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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Fatty acid capped, metal oxo clusters as the smallest conceivable nanocrystal prototypes

Metal oxo clusters of the type M 6 O 4 (OH) 4 (OOCR) 12 (M = Zr or Hf) are valuable building blocks for materials science. Here, we synthesize a series of zirconium and hafnium oxo clusters with ligands that are typically used to stabilize oxide nanocrystals (fatty acids with long and/or branched chains). The fatty acid capped oxo clusters have a high solubility but do not crystallize, precluding traditional purification and single-crystal XRD analysis. We thus develop alternative purification strategies and we use X-ray total scattering and Pair Distribution Function (PDF) analysis as our main method to elucidate the structure of the cluster core. We identify the correct structure from a series of possible clusters (Zr3, Zr4, Zr6, Zr12, Zr10, and Zr26). Excellent refinements are only obtained when the ligands are part of the structure model. Further evidence for the cluster composition is provided by nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), and mass spectrometry (MS). We find that hydrogen bonded carboxylic acid is an intrinsic part of the oxo cluster. Using our analytical tools, we elucidate the conversion from a Zr6 monomer to a Zr12 dimer (and vice versa), induced by carboxylate ligand exchange. Finally, we compare the catalytic performance of Zr12-oleate clusters with oleate capped, 5.5 nm zirconium oxide nanocrystals in the esterification of oleic acid with ethanol. The oxo clusters present a five times higher reaction rate, due to their higher surface area. Since the oxo clusters are the lower limit of downscaling oxide nanocrystals, we present them as appealing catalytic materials, and as atomically precise model systems. In addition, the lessons learned regarding PDF analysis are applicable to other areas of cluster science as well, from semiconductor and metal clusters, to polyoxometalates.

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

Structural transitions in the GTP cap visualized by cryo-electron microscopy of catalytically inactive microtubules

Microtubules (MTs) are nonequilibrium polymers that switch between states of growth and shrinkage. This property is critical for their function and is a consequence of GTP hydrolysis in the MT. The structure of the stable GTP part of the MT (the GTP cap) has previously been inferred from MTs polymerized with nonhydrolyzable GTP analogs. Here, we report high-resolution structures of MTs truly containing GTP, polymerized from mutated, hydrolysis-deficient tubulins. We find that GTP-MTs have an “expanded lattice” and a “closed seam,” structural characteristics possibly responsible for stabilizing the GTP cap. These results provide insight into the structural transitions at growing MT ends, furthering our understanding of the bistable nature of MTs.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Development and validation of a humidified CAPS-PMSSA with an improved methodology to calculate the truncation correction factor

Absorbing aerosols play an important role in the Earth’s radiation budget, and current uncertainties associated with their radiative impacts remain substantial. An element of this uncertainty derives from insufficient understanding of the extent to which water, as a coating on absorbing particles, enhances the absorption. Here, we describe and characterize the performance of a cavity-attenuated phase shift single scatter albedo spectrometer (CAPS-PMSSA) system that has been modified to enable concurrent aerosol extinction and scattering measurements, from which aerosol absorption is derived, at relative humidities up to ~90%. The modified instrument is referred to as the humidified CAPS (HCAPS). Additionally, we develop and validate an update to a method to calculate the truncation correction factor, used to correct the scattering measurements, that can account for the effects of particle growth and compositional changes resulting from water uptake. The method can be applied to experiments that use either size-selected or polydisperse aerosol samples of either known or unknown composition. Overall, we show that measurements made with the HCAPS, when processed using the updated truncation correction method, enable accurate measurement of the influence of water uptake on light absorption.

Dal Porto, Rachael [University of California, Davi↗
DOE OSTI2023

Structural and double magnetic transitions in the frustrated spin- 1 2 capped-kagome antiferromagnet ( RbCl ) Cu 5 P 2 O 10

The structural and magnetic properties of the geometrically frustrated spin- 1 2 capped-kagome antiferromagnet (RbCl) Cu 5 P 2 O 10 are investigated via temperature-dependent x-ray diffraction, magnetization, heat capacity, and 31 P NMR experiments on a polycrystalline sample. It undergoes a structural transition at around T t ≃ 310 K from a high-temperature trigonal (P ¯3m1) to a low-temperature monoclinic (C2/c) unit cell, where the low-temperature structure features the capped-kagome geometry of Cu 2+ ions. Interestingly, it shows the onset of two successive magnetic transitions at T N1 ≃ 20 K and T N2 ≃ 7 K. The shape of the 31 P NMR spectra unfolds the possible nature of the transitions below T N1 and T N2 to be of incommensurate and commensurate antiferromagnetic type, respectively. A large value of the Curie-Weiss temperature as compared to T N1 sets the frustration parameter f ≃ 8, ensuring strong magnetic frustration in the compound. From the 31 P NMR spin-lattice relaxation rate, the leading antiferromagnetic exchange coupling is estimated to be J/k B ≃ 117 K. Furthermore, these unusual double magnetic transitions make this compound beguiling for further investigations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Thermal Instability in the Manufacturing of Wind Turbine Blade Spar Caps – Phase 2

