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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Magnetic correlations and pairing tendencies of the hybrid stacking nickelate superlattice La 7 Ni 5 O 17 (La 3 ⁢Ni 2 ⁢O 7 /La 4 Ni 3 ⁢O 10 ) under pressure

Motivated by the recent rapid progress in high-𝑇 𝑐 nickelate superconductors, we comprehensively study the physical properties of the alternating bilayer trilayer stacking nickelate La 7 ⁢Ni 5 ⁢O 17 . The high-symmetry phase of this material, without the tilting of oxygen octahedra, is not stable at ambient conditions but becomes stable under high pressure, where a small hole pocket 𝛾 0 , composed of the 𝑑 3⁢𝑧 2 −𝑟 2 states in the trilayer sublattice, appears. Here, this pocket was identified in our previous work for trilayer La 4 ⁢Ni 3 ⁢O 10 as important to develop superconductivity. Moreover, using random-phase approximation calculations, we find a leading 𝑠 ± pairing state for the high-symmetry phase under pressure with similar pairing strength as that obtained previously for the bilayer La 3⁢ Ni 2 ⁢O 7 compound, suggesting a similar or higher superconducting transition temperature 𝑇 𝑐 , at the random-phase approximation level. In addition, we find that the dominant magnetic fluctuations in the system driving this pairing state have antiferromagnetic structure both in-plane and between the planes of the top and bottom trilayer and bilayer sublattices, while the middle trilayer is magnetically decoupled.

Zhang, Yang [Univ. of Tennessee, Knoxville, TN (Un↗
DOE OSTI2026

Controlled expansion for pairing in a polarized band with strong repulsion

Can strong repulsive interactions be shown to give rise to pairing in a controlled way? We find that for a single flavor polarized band, there is a small expansion parameter in the low density limit, once the Bloch wavefunction form factor is taken into account. A perturbative expansion is possible, even if the interaction is much stronger than the Fermi energy ε F . As a matter of principle, our work shows analytically how strong pairing can emerge from strong repulsion. Here, we illustrate our method with two examples: a 2D Dirac model and a 1D tight binding model with two orbitals. In the latter case, using density matrix renormalization group, we show that the analytical theory indeed guided us to discover the parameter regime where p-wave pairing with order-1 strength is dominant.

Ferromagnetic superconductors↗
DOE OSTI2023

MJL-1 is a nuclear envelope protein required for homologous chromosome pairing and regulation of synapsis during meiosis in C. elegans

Interactions between chromosomes and LINC (linker of nucleoskeleton and cytoskeleton) complexes in the nuclear envelope (NE) promote homolog pairing and synapsis during meiosis. By tethering chromosomes to cytoskeletal motors, these connections lead to processive chromosome movements along the NE. This activity is usually mediated by telomeres, but in the nematode Caenorhabditis elegans, special chromosome regions called “pairing centers” (PCs) have acquired this meiotic function. Here, we identify a previously uncharacterized meiosis-specific NE protein, MJL-1 (MAJIN-Like-1), that is essential for interactions between PCs and LINC complexes in C. elegans. Mutations in MJL-1 eliminate active chromosome movements during meiosis, resulting in nonhomologous synapsis and impaired homolog pairing. Fission yeast and mice also require NE proteins to connect chromosomes to LINC complexes. Extensive similarities in the molecular architecture of meiotic chromosome-NE attachments across eukaryotes suggest a common origin and/or functions of this architecture during meiosis.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Measurement of the transverse momentum distribution of Drell–Yan lepton pairs in proton–proton collisions at √s=13 TeV with the ATLAS detector

This paper describes precision measurements of the transverse momentum $p_\mathrm {T}^{\ell \ell }$ ($\ell =e,\mu $) and of the angular variable $\phi ^{*}_{\eta }$ distributions of Drell–Yan lepton pairs in a mass range of 66–116 GeV. The analysis uses data from 36.1 fb$^{-1}$ of proton–proton collisions at a centre-of-mass energy of $\sqrt{s}=13\,$TeV collected by the ATLAS experiment at the LHC in 2015 and 2016. Measurements in electron-pair and muon-pair final states are performed in the same fiducial volumes, corrected for detector effects, and combined. Compared to previous measurements in proton–proton collisions at $\sqrt{s}=7$ and $8\,$TeV, these new measurements probe perturbative QCD at a higher centre-of-mass energy with a different composition of initial states. They reach a precision of 0.2$\%$ for the normalized spectra at low values of $p_\mathrm {T}^{\ell \ell }$. The data are compared with different QCD predictions, where it is found that predictions based on resummation approaches can describe the full spectrum within uncertainties.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Search for chargino–neutralino pair production in final states with three leptons and missing transverse momentum in $$\sqrt{s} = 13$$ TeV pp collisions with the ATLAS detector

