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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 1,243 records · Page 69
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Toward controlled functional sequencing and hierarchical structuring in imidazolium ionenes

This focused mini-review highlights recent advances related to the design and applications of imidazolium ionenes and forward-looking perspectives. Creative strategies which employ established synthetic approaches and utilize the modularity of the imidazole moiety unlock great potential for tailoring both functional and structural features arising from precise spacing of ionic groups within the polymer backbone. Here, as imidazolium ionenes draw more interest, increased sophistication of chemical modifications and material processing is occurring, with a corresponding shift toward more demanding applications. Synthetic routes for placement and sequencing of ionic content are discussed, in addition to recent approaches to control structure and self-assembly or tune behaviors of imidazolium ionenes and composites.

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

An Algal Nutrient‐Replete, Optimized Medium for Fast Growth and High Triacylglycerol Accumulation

Microalgae are promising sources to sustainably meet the global needs for energy and products. Algae grow under different trophic conditions, where nutritional status regulates biosynthetic pathways, energy production, and growth. The green alga Chromochloris zofingiensis has strong economic potential because it co-produces biofuel precursors and the high-value antioxidant astaxanthin while accumulating biomass when grown mixotrophically. As an emerging reference alga for photosynthesis, metabolism, and bioproduction, C. zofingiensis needs a defined, optimized medium to standardize experiments during fast growth for batch cultivation. Because the interplay of glucose treatment (+Glc) and mineral deficiency influences photosynthesis, growth, and the production of lipids and astaxanthin, we designed a replete nutrient medium tailored to the C. zofingiensis cellular ionome. We combined inductively coupled plasma mass spectrometry (ICP-MS) and +Glc growth curves to determine a medium that is nutrient replete for at least 5 days of +Glc logarithmic growth. We found that there are high nutritional needs for phosphorus and sulfur during mixotrophy. Iron was the only element measured for which the cellular concentration correlated with exogenous concentration and was iteratively adjusted until the cellular ionome was consistent through the logarithmic growth phase. This Chromochloris-Optimized Ratio of Elements (CORE) medium supports fast growth and high biomass and lipid accumulation without causing excess nutrient toxicity. This defined, nutrient-replete standard is important for future C. zofingiensis investigations and can be adapted for other species to support high biomass for batch cultivation. The method used to develop CORE medium shows how ionomics informs replicable media design and may be applied in industrial settings to inform cost-effective biofuel production.

Jeffers, Tim L. [University of California, Berkele↗
DOE OSTI2024

Computational tools and algorithms for ion mobility spectrometry-mass spectrometry

Ion mobility spectrometry-mass spectrometry (IMS-MS or IM-MS) is a powerful analytical technique that combines the gas-phase separation capabilities of IM with the identification and quantification capabilities of MS. IM-MS can differentiate molecules with indistinguishable masses but different structures (e.g., isomers, isobars, molecular classes, and contaminant ions). The importance of this analytical technique is reflected by a staged increase in the number of applications for molecular characterization across a variety of fields, from different MS-based omics (proteomics, metabolomics, lipidomics, etc.) to the structural characterization of glycans, organic matter, proteins, and macromolecular complexes. With the increasing application of IM-MS there is a pressing need for effective and accessible computational tools. This article presents an overview of the most recent free and open-source software tools specifically tailored for the analysis and interpretation of data derived from IM-MS instrumentation. This review enumerates these tools and outlines their main algorithmic approaches, while highlighting representative applications across different fields. Finally, a discussion of current limitations and expectable improvements is presented.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Development of a Printable Prill Formulation Technique and Demonstration of Monomodal Prill Size on Compaction Density and Compressive Strength