As the wind turbine industry continues to develop, the technology surrounding the design, development, and manufacturing of blades requires advancement as well. Wind turbine blades continue to increase in size, increasing the cost and time associated with manufacturing. Simulation driven manufacturing cycle design is required for the industry to maintain manufacturing schedules and optimize the manufacturing process. A recent effort to reduce the cycle time of wind blade spar caps encountered a recurring manufacturing defect during the exotherm and curing of the resin system after filling in the vacuum-assisted resin transfer molding (VARTM) process. Thermal waves developed in sections of the spar cap resulting in unacceptable part tolerances, requiring the parts to be thrown out. The first phase of this IACMI project focused on characterizing the fabric and epoxy system used in manufacturing and simulating the manufacturing process to determine the root cause of the thermal waves. The second phase of this project refined and validated the manufacturing simulations. The simulation workflow was then used to analyze multiple cure cycle options to determine if the thermal waves would appear. The estimated filling time from the filling simulation was shown to match well to experiment, and the temperature history from the curing simulation lined up well with experiment. This indicates that these simulations could be used to evaluate future curing cycles to be used with manufacturing. It is recommended that the distortion simulation work be completed for this project, as it would allow for further manufacturing cycle evaluation through the prediction of stresses and strains in the part. This could provide indicators of defects like the thermal waves seen in manufacturing earlier.

17 WIND ENERGY↗
DOE OSTI2021

Chalcogenide Glass-Capped Fiber-Optic Sensor for Real-Time Temperature Monitoring in Extreme Environments

We demonstrate a novel chalcogenide glass (ChG)-capped optical fiber temperature sensor capable of operating within harsh environment. The sensor architecture utilizes the heat-induced phase change (amorphous-to-crystalline) property of ChGs, which rapidly (80–100 ns) changes the optical properties of the material. The sensor response to temperature variation around the phase change of the ChG cap at the tip of the fiber provides abrupt changes in the reflected power intensity. This temperature is indicative of the temperature at the sensing node. We present the sensing performance of six different compositions of ChGs and a method to interpret the temperature profile between 440 °C and 600 °C in real-time using an array structure. The unique radiation-hardness property of ChGs makes the devices compatible with high-temperature and high-radiation environments, such as monitoring the cladding temperature of Light Water (LWR) or Sodium-cooled Fast (SFR) reactors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

CAPS PMssa Aerosol Extinction and SSA Data

We collected rapid (1 second time response) measurements of aerosol extinction and scattering (Mm-1) using an Aerodyne CAPS PMssa deployed during LASIC (as part of the LASIC SSA-constraint study) to measure ambient SSA at 530 nm wavelength to compare with other optical measurement methods. Measured from August 4 to September 22, 2017. Sampled from both PM1 and PM10 inlets. CAPS PMssa monitors have been tested extensively for PM2.5 and smaller particle sizes, but not for particles greater than 2,500 nm in diameter (i.e., PM10). The data were collected in order to provide an independent measurement of aerosol single scattering albedo at 530 nm wavelength to compare with ARM standard methods.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

BETO 2021 Peer Review - CAP Process Research

Combined Algal Processing (CAP) is an algae biorefining approach that employs pretreatment and extraction operations to fractionate algal biomass into an organic liquid phase containing lipids, an aqueous hydrolysate phase containing carbohydrates and protein, and a residual solid phase containing insoluble matter. Each of these fractions is upgraded to fuels and/or co-products, including non-isocyanate polyurethanes from unsaturated lipids, fuels from saturated lipids, fuel precursor carboxylic acids from the hydrolysate, and conductive carbons from the solid residue. Techno-economic analysis of multiple CAP configurations suggests that some configurations have a viable pathway to algal biofuels at $2.50/gallon of gasoline equivalent.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

Donor End-Capped Alkyl Chain Length Dependent Non-Radiative Energy Loss in All-Small-Molecule Organic Solar Cells