A search for chargino–neutralino pair production in three-lepton final states with missing transverse momentum is presented. The study is based on a dataset of $\sqrt{s}$=13 TeV pp collisions recorded with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 fb -1 . No significant excess relative to the Standard Model predictions is found in data. The results are interpreted in simplified models of supersymmetry, and statistically combined with results from a previous ATLAS search for compressed spectra in two-lepton final states. Various scenarios for the production and decay of charginos ($\tilde{χ}^±_1$) and neutralinos ($\tilde{χ}^0_2$) are considered. For pure higgsino $\tilde{χ}^±_1$$\tilde{χ}^0_2$ pair-production scenarios, exclusion limits at 95% confidence level are set on $\tilde{χ}^0_2$ masses up to 210 GeV. Limits are also set for pure wino $\tilde{χ}^±_1$$\tilde{χ}^0_2$ pair production, on $\tilde{χ}^0_2$ masses up to 640 GeV for decays via on-shell W and Z bosons, up to 300 GeV for decays via off-shell W and Z bosons, and up to 190 GeV for decays via W and Standard Model Higgs bosons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Search for exotic decays of the Higgs boson to a pair of pseudoscalars in the $μμ bb$ and $ττ bb$ final states

A search for exotic decays of the Higgs boson (H) with a mass of 125 GeV to a pair of light pseudoscalars a 1 is performed in final states where one pseudoscalar decays to two quarks and the other to a pair of muons or leptons. A data sample of proton–proton collisions at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 138 fb -1 recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set at 95% confidence level (CL) on the Higgs boson branching fraction to μ μ b b and to τ τ b b via a pair of a 1 s. The limits depend on the pseudoscalar mass m a 1 and are observed to be in the range (0.17–3.3) x 10 -4 and (1.7–7.7) x 10 -2 in the μ μ b b and τ τ b b final states, respectively. In the framework of models with two Higgs doublets and a complex scalar singlet (2HDM+S), the results of the two final states are combined to determine upper limits on the branching fraction ${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} \rightarrow \ell \ell \text{ b } \text{ b})$ at 95% CL, with ℓ being a muon or a τ lepton. For different types of 2HDM+S, upper bounds on the branching fraction ${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$ are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space ${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$, values above 0.23 are excluded at 95% CL for m a 1 values between 15 and 60 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

The underappreciated lone pair in halide perovskites underpins their unusual properties

The presence of 6s 2 (5s 2 ) lone-pair electrons on the B-site Pb (Sn) in all-inorganic and hybrid halide ABX 3 perovskites distinguishes these materials from the familiar tetrahedral semiconductors traditionally employed in optoelectronics and is key to many of their appealing properties. These electrons are stereochemically active, albeit often in a hidden fashion, resulting in unusual and highly anharmonic lattice dynamics that are linked to many of the special optoelectronic properties displayed by this material class. This article describes the connections between this atypical electronic configuration and the electronic structure and lattice dynamics of these compounds. We illustrate how the lone pair leads to favorable bandwidths and band alignments, mobile holes, large ionic dielectric response, large positive thermal expansion, and even possibly defect-tolerant electronic transport. Taken together, the evidence suggests that other high-performing semiconductors may be found among compounds with lone-pair-bearing cations in high symmetry environments and a high degree of connectivity between atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Dedicated beam position monitor pair for model-independent lattice characterization at NSLS-II

This paper reports recent lattice characterization results obtained at the National Synchrotron Light Source II (NSLS-II) storage ring, conducted without reliance on a lattice model. A pair of beam position monitors (BPMs) with bunch-by-bunch (B×B) resolution, were recently installed in a section of the storage ring free of magnetic fields. The new BPM pair measured the beam, or bunch’s transverse Poincar´e map precisely after the beam was excited. Linear one-turn-matrices (OTM) were then derived, and from these, the 4-dimensional coupled Twiss parameters were extracted at the locations of the BPM pair. By normalizing beam oscillation amplitudes with the Twiss parameters, the global action-variables were obtained. These action-variables facilitated the measurement of the local Twiss parameters observed by other BPMs independent on lattice model. This method is general, and particularly useful in certain scenarios such as a round beam mode in a diffraction-limited light source ring. We applied it to assess both weakly and strongly coupled lattices at the NSLS-II ring. Through analysis of the strongly coupled lattice, the quadrupole tilt errors were estimated to be less than 400 µrad. Utilizing the BPMs’ B×B resolution, for the first time we observed the variations of the linear lattice along a long bunch-train.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Equitable Resilience: Opportunities to Advance Solar Paired with Battery Storage in Historically Marginalized Communities

