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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 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Equation of state measurement of detonation carbon condensates using optical microscopy and interferometry

Thermochemical models of detonation that estimate performance (e.g., detonation velocity, energy delivery, etc.), are based on assumptions that carbon condensates (soot) formed during detonation is largely similar to bulk carbon. However, soot constituents can range from amorphous carbon to nanodiamond and include other material phases. Since thermodynamic properties of the soot such as compressibility are imperative for accurate thermochemical modeling of detonation reaction chemistry, experimental measurements of the equation of state (EOS) which determine the compressibility are vital. Due to the mixed-phase nature of detonation soot, typical methods to measure the EOS (e.g., x-ray diffraction) are untenable. In this study, the high-pressure EOS up to 20 GPa was determined for detonation soot collected from PBX 9502, Composition B (Comp B), Hexanitrostilbene (HNS), and LX-21 high explosives by employing a direct volume technique using optical microscopy and interferometry in a diamond anvil cell. Comp B soot was determined to be the least compressible [K 0 = 57.9(17) GPa] with HNS soot [K 0 = 53.7(15) GPa], LX-21 soot [K 0 = 45.8(51) GPa], and PBX 9502 soot [K 0 = 28.2(27) GPa] being more compressible, likely due to differences in nanodiamond content as compared to amorphous carbon and graphite content.

Amorphous materials↗
DOE OSTI2025

Parameterized anomalous transport model for current-carrying collisionless plasmas in pulsed power inertial confinement fusion

Current delivery in pulsed power inertial confinement fusion is influenced by collisionless current-carrying microturbulent plasmas, which are sourced from electrode surfaces. In this setting, the lower hybrid drift instability—triggered by plasma acceleration—is a leading candidate driver of difficult-to-predict momentum and energy transport. To characterize the nonlinear state of the microturbulent plasma, a parameterized anomalous transport model is developed for the instability, with analytic formulas for anomalous collision frequency, resistivity, and species heating rates. The formulas are expressed in terms of linear-theory variables and four dimensionless parameters that characterize the macroscopic plasma state. The model is built on linear theory analysis, power law analysis, and quasilinear theory analysis, and is validated using a series of nonlinear continuum kinetic Vlasov–Poisson simulations. The theoretical and computational investigation demonstrates that the anomalous collision frequency associated with the instability can be reliably approximated, within about a factor of five or better, by the unscaled linear theory growth rate of the fastest-growing wavenumber mode. This finding enables efficient calculation of anomalous resistivity and species heating rates over a wide range of plasma conditions, resulting in improved predictive capabilities.

Complex functions↗
DOE OSTI2026

Microwave-photonic control of optically accessible spin defects in diamond

A growing variety of optically accessible spin qubits have emerged in recent years as key components for quantum sensors, computers, and memories. However, the scalability of conventional spin-based quantum architectures remains limited by direct microwave delivery, which introduces thermal noise, electromagnetic crosstalk, and design constraints for cryogenic, high-field, and distributed systems. In this work, we present a unified framework for RF-over-fiber (RFoF) control of spins accessible through optically detected magnetic resonance (ODMR) spectroscopy of nitrogen-vacancy (NV) centers in diamond. The RFoF platform relies on an intensity-modulated 1310 nm laser carrying microwave signals over fiber and a high-speed photodiode for optical-to-electrical conversion to drive NV spin transitions. We report an RFoF power-conversion efficiency of 3.42% for an RF output PRF,out=-5.5 dBm at 2.87 GHz, enabling clear resolution of Zeeman splitting in

Rahman, M Reefaz [ORNL] (ORCID:0000000323541611)↗
DOE OSTI2020

Structural and optical properties of nanoparticles formed by laser ablation of porous silicon in liquids: Perspectives in biophotonics

The paper discusses the possibility of manufacturing silicon nanoparticles, which are suitable for contrasting biological tissues imaged by optical coherence tomography, by femtosecond laser ablation of porous silicon in various liquids. The manufactured nanoparticles are characterised by average sizes of 87, 112, and 102 nm for cases of ablation in water, ethanol, and liquid nitrogen, respectively, as well as a relatively narrow size distribution, which provides additional advantages for subsequent delivery into biological tissues. Electrochemical etching, which results in the formation of layers of porous silicon, allows the yield of ablation products to be increased several-fold by lowering the ablation threshold, thereby increasing the light scattering efficiency of the prepared suspensions compared with the case of using crystalline silicon as targets. The possibility of obtaining high-contrast images of a biotissue phantom based on an agar gel with embedded nanoparticles is shown. The magnitude of the contrast depends on the liquid used for ablation and correlates with the values of the reduced scattering coefficient of the studied suspensions. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

