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All sources NASA NTRS DOE OSTI

DOE OSTI2025

Evaluating Extreme Storm Events in an Ensemble of High‐Resolution Projections

This study uses different downscaling techniques and reference observations to investigate the characteristics of extreme storm events over the conterminous United States in historical and a projected future scenario. While previous studies agree on the projected changes in intensity and frequency of precipitation extremes, there is a lack of consensus regarding how their size will change in response to an increase in radiative forcing. Moreover, the influence of different downscaling techniques on their characteristics has not been thoroughly examined. This study employs an ensemble of high‐resolution projections derived from six CMIP6 GCMs, using dynamical, statistical and artificial intelligence based downscaling techniques and two reference observations. Overall, we find noticeable differences in the size, average depth, and total precipitation volume of these storms among the climate ensembles in the historical period. Despite these differences in the historical period, we find consistent future changes across various ensembles. We find a robust projected increase in storm size during Winter and Spring but a decrease in size during Summer in the East. Nevertheless, irrespective of changes in their size, extreme storms are projected to intensify across all the ensembles and seasons.

Rastogi, Deeksha [Oak Ridge National Laboratory (O↗

DOE OSTI2025

Quantifying the Effect of Pore‐Size Dependent Wettability on Relative Permeabilities Using Lattice Boltzmann Simulation

Relative permeability is a crucial two-phase property in porous media that can be significantly impacted by wettability conditions. While traditional research has predominantly examined homogeneous wettability, this work explores the less studied pore-size dependent (PSD) wettability, featured by a pore-size dependent wettability distribution. Leveraging high-fidelity Lattice Boltzmann simulations on CT-scanned porous samples, we demonstrate how PSD wettability would impact relative permeability at the pore scale. Our findings reveal that the deviation of relative permeability from the homogeneous wettabilitity induced by PSD wettability can be 5%–20%. The deviation of relative permeability curves increases as the spanning range of the contact angle increases. We also find that this impact is less pronounced as the capillary number increases. By adopting a pore-size-dependent contact angle relationship, our approach provides a more accurate and nuanced understanding of how PSD wettability would impact two-phase flow. These findings discovered at the pore scale may also provide valuable insights on relative permeability at the core to reservoir scales.

25 ENERGY STORAGE↗

DOE OSTI2026

Early Solar Wind and Dynamo Magnetic Field Topology Predictions for (16) Psyche and Other Asteroids

Abstract Asteroid (16) Psyche is a metal‐rich body that might record an ancient coherent magnetization if some relict crust or mantle is preserved. Herein, we use magnetohydrodynamic simulations to predict (16) Psyche's field topology for several distinct pathways: (i) an early solar wind‐induced magnetization imparted after a larger body was impacted, forming the present‐day asteroid, (ii) a core dynamo magnetization imparted in an asteroid that is either presently largely intact or was a rubble pile, and (iii) magnetization in the turbulent solar nebula disk. For pathway (i) we find the field to be predominantly dipolar and spin axis‐aligned. For pathway (ii) we find the field to be either dipolar and spin axis‐misaligned, or highly multipolar. We also find that (iii) a field produced earlier before the solar nebula cleared, would be highly multipolar. In cases (i) and (ii) we also place constraints on the field strength. Simple detection of a magnetic field without constraining its topology and temporal variability would be insufficient to confirm a remanent source, due to the influence of the present‐day solar wind, electromagnetic induction, and (16) Psyche's high obliquity. For sufficiently strong fields however, the field topology and orientation may reveal key observable consequences of the nature and history of (16) Psyche. Our framework is also broadly applicable to the study of magnetic fields from other asteroids.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2021

Spatially dispersing Yu-Shiba-Rusinov states in the unconventional superconductor FeTe 0.55 Se 0.45

By using scanning tunneling microscopy (STM) we find and characterize dispersive, energy-symmetric in-gap states in the iron-based superconductor FeTe 0.55 Se 0.45 , a material that exhibits signatures of topological superconductivity, and Majorana bound states at vortex cores or at impurity locations. We use a superconducting STM tip for enhanced energy resolution, which enables us to show that impurity states can be tuned through the Fermi level with varying tip-sample distance. We find that the impurity state is of the Yu-Shiba-Rusinov (YSR) type, and argue that the energy shift is caused by the low superfluid density in FeTe 0.55 Se 0.45 , which allows the electric field of the tip to slightly penetrate the sample. We model the newly introduced tip-gating scenario within the single-impurity Anderson model and find good agreement to the experimental data.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2022