Polymer-bonded explosive molding powder, or “prills,” are relied on for the fabrication of pressed high explosives since the 1950's. The wet granulation technique, also known as “slurry coating,” that is used to formulate prills, is a complex process that results in polydisperse and variable yields. This makes it difficult to study the mesoscale effect that prills have on the microstructure of a pressed article. The following study introduces a novel approach to energetic granulation that leverages techniques used in the additive manufacturing of paste-like energetic materials. This extrusion granulation, or prill printing technique, makes it possible to tailor the sizes and shapes of prills, allowing for their morphological influences to be studied in a controlled manner. The following work details the fabrication and characterization of four monomodal size lots of prills using an inert formulation (95 wt.% melamine, 5 wt.% polymer binder). Prills from each size lot were die-pressed using a fixed recipe to investigate how prill size impacts compaction density and therefore compressive strength. It was found that larger prills influence the pressing density by creating larger defects within the microstructure of a pressed article, resulting in a decrease in compressive strength.

direct ink write↗
DOE OSTI2022

The Wormholes Within: A Study of 1, 3, 5–Triamino–2, 4, 6–Trinitrobenzene Crystal Morphology by Micro and Nano–Scale X–Ray Computed Tomography and its Effects Upon the Shock Sensitivity of Detonation

We report that we understand heterogeneous-explosive detonation only to the extent that we can first measure the salient chemical and microstructural features. Barring an inordinate amount of trial and error, we can tailor the detonation properties of our HE formulations only to the extent that we understand (at least qualitatively) the same effects. As an insensitive high explosive, 1, 3, 5-triamino-2, 4, 6-trinitrobenzene (TATB) burns more heterogeneously than conventional high explosives, making its detonation properties sensitive to microstructure. The Benziger route can produce various grain morphologies depending on the amount of water used in the amination step. So-called dry-aminated (DA) TATB crystals are riddled with a void structure called wormholes, which are washed out ammonium chloride (NH4Cl) inclusions that form during synthesis. So-called wet-aminated (WA) TATB crystals do not contain NH 4 Cl inclusions but possess a very convoluted external structure. Using both micro and nano-scale CT, we explore three DA-TATB lots that reflect evolutionary processing changes, plus one WA-TATB material. Micro CT imaged crystal collections show the exterior grain structure, revealing its roughness and providing a crude particle size measurement. The DA-TATB lots that test most sensitively in the LANL ECOT corner-turning test are roughest, having the appearance of being “corroded”. Nano-scale CT reveals both internal NH 4 Cl inclusions and void structures. The DA-TATB lots that tested intermediate and high sensitivity in ECOT exhibited similar wormhole structures, which were more extensive than that of the low-sensitivity lot. The least sensitive DA-TATB lot also retained more NH 4 Cl, consistent with reduced connectivity of voids to the surface.

1, 3, 5-triamino-2,4↗
DOE OSTI2024

The Effects of Material-Filled Voids on Detonation Wave Shape in Rubberized RDX Explosives

The sensitivity of explosives is affected by inhomogeneities within the material. This is evident in the increased shock sensitivity of explosives with slightly lower densities resulting from an increased number of hotspots. The influence of hotspots on explosive initiation has been well studied; however, few studies have been conducted on the effect of intermediate-sized voids (0.1–10 mm) on a propagating detonation wave. Cylindrical voids filled with air have been studied for diameters ranging from 0.3 mm to 0.8 mm for both 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) and 1,3,5-trinitro-1,3,5-triazinane (RDX)-based rubberized explosives. Continuing the investigation into single cylindrical voids, this study examined the effects of 0.5 mm diameter voids filled with different inert cylindrical metals on the detonation wave shape for an RDX-based rubberized explosive. The metals selected for experiments were 1066 aluminum, brass, copper, and tungsten. The propagation of the detonation wave was captured using a digital streak camera. Experimental results showed that the extent of detonation wave shaping was closely tied to the density differential between the bulk explosive and metal insert. Forty-four different filler materials, including non-metals, were simulated using a hydrodynamic code to further analyze material inclusion effects. The main factors hypothesized to be of interest were bulk sound speed, shock impedance, and filler material density. We found that the local detonation delay could be correlated fairly well to a ratio of bulk sound speed and density. Understanding the influence of material inclusions on detonation performance and wave shape allows for tailoring of detonations.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2021

Elastic Properties and Deformation Mechanisms in the van der Waals Single-Crystalline Indium Selenide

