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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Measurement of differential $ b\overline{b} $- and $ c\overline{c} $-dijet cross-sections in the forward region of pp collisions at $ \sqrt{s} $ = 13 TeV

The inclusive \( b\overline{b} \) - and \( c\overline{c} \) -dijet production cross-sections in the forward region of pp collisions are measured using a data sample collected with the LHCb detector at a centre-of-mass energy of 13 TeV in 2016. The data sample corresponds to an integrated luminosity of 1.6 fb - 1 . Differential cross-sections are measured as a function of the transverse momentum and of the pseudorapidity of the leading jet, of the rapidity difference between the jets, and of the dijet invariant mass. A fiducial region for the measurement is defined by requiring that the two jets originating from the two b or c quarks are emitted with transverse momentum greater than 20 GeV/ c , pseudorapidity in the range 2 . 2 < η < 4 . 2, and with a difference in the azimuthal angle between the two jets greater than 1.5. The integrated \( b\overline{b} \) -dijet cross-section is measured to be 53 . 0 ± 9 . 7 nb, and the total \( c\overline{c} \) -dijet cross-section is measured to be 73 ± 16 nb. The ratio between \( c\overline{c} \) - and \( b\overline{b} \) -dijet cross-sections is also measured and found to be 1 . 37 ± 0 . 27. The results are in agreement with theoretical predictions at next-to-leading order.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Mesoporous Textured Fe-N-C Electrocatalysts as Highly Efficient Cathodes for Proton Exchange Membrane Fuel Cells

A new platinum group metal (PGM)-free proton exchange membrane fuel cell (PEMFC) cathode catalyst materials, synthesized using the VariPore™ method by Pajarito Powder, LLC, are characterized for their structure and activity. The physico-chemical analysis of the iron-nitrogen-carbon (Fe-N-C) electrocatalysts show mesoporous carbon material effectively doped with iron and nitrogen. The materials have an average pore size of 7-8 nm and high specific surface area. The Fe-N-C catalysts exhibit good oxygen reduction reaction (ORR) activity in 0.5 M H2SO4 electrolyte with high half-wave potential and sustainable electrochemical stability over 10,000 repeated potential cycles with insignificant losses in their activities. As cathode catalysts in a PEMFC, the Fe-N-C materials deliver remarkably good fuel cell performance at low overpotential approaching that of the commercial Pt catalyst. The high ORR electrocatalytic activity of these Fe-N-C catalysts is credited to the synergy between nitrogen-moieties, specifically pyrrolic-N, pyridinic-N, and graphitic-N, and iron in addition to the high mesoporosity that facilitate an effective reaction path in boosting the electrocatalytic activity and stability.

DIRECT ENERGY CONVERSION↗
DOE OSTI2021

Hydrological projections over the Upper Indus Basin at 1.5 °C and 2.0 °C temperature increase

We analyse an ensemble of statistically downscaled Global Climate Models (GCMs) to investigate future water availability in the Upper Indus Basin (UIB) of Pakistan for the time horizons when the global and/or regional warming levels cross Paris Agreement (PA) targets. The GCMs data is obtained from the 5th Phase of Coupled Model Inter-Comparison Project under two Representative Concentration Pathways (RCP4.5 and RCP8.5). Based on the five best performing GCMs, we note that global 1.5 °C and 2.0 °C warming thresholds are projected in 2026 and 2047 under RCP4.5 and 2022 and 3036 under RCP8.5 respectively while these thresholds are reached much earlier over Pakistan i.e. 2016 and 2030 under RCP4.5 and 2012 and 2025 under RCP8.5 respectively. Interestingly, the GCMs with the earliest emergence at the global scale are not necessarily the ones with the earliest emergence over Pakistan, highlighting spatial non-linearity in GCMs response. The emergence of 2.0 °C warming at global scale across 5 GCMs ranges from 2031 (CCSM4) to 2049 (NorESM) under RCP8.5. Precipitation generally exhibits a progressive increasing trend with stronger changes at higher warming or radiative forcing levels. Hydrological simulations representing the historical, 1.5 °C and 2.0 °C global and region warming time horizons indicate a robust but seasonally varying increase in the inflows. The highest inflows in the baseline and future are witnessed in July. However, the highest future increase in inflows is projected in October under RCP4.5 (37.99% and 65.11% at 1.5 °C and 2.0 °C) and in April under RCP8.5 (37% and 62.05% at 1.5 °C and 2.0 °C). These hydrological changes are driven by increases in the snow and glacial melt contribution, which are more pronounced at 2.0 °C warming level. These findings should help for effective water management in Pakistan over the coming decades.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Similar photosynthetic but different yield responses of C 3 and C 4 crops to elevated O 3

