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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Microbiomes Have the Power to Help or Hinder Your Health

They are everywhere: countless microorganisms that inhabit our world—even in your skin, mouth, gut and other parts of your body. Called microbiomes, these communities play a fundamental role in our ecosystem and our bodies, influencing everything from climate to human health. And scientists at PNNL are studying microbiomes to better understand how they influence our daily lives. Scientist Janet Jansson studies complex microbiomes in soil and the human intestine to understand changes in the composition or function of microbes. In the soil, these microbes are associated with carbon cycling and degrading pollutants, as well as plant health. In the intestine, they are responsible for digestion of our food and protection from pathogens. When they go awry, they can be associated with numerous inflammatory bowel diseases, such as Crohn’s. Understanding the factors underlying these microbiome changes will ultimately help researchers develop solutions to problems encountered within our world and our bodies.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Method and apparatus for fabricating ceramic and metal components via additive manufacturing with uniform layered radiation drying

A freeform extrusion fabrication process for producing three-dimensional ceramic, metal and functionally gradient composite objects, including the steps of filling a plurality of paste sources with a respective plurality of aqueous paste compositions, operationally connecting respective syringes containing respective aqueous paste compositions to a mixing chamber, moving a first aqueous paste composition from a first respective paste source into the mixing chamber, moving a second aqueous paste composition from a second respective paste source into the mixing chamber, mixing the first and second aqueous paste compositions to define a first admixture having a first admixture composition, extruding the first admixture onto a surface to define an extruded layer having a first admixture composition, surrounding the sides of the extruded layer with an oil bath, radiatively drying the extruded layer.

Leu, Ming C.↗
DOE OSTI2019

Compositions and methods for hydrocarbon functionalization

Embodiments of the present disclosure provide for methods of hydrocarbon functionalization, methods and systems for converting a hydrocarbon into a compound including at least one group ((e.g., hydroxyl group) (e.g., methane to methanol)), functionalized hydrocarbons, and the like. Systems and methods as described herein can utilize photocatalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Multiple-objective Reinforcement Learning for Inverse Design and Identification

Inverse chemical design using generative deep learning (DL) models is an emerging tool, which has early success in generating molecular structures with desired properties. We enhance this tool by developing heuristics for curriculum-learning based multiple-objective (20+ objectives) reinforcement learning, and apply it to the context of chemical identi?cation. We develop a generative DL framework that utilizes constraints pertaining to the unknown molecule’s mass and functional group composition, and show that multiple-objective RL-based generative DL models can correctly identify unknown molecules with a 80% success rate, compared to the baseline approach of 0%. Lastly, the heuristics developed are not limited to just chemistry research challenges; we anticipate any problem that utilizes reinforcement learning with multiple-objectives will bene?t from it.

Artificial Intelligence, Data Science, deep learni↗
DOE OSTI2015

Photoluminescence in solid solutions and thin films of tungstates CaWO{sub 4}-CdWO{sub 4}

In this study, we present two types of studies on the luminescence properties under UV and X-ray excitations of solid solutions Ca{sub 1-x}Cd{sub x}WO{sub 4} and of thin layers of CaWO{sub 4} and CdWO{sub 4}. These tungstate based solid solutions are susceptible to be integrated into new radiation sensors, in order to be used in different fields of applications such as reactor measurements, safeguards, homeland security, nuclear nondestructive assays, LINAC emission radiation measurement. However these complex materials were rarely investigated in the literature. One first objective of our studies was to establish correlations between luminescence efficiency, chemical substitution and the degree of crystallization resulting from elaboration conditions. A second objective will be to determine the efficiency of luminescence properties of thin layers of these materials. In the present work, we focus our attention on the role of chemical substitution on photon emissions under UV and X-ray irradiations. The luminescence spectra of Ca{sub 1-x}Cd{sub x}WO{sub 4} polycrystalline materials have been investigated at room temperature as a function of composition (0≤x≤1). In addition, we present a preliminary study of the luminescence of CaWO{sub 4} and CdWO{sub 4} thin layers: oscillations observed in the case of X-ray excitations in the luminescence spectra are discussed. (authors)

