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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Catabolism of β-5 linked aromatics by Novosphingobium aromaticivorans

ABSTRACT Aromatic compounds are an important source of commodity chemicals traditionally produced from fossil fuels. Aromatics derived from plant lignin can potentially be converted into commodity chemicals through depolymerization followed by microbial funneling of monomers and low molecular weight oligomers. This study investigates the catabolism of the β-5 linked aromatic dimer dehydrodiconiferyl alcohol (DC-A) by the bacterium Novosphingobium aromaticivorans . We used genome-wide screens to identify candidate genes involved in DC-A catabolism. Subsequent in vivo and in vitro analyses of these candidate genes elucidated a catabolic pathway composed of four required gene products and several partially redundant dehydrogenases that convert DC-A to aromatic monomers that can be funneled into the central aromatic metabolic pathway of N. aromaticivorans . Specifically, a newly identified γ-formaldehyde lyase, PcfL, opens the phenylcoumaran ring to form a stilbene and formaldehyde. A lignostilbene dioxygenase, LsdD, then cleaves the stilbene to generate the aromatic monomers vanillin and 5-formylferulate (5-FF). We also showed that the aldehyde dehydrogenase FerD oxidizes 5-FF before it is decarboxylated by LigW, yielding ferulic acid. We found that some enzymes involved in the β-5 catabolism pathway can act on multiple substrates and that some steps in the pathway can be mediated by multiple enzymes, providing new insights into the robust flexibility of aromatic catabolism in N. aromaticivorans . A comparative genomic analysis predicted that the newly discovered β-5 aromatic catabolic pathway is common within the order Sphingomonadales. IMPORTANCE In the transition to a circular bioeconomy, the plant polymer lignin holds promise as a renewable source of industrially important aromatic chemicals. However, since lignin contains aromatic subunits joined by various chemical linkages, producing single chemical products from this polymer can be challenging. One strategy to overcome this challenge is using microbes to funnel a mixture of lignin-derived aromatics into target chemical products. This approach requires strategies to cleave the major inter-unit linkages of lignin to release monomers for funneling into valuable products. In this study, we report newly discovered aspects of a pathway by which the Novosphingobium aromaticivorans DSM12444 catabolizes aromatics joined by the second most common inter-unit linkage in lignin, the β-5 linkage. This work advances our knowledge of aromatic catabolic pathways, laying the groundwork for future metabolic engineering of this and other microbes for optimized conversion of lignin into products.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Auto-deconvolution and molecular networking of gas chromatography–mass spectrometry data

We engineered a machine learning approach, MSHub, to enable auto-deconvolution of gas chromatography–mass spectrometry (GC–MS) data. We then designed workflows to enable the community to store, process, share, annotate, compare and perform molecular networking of GC–MS data within the Global Natural Product Social (GNPS) Molecular Networking analysis platform. MSHub/GNPS performs auto-deconvolution of compound fragmentation patterns via unsupervised non-negative matrix factorization and quantifies the reproducibility of fragmentation patterns across samples.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Local chemical fluctuation mediated ultra-sluggish martensitic transformation in high-entropy intermetallics

Superelasticity associated with martensitic transformation has found a broad range of engineering applications, such as in low-temperature devices in the aerospace industry. Nevertheless, the narrow working temperature range and strong temperature sensitivity of the first-order phase transformation significantly hinder the usage of smart metallic components in many critical areas. Here, we scrutinized the phase transformation behavior and mechanical properties of multicomponent B2-structured intermetallic compounds. Strikingly, the (TiZrHfCuNi) 83.3 Co 16.7 high-entropy intermetallics (HEIs) show superelasticity with high critical stress over 500 MPa, high fracture strength of over 2700 MPa, and small temperature sensitivity in a wide range of temperatures over 220 K. The complex sublattice occupation in these HEIs facilitates formation of nano-scaled local chemical fluctuation and then elastic confinement, which leads to an ultra-sluggish martensitic transformation. The thermal activation of the martensitic transformation was fully suppressed while the stress activation is severely retarded with an enhanced threshold stress over a wide temperature range. Moreover, the high configurational entropy also results in a small entropy change during phase transformation, consequently giving rise to the low temperature sensitivity of the superelasticity stress. Furthermore, our findings may provide a new paradigm for the development of advanced superelastic alloys, and shed new insights into understanding of martensitic transformation in general.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Novel in-capsule synthesis of metal–organic framework for innovative carbon dioxide capture system