The deleterious effects of ozone (O 3 ) pollution on crop physiology, yield, and productivity are widely acknowledged. It has also been assumed that C 4 crops with a carbon concentrating mechanism and greater water use efficiency are less sensitive to O 3 pollution than C 3 crops. This assumption has not been widely tested. Therefore, we compiled 46 journal articles and unpublished datasets that reported leaf photosynthetic and biochemical traits, plant biomass, and yield in five C 3 crops (chickpea, rice, snap bean, soybean, and wheat) and four C 4 crops (sorghum, maize, Miscanthus × giganteus , and switchgrass) grown under ambient and elevated O 3 concentration ([O 3 ]) in the field at free-air O 3 concentration enrichment (O 3 -FACE) facilities over the past 20 y. When normalized by O 3 exposure, C 3 and C 4 crops showed a similar response of leaf photosynthesis, but the reduction in chlorophyll content, fluorescence, and yield was greater in C 3 crops compared with C 4 crops. Additionally, inbred and hybrid lines of rice and maize showed different sensitivities to O 3 exposure. This study quantitatively demonstrates that C 4 crops respond less to elevated [O 3 ] than C 3 crops. This understanding could help maintain cropland productivity in an increasingly polluted atmosphere.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Robust production of monovalent bispecific IgG antibodies through novel electrostatic steering mutations at the C H 1-C λ interface

Bispecific antibodies represent an increasingly large fraction of biologics in therapeutic development due to their expanded scope in functional capabilities. Asymmetric monovalent bispecific IgGs (bsIgGs) have the additional advantage of maintaining a native antibody-like structure, which can provide favorable pharmacology and pharmacokinetic profiles. The production of correctly assembled asymmetric monovalent bsIgGs, however, is a complex engineering endeavor due to the propensity for non-cognate heavy and light chains to mis-pair. Previously, we introduced the DuetMab platform as a general solution for the production of bsIgGs, which utilizes an engineered interchain disulfide bond in one of the C H 1-C L domains to promote orthogonal chain pairing between heavy and light chains. While highly effective in promoting cognate heavy and light chain pairing, residual chain mispairing could be detected for specific combinations of Fv pairs. Here, we present enhancements to the DuetMab design that improve chain pairing and production through the introduction of novel electrostatic steering mutations at the C H 1-C L interface with lambda light chains (C H 1-C λ ). These mutations work together with previously established charge-pair mutations at the C H 1-C L interface with kappa light chains (C H 1-C κ ) and Fab disulfide engineering to promote cognate heavy and light chain pairing and enable the reliable production of bsIgGs. Importantly, these enhanced DuetMabs do not require engineering of the variable domains and are robust when applied to a panel of bsIgGs with diverse Fv sequences. We present a comprehensive biochemical, biophysical, and functional characterization of the resulting DuetMabs to demonstrate compatibility with industrial production benchmarks. Overall, this enhanced DuetMab platform substantially streamlines process development of these disruptive biotherapeutics.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

An investigation of non-canonical mixing in red giant stars using APOGEE 12 C/ 13 C ratios observed in open cluster stars