A critical bottleneck for further efficiency breakthroughs in organic solar cells (OSCs) is to minimize the non-radiative energy loss (eΔV nr ) while maximizing the charge generation. With the development of highly emissive low-bandgap non-fullerene acceptors, the design of high-performance donors becomes critical to enable the blend with the electroluminescence quantum efficiency to approach or surpass the pristine acceptor. Herein, by shortening the end-capped alkyl chains of the small-molecular donors from hexyl (MPhS-C6) to ethyl (MPhS-C2), the material obtained aggregation that was insensitive to thermal annealing (TA) along with condensed packing simultaneously. The former leads to small phase separation and suppressed upshifts of the highest occupied molecular orbital energy level during TA, and the latter facilitates its efficient charge-transport at aggregation-less packing. Hence, the ΔV nr decreases from 0.242 to 0.182 V, from MPhS-C6 to MPhS-C2 based OSCs. An excellent PCE of 17.11% is obtained by 1,8-diiodoctane addition due to almost unchanged high J sc (26.6 mA cm –2 ) and V oc (0.888 V) with improved fill factor, which is the record efficiency with the smallest energy loss (0.497 eV) and ΔV nr (0.192 V) in all-small-molecule OSCs. Finally, these results emphasize the potential material design direction of obtaining concurrent TA-insensitive aggregation and condensed packing to maximize the device performances with a super low ΔV nr .

36 MATERIALS SCIENCE↗
DOE OSTI2020

Perovskite Solar Cells with Enhanced Fill Factors Using Polymer-Capped Solvent Annealing

Despite huge improvements in power conversion efficiencies of perovskite solar cells, the technology is still limited by fill factors at around 80%. In this work, we report perovskite solar cells having exceptionally high fill factors of 85% and enhanced open-circuit voltage without sacrificing short-circuit current through a polymer-capped solvent-annealing process assisted by a hot air blower. Additionally, during the solvent-annealing, the perovskite surface flattens and the perovskite grains agglomerate into micrometer-sized clusters having enlarged α-phase crystallites, while the δ-phase simultaneously disappears. The optimized structure reduces energetic disorder and trap-assisted recombination in the perovskite layer, resulting in an enhanced efficiency from 18.2% to 19.8% and improved device lifetime. Our results provide a pathway to increase the device efficiency and stability of perovskite solar cells, and have the potential to stimulate research on scalable poly-crystal perovskite layer fabrication in optoelectronic devices.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2020

Materials Data on CaP by Materials Project

CaP is alpha boron-derived structured and crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six P2- atoms. There are two shorter (2.96 Å) and four longer (3.00 Å) Ca–P bond lengths. In the second Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six P2- atoms. There are four shorter (2.89 Å) and two longer (2.93 Å) Ca–P bond lengths. There are two inequivalent P2- sites. In the first P2- site, P2- is bonded in a 7-coordinate geometry to six Ca2+ and one P2- atom. The P–P bond length is 2.25 Å. In the second P2- site, P2- is bonded in a 7-coordinate geometry to six Ca2+ and one P2- atom. The P–P bond length is 2.31 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaP(HO3)2 by Materials Project

CaP(HO3)2 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.30–2.82 Å. P is bonded in a tetrahedral geometry to four O atoms. There are a spread of P–O bond distances ranging from 1.52–1.60 Å. There are two inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (0.99 Å) and one longer (1.71 Å) H–O bond length. In the second H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.00 Å) and one longer (1.67 Å) H–O bond length. There are six inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Ca and one P atom. In the second O site, O is bonded in a 1-coordinate geometry to two equivalent Ca and one P atom. In the third O site, O is bonded in a 1-coordinate geometry to one Ca, one P, and two H atoms. In the fourth O site, O is bonded in a 3-coordinate geometry to two equivalent Ca and one P atom. In the fifth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the sixth O site, O is bonded in a single-bond geometry to one Ca atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Modeling Protocol for Evaluation of Air Emissions for the Idaho National Laboratory Site-wide Permit to Construct and Facility Emission Cap (PTC/FEC)

This document outlines the methods to be used for calculating non-radiological air quality impacts from proposed emissions at the Idaho National Laboratory (INL) Site in support of applying for a renewal to a Permit to Construct with a Facility Emissions Cap (PTC/FEC). The INL Site is seeking to maintain a state enforceable limit on emissions to maintain synthetic minor status in accordance with Idaho Administrative Procedures Act (IDAPA) 58.01.01.175-181 and IDAPA 58.01.01.200-228.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Metal-Mediated Directional Capping of Rod-Packing Metal–Organic Frameworks

We report two new rod-packing metal–organic frameworks (RPMOF) are constructed by regulating the in situ formation of the capping agent. In CPM-s7, carboxylate linkers extend 1D manganese-oxide chains in four additional directions, forming 3D RPMOF. The substitution of Mn 2+ with a stronger Lewis acidic Co 2+ , leads to an acceleration of the hydrolysis-prone sulfonate linker, resulting in presence of sulfate ions to reduce two out of the four carboxylate-extending directions, and thus forming a new 2D rod-packing CPM-s8. Density functional theory calculations and magnetization measurements reveal ferrimagnetic ordering of CPM-s8, signifying the potential of exploring 2D RPMOF for effective low-dimensional magnetic materials.