Metal-Organic Frameworks (MOFs) have been developed as solid sorbents for CO2 capture applications and their properties can be controlled by tuning the chemical blocks of their crystalline units. A number of MOFs (e.g., HKUST-1) have been developed but the question remains how to deploy them for gas–solid contact. Unfortunately, the direct use of MOFs as nanocrystals would lead to serious problems and risks. Here, for the first time, we report a novel MOF-based hybrid sorbent that is produced via an innovative in-situ microencapsulated synthesis. Using a custom-made double capillary microfluidic assembly, double emulsions of the MOF precursor solutions and UV-curable silicone shell fluid are produced. Subsequently, HKUST-1 MOF is successfully synthesized within the droplets enclosed in the gas permeable microcapsules. The developed MOF-bearing microcapsules uniquely allow the deployment of functional nanocrystals without the challenge of handling ultrafine particles, and further, can selectively reject undesired compounds to protect encapsulated MOFs.

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

Inorganic Halide Double Perovskites with Optoelectronic Properties Modulated by Sublattice Mixing

All-inorganic halide double perovskites have emerged as a promising class of materials that are potentially more stable and less toxic than lead-containing hybrid organic-inorganic perovskite optoelectronic materials. In this work, 311 cesium chloride double perovskites (Cs 2 BB'Cl 6 ) were selected from a set of 903 compounds as likely being stable on the basis of a statistically learned tolerance factor (t) for perovskite stability. First-principles calculations on these 311 double perovskites were then performed to assess their stability and identify candidates with band gaps appropriate for optoelectronic applications. We predict that 261 of the 311 Cs 2 BB'Cl 6 compounds are likely synthesizable on the basis of a thermodynamic analysis of their decomposition to competing compounds (decomposition enthalpy <0.05 eV/atom). Of these 261 likely synthesizable compounds, 47 contain no toxic elements and have direct or nearly direct (within 100 meV) band gaps between 1 and 3 eV, as computed with hybrid density functional theory (HSE06). Within this set, we identify the triple-alkali perovskites Cs 2 [Alk] + [TM] 3+ Cl 6 , where Alk is a group 1 alkali cation and TM is a transition-metal cation, as a class of Cs 2 BB'Cl 6 double perovskites with remarkable optical properties, including large and tunable exciton binding energies as computed by the GW-Bethe-Salpeter equation (GW-BSE) method. We attribute the unusual electronic structure of these compounds to the mixing of the Alk-Cl and TM-Cl sublattices, leading to materials with small band gaps, large exciton binding energies, and absorption spectra that are strongly influenced by the identity of the transition metal. The role of the double-perovskite structure in enabling these unique properties is probed through an analysis of the electronic structures and chemical bonding of these compounds in comparison with other transition-metal and alkali transition-metal halides.

14 SOLAR ENERGY↗
DOE OSTI2021

DeepMC: a deep learning method for efficient Monte Carlo beamlet dose calculation by predictive denoising in magnetic resonance-guided radiotherapy

Abstract Emerging magnetic resonance (MR) guided radiotherapy affords significantly improved anatomy visualization and, subsequently, more effective personalized treatment. The new therapy paradigm imposes significant demands on radiation dose calculation quality and speed, creating an unmet need for the acceleration of Monte Carlo (MC) dose calculation. Existing deep learning approaches to denoise the final plan MC dose fail to achieve the accuracy and speed requirements of large-scale beamlet dose calculation in the presence of a strong magnetic field for online adaptive radiotherapy planning. Our deep learning dose calculation method, DeepMC, addresses these needs by predicting low-noise dose from extremely noisy (but fast) MC-simulated dose and anatomical inputs, thus enabling significant acceleration. DeepMC simultaneously reduces MC sampling noise and predicts corrupted dose buildup at tissue-air material interfaces resulting from MR-field induced electron return effects. Here we demonstrate our model’s ability to accelerate dose calculation for daily treatment planning by a factor of 38 over traditional low-noise MC simulation with clinically meaningful accuracy in deliverable dose and treatment delivery parameters. As a post-processing approach, DeepMC provides compounded acceleration of large-scale dose calculation when used alongside established MC acceleration techniques in variance reduction and graphics processing unit-based MC simulation.