Standard stellar evolution theory poorly predicts the surface abundances of chemical species in low-mass, red giant branch (RGB) stars. Observations show an enhancement of p–p chain and CNO cycle products in red giant envelopes, which suggests the existence of non-canonical mixing that brings interior burning products to the surface of these stars. The 12 C/ 13 C ratio is a highly sensitive abundance metric used to probe this mixing. We investigate extra RGB mixing by examining: (1) how 12 C/ 13 C is altered along the RGB, and (2) how 12 C/ 13 C changes for stars of varying age and mass. Our sample consists of 43 red giants, spread over 15 open clusters from the Sloan Digital Sky Survey’s APOGEE DR17, that have reliable 12 C/ 13 C ratios derived from their APOGEE spectra. We vetted these 12 C/ 13 C ratios and compared them as a function of evolution and age/mass to the standard mixing model of stellar evolution, and to a model that includes prescriptions for RGB thermohaline mixing and stellar rotation. We find that the observations deviate from standard mixing models, implying the need for extra mixing. Additionally, some of the abundance patterns depart from the thermohaline model, and it is unclear whether these differences are due to incomplete observations, issues inherent to the model, our assumption of the cause of extra mixing, or any combination of these factors. Nevertheless, the surface abundances across our age/mass range clearly deviate from the standard model, agreeing with the notion of a universal mechanism for RGB extra mixing in low-mass stars.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Warming and elevated CO 2 alter tamarack C fluxes, growth and mortality: evidence for heat stress-related C starvation in the absence of water stress

Climate warming is increasing the frequency of climate-induced tree mortality events. While drought combined with heat is considered the primary cause of this mortality, little is known about whether moderately high temperatures alone can induce mortality, or whether rising CO 2 would prevent mortality at high growth temperatures. In this study, we grew tamarack ( Larix laricina ) under ambient (400 p.p.m.) and elevated (750 p.p.m.) CO 2 concentrations combined with ambient, ambient +4 °C and ambient +8 °C growth temperatures to investigate whether high growth temperatures lead to carbon (C) limitations and mortality. Growth at +8 °C led to 40% mortality in the ambient CO 2 (8TAC) treatment, but no mortality in the elevated CO 2 treatment. Thermal acclimation of respiration led to similar leaf C balances across the warming treatments, despite a lack of photosynthetic acclimation. Photosynthesis was stimulated under elevated CO 2 , increasing seedling growth, but not leaf C concentrations. However, growth and foliar C concentrations were lowest in the +8 °C treatments, even with elevated CO 2 . Dying 8TAC seedlings had lower needle C concentrations and lower ratios of photosynthesis to respiration than healthy 8TAC seedlings, indicating that C limitations were likely the cause of seedling mortality under high growth temperatures.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1993

Determination of (C-12)/(C-13) in the interstellar medium toward Zeta Ophiuchi and Xi Persei

The Lick Observatory Reticon (LOR) data presented in Hawkins et al. (1985) are reanalyzed in order to determine the cause of the significant discrepancy in (C-12)/(C-13) isotope ratios determined on the basis of observations of this isotope in the interstellar medium toward Zeta Ophiuchi and Xi Persei. A new set of Lick Observatory observations toward Zeta Oph are obtained using a CCD detector. The KPNO coude feed echelle spectrograph and a CCD detector are used to carry out high-resolution, high SNR ratio observations toward Zeta Oph and Xi Per. The LOR results for Zeta Oph are uncertain, ranging to 40 to 60, owing to the error in continuum placement. The KPNO results toward Zeta Oph are (C-12)H/(C-13)H(+)(0, 0) = 63 +/- 8, (C-12)H(+)/(C-13)H(+)(1, 0) = 67 +/- 19, and (C-12)N/(C-13)N = 100 + 88/- 33. Toward Xi Per, the KPNO measurements yield (C-12)H(+)/(C-13)H(+) = 49 +/- 15 from the 4232-A band, and a lower limit of 45 from the 3957-A observations.