The bulk van der Waals (vdW) single-crystalline indium selenide (β-InSe) displays exceptional plasticity in a layered crystalline form at both micro- and macroscale. However, the nanoscale origin of plasticity remains unclear. Herein, an atomic-level study on the deformation mechanisms of InSe by using first-principles calculations is reported. Remarkable anisotropic elasticity is observed in the vdW InSe layered crystal, and the stiffness is dramatically softened because of the vdW gap in the layered structure. The simulations capture the distinct fracture modes in the uniaxial tensile deformation, depending on the loading directions—brittle fracture in the [100] and [110] directions while ductile failure in the [001] direction. The InSe layered crystal structure exhibits superplastic deformability under uniaxial compression. Different transition pathways, including interlayer tangling, amorphization, and cross-linking, are tracked along respective deformation directions. The unprecedented plasticity of InSe layered crystals can be attributed to the phase transition coupled with interlayer gliding and cross-layer dislocation slipping. Here, this study deepens our understanding of the deformation mechanisms of layered materials at the atomistic level and provides insights into tailoring material properties for low-dimensional material design based on its deformation mechanisms.

2D materials↗
DOE OSTI2025

Bayesian D‐Optimal Designs for Gaussian Process Surrogate Models

Computer experiments often employ space-filling strategies to create surrogate models with strong predictive performance. The impact of model parameter estimation for Gaussian process surrogates, however, is often overlooked. Obtaining a better initial estimate of the covariance lengthscale parameter, θ, can greatly improve the resulting Gaussian process fit through more effective sequential acquisitions during active learning. In this work, we propose a novel initial design maximizing the Bayesian D-optimality criterion of the Gaussian process lengthscale parameter. Previously published results have shown the emphasis on lengthscale estimation to be promising, but relied on an empirically driven design creation process. Our Bayesian D-optimal designs are rooted in information theory and lead to more informative sequential acquisitions by improving lengthscale estimation. In many cases, these gains eventually result in better surrogates than those seeded with space-filling initial designs. Furthermore, Bayesian D-optimal designs can be tailored to either isotropic or anisotropic covariance structures, and the Bayesian framework enables the inclusion of prior knowledge in the design process, offering greater flexibility and adaptability. Through several simulation studies, we demonstrate the advantages of Bayesian D-optimal designs in terms of both lengthscale estimation accuracy and predictive performance during active learning.

Bayesian experimental design↗
DOE OSTI2026

A Review of Software for Designing and Operating Quantum Networks

Quantum networks development is crucial to realizing a production-grade network that can support distributed sensing, secure communication, and utility-scale quantum computation. However, the transition from laboratory demonstration to deployable networks requires software implementations of architectures and protocols tailored to the unique constraints of quantum systems. This paper reviews the current state of software implementations for quantum networks, organized around a three-plane abstraction of infrastructure, logical, and control/service planes. We cover software for both designing quantum network protocols (e.g., SeQUeNCe, QuISP, and NetSquid) and operating testbeds, with a focus on essential control/service plane functions such as entanglement, topology, and resource management, in a proposed taxonomy. Our review highlights a persistent gap between theoretical architecture and protocol proposals and their realization in simulators or testbeds, particularly in dynamic topology and network management. We conclude by outlining open challenges and proposing a roadmap for developing scalable software architectures to enable hybrid, large-scale quantum networks.

Network Design↗
DOE OSTI2020

Large-Scale Plasmonic Hybrid Framework with Built-In Nanohole Array as Multifunctional Optical Sensing Platforms

Light coupling with patterned subwavelength hole arrays induces enhanced transmission supported by the strong surface plasmon mode. In this work, a nanostructured plasmonic framework with vertically built-in nanohole arrays at deep-subwavelength scale (6 nm) is demonstrated using a two-step fabrication method. The nanohole arrays are formed first by the growth of a high-quality two-phase (i.e., Au–TiN) vertically aligned nanocomposite template, followed by selective wet-etching of the metal (Au). Such a plasmonic nanohole film owns high epitaxial quality with large surface coverage and the structure can be tailored as either fully etched or half-way etched nanoholes via careful control of the etching process. The chemically inert and plasmonic TiN plays a role in maintaining sharp hole boundary and preventing lattice distortion. Optical properties such as enhanced transmittance and anisotropic dielectric function in the visible regime are demonstrated. Numerical simulation suggests an extended surface plasmon mode and strong field enhancement at the hole edges. Furthermore, two demonstrations, including the enhanced and modulated photoluminescence by surface coupling with 2D perovskite nanoplates and the refractive index sensing by infiltrating immersion liquids, suggest the great potential of such plasmonic nanohole array for reusable surface plasmon-enhanced sensing applications.