A comparative genomics approach identifies contact-dependent growth inhibition as a virulence determinant

Emerging evidence suggests the Pseudomonas aeruginosa accessory genome is enriched with uncharacterized virulence genes. Identification and characterization of such genes may reveal novel pathogenic mechanisms used by particularly virulent isolates. In this work, we utilized a mouse bacteremia model to quantify the virulence of 100 individual P. aeruginosa bloodstream isolates and performed whole-genome sequencing to identify accessory genomic elements correlated with increased bacterial virulence. From this work, we identified a specific contact-dependent growth inhibition (CDI) system enriched among highly virulent P. aeruginosa isolates. CDI systems contain a large exoprotein (CdiA) with a C-terminal toxin (CT) domain that can vary between different isolates within a species. Prior work has revealed that delivery of a CdiA-CT domain upon direct cell-to-cell contact can inhibit replication of a susceptible target bacterium. Aside from mediating interbacterial competition, we observed our virulence-associated CdiA-CT domain to promote toxicity against mammalian cells in culture and lethality during mouse bacteremia. Structural and functional studies revealed this CdiA-CT domain to have in vitro tRNase activity, and mutations that abrogated this tRNAse activity in vitro also attenuated virulence. Furthermore, CdiA contributed to virulence in mice even in the absence of contact-dependent signaling. Overall, our findings indicate that this P. aeruginosa CDI system functions as both an interbacterial inhibition system and a bacterial virulence factor against a mammalian host. These findings provide an impetus for continued studies into the complex role of CDI systems in P. aeruginosa pathogenesis.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Structure of the cell-binding component of the Clostridium difficile binary toxin reveals a di-heptamer macromolecular assembly

Targeting Clostridium difficile infection is challenging because treatment options are limited, and high recurrence rates are common. One reason for this is that hypervirulent C. difficile strains often have a binary toxin termed the C. difficile toxin, in addition to the enterotoxins TsdA and TsdB. The C. difficile toxin has an enzymatic component, termed CDTa, and a pore-forming or delivery subunit termed CDTb. CDTb was characterized here using a combination of single-particle cryoelectron microscopy, X-ray crystallography, NMR, and other biophysical methods. In the absence of CDTa, 2 di-heptamer structures for activated CDTb (1.0 MDa) were solved at atomic resolution, including a symmetric ( Sym CDTb; 3.14 Å) and an asymmetric form ( Asym CDTb; 2.84 Å). Roles played by 2 receptor-binding domains of activated CDTb were of particular interest since the receptor-binding domain 1 lacks sequence homology to any other known toxin, and the receptor-binding domain 2 is completely absent in other well-studied heptameric toxins (i.e., anthrax). For Asym CDTb, a Ca 2+ binding site was discovered in the first receptor-binding domain that is important for its stability, and the second receptor-binding domain was found to be critical for host cell toxicity and the di-heptamer fold for both forms of activated CDTb. Together, these studies represent a starting point for developing structure-based drug-design strategies to target the most severe strains of C. difficile .

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

The carbon content of Earth and its core

Earth’s core is likely the largest reservoir of carbon (C) in the planet, but its C abundance has been poorly constrained because measurements of carbon’s preference for core versus mantle materials at the pressures and temperatures of core formation are lacking. Using metal–silicate partitioning experiments in a laser-heated diamond anvil cell, we show that carbon becomes significantly less siderophile as pressures and temperatures increase to those expected in a deep magma ocean during formation of Earth’s core. Based on a multistage model of core formation, the core likely contains a maximum of 0.09(4) to 0.20(10) wt% C, making carbon a negligible contributor to the core’s composition and density. However, this accounts for ~80 to 90% of Earth’s overall carbon inventory, which totals 370(150) to 740(370) ppm. The bulk Earth’s carbon/sulfur ratio is best explained by the delivery of most of Earth’s volatiles from carbonaceous chondrite-like precursors.