Hawkins, Isabel↗
DOE OSTI2025

Observation of the Charmonium Decay η c → γ γ in J / ψ → γ η c

Using ( 2712.4 ± 14.3 ) × 10 6 ψ ( 3686 ) events collected with the BESIII detector at the BEPCII collider, the decay η c → γ γ in J / ψ → γ η c is observed. We determine the product branching fraction B ( J / ψ → γ η c ) × B ( η c → γ γ ) = ( 5.23 ± 0.2 6 stat ± 0.3 0 syst ) × 10 − 6 . This result is consistent with the lattice QCD calculation ( 5.34 ± 0.16 ) × 10 − 6 from HPQCD in 2023. By using the world-average values of B ( J / ψ → γ η c ) and the total decay width of η c , the partial decay width Γ ( η c → γ γ ) is determined to be ( 11.30 ± 0.5 6 stat ± 0.6 6 syst ± 1.1 4 ref ) keV , which deviates from the corresponding world-average value by 3.4 σ . Published by the American Physical Society 2025

Ablikim, M.↗
NASA NTRS1993

Comparison of reflectance spectra of C asteroids and unique C chondrites Y86720, Y82162, and B7904

Reflectance spectra (0.3-2.6 microns) of 11 carbonaceous (C) chondrite powders (less than 100 or less than 125 microns) including 'unique' ones Y86720, Y82162, and B7904, have been measured and compared with those of 14 C asteroids. Among those C chondrites, only three 'unique' ones had close counterparts among C asteroids (Y86720 and 1 Ceres, Y82162 and 704 Interamnia, and B7904 and 31 Euphrosyne). Mixing calculations of those C chondrites by Hapke's isotropic model were also performed to improve fits of reflectance spectra of all the 14 C asteroids. If the grain-size distributions of those asteroid surfaces are similar to those C chondrite powders, the result suggests that all tested C asteroids contain a high amount of heated C chondrite material, such as Y86720, Y82162, and B7904.

Hiroi, T.↗
DOE OSTI2025

Search for resonance-enhanced C P and angular asymmetries in the Λ c + → p μ + μ − decay at LHCb

The first measurement of the C P asymmetry of the decay rate ( A C P ) and the C P average ( Σ A FB ) and C P asymmetry ( Δ A FB ) of the forward-backward asymmetry in the muon system of Λ c + → p μ + μ − decays is reported. The measurement is performed using a data sample of proton-proton collisions, recorded by the LHCb experiment from 2016 to 2018 at a center-of-mass energy of 13 TeV, which corresponds to an integrated luminosity of 5.4 fb − 1 . The asymmetries are measured in two regions of dimuon mass near the ϕ -meson mass peak. The dimuon-mass integrated results are A C P = ( − 1.1 ± 4.0 ± 0.5 ) % , Σ A FB = ( 3.9 ± 4.0 ± 0.6 ) % , Δ A FB = ( 3.1 ± 4.0 ± 0.4 ) % , where the first uncertainty is statistical and the second systematic. The results are consistent with the conservation of C P symmetry and the Standard Model expectations. © 2025 CERN, for the LHCb Collaboration 2025 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2024

Measurement of Λ b 0 , Λ c + , and Λ Decay Parameters Using Λ b 0 → Λ c + h − Decays

A comprehensive study of the angular distributions in the bottom-baryon decays Λ b 0 → Λ c + h − ( h = π , K ) , followed by Λ c + → Λ h + with Λ → p π − or Λ c + → p K S 0 decays, is performed using a data sample of proton-proton collisions corresponding to an integrated luminosity of 9 fb − 1 collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. The decay parameters and the associated charge-parity ( C P ) asymmetries are measured, with no significant C P violation observed. For the first time, the Λ b 0 → Λ c + h − decay parameters are measured. The most precise measurements of the decay parameters α , β , and γ are obtained for Λ c + decays and an independent measurement of the decay parameters for the strange-baryon Λ decay is provided. The results deepen our understanding of weak decay dynamics in baryon decays. © 2024 CERN, for the LHCb Collaboration 2024 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2021

Switching CO 2 Electroreduction Selectivity Between C 1 and C 2 Hydrocarbons on Cu Gas-Diffusion Electrodes