A global lipid map reveals host dependency factors conserved across SARS-CoV-2 variants

A comprehensive understanding of host dependency factors for SARS-CoV-2 remains elusive. Here, we map alterations in host lipids following SARS-CoV-2 infection using nontargeted lipidomics. We find that SARS-CoV-2 rewires host lipid metabolism, significantly altering hundreds of lipid species to effectively establish infection. We correlate these changes with viral protein activity by transfecting human cells with each viral protein and performing lipidomics. We find that lipid droplet plasticity is a key feature of infection and that viral propagation can be blocked by small-molecule glycerolipid biosynthesis inhibitors. We find that this inhibition was effective against the main variants of concern (alpha, beta, gamma, and delta), indicating that glycerolipid biosynthesis is a conserved host dependency factor that supports this evolving virus.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2023

Fragment-based drug nanoaggregation reveals drivers of self-assembly

Drug nanoaggregates are particles that can deleteriously cause false positive results during drug screening efforts, but alternatively, they may be used to improve pharmacokinetics when developed for drug delivery purposes. The structural features of molecules that drive nanoaggregate formation remain elusive, however, and the prediction of intracellular aggregation and rational design of nanoaggregate-based carriers are still challenging. We investigate nanoaggregate self-assembly mechanisms using small molecule fragments to identify the critical molecular forces that contribute to self-assembly. We find that aromatic groups and hydrogen bond acceptors/donors are essential for nanoaggregate formation, suggesting that both π-π stacking and hydrogen bonding are drivers of nanoaggregation. We apply structure-assembly-relationship analysis to the drug sorafenib and discover that nanoaggregate formation can be predicted entirely using drug fragment substructures. We also find that drug nanoaggregates are stabilized in an amorphous core-shell structure. These findings demonstrate that rational design can address intracellular aggregation and pharmacologic/delivery challenges in conventional and fragment-based drug development processes.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2024

Interfacial dynamics mediate surface binding events on supramolecular nanostructures

The dynamic behavior of biological materials is central to their functionality, suggesting that interfacial dynamics could also mediate the activity of chemical events at the surfaces of synthetic materials. Here, we investigate the influence of surface flexibility and hydration on heavy metal remediation by nanostructures self-assembled from small molecules that are decorated with surface-bound chelators in water. We find that incorporating short oligo(ethylene glycol) spacers between the surface and interior domain of self-assembled nanostructures can drastically increase the conformational mobility of surface-bound lead-chelating moieties and promote interaction with surrounding water. In turn, we find the binding affinities of chelators tethered to the most flexible surfaces are more than ten times greater than the least flexible surfaces. Accordingly, nanostructures composed of amphiphiles that give rise to the most dynamic surfaces are capable of remediating thousands of liters of 50 ppb Pb 2+ -contaminated water with single grams of material. These findings establish interfacial dynamics as a critical design parameter for functional self-assembled nanostructures.

42 ENGINEERING↗

DOE OSTI2021

High-energy magnetic excitations from heavy quasiparticles in CeCu 2 Si 2

Magnetic fluctuations is the leading candidate for pairing in cuprate, iron-based, and heavy fermion superconductors. This view is challenged by the recent discovery of nodeless superconductivity in CeCu 2 Si 2 , and calls for a detailed understanding of the corresponding magnetic fluctuations. Here, we mapped out the magnetic excitations in superconducting (S-type) CeCu 2 Si 2 using inelastic neutron scattering, finding a strongly asymmetric dispersion for E ≲ 1.5 meV, which at higher energies evolves into broad columnar magnetic excitations that extend to E ≳ 5 meV. While low-energy magnetic excitations exhibit marked three-dimensional characteristics, the high-energy magnetic excitations in CeCu 2 Si 2 are almost two-dimensional, reminiscent of paramagnons found in cuprate and iron-based superconductors. By comparing our experimental findings with calculations in the random-phase approximation, we find that the magnetic excitations in CeCu 2 Si 2 arise from quasiparticles associated with its heavy electron band, which are also responsible for superconductivity. Our results provide a basis for understanding magnetism and superconductivity in CeCu 2 Si 2 , and demonstrate the utility of neutron scattering in probing band renormalization in heavy fermion metals.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2025