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

Entanglement and topology in RG flows across dimensions: caps, bridges and corners

We quantitatively address the following question: for a QFT which is partially compactified, so as to realize an RG flow from a D-dimensional CFT in the UV to a d-dimensional CFT in the IR, how does the entanglement entropy of a small spherical region probing the UV physics evolve as the size of the region grows to increasingly probe IR physics? This entails a generalization of spherical regions to setups without full Lorentz symmetry, and we study the associated entanglement entropies holographically. We find a tight interplay between the topology and geometry of the compact space and the evolution of the entanglement entropy, with universal transitions from ‘cap’ through ‘bridge’ and ‘corner’ phases, whose features reflect the details of the compact space. As concrete examples we discuss twisted compactifications of 4d $\mathcal{N}$ = 4 SYM on T 2 , S 2 and hyperbolic Riemann surfaces.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Carbon dots from surface-capping/passivation of small carbon nanoparticles with nanoscale titanium dioxide

Carbon dots are classically defined as small carbon nanoparticles (CNPs) with effective surface passivation, which has been accomplished predominantly by surface organic functionalization. In the current work, the passivation is achieved by the surface coating of CNPs with nanoscale TiO 2 for CNP/TiO 2 core/shell nanostructures, which are analogous to conventional semiconductor core/shell quantum dots (QDs). The TiO 2 capping of CNPs results in substantial enhancements in the fluorescence quantum yields, also analogous to the similar enhancements famously known for the semiconductor QDs. In conclusion, mechanistic implications of the findings, including the associated further validation on the classical definition of carbon dots, are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Modelling yield cap evolution in sandstone based on brittle creep experiments

The Zenifim Formation is being considered as a potential disposal formation for a deep borehole nuclear repository concept in Israel. Site selection and repository construction are intended to ensure that waste is separated from circulating groundwater, but long-term deformation of the wellbore could potentially create fluid flow pathways. To understand how time-dependent rock strength could affect wellbore stability, here we conducted creep tests under low to moderate confining pressures on retrieved core from the Zenifim formation. During creep, samples strain slowly as gradual damage accumulation progressively weakens the samples. Failure eventually occurred through the near-instantaneous formation of a shear fracture. Experimental results were used to calibrate a continuum damage poro-elastic model for sandstones. The calibrated damage-poro-elastic model successfully simulates different types of loading experiments including quasi-static and creep. The state of strain in experiments is close to yield during loading as the yield cap continuously evolves with damage accumulation. For creep tests, most damage occurs during triaxial loading. Minor damage accumulation occurs under constant load until the final stage of creep, where damage accelerates and promotes unstable fracturing.

58 GEOSCIENCES↗
DOE OSTI2020

Green synthesis and characterization of nontoxic L-methionine capped silver and gold nanoparticles

The simple green method for synthesis of stable L-Methionine (L-Met) capped silver (Ag@LM NPs) and gold (Au@LM NPs) nanoparticles (NPs) without adding any additional reduction agent or stabilizer was developed. Colloidal dispersions were characterized by UV–Vis spectrophotometry. The size and spherical shape of NPs were evaluated by transmission electron microscopy. Their surface covering was confirmed by atomic force microscopy, Fourier transform infrared spectroscopy, dynamic light scattering, and zeta potential measurements. Density functional theory calculations pointed that the preferential adsorption mode of L-Met on both Ag and Au surfaces was a vertical binding geometry via –NH2 group, while horizontal binding mode via [sbnd]S[sbnd] and –NH2 groups is also possible. The genotoxicity (evaluated by the micronucleus assay) of NPs, as well as their effects on some oxidative stress parameters (catalase activity, malondialdehyde level), were assessed in vitro using human peripheral blood cells as a model system. The influence of NPs on the morphology of lymphocyte cells studied using atomic force microscopy revealed that the membrane of cells remained unaffected after the treatment with NPs. When considering the effects of NPs on catalase activity and malondialdehyde level, neither particle type promoted oxidative stress. However, the treatment of lymphocytes with Ag@LM NPs induced a concentration-dependent enhancement of the micronuclei incidence and suppression of the cell proliferation while Au@LM NPs promoted cell proliferation, with no significant effects on micronuclei formation. The Ag@LM NPs were more prone to induce DNA damage than Au@LM NPs, which makes the latter type more suitable for further studies in nano-medicine. © 2019.

60 APPLIED LIFE SCIENCES↗