11-foot unitary plan wind tunnel for Mach range 0.6 to 1.4 (IA14A), volume 1

The results of the tests are presented along with aerodynamic loads data obtained at Mach numbers from 0.6 to 1.4. Surface pressure distributions were obtained simultaneously with six-component stability and control force data on the complete launch configuration. The configuration consisted of the orbiter, an external tank, two solid rocket boosters, and associated intercomponent attach hardware. Angles of attack and sideslip from -10 deg to +10 deg were investigated. The tests were conducted from 4 September 1973 through 13 September 1973.

Gillins, R. L.↗
NASA NTRS1978

Tidal perturbations on the satellite 1967-92A

The orbit of the 1967-92A satellite has been studied to ascertain the extent to which tidal forces contribute to orbital perturbations. This study has permitted an estimation of the magnitudes of ocean tide effects on the satellite's inclination, in particular for the M sub 2 and S sub 2 constituents. The ocean tide estimates are based upon the use of a value of 0.3 for the solid earth tide Love number and a lag angle of zero deg in the orbit determination procedure. The amplitudes and phases of these tidal effects are in good agreement with those calculated from numerical models of the tidal parameters derived from surface data.

Felsentreger, T. L.↗
NASA NTRS1979

Study program to develop and evaluate die and container materials for the growth of silicon ribbons

The development and evaluation of proprietary coatings of pure silicon carbide, silicon nitride, and aluminum nitride on less pure hot pressed substrates of the respective ceramic materials, is described. Silicon sessile drop experiments were performed on coated test specimens under controlled oxygen partial pressure. Prior to testing, X-ray diffraction and SEM characterization was performed. The reaction interfaces were characterized after testing with optical and scanning electron microscopy and Auger electron spectroscopy. Increasing the oxygen partial pressure was found to increase the molten silicon contact angle, apparently because adsorbed oxygen lowers the solid-vapor interfacial free energy. It was also found that adsorbed oxygen increased the degree of attack of molten silicon upon the chemical vapor deposited coatings. Cost projections show that reasonably priced, coated, molten silicon resistant refractory material shapes are obtainable.

Addington, L. A.↗
NASA NTRS1980

Visible and infrared polarization ratio spectroreflectometer

The instrument assists in determining the refractive index and absorption index, at different spectral frequencies, of a solid sample by illuminating the sample at various angles in incidence and measuring the corresponding reflected intensities at various spectral frequencies and polarization angles. The ratio of the intensity of the reflected light for parallel polarized light to that for perpendicular polarized light at two different angles of incidence can be used to determine the optical constants of the sample. The invention involves an apparatus for facilitating the utilization of a wide variety of angles of incidence. The light source and polarizing element are positioned on an outer platform; the sample is positioned on an inner platform. The two platforms rotate about a common axis and cooperate in their rotation such that the sample is rotated one degree for every two degrees of rotation of the light source. This maintains the impingement of the reflected light upon the detector for any angle of incidence without moving or adjusting the detector which allows a continuous change in the angle of incidence.

Batten, C. E.↗
NASA NTRS1981

Analytical and experimental study of flow phenomena in noncavitating rocket pump inducers

The flow processes in rocket pump inducers are summarized. The experimental investigations were carried out with air as the test medium. The major characteristics features of the rocket pump inducers are low flow coefficient (0.05 to 0.2) large stagger angle (70 deg to 85 deg) and high solidity blades of little or no camber. The investigations are concerned with the effect of viscosity not the effects of cavitation. Flow visualization, conventional and hot wire probe measurement inside and at the exit of the blade passage, were the analytical methods used. The experiment was carried out using four three and two bladed inducers with cambered blades. Both the passage and the exit flow were measured. The basic research and boundary layer investigation was carried out using a helical flat plate (of some dimensions as the inducer blades tested), and flat plate helical inducer (four bladed). Detailed mean and turbulence flow field inside the passage as well as the exit of the rotor were derived from these measurement. The boundary layer, endwall, and other passage data reveal extremely complex nature of the flow, with major effects of viscosity present across the entire passage. Several analyses were carried out to predict the flow field in inducers. These included an approximate analysis, the shear pumping analysis, and a numerical solution of exact viscous equations with approximate modeling for the viscous terms.

Lakshminarayana, B.↗
NASA NTRS1982

Design of supercritical cascades with high solidity

The method of complex characteristics of Garabedian and Korn was successfully used to design shockless cascades with solidities of up to one. A code was developed using this method and a new hodograph transformation of the flow onto an ellipse. This code allows the design of cascades with solidities of up to two and larger turning angles. The equations of potential flow are solved in a complex hodograph like domain by setting a characteristic initial value problem and integrating along suitable paths. The topology that the new mapping introduces permits a simpler construction of these paths of integration.

Sanz, J. M.↗