Geosciences↗
DOE OSTI2021

Mechanisms of transport enhancement for self-propelled nanoswimmers in a porous matrix

Significance As with living microorganisms, many real-world applications of synthetic micro/nanoswimmers are likely to rely on transport in complex environments, a phenomenon that remains poorly understood. Here, we report anomalously rapid transport of self-propelled particles in a porous medium, where nanoswimmers escaped from cavities more than an order of magnitude faster than expected compared to corresponding Brownian particles. This phenomenon was determined to be due to nuanced effects associated with self-propulsion, including enhanced mobility in confinement, efficient surface-mediated searching for holes, and the abolition of barriers at cavity exits. These mechanisms are broadly generalizable, and the previously unknown transport efficiency of nanoswimmers in complex porous environments suggests tremendous opportunities in forward-looking applications, including drug delivery and environmental remediation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Omicron mutations enhance infectivity and reduce antibody neutralization of SARS-CoV-2 virus-like particles

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant contains extensive sequence changes relative to the earlier-arising B.1, B.1.1, and Delta SARS-CoV-2 variants that have unknown effects on viral infectivity and response to existing vaccines. Using SARS-CoV-2 virus-like particles (VLPs), we examined mutations in all four structural proteins and found that Omicron and Delta showed 4.6-fold higher luciferase delivery overall relative to the ancestral B.1 lineage, a property conferred mostly by enhancements in the S and N proteins, while mutations in M and E were mostly detrimental to assembly. Thirty-eight antisera samples from individuals vaccinated with Pfizer/BioNTech, Moderna, or Johnson & Johnson vaccines and convalescent sera from unvaccinated COVID-19 survivors had 15-fold lower efficacy to prevent cell transduction by VLPs containing the Omicron mutations relative to the ancestral B.1 spike protein. A third dose of Pfizer vaccine elicited substantially higher neutralization titers against Omicron, resulting in detectable neutralizing antibodies in eight out of eight subjects compared to one out of eight preboosting. Furthermore, the monoclonal antibody therapeutics casirivimab and imdevimab had robust neutralization activity against B.1 and Delta VLPs but no detectable neutralization of Omicron VLPs, while newly authorized bebtelovimab maintained robust neutralization across variants. Our results suggest that Omicron has similar assembly efficiency and cell entry compared to Delta and that its rapid spread is due mostly to reduced neutralization in sera from previously vaccinated subjects. In addition, most currently available monoclonal antibodies will not be useful in treating Omicron-infected patients with the exception of bebtelovimab.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Elucidation of the physical factors that control activated transport of penetrants in chemically complex glass-forming liquids

Understanding the activated transport of penetrant or tracer atoms and molecules in condensed phases is a challenging problem in chemistry, materials science, physics, and biophysics. Many angstrom- and nanometer-scale features enter due to the highly variable shape, size, interaction, and conformational flexibility of the penetrant and matrix species, leading to a dramatic diversity of penetrant dynamics. Based on a minimalist model of a spherical penetrant in equilibrated dense matrices of hard spheres, a recent microscopic theory that relates hopping transport to local structure has predicted a novel correlation between penetrant diffusivity and the matrix thermodynamic dimensionless compressibility, S 0 ( T ) (which also quantifies the amplitude of long wavelength density fluctuations), as a consequence of a fundamental statistical mechanical relationship between structure and thermodynamics. Moreover, the penetrant activation barrier is predicted to have a factorized/multiplicative form, scaling as the product of an inverse power law of S 0 ( T ) and a linear/logarithmic function of the penetrant-to-matrix size ratio. This implies an enormous reduction in chemical complexity that is verified based solely on experimental data for diverse classes of chemically complex penetrants dissolved in molecular and polymeric liquids over a wide range of temperatures down to the kinetic glass transition. The predicted corollary that the penetrant diffusion constant decreases exponentially with inverse temperature raised to an exponent determined solely by how S 0 ( T ) decreases with cooling is also verified experimentally. Our findings are relevant to fundamental questions in glassy dynamics, self-averaging of angstrom-scale chemical features, and applications such as membrane separations, barrier coatings, drug delivery, and self-healing.

Science & Technology - Other Topics↗
DOE OSTI2023

Insights from high-fidelity modeling of industrial rotary bell atomization

The global automotive industry sprayed over 2.6 billion liters of paint in 2018, much of which through electrostatic rotary bell atomization, a highly complex process involving the fluid mechanics of rapidly rotating thin films tearing apart into micrometer-thin filaments and droplets. Coating operations account for 65% of the energy usage in a typical automotive assembly plant, representing 10,000s of gigawatt-hours each year in the United States alone. Optimization of these processes would allow for improved robustness, reduced material waste, increased throughput, and significantly reduced energy usage. Here, we introduce a high-fidelity mathematical and algorithmic framework to analyze rotary bell atomization dynamics at industrially relevant conditions. Our approach couples laboratory experiment with the development of robust non-Newtonian fluid models; devises high-order accurate numerical methods to compute the coupled bell, paint, and gas dynamics; and efficiently exploits high-performance supercomputing architectures. These advances have yielded insight into key dynamics, including i) parametric trends in film, sheeting, and filament characteristics as a function of fluid rheology, delivery rates, and bell speed; ii) the impact of nonuniform film thicknesses on atomization performance; and iii) an understanding of spray composition via primary and secondary atomization. These findings result in coating design principles that are poised to improve energy- and cost-efficiency in a wide array of industrial and manufacturing settings.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