We report that regulating the selectivity toward a target hydrocarbon product is still the focus of CO 2 electroreduction. Here, we discover that the original surface Cu species in Cu gas-diffusion electrodes plays a more important role than the surface roughness, local pH, and facet in governing the selectivity toward C 1 or C 2 hydrocarbons. The selectivity toward C 2 H 4 progressively increases, while CH 4 decreases steadily upon lowering the Cu oxidation species fraction. At a relatively low electrodeposition voltage of 1.5 V, the Cu gas-diffusion electrode with the highest Cu δ+ /Cu 0 ratio favors the pathways of hydrogenation to form CH 4 with maximum Faradaic efficiency of 65.4% and partial current density of 228 mA cm -2 at -0.83 V vs RHE. At 2.0 V, the Cu gas-diffusion electrode with the lowest Cu δ+ /Cu 0 ratio prefers C–C coupling to form C 2+ products with Faradaic efficiency topping 80.1% at -0.75 V vs RHE, where the Faradaic efficiency of C 2 H 4 accounts for 46.4% and the partial current density of C 2 H 4 achieves 279 mA cm -2 . This work demonstrates that the selectivity from CH 4 to C 2 H 4 is switchable by tuning surface Cu species composition of Cu gas-diffusion electrodes.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Long-Term 13 C Uptake by 12 C-Enriched Calcite

Knowledge of the exchange of carbon isotopes between dissolved inorganic carbon and calcite minerals is of long-standing importance for the interpretation of sedimentary paleoclimate records and 14 C transport in the geosphere. To assess the mechanism and rates of carbon isotope exchange, we equilibrated 12 C-pure synthetic calcite particles in water, first in a glovebox and then in contact with atmospheric P CO 2 and 13 C/ 12 C ratio, at two different temperatures. Cavity ring-down infrared spectroscopy δ 13 C measurements of the solid revealed sustained 13C incorporation for over a period of 500 days (21 °C) and 125 days (50 °C). We developed a quantitative model for recrystallization and isotope exchange, assuming that the interfacial free energy provides a thermodynamic driving force for the growth of larger particles at the expense of smaller ones. Furthermore, this Ostwald ripening model did not reproduce the kinetics of 13C uptake and required greater coarsening than observed. Rather, the data were best explained by a mechanism involving surface exchange and solid-phase diffusion of 13C into the particles with an inferred effective diffusion constant at 21 °C of about 10 –25 m 2 /s. Although this work cannot rule out the possibility that structural or chemical aspects of the synthetic particles enabled faster 13 C uptake than could be observed in natural systems, this study adds to the body of the recent work, suggesting that fast exchange processes are possible, likely through grain boundaries and other defects.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1972

Boundary lubrication of formulated C-ether in air to 300 deg C. 1: Phosphorus ester additives

Friction and wear measurements were made on CVM M-50 steel lubricated with three C-ether (modified polyphenyl ether) formulations in dry and wet air. Results were compared to those obtained with a formulated Type 2 ester and the C-ether base fluid. A ball-on-disk sliding friction apparatus was used. Experimental conditions were a 1-kilogram load, a 17-meter-perminute (100-rpm) surface speed, and a 25 to 300 C (77 to 572 F) disk temperature range. The C-ether base fluid and the three formulated C-ether fluids yielded lower wear than the Type 2 ester over the entire temperature range. All C-ether fluids exhibited slightly higher friction coefficients than the ester from 150 to 300 C (302 to 572 F) and similar values from 25 to 150 C (77 to 302 F). In general, lower wear rates were observed with the C-ethers when tested in wet air as compared to a dry air atmosphere.

Jones, W. R., Jr.↗
NASA NTRS1975

Boundary lubrication of formulated C-ethers in air to 300 C

Six C-ether formulations (containing organic acid and phosphorus ester additives) were tested in dry (less than 100 ppm H2O) and moist air (relative humidity 50 percent at 25 C) and temperatures from 25 to 300 C, in order to determine the boundary lubricating characteristics and to compare these results to those obtained with a fully formulated Type II ester and the unformulated C-ether base fluid. The apparatus, procedures and detailed results of the test are described. Friction and wear measurements were made on CVM M-50 steel under 1 kg load and 17 meter per minute (100 rpm) surface speed conditions, for a duration of 25 minutes. In general, the C-ether formulations exhibited higher friction coefficients than the ester from 150 to 300 C and similar or lower values from 25 to 150 C, furthermore, in most test conditions the C-ether base fluid and the six C-ether formulations yielded lower wear than the ester. Possible applications in the aerospace industry are mentioned.

Jones, W. R., Jr.↗