Ultrafast simultaneous manipulation of multiple ferroic orders through nonlinear phonon excitation

Recent experimental studies have demonstrated the possibility of utilizing strong terahertz pulses to manipulate individual ferroic orders on pico- and femtosecond timescales. Here, we extend these findings and showcase the simultaneous manipulation of multiple ferroic orders in BiFeO 3 , a material that is both ferroelectric and antiferromagnetic at room temperature. We find a concurrent enhancement of ferroelectric and antiferromagnetic second-harmonic generation (SHG) following the resonant excitation of a high-frequency fully-symmetric phonon mode. Based on first-principles calculations and phenomenological modeling, we ascribe this observation to the inherent coupling of the two ferroic orders to the nonequilibrium distortions induced in the crystal lattice by nonlinearly driven phonons. Our finding highlights the potential of nonlinear phononics as a technique for manipulating multiple ferroic order parameters at once. In addition, this approach provides a promising avenue to studying the dynamical magnetic and polarization behavior, as well as their intrinsic coupling, on ultrashort timescales.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Soil microbiome predictability increases with spatial and taxonomic scale

Soil microorganisms shape ecosystem function, yet it remains an open question whether we can predict the composition of the soil microbiome in places before observing it. Furthermore, it is unclear whether the predictability of microbial life exhibits taxonomic- and spatial-scale dependence, as it does for macrobiological communities. Here, we leverage multiple large-scale soil microbiome surveys to develop predictive models of bacterial and fungal community composition in soil, then test these models against independent soil microbial community surveys from across the continental United States. We find remark- able scale dependence in community predictability. The predictability of bacterial and fungal communities increases with the spatial scale of observation, and fungal predictability increases with taxonomic scale. These patterns suggest that there is an increasing importance of deterministic versus stochastic processes with scale, consistent with findings in plant and animal communities, suggesting a general scaling relationship across biology. Biogeochemical functional groups and high-level taxonomic groups of microorganisms were equally predictable, indicating that traits and taxonomy are both powerful lenses for understanding soil communities. Here, by focusing on out-of-sample prediction, these findings suggest an emerging generality in our understanding of the soil microbiome, and that this understanding is fundamentally scale dependent

Biogeography↗

DOE OSTI2025

Multiple freezing–melting pathways of high-density ice through ice XXI phase at room temperature

Various metastable ice phases and their complicated transition pathways have been found by pressurization at low temperatures at which slow kinetics and high metastability are easily achieved. By contrast, such diversity is less expected at room or elevated temperatures. Here, using a combination of a dynamic diamond anvil cell and X-ray free electron laser techniques, we demonstrate that supercompressed water transforms into ice VI through multiple freezing–melting pathways at room temperature, hidden within the pressure region of ice VI. These multiple transition pathways occur via a metastable ice (more specifically, ice XXI with body-centred tetragonal structure ($I\bar{4}2d$)) discovered in this study and a metastable ice VII that exists within the pressure range of ice VI. We find that supercompressed water structurally evolves from high-density water to very-high-density water, causing multiple transition pathways. These findings provide an insight to find more metastable ice phases and their transition pathways at elevated temperatures.

Lee, Yun-Hee [Korea Research Institute of Standard↗

DOE OSTI2024

Network-level encoding of local neurotransmitters in cortical astrocytes

Abstract Astrocytes, the most abundant non-neuronal cell type in the mammalian brain, are crucial circuit components that respond to and modulate neuronal activity through calcium (Ca 2+ ) signalling 1–7 . Astrocyte Ca 2+ activity is highly heterogeneous and occurs across multiple spatiotemporal scales—from fast, subcellular activity 3,4 to slow, synchronized activity across connected astrocyte networks 8–10 —to influence many processes 5,7,11 . However, the inputs that drive astrocyte network dynamics remain unclear. Here we used ex vivo and in vivo two-photon astrocyte imaging while mimicking neuronal neurotransmitter inputs at multiple spatiotemporal scales. We find that brief, subcellular inputs of GABA and glutamate lead to widespread, long-lasting astrocyte Ca 2+ responses beyond an individual stimulated cell. Further, we find that a key subset of Ca 2+ activity—propagative activity—differentiates astrocyte network responses to these two main neurotransmitters, and may influence responses to future inputs. Together, our results demonstrate that local, transient neurotransmitter inputs are encoded by broad cortical astrocyte networks over a minutes-long time course, contributing to accumulating evidence that substantial astrocyte–neuron communication occurs across slow, network-level spatiotemporal scales 12–14 . These findings will enable future studies to investigate the link between specific astrocyte Ca 2+ activity and specific functional outputs, which could build a consistent framework for astrocytic modulation of neuronal activity.