42 ENGINEERING↗
DOE OSTI2020

Quantized Grain Boundary States Promote Nanoparticle Alignment During Imperfect Oriented Attachment

Oriented attachment (OA) has become a well-recognized mechanism for the growth of metal, ceramic, and biomineral crystals. While many computational and experimental studies of OA have shown that particles can attach with some misorientation then rotate to remove adjoining grain boundaries, the underlying atomistic pathways for this “Imperfect OA” process remain the subject of debate. In this paper, molecular dynamics and in situ TEM were used to probe the crystallographic evolution of up to 30 gold and copper nanoparticles during aggregation. It was found that Imperfect OA occurs because (1) grain boundaries become quantized when their size is comparable to the separation between constituent dislocations and (2) kinetic barriers associated with the glide of grain boundary dislocations are small. In support of these findings, TEM experiments show the formation of a single crystal aggregate after annealing 9 initially misoriented, agglomerated particles with evidence of dislocation slip and twin formation during particle/grain alignment. These observations motivate future work on assembled nanocrystals with tailored defects and call for a revision of Read-Shockley models for grain boundary energies in nanocrystalline materials.

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

Enhancement of Magneto‐Mechanical Actuation of Micropillar Arrays by Anisotropic Stress Distribution

Abstract Magnetically active shape‐reconfigurable microarrays undergo programmed actuation according to the arrangement of magnetic dipoles within the structures, achieving complex twisting and bending deformations. Cylindrical micropillars have been widely used to date, whose circular cross‐sections lead to identical actuation regardless of the actuating direction. In this study, micropillars with triangular or rectangular cross‐sections are designed and fabricated to introduce preferential actuation directions and explore the limits of their actuation. Using such structures, controlled liquid wetting is demonstrated on micropillar surfaces. Liquid droplets pinned on magnetic micropillar arrays undergo directional spreading when the pillars are actuated as depinning of the droplets is enabled only in certain directions. The enhanced deformation due to direction dependent magneto‐mechanical actuation suggests that micropillar arrays can be fundamentally tailored to possess application specific responses and opens up opportunities to exploit more complex designs such as micropillars with polygonal cross sections. Such tunable wetting of liquids on microarray surfaces has potential to improve printing technologies via contactless reconfiguration of stamp geometry by magnetic field manipulation.

Park, Jeong Eun↗
DOE OSTI2021

Advanced Nanocarbons for Enhanced Performance and Durability of Platinum Catalysts in Proton Exchange Membrane Fuel Cells

Insufficient stability of current carbon supported Pt and Pt alloy catalysts is a significant barrier for proton-exchange membrane fuel cells (PEMFCs). As a primary degradation cause to trigger Pt nanoparticle migration, dissolution, and aggregation, carbon corrosion remains a significant challenge. Compared with enhancing Pt and PtM alloy particle stability, improving support stability is rather challenging due to carbon's thermodynamic instability under fuel cell operation. In recent years, significant efforts have been made to develop highly durable carbon-based supports concerning innovative nanostructure design and synthesis along with mechanistic understanding. Here, this review critically discusses recent progress in developing carbon-based materials for Pt catalysts and provides synthesis–structure–performance correlations to elucidate underlying stability enhancement mechanisms. The mechanisms and impacts of carbon support degradation on Pt catalyst performance are first discussed. The general strategies are summarized to tailor the carbon structures and strengthen the metal–support interactions, followed by discussions on how these designs lead to enhanced support stability. Based on current experimental and theoretical studies, the critical features of carbon supports are analyzed concerning their impacts on the performance and durability of Pt catalysts in fuel cells. Finally, the perspectives are shared on future directions to develop advanced carbon materials with favorable morphologies and nanostructures to increase Pt utilization, strengthen metal-support interactions, facilitate mass/charge transfer, and enhance corrosion resistance.