36 MATERIALS SCIENCE↗
DOE OSTI2026

RidgeAlloy: A high pressure die casting alloy that captures the approaching wave of automotive body sheet scrap

Oak Ridge National Laboratory (ORNL) has recently launched an effort to economically expand the North American aluminum supply chain by designing and developing a new family of Al-Mg-Si-Fe-Mn structural die cast aluminum alloys that can be made from up to 100% mixed 5xxx and 6xxx series automotive post-consumer sheet scrap and do not require heat treatment. The goal is to develop an alloy capable of capturing the approaching scrap wave of aluminum sheet intensive vehicles (in the 2030’s) into integrated structural high pressure die castings, rather than down-cycling these high-grade sheet alloys into non-structural castings. ORNL discovered a significant gap in the commercial thermodynamic databases that were unable to predict the trends of a key primary intermetallic phase as a function of composition. Experiments were performed to correct this gap and to create a unique, corrected quaternary database for Al-Mg-Si-Fe. High throughput computational methods, including solidification simulations, were used to identify a composition volume capable of avoiding this embrittling primary intermetallic phase, even at higher Fe + Si contents. Laboratory scale castings validated the thermodynamic and solidification predictions and resulted in lab-cast alloys with little primary intermetallic, and which met or exceeded structural casting properties requirements for yield strength and ductility. An accelerated demonstration of an HPDC automotive part was conducted in collaboration with two U.S. small businesses. Ingots made from 100% recycled 5xxx and 6xxx series scrap (plus Fe) were used to die cast one variant of this new family of Al-Mg-Si-Fe-Mn alloys (with high Si + Fe content) into a mid-sized HPDC structural-type automotive component. The HPDC alloy demonstration part showed good properties (especially ductility) and good castability for a complex component.

Plotkowski, Alex [ORNL] (ORCID:0000000154718681)↗
DOE OSTI2016

Material properties of perovskites in the quasi-ternary system LaFeO{sub 3}–LaCoO{sub 3}–LaNiO{sub 3}

An overview is presented on the variation of electrical conductivity, oxygen permeation, and thermal expansion coefficient as a function of the composition of perovskites in the quasi-ternary system LaFeO{sub 3}–LaCoO{sub 3}–LaNiO{sub 3}. Powders of thirteen nominal perovskite compositions were synthesized under identical conditions by the Pechini method. The powder X-ray diffraction data of two series, namely La(Ni{sub 0.5}Fe{sub 0.5}){sub 1−x}Co{sub x}O{sub 3} and LaNi{sub 0.5-x}Fe{sub x}Co{sub 0.5}O{sub 3}, are presented after the powders had been sintered at 1100 °C for 6 h in air. The measurements revealed a rhombohedral structure for all compositions except LaNi{sub 0.5}Fe{sub 0.5}O{sub 3} for which 60% rhombohedral and 40% orthorhombic phase was found. The maximum DC electrical conductivity value of the perovskites at 800 °C was 1229 S cm{sup −1} for the composition LaCoO{sub 3} and the minimum was 91 S cm{sup −1} for the composition LaCo{sub 0.5}Fe{sub 0.5}O{sub 3}. The oxygen permeation of samples with promising conductivities at 800 °C was one order of magnitude lower than that of La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3} (LSCF). The highest value of 0.017 ml cm{sup −2} min{sup −1} at 950 °C was obtained with LaNi{sub 0.5}Co{sub 0.5}O{sub 3}. The coefficients of thermal expansion varied in the range of 13.2×10{sup −6} K{sup −1} and 21.9×10{sup −6} K{sup −1} for LaNi{sub 0.5}Fe{sub 0.5}O{sub 3} and LaCoO{sub 3}, respectively. {sup 57}Fe Mössbauer spectroscopy was used as probe for the oxidation states, local environment and magnetic properties of iron ions as a function of chemical composition. The substitution had a great influence on the chemical properties of the materials. - Graphical abstract: Compositional dependence of isothermal electrical conductivity at 800 °C and thermal expansion coefficient in the series La(Fe{sub 0.5}Ni{sub 0.5}){sub (1−x)}Co{sub x}O{sub 3} and LaNi{sub 0.5−x}Fe{sub x}Co{sub 0.5}O{sub 3}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Surface-functionalized mesoporous carbon materials