Science & Technology - Other Topics↗

DOE OSTI2021

Time-resolved nanosecond optical pyrometry of the vapor to plasma transitions in exploding bridgewires

Electrically exploded wires find uses throughout high-energy physics. For example, they are commonly used as high-temperature sources, X-ray generators, and in precision timing detonators. However, the detailed and complete physics that occurs is complex and still poorly understood. A full mechanistic description of these complex phenomena is beyond the scope of a single paper. Instead, we focus on the formation of metal vapor and its transition to plasma. This single transition is commonly assumed to comprise “bridge-burst”. We use a suite of diagnostics including a novel, fiber-based, high-speed, optical pyrometer to better characterize this transition. The primary finding from this project is that peak light output from an exploding wire does not temporally match the peak temperature. Additionally, it is found that peak light does not align with peak bridge-burst voltage and that the peak temperature is not voltage-dependent. These findings are non-intuitive and will allow for the correction of false assumptions previously made about this topic.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Correlation versus hybridization gap in CaMn$$_{2}$$Bi$$_{2}$$

Abstract We study the interplay between electronic correlations and hybridization in the low-energy electronic structure of CaMn $$_2$$ 2 Bi $$_2$$ 2 , a candidate hybridization-gap semiconductor. By employing a DFT+ U approach we find both the antiferromagnetic Néel order and band gap in good agreement with the corresponding experimental values. Under hydrostatic pressure, we find a crossover from hybridization gap to charge-transfer insulting physics due to the delicate balance of hybridization and correlations. Increasing the pressure above $$P_c=4$$ P c = 4 GPa we find a simultaneous pressure-induced volume collapse, plane-to-chain, insulator to metal transition. Finally, we have also analyzed the topology in the antiferromagnetic CaMn $$_2$$ 2 Bi $$_2$$ 2 for all pressures studied.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Mitigating urban heat island and enhancing indoor thermal comfort using terrace garden

The United Nations advocates for sustainable urban planning and design, emphasizing green infrastructure initiatives to mitigate urban heat island effects and enhance the resilience and livability of cities globally. To address urban heat challenges, a study was conducted in Chennai, India, from April to June 2023. The study focused on assessing temperature dynamics on a building's terrace by comparing a well-maintained garden area with an exposed region. Temperature and humidity sensors were deployed in both the garden and exposed areas of the terrace, as well as within rooms beneath it, to monitor hourly temperature fluctuations. The findings indicate a significant reduction in internal room temperatures in areas with rooftop gardens, ranging from 4 to 11 °C, depending on the time of year and sun's position, compared to rooms with fully exposed roof configurations. Additionally, simulation studies were performed to validate these findings, suggesting that optimizing the distribution of soil beds and plant density across the roof could yield an additional temperature reduction of 3–4 °C, resulting in an overall difference of up to 14–15 °C. The study highlights the efficacy of rooftop gardens in providing cooling effects during daylight hours and maintaining temperature parity post-sunset. Through analysis of sensor data, the research elucidates the intricate relationship between green infrastructure and thermal comfort, offering insights for energy-efficient building design and resilient urban planning. The findings underscore the potential of rooftop gardens in fostering a more comfortable, energy-efficient, and sustainable urban living environment.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2025

Effect of multiple calcination cycles on CO 2 capture efficiency during carbonation of MgO in a mineral looping process