25 ENERGY STORAGE↗
DOE OSTI2021

Reconfiguration of Amorphous Complex Oxides: A Route to a Broad Range of Assembly Phenomena, Hybrid Materials, and Novel Functionalities

This work demonstrate that reconfiguration of amorphous oxide layers drives the assembly of oxide-based and freestanding nanomembranes into 3D structures with a radius of a few hundred nanometers. Reconfiguration-driven assembly is a versatile approach to impart large strains and strain gradients in a broad palette of complex oxides. This capability allows for manipulating and enhancing ferroelectricity, flexoelectricity, piezoelectricity, superconductivity, and ferromagnetism in complex oxides. Moreover, by the approach presented in this work, strain-engineered oxides are obtained in the form of 3D structures that can be fabricated in parallel on any substrate, including large-area and single crystalline semiconductor substrates. This approach will create a vast expanse of possibilities to investigate and leverage strain-tunable effects in amorphous, poly-crystalline, and single-crystalline complex oxides. Reconfiguration-driven assembly of NMs also allows combining different materials in a radial geometry and through scalable processes. For example, radial superlattices of Si (or GaAs) and various complex oxides or alternating layers of different complex oxides (e.g., SrTiO 3 and LaAlO 3 ) could be fabricated by release and heating of bilayer NMs. Here, a broad palette of electronic band structures and spin–orbit interactions could then be obtained by tailoring the curvature of the self-assembled NMs and the materials that the heterostructure comprises.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Linker-Based Bandgap Tuning in Conductive MOF Solid Solutions

Herein, the synthesis of Cu 3 (HAB) x (TATHB) 2-x (HAB: hexaaminobenzene, TATHB: triaminotrihydroxybenzene) is reported. Synthetic improvement of Cu 3 (TATHB) 2 leads to a more crystalline framework with higher electrical conductivity value than previously reported. The improved crystallinity and analogous structure between TATHB and HAB enable the synthesis of Cu 3 (HAB) x (TATHB) 2-x with ligand compositions precisely controlled by precursor ratios. The electrical conductivity is tuned from 4.2 × 10 -8 to 2.9 × 10 -5 S cm -1 by simply increasing the nitrogen content in the crystal lattice. Furthermore, computational calculation supports that the solid solution facilitates the band structure tuning. In conclusion, it is envisioned that the findings not only shed light on the ligand-dependent structure–property relationship but create new prospects in synthesizing multicomponent electrically conductive metal-organic frameworks (MOFs) for tailoring optoelectronic device applications.

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

Selective Catalytic Behavior Induced by Crystal–Phase Transformation in Well–Defined Bimetallic Pt–Sn Nanocrystals

The Pt-Sn bimetallic system is a much studied and commercially used catalyst for propane dehydrogenation. The traditionally prepared catalyst, however, suffers from inhomogeneity and phase separation of the active Pt–Sn phase. Colloidal chemistry offers a route for the synthesis of Pt–Sn bimetallic nanoparticles (NPs) in a systematic, well-defined, tailored fashion over conventional methods. Here, the successful synthesis of well-defined ≈2 nm Pt, PtSn, and Pt 3 Sn nanocrystals with distinct crystallographic phases is reported; hexagonal close packing (hcp) PtSn and fcc Pt 3 Sn show different activity and stability depending on the hydrogen-rich or poor environment in the feed. Moreover, face centred cubic (fcc) Pt 3 Sn/Al 2 O 3 , which exhibited the highest stability compared to hcp PtSn, shows a unique phase transformation from an fcc phase to an L1 2 -ordered superlattice. Contrary to PtSn, H 2 cofeeding has no effect on the Pt 3 Sn deactivation rate. Finally, the results reveal structural dependency of the probe reaction, propane dehydrogenation, and provide a fundamental understanding of the structure–performance relationship on emerging bimetallic systems.

36 MATERIALS SCIENCE↗