A functionalized mesoporous carbon composition comprising a mesoporous carbon scaffold having mesopores in which polyvinyl polymer grafts are covalently attached, wherein said mesopores have a size of at least 2 nm and up to 50 nm. Also described is a method for producing the functionalized mesoporous composition, wherein a reaction medium comprising a precursor mesoporous carbon, vinyl monomer, initiator, and solvent is subjected to sonication of sufficient power to result in grafting and polymerization of the vinyl monomer into mesopores of the precursor mesoporous carbon. Also described are methods for using the functionalized mesoporous carbon, particularly in extracting metal ions from metal-containing solutions.

25 ENERGY STORAGE↗
DOE OSTI2020

Large‐ and small‐seeded species have contrasting functional neighborhoods in a subtropical forest

Abstract Forest community composition is the outcome of multiple forces, including those that increase taxonomic and functional divergence and those that promote convergence in traits. The mechanisms underlying these forces may not operate homogenously within communities; individuals of different species are never perfectly mixed, and thus, species tend to be surrounded and interact with different subsets of species. In fact, taxonomic and functional composition of neighborhoods of different focal species can be highly variable. Here, we examine whether mechanisms driving species‐level neighborhoods relate to intrinsic characteristics of focal species such as differences in life‐history and resource‐uptake strategies and in turn relate to species survival. We focus on two key characteristics: (1) seed mass, which defines a dominant axis of life‐history strategies related to stress tolerance, and (2) understory light preferences that sort species from light‐demanding pioneers to shade‐tolerant. We monitored seedling communities over 10 yr in Puerto Rico and calculated neighborhood trait dispersion in species‐level neighborhoods using seven functional traits. We examined whether species‐level characteristics, seed mass and preferred light conditions, influence patterns of functional dispersion in seedling neighborhoods using linear models. Then, we examined how species‐level functional neighborhoods impact seedling survival. We found that small‐ and large‐seeded species diverge in the type of functional neighborhoods they associate with. Large‐seeded species associate with neighbors that are more similar than expected in leaf economic traits, but more different than expected in seed mass and leaf area traits, while the opposite was found for small‐seeded species. This variation in species functional neighborhood was important in determining seedling survival. In sum, our results suggest that divergent and convergent forces do not operate homogenously over entire communities. Their relative role changes in space, and on a species‐by‐species basis, probably with a deterministic foundation linked to traits such as seed mass.

Umaña, María Natalia↗
DOE OSTI2017

ISS observations offer insights into plant function

Technologies on the International Space Station will provide ~1 year of synchronous observations of ecosystem composition, structure and function, in 2018. Here, we discuss these instruments and how they can be used to constrain global models and improve our understanding of the current state of terrestrial ecosystems.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Direct and indirect effects of climate change on soil microbial and soil microbial-plant interactions: What lies ahead?

Global change is altering species distributions and thus interactions among organisms. Organisms live in concert with thousands of other species, some beneficial, some pathogenic, some which have little to no effect in complex communities. Since natural communities are composed of organisms with very different life history traits and dispersal ability it is unlikely they will all respond to climatic change in a similar way. Disjuncts in plant-pollinator and plant-herbivore interactions under global change have been relatively well described, but plant-soil microorganism and soil microbe-microbe relationships have received less attention. Since soil microorganisms regulate nutrient transformations, provide plants with nutrients, allow co-existence among neighbors, and control plant populations, changes in soil microorganism-plant interactions could have significant ramifications for plant community composition and ecosystem function. Finally, in this paper we explore how climatic change affects soil microbes and soil microbe-plant interactions directly and indirectly, discuss what we see as emerging and exciting questions and areas for future research, and discuss what ramifications changes in these interactions may have on the composition and function of ecosystems.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Extremal chiral ring states in the AdS/CFT correspondence are described by free fermions for a generalized oscillator algebra