Magnesium oxide (MgO) is considered as a potential sorbent for direct air capture of carbon dioxide in a looping process. Previous research on mineral looping for carbon capture from flue gas using MgO has shown deactivation of the sorbent with repeated cycles but repeated cycling for carbonation at ambient conditions has not been yet investigated. Here, we tested three cycles of carbonation for MgO nano-scale powders with different starting surface area. We find that carbonation efficiency is higher at higher surface area. No decrease in carbonation efficiency was observed with cycling, instead we find that carbonation efficiency and surface area are stable or even increasing with cycling. Based on our experimental data, we hypothesize that the carbonation in presence of relative humidity leads to first hydration of MgO, leading to formation of brucite (Mg(OH) 2 ). This formation of Mg(OH) 2 is a volume-increasing reaction, which leads to fracturing of MgO particles and results in an increase in surface area. We observed formation of amorphous and crystalline hydrated carbonates. The crystalline phase observed was nesquehonite (MgCO 3 ⋅ 3H 2 O). Our results show that MgO does not show any deactivation with repeated cycling for carbon capture at ambient conditions and in the presence of humidity. These findings therefore indicate that MgO is a suitable candidate as sorbent material for direct air capture of carbon dioxide.

Ambient weathering↗

DOE OSTI2024

Electronic excitations and spin interactions in chromium trihalides from embedded many-body wavefunctions

Although chromium trihalides are widely regarded as a promising class of two-dimensional magnets for next-generation devices, an accurate description of their electronic structure and magnetic interactions has proven challenging to achieve. Here, we quantify electronic excitations and spin interactions in CrX 3 (X = Cl, Br, I) using embedded many-body wavefunction calculations and fully generalized spin Hamiltonians. We find that the three trihalides feature comparable d-shell excitations, consisting of a high-spin 4 A 2 ($t^3_{2g}$$e^0_g$) ground state lying 1.5–1.7 eV below the first excited state 4 T 2 ($t^2_{2g}$$e^1_g$). CrCl 3 exhibits a single-ion anisotropy A sia = - 0.02 meV, while the Cr spin-3/2 moments are ferromagnetically coupled through bilinear and biquadratic exchange interactions of J 1 = - 0.97 meV and J 2 = - 0.05 meV, respectively. The corresponding values for CrBr 3 and CrI 3 increase to A sia = -0.08 meV and A sia = - 0.12 meV for the single-ion anisotropy, J 1 = -1.21 meV, J 2 = -0.05 meV and J 1 = -1.38 meV, J 2 = -0.06 meV for the exchange couplings, respectively. We find that the overall magnetic anisotropy is defined by the interplay between A sia and A dip due to magnetic dipole–dipole interaction that favors in-plane orientation of magnetic moments in ferromagnetic monolayers and bulk layered magnets. The competition between the two contributions sets CrCl 3 and CrI 3 as the easy-plane (A sia + A dip >0) and easy-axis (A sia + A dip <0) ferromagnets, respectively. The differences between the magnets trace back to the atomic radii of the halogen ligands and the magnitude of spin–orbit coupling. Our findings are in excellent agreement with recent experiments, thus providing reference values for the fundamental interactions in chromium trihalides.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Layer-resolved many-electron interactions in delafossite PdCoO2 from standing-wave photoemission spectroscopy

Abstract When a three-dimensional material is constructed by stacking different two-dimensional layers into an ordered structure, new and unique physical properties can emerge. An example is the delafossite PdCoO 2 , which consists of alternating layers of metallic Pd and Mott-insulating CoO 2 sheets. To understand the nature of the electronic coupling between the layers that gives rise to the unique properties of PdCoO 2 , we revealed its layer-resolved electronic structure combining standing-wave X-ray photoemission spectroscopy and ab initio many-body calculations. Experimentally, we have decomposed the measured VB spectrum into contributions from Pd and CoO 2 layers. Computationally, we find that many-body interactions in Pd and CoO 2 layers are highly different. Holes in the CoO 2 layer interact strongly with charge-transfer excitons in the same layer, whereas holes in the Pd layer couple to plasmons in the Pd layer. Interestingly, we find that holes in states hybridized across both layers couple to both types of excitations (charge-transfer excitons or plasmons), with the intensity of photoemission satellites being proportional to the projection of the state onto a given layer. This establishes satellites as a sensitive probe for inter-layer hybridization. These findings pave the way towards a better understanding of complex many-electron interactions in layered quantum materials.

36 MATERIALS SCIENCE↗