Engineering↗
DOE OSTI2025

Electro-activated indigos intensify ampere-level CO 2 reduction to CO on silver catalysts

The electrochemical reduction of carbon dioxide (CO 2 ) to carbon monoxide (CO) is challenged by a selectivity decline at high current densities. Here we report a class of indigo-based molecular promoters with redox-active CO 2 binding sites to enhance the high-rate conversion of CO 2 to CO on silver (Ag) catalysts. Theoretical calculations and in situ spectroscopy analyses demonstrate that the synergistic effect at the interface of indigo-derived compounds and Ag nanoparticles could activate CO 2 molecules and accelerate the formation of key intermediates (*CO 2 – and *COOH) in the CO pathway. Indigo derivatives with electron-withdrawing groups further reduce the overpotential for CO production upon optimizing the interfacial CO 2 binding affinity. By integrating the molecular design of redox-active centres with the defect engineering of Ag structures, we achieve a Faradaic efficiency for CO exceeding 90% across a current density range of 0.10 − 1.20 A cm –2 . The Ag mass activity toward CO increases to 174 A mg –1 Ag . This work showcases that employing redox-active CO 2 sorbents as surface modification agents is a highly effective strategy to intensify the reactivity of electrochemical CO 2 reduction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Structural characterization of a new samarium–sodium heterometallic coordination polymer

Lanthanide-containing materials are of interest in the field of crystal engineering because of their unique properties and distinct structure types. In this context, a new samarium–sodium heterometallic coordination polymer, poly[tetrakis(μ 2 -2-formyl-6-methoxyphenolato)samarium(III)sodium(I)], {[SmNa(C 8 H 7 O 3 ) 4 ]·solvent} n ( Sm-1 ), was synthesized and crystallized via slow evaporation from a mixture of ethanol and acetonitrile. The compound features alternating Sm III and Na I ions, which are linked by ortho -vanillin ( o -vanillin) ligands to form a mono-periodic chain-like coordination polymer. The chains propagate along the [001] direction. Residual electron density of disordered solvent molecules in the void space could not be reasonably modeled, thus the SQUEEZE function was applied. The structural, vibrational, and optical properties are reported.

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

Pnictogen-Bonding Catalysis: Copolymerization of CO 2 and Epoxides on Antimony(V) Platforms

The copolymerization of CO 2 and epoxides to access polycarbonates represents a promising strategy for CO 2 utilization and for the production of useful polymers. Aiming to explore alternative transition-metal-free approaches that support this chemistry, we have investigated a series of triaryl-catecholatostiboranes as pnictogen-bonding platforms for the copolymerization of CO 2 and cyclohexene oxide (CHO). Our survey of these antimony species has identified motifs that promote this polymerization reaction efficiently, provided that bis(triphenylphosphine)iminium chloride is administered as an activator. By coupling these polymerization studies with a careful assessment of the structure, electronic attributes and Lewis acidity of the catecholatostiboranes, this work shows that high activity is generally observed with the weakest pnictogen-bond donors or Lewis acids investigated. Mechanistic studies, which indicate that the polymerization reaction is first order in stiborane, reveal a nonlinear dependence on the CO 2 pressure. This nonlinear dependence could be satisfactorily modeled based on a pre-equilibrium process involving the reversible insertion of the gaseous monomer into the growing chain. Altogether these findings greatly expand the reach of pnictogen bond catalysis while also providing an entry for the use of heavy group 15 elements as competent platforms for CO 2 utilization.

antimony↗
DOE OSTI2020

Advances in catalytic production processes of biomass-derived vinyl monomers

Plastic industries currently source the majority of monomers from crude oil substances. Although we have witnessed a significant interest of companies in the utilization of sustainable feedstock materials for bio-based compound synthesis in the past decade, the transition to photosynthetic or chemosynthetic plant-based production in a circular carbon economy is largely slow due to complex biomass processing, costs and related reaction factors. The upgrade of the separated platform chemicals with a deeper supporting understanding of processes, models and a root–cause analysis about the underlying distribution challenges of engineered transformation mechanisms, catalyzed conversion pathways and selectivity would be beneficial to advance applied scientific development, bio-refining and manufacturing output amount. This review provides a summary, assessment and perspective for three important polymer-forming vinyl molecules, i.e. acrylic acid, methacrylic acid and styrene. These provide a backbone to produce acrylates, polystyrene, resins, rubbers, protective surface coatings, adhesives, textiles and other obtained copolymers. A succinct analytical overview on the thermo-catalytic intermediate routes for property-wise drop-in alternatives is presented. Sugars, acrolein, allyl alcohol, ethylbenzene, glycerol, 3-hydroxypropionic acid, isobutene, itaconic acid and lactic acid are considered as the main starting reactants. Catalysts span mixed metal oxides, silicates, native or impregnated zeolite frameworks (HBEA, HZSM, and MFI) and hetero-poly acids as well as homogeneous base hydroxides or platinum group metals, supported on carbon, alumina and sulfates. Finally, the article concludes with a brief state sum-up of the results, topics and opportunities for systematic future research or scaling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Highly sensitive spin-flop transition in antiferromagnetic van der Waals material M PS 3 ( M = Ni and Mn)