Viral afterlife: SARS-CoV-2 as a reservoir of immunomimetic peptides that reassemble into proinflammatory supramolecular complexes

It is unclear how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to the strong but ineffective inflammatory response that characterizes severe Coronavirus disease 2019 (COVID-19), with amplified immune activation in diverse cell types, including cells without angiotensin-converting enzyme 2 receptors necessary for infection. Proteolytic degradation of SARS-CoV-2 virions is a milestone in host viral clearance, but the impact of remnant viral peptide fragments from high viral loads is not known. Here, we examine the inflammatory capacity of fragmented viral components from the perspective of supramolecular self-organization in the infected host environment. Interestingly, a machine learning analysis to SARS-CoV-2 proteome reveals sequence motifs that mimic host antimicrobial peptides (xenoAMPs), especially highly cationic human cathelicidin LL-37 capable of augmenting inflammation. Such xenoAMPs are strongly enriched in SARS-CoV-2 relative to low-pathogenicity coronaviruses. Moreover, xenoAMPs from SARS-CoV-2 but not low-pathogenicity homologs assemble double-stranded RNA (dsRNA) into nanocrystalline complexes with lattice constants commensurate with the steric size of Toll-like receptor (TLR)-3 and therefore capable of multivalent binding. Such complexes amplify cytokine secretion in diverse uninfected cell types in culture (epithelial cells, endothelial cells, keratinocytes, monocytes, and macrophages), similar to cathelicidin’s role in rheumatoid arthritis and lupus. The induced transcriptome matches well with the global gene expression pattern in COVID-19, despite using <0.3% of the viral proteome. Delivery of these complexes to uninfected mice boosts plasma interleukin-6 and CXCL1 levels as observed in COVID-19 patients.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

De novo design of modular protein hydrogels with programmable intra- and extracellular viscoelasticity

Relating the macroscopic properties of protein-based materials to their underlying component microstructure is an outstanding challenge. Here, we exploit computational design to specify the size, flexibility, and valency of de novo protein building blocks, as well as the interaction dynamics between them, to investigate how molecular parameters govern the macroscopic viscoelasticity of the resultant protein hydrogels. We construct gel systems from pairs of symmetric protein homo-oligomers, each comprising 2, 5, 24, or 120 individual protein components, that are crosslinked either physically or covalently into idealized step-growth biopolymer networks. Through rheological assessment, we find that the covalent linkage of multifunctional precursors yields hydrogels whose viscoelasticity depends on the crosslink length between the constituent building blocks. In contrast, reversibly crosslinking the homo-oligomeric components with a computationally designed heterodimer results in viscoelastic biomaterials exhibiting fluid-like properties under rest and low shear, but solid-like behavior at higher frequencies. Exploiting the unique genetic encodability of these materials, we demonstrate the assembly of protein networks within living mammalian cells and show via fluorescence recovery after photobleaching (FRAP) that mechanical properties can be tuned intracellularly in a manner similar to formulations formed extracellularly. We anticipate that the ability to modularly construct and systematically program the viscoelastic properties of designer protein-based materials could have broad utility in biomedicine, with applications in tissue engineering, therapeutic delivery, and synthetic biology.

36 MATERIALS SCIENCE↗
DOE OSTI2024

A bioactive supramolecular and covalent polymer scaffold for cartilage repair in a sheep model

Regeneration of hyaline cartilage in human-sized joints remains a clinical challenge, and it is a critical unmet need that would contribute to longer healthspans. Injectable scaffolds for cartilage repair that integrate both bioactivity and sufficiently robust physical properties to withstand joint stresses offer a promising strategy. We report here on a hybrid biomaterial that combines a bioactive peptide amphiphile supramolecular polymer that specifically binds the chondrogenic cytokine transforming growth factor β-1 (TGFβ-1) and crosslinked hyaluronic acid microgels that drive formation of filament bundles, a hierarchical motif common in natural musculoskeletal tissues. The scaffold is an injectable slurry that generates a porous rubbery material when exposed to calcium ions once placed in cartilage defects. The hybrid material was found to support in vitro chondrogenic differentiation of encapsulated stem cells in response to sustained delivery of TGFβ-1. Using a sheep model, we implanted the scaffold in shallow osteochondral defects and found it can remain localized in mechanically active joints. Evaluation of resected joints showed significantly improved repair of hyaline cartilage in osteochondral defects injected with the scaffold relative to defects injected with the growth factor alone, including implantation in the load-bearing femoral condyle. These results demonstrate the potential of the hybrid biomimetic scaffold as a niche to favor cartilage repair in mechanically active joints using a clinically relevant large-animal model.