This report was produced as part of the Equitable Solar Communities of Practice program through the U.S. Department of Energy (DOE) Solar Energy Technologies Office (SETO). Clean Energy Group (CEG) managed the Resilience, Storage, and Grid Benefits Community of Practice, which aimed to research, evaluate, and identify opportunities to scale the meaningful benefits of solar paired with battery storage in historically marginalized communities. The report is designed to 1) educate a broad audience on the benefits of solar paired with battery storage, 2) identify barriers to deploying solar paired with battery storage in historically marginalized communities, 3) amplify early-adopters and innovative programs that support battery storage access across the nation, and 4) recommend best practices for programs and policies to adopt in advancing equitable access to solar and battery storage technologies.

14 SOLAR ENERGY↗
DOE OSTI2024

Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydrothermally Stable Co-, Cu- and Pd-SSZ-13 Materials

Replacing alkaline for alkaline-earth metal hydroxide in the synthesis gel during the synthesis of siliceous SSZ-13 zeolite (Si/Al~10) yields SSZ-13 with novel, advantageous properties. Its NH 4 -form ion-exchanges higher amount of isolated divalent M(II) ions than the conventional one: this is the consequence of an increased number of Al pairs in the structure induced by the +2 charge of Sr(II) cations in the synthesis gel that force two charge-compensating AlO 4 – motives to reside closer together. We characterize the +2 state of Co(II) ions in these materials with infra-red spectroscopy and X-ray absorption spectroscopy measurements and show their utility for NOx pollutant adsorption from ambient air: the ones derived from SSZ-13 with higher Al pair content contain more isolated cobalt(II) and, thus, perform better as ambient-air NOx adsorbers. Notably, Co(II)/SSZ-13 with an increased number of Al pairs is significantly more hydrothermally stable than its NaOH-derived analogue. Loading Pd(II) into Co-SSZ-13(Sr) produces an active NOx adsorber (PNA) material that can be used for NOx adsorption from simulated diesel engine exhaust. The critical issue for these applications is hydrothermal stability of Pd-zeolites. Pd/SSZ-13 synthesized in the presence of Sr(OH) 2 does not lose its PNA capacity after extremely harsh aging at 850 and 900 °C (10 h in 10% H 2 O/air flow) and loses only ~55% capacity after hydrothermal aging at 930 °C. This can be extended to other divalent metals for catalytic applications, such as copper: we show that Cu/SSZ-13 catalyst can survive hydrothermal aging at 920 °C without losing its catalytic properties, metal dispersion and crystalline structure. Thus, we provide a new, simple, and scalable strategy for making remarkably (hydro)thermally stable metal-zeolite materials/catalysts with a number of useful applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Transition to Petschek Reconnection in Subrelativistic Pair Plasmas: Implications for Particle Acceleration

While relativistic magnetic reconnection in pair plasmas has emerged in recent years as a candidate for the origin of radiation from extreme astrophysical environments, the corresponding subrelativistic pair-plasma regime has remained less explored, leaving open the question of how relativistic physics affects reconnection. In this paper, we investigate the differences between these regimes by contrasting two-dimensional particle-in-cell simulations of reconnection in pair plasmas with relativistic magnetization (σ ≫ 1) and subrelativistic magnetization (σ < 1). By utilizing unprecedentedly large domain sizes and outflow boundary conditions, we demonstrate that lowering the magnetization results in a change in the reconnection geometry from a plasmoid chain to a Petschek geometry, where laminar exhausts bounded by slow-mode shocks emanate from a single diffusion region. We attribute this change to the reduced plasmoid production rate in the low-σ case: When the secondary tearing rate is sufficiently low, plasmoids are too few in number to prevent the system from relaxing into a stable Petschek configuration. This geometric change also affects particle energization: We show that while high-σ plasmoid chains generate power-law energy spectra, low-σ Petschek exhausts merely heat incoming plasma and yield negligible nonthermal acceleration. These results have implications for predicting the global current sheet geometry and the resulting energy spectra in a variety of systems.