Recent developments in two-dimensional (2D) magnetism have motivated the search for van der Waals (vdW) magnetic materials to explore magnetic phenomena in the 2D limit. Metal thiophosphates, MPX 3 , are a class of magnetic vdW materials with antiferromagnetic ordering persisting down to the atomically thin limit. The magnetism in this material family has been found to be highly dependent on the choice of transition metal M. In this paper, we have synthesized the intermediate compounds Ni 1–x Mn x PS 3 (0 ≤ x ≤ 1) and investigated their magnetic properties. Our study reveals that the variation of Ni and Mn content in Ni 1–x Mn x PS 3 can efficiently tune the spin-flop transition, likely due to the modulation of the magnetic anisotropy. Such effective tuning offers a promising candidate to engineer 2D magnetism for future device applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

High Flux Through the Oxidative Pentose Phosphate Pathway Lowers Efficiency in Developing Camelina Seeds

Many seeds are green during development, and light has been shown to play a role in the efficiency with which maternally supplied substrates are converted into storage compounds. However, the effects of light on the fluxes through central metabolism that determine this efficiency are poorly understood. Here, we used metabolic flux analysis to determine the effects of light on central metabolism in developing embryos of false flax (Camelina sativa). Metabolic efficiency in C. sativa is of interest because, despite its growing importance as a model oilseed and engineering target and its potential as a biofuel crop, its yields are lower than other major oilseed species. Culture conditions under which steady-state growth and composition of developing embryos match those in planta were used to quantify substrate uptake and respiration rates. The carbon conversion efficiency (CCE) was 21% 6 3% in the dark and 42% 6 4% under high light. Under physiological illumination, the CCE (32% 6 2%) was substantially lower than in green and nongreen oilseeds studied previously. 13C and 14C isotopic labeling experiments were used together with computer-aided modeling to map fluxes through central metabolism. Fluxes through the oxidative pentose phosphate pathway (OPPP) were the principal source of CO2 production and strongly negatively correlated with CCE across light levels. OPPP fluxes were greatly in excess of demand for NAD(P)H for biosynthesis and larger than those measured in other systems. Excess reductant appears to be dissipated via cyanide-insensitive respiration. OPPP enzymes therefore represent a potential target for increasing efficiency and yield in C. sativa.

09 BIOMASS FUELS↗
DOE OSTI2023

A High-Quality Genome-Scale Model for Rhodococcus opacus Metabolism

Rhodococcus opacus is a bacterium that has a high tolerance to aromatic compounds and can produce significant amounts of triacylglycerol (TAG). Here, we present iGR1773, the first genome-scale model (GSM) of R. opacus PD630 metabolism based on its genomic sequence and associated data. The model includes 1773 genes, 3025 reactions, and 1956 metabolites, was developed in a reproducible manner using CarveMe, and was evaluated through Metabolic Model tests (MEMOTE). We combine the model with two Constraint-Based Reconstruction and Analysis (COBRA) methods that use transcriptomics data to predict growth rates and fluxes: E-Flux2 and SPOT (Simplified Pearson Correlation with Transcriptomic data). Growth rates are best predicted by E-Flux2. Flux profiles are more accurately predicted by E-Flux2 than flux balance analysis (FBA) and parsimonious FBA (pFBA), when compared to 44 central carbon fluxes measured by 13C-Metabolic Flux Analysis (13C-MFA). Under glucose-fed conditions, E-Flux2 presents an R2 value of 0.54, while predictions based on pFBA had an inferior R2 of 0.28. We attribute this improved performance to the extra activity information provided by the transcriptomics data. For phenol-fed metabolism, in which the substrate first enters the TCA cycle, E-Flux2’s flux predictions display a high R2 of 0.96 while pFBA showed an R2 of 0.93. We also show that glucose metabolism and phenol metabolism function with similar relative ATP maintenance costs. These findings demonstrate that iGR1773 can help the metabolic engineering community predict aromatic substrate utilization patterns and perform computational strain design.

Roell, Garrett W.↗
DOE OSTI2019

Auditory performance in bald eagles and red-tailed hawks: a comparative study of hearing in diurnal raptors

Collision with wind turbines is a conservation concern for eagles with population abundance implications. The development of acoustic alerting technologies to deter eagles from entering hazardous air spaces is a potentially significant mitigation strategy to diminish associated morbidity and mortality risks. As a prelude to the engineering of deterrence technologies, auditory function was assessed in bald eagles (Haliaeetus leucocephalus), as well as in red tailed hawks (Buteo jamaicensis). Auditory brainstem responses (ABRs) to a comprehensive battery of clicks and tone bursts varying in level and frequency were acquired to evaluate response thresholds, as well as suprathreshold response characteristics of wave I of the ABR, which represents the compound potential of the VIII cranial nerve. Sensitivity curves exhibited an asymmetric convex shape similar to those of other avian species, response latencies decreased exponentially with increasing stimulus level and response amplitudes grew with level in an orderly manner. Both species were responsive to a frequency band at least 4 octaves wide, with a most sensitive frequency of 2 kHz, and a high frequency limit of approximately 5.7 kHz in bald eagles and 8 kHz in red tailed hawks. Here, findings reported here provide a framework within which acoustic alerting signals might be developed.

17 WIND ENERGY↗
DOE OSTI2025

Biotechnological advances in algae-based foods: applications in nutrition and microbiome health

Algae are a sustainable, nutrient-rich resource with growing potential in food biotechnology. Their ability to thrive in diverse environments makes them a promising alternative to conventional crops. Rich in proteins, essential fatty acids, and bioactive compounds, algae support the development of functional foods, including plant-based meat and seafood alternatives. Advances in synthetic biology and fermentation have enhanced algal nutrient profiles and enabled novel applications. Algae-derived polysaccharides, such as alginate, fucoidan, laminarin, and porphyran, exhibit prebiotic effects by modulating the gut microbiota and promoting SCFA production. Enzymatic hydrolysis efficiently produces bioactive oligosaccharides, while engineered microbial systems support scalable production. Algae also enable synbiotic food development by serving as both prebiotic substrates and probiotic carriers.

Yu, Sora↗
DOE OSTI2021

All-Dielectric Meta-Optics for High-Efficiency Independent Amplitude and Phase Manipulation

Optical metasurfaces, composed of subwavelength scattering elements, demonstrate remarkable control over the transmitted amplitude, phase, and polarization of light. However, manipulating the amplitude upon transmission, without the use of surface waves, requires loss if a single metasurface is used. Herein, high-efficiency independent manipulation of the amplitude and phase of a beam is described using two lossless phase-only metasurfaces separated by a distance. With this configuration, optical components such as combined beam-forming and splitting devices are experimentally demonstrated, as well as those for forming complex-valued, 3D holograms. The compound meta-optic platform provides a promising approach for achieving high-performance holographic displays and compact optical components, while exhibiting a high overall efficiency.

42 ENGINEERING↗
DOE OSTI2021

Thermochemistry of sodium rare earth ternary fluorides, NaREF 4

Sodium rare earth fluorides, NaREF 4 (RE = rare earth), are used as luminescent materials for light emission and biomedical applications and are important compositions for extracting and separating RE elements. Solution calorimetric measurements of a series of β-structured NaREF 4 (Na 1.5 RE 1.5 F 6 ) phases with various RE elements determined their heats of formation. Though the lattice contracts from light to heavy RE elements, NaREF 4 compounds show more exothermic enthalpies of formation from binary components with the decrease of RE 3+ radii, contrary to behavior seen in most RE oxide ternary compounds. Furthermore, by constructing Born–Haber cycles, the different slopes of lines relating lattice energies to lattice parameters in binary and ternary fluorides appear to be the reason for this reverse trend, which can be associated with changes in the coordination number of RE cations. These trends and the metastability of sodium light RE fluorides not only reveal the key role of ionic radius in RE compound stability, but also are significant for the design and synthesis of new materials and motivate the more effective utilization of RE.

36 MATERIALS SCIENCE↗