This paper studies a special class of states for the dual conformal field theories associated with supersymmetric AdS 5 ×X compactifications, where X is a Sasaki-Einstein manifold with additional U(1) symmetries. Under appropriate circumstances, it is found that elements of the chiral ring that maximize the additional U(1) charge at fixed R-charge are in one to one correspondence with multitraces of a single composite field. This is also equivalent to Schur functions of the composite field. It is argued that in the formal zero coupling limit that these dual field theories have, the different Schur functions are orthogonal. Together with large N counting arguments, one predicts that various extremal three point functions are identical to those of N=4 SYM, except for a single normalization factor, which can be argued to be related to the R-charge of the composite word. The leading and subleading terms in 1/N are consistent with a system of free fermions for a generalized oscillator algebra. Finally, one can further test this conjecture by constructing coherent states for the generalized oscillator algebra that can be interpreted as branes exploring a subset of the moduli space of the field theory and use these to compute the effective Kähler potential on this subset of the moduli space.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Metagenomics Reveals Diet-Specific Specialization of Bacterial Communities in Fungus Gardens of Grass- and Dicot-Cutter Ants

Leaf-cutter ants in the genus Atta are dominant herbivores in the Neotropics. While most species of Atta cut dicots to incorporate into their fungus gardens, some species specialize on grasses. Here we examine the bacterial community associated with the fungus gardens of grass- and dicot-cutter ants to examine how changes in substrate input affect the bacterial community. We sequenced the metagenomes of 12 Atta fungus gardens, across four species of ants, with a total of 5.316 Gbp of sequence data. We show significant differences in the fungus garden bacterial community composition between dicot- and grass-cutter ants, with grass-cutter ants having lower diversity. Reflecting this difference in community composition, the bacterial functional profiles between the fungus gardens are significantly different. Specifically, grass-cutter ant fungus garden metagenomes are particularly enriched for genes responsible for amino acid, siderophore, and terpenoid biosynthesis while dicot-cutter ant fungus gardens metagenomes are enriched in genes involved in membrane transport. Differences between community composition and functional capacity of the bacteria in the two types of fungus gardens reflect differences in the substrates that the ants incorporated. These results show that different substrate inputs matter for fungus garden bacteria and shed light on the potential role of bacteria in mediating the ants’ transition to the use of a novel substrate.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Interatomic potential to predict the favored and optimized compositions for ternary Cu-Zr-Hf metallic glasses

Under the framework of smoothed and long range second-moment approximation of tight-binding, a realistic interatomic potential was first constructed for the Cu-Zr-Hf ternary metal system. Applying the constructed potential, Monte Carlo simulations were carried out to compare the relative stability of crystalline solid solution versus its disordered counterpart over the entire composition triangle of the system (as a function of alloy composition). Simulations not only reveal that the origin of metallic glass formation but also determine, in the composition triangle, a quadrilateral region, within which metallic glass formation is energetically favored. It is proposed to define the energy differences between the crystalline solid solutions and disordered states as the driving force for amorphization and the corresponding calculations pinpoint an optimized composition locating at an composition of Cu{sub 55}Zr{sub 10}Hf{sub 35}, around which the driving force for metallic glass formation reaches its maximum, suggesting that the ternary Cu-Zr-Hf metallic glasses designed to have the compositions around Cu{sub 55}Zr{sub 10}Hf{sub 35} could be more stable than other alloys in the system. Moreover, for the Cu{sub 55}Zr{sub 10}Hf{sub 35} metallic glass, the Voronoi tessellation calculations reveal some interesting features of its atomic configurations and coordination polyhedra distribution.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Direct photopatterning of robust and diverse materials

The present invention relates to methods of metathesizing olefins using catalysts previously considered to be practically inactive. The present invention further relates to novel photosensitive compositions, their use as photoresists, and methods related to patterning polymer layers on substrates. Further, modifications to the compositions and method provide for an unprecedented functionalization of the compositions, useful for example in the preparation of sensors, drug delivery systems, and tissue scaffolds. The novel compositions and associated methods also provide for the opportunity to prepare 3-dimensional objects which provide new access to critically dimensioned devices, including for example photonic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Examining Constituent Redistribution in U-19Pu-10Zr Fuel as it Evolves with Local Burnup

While constituent redistribution is a known irradiation behavior in