Science & Technology - Other Topics↗
DOE OSTI2025

Bridging microscopic dynamics and rheology in the yielding of charged colloidal suspensions

The yielding of soft materials is critical to many natural and industrial processes, yet experimental insights into microscopic aspects of yielding are limited. This study combines angle X-ray scattering, X-ray photon correlation spectroscopy, and in situ rheology (Rheo-SAXS-XPCS) with fast lubrication dynamics simulations to examine how interparticle interactions influence yielding in charged colloidal suspensions. By tuning attraction through salt addition, we compare repulsive and attractive systems under deformation. Repulsive suspensions yield uniformly with Andrade-like creep and minimal structural change. In contrast, attractive suspensions show complex behaviors, including shear banding, delayed yielding, and resolidification, governed by transient dynamics at shear band interfaces. These results directly link microscopic particle dynamics to macroscopic flow and demonstrate how interaction potentials control rheological behavior. This work offers a framework for designing soft materials with tailored properties for applications in coatings, food processing, drug delivery, and other technologies requiring precise mechanical control.

Molecular Dynamics Simulation↗
DOE OSTI2026

Ambient-pressure 151-K superconductivity in HgBa 2 Ca 2 Cu 3 O 8+δ via pressure quench

Superconductivity has been a vigorously researched topic since its discovery in 1911. Raising the superconducting transition temperature (T c ) has been the main driving force behind such long-sustained efforts due to its potential for impacting humanity and the fundamental knowledge gained from understanding this macroscopic coherent quantum state at high temperatures. The successful development of high-T c superconductivity will make possible extraordinarily efficient generation, delivery, and utilization of energy and could also enable the development of controlled fusion while impacting other burgeoning fields like quantum computation and quantum electronics. However, progress has been hindered by a longstanding plateau in the record ambient-pressure T c , unchanged since 1993. Subsequent significant advancements in T c have been achieved only under high pressures, preventing the realization of superconductivity’s full potential. To directly address this challenge, we developed a pressure-quench protocol (PQP) to stabilize pressure-induced/-enhanced superconducting states at ambient pressure. Here, we achieve a record ambient-pressure T c of 151 K in the cuprate HgBa 2 Ca 2 Cu 3 O 8+δ via PQP. The experimental results are further supported by synchrotron X-ray diffraction measurements and phonon and electronic structure calculations. This breakthrough opens avenues for stabilizing and exploring ambient-pressure high-T c superconducting states and other quantum states that have been previously only accessible under pressure, paving the way for deeper understanding and practical applications of high-T c superconductivity and beyond.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

An investigation of aqueous ammonium nitrate aerosols with soft X-ray spectroscopy

Aqueous aerosols are important in atmospheric chemistry, drug delivery, and human health. X-ray photoelectron spectroscopy (XPS), a surface-sensitive technique and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy which informs on the bulk, is deployed to study the solvation of ammonium nitrate (NH 4 NO 3 ). Aerosolised solutions of NH 4 NO 3 were introduced into a photoelectron spectrometer via an aerodynamic lens, and interrogated with soft X-ray photons, the resulting electrons were imaged via velocity map imaging. Density functional theory calculations were performed to compare with the measured binding energies of NH 4 + and NO 3 - solvated in water. The results reveal that the nitrate anion has a slight propensity for the surface, while both ammonium and nitrate ions are present in equal measure in the bulk.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

A Cable Condition Monitoring Strategy for Safe and Reliable Plant Operation

Electrical cables provide essential functions, such as delivery of power or instrumentation signals for monitoring systems. Most cables installed in industrial applications are constructed with organic polymer insulations that can become brittle, crack, or degrade over time from exposure to harsh environmental conditions, such as elevated temperatures, moisture, vibration, mechanical shock, and radiation. This paper describes an overall strategy for assessing the health and managing the aging of cables during the operating life of an industrial facility. This strategy involves performing condition assessments and monitoring of electrical cables using both in situ and laboratory testing techniques. It includes in situ testing to identify anomalies in the circuits, such as degraded terminations, splices, connections, and degraded sections of cable insulation, as well as as-found evaluations to determine the current condition of installed cables. Furthermore, these cable condition evaluations provide important information about the current state of the cable circuits. Moreover, the test results can be used to trend/monitor age-related degradation and estimate the remaining useful life of installed cables.

36 MATERIALS SCIENCE↗