Plasma astrophysics↗
DOE OSTI2026

Probing the Coherence of Metal Absorbers toward Background Quasar Pairs

Abstract We investigate the spatial coherence of metal absorption lines in the circumgalactic medium using 4115 quasar pairs from Sloan Digital Sky Survey DR16. We identify 184 Mg ii (15 with dual detections) and 50 C iv (11 with dual detections) absorber pairs. The fraction of pairs with fractional equivalent width difference δW r ≤ 0.5 declines with projected separation: for Mg ii , it drops from ∼52% at 0–25 kpc to ∼7% at 100–200 kpc, while for C iv , it decreases from ∼100% to ∼21% over 0–200 kpc. In every separation bin, C iv absorbers with δW r ≤ 0.5 maintain a higher fraction than Mg ii absorbers. Similar results are obtained when the nondetections are treated as 2 σ W r upper limits in a survival analysis. The transverse autocorrelation function shows strong Mg ii clustering within 0–25 kpc, whereas the C iv excess remains relatively flat out to ∼100 kpc. These findings suggest that high-ionization C iv gas retains coherence over larger transverse scales than low-ionization Mg ii gas, in agreement with previous lensed quasar and high-resolution studies.

Li, Jing [Guangxi University] (ORCID:0009000148751↗
NASA NTRS1973

Hydrogen depolarized carbon dioxide concentrator performance improvements and cell pair structural tests

The investigations and testing associated with the CO2 removal efficiency and voltage degradation of a hydrogen depolarized carbon oxide concentrator are reported. Also discussed is the vibration testing of a water vapor electrolysis cell pair. Performance testing of various HDC cell pairs with Cs2CO3 electrolyte provided sufficient parametric and endurance data to size a six man space station prototype CO2 removal system as having 36 HDC cell pairs, and to verify a life capability exceeding six moths. Testing also demonstrated that tetramethylammonium carbonate is an acceptable HDC electrolyte for operating over the relative humidity range of 30 to 90 percent and over a temperature range of 50 to 80 F.

Huddleston, J. D.↗
NASA NTRS1974

Statistical analysis of close pairs of QSOs

The observation of close pairs of QSOs with very different redshifts has been suggested by some as evidence in support of the noncosmological redshift hypothesis. A method is described for determining the statistical significance of such pairs. As an example, it is shown that the statistical significance of the pair 1548+115a,b is not well defined and ranges from approximately 99% confidence to about 60%. If statistical methods are to be used in such cases, they must not be argued a posteriori.

Burbidge, E. M.↗
NASA NTRS1974

Extracting depth information from a stereo pair

An approach to extracting depth information out of a stereo pair of images is described. Special camera pair configurations are shown to be effective in reducing complexity. A simple algorithm which pairs objects in the two images and allows verification is described.

Yakimovsky, Y.↗
NASA NTRS1974

Quantum descriptions of singularities leading to pair creation

A class of cosmological models is analyzed which provide a mathematically convenient (but idealized) description of a cosmological singularity that develops into a pair creation epoch and terminates in an adiabatic expansion with redshifting particle energies. This class of models was obtained by Gowdy (1971, 1974) as a set of exact solutions of the classical empty space Einstein equations describing inhomogeneous universes populated only by gravitational waves. It is shown that these models can be used to exhibit simplified models of quantized gravitational fields, and that a quantum description can be given arbitrarily near a cosmological singularity. Graviton pair creation occurs, and can be seen to convert anisotropic expansion rates into the energy of graviton pairs.

Misner, C. W.↗
NASA NTRS1977

Limitations of the narrow-angle convergent pair

Spatial triangulations and topographies of the Martian surface derived from Viking Orbiter pictures depend on the use of symmetric narrow-angle convergent pairs. The overlap in each pair is close to 100 percent and the ground principal points virtually coincide. The analysis of this paper reveals a high degree of indeterminacy in such pairs and at least in part explains the rather disappointing precision of the associated spatial triangulations.

Arthur, D. W. G.↗
NASA NTRS1979

Upper limits on production rate of NO per ion pair

The maximum production rate of NO per ion pair during a solar proton event has been calculated using an approach described by Porter et al. (1976). For altitudes between 80 and 120 km the calculation yields a limit of 2.68 NO per ion pair for 10 keV electrons, a value which is consistent with the rates implied by the measurements of Arnold (1978) as quoted by Fabian et al. (1979). For altitudes below 80 km the maximum rate of NO production is calculated to be 1.46 to 1.53 NO per ion pair.

Jackman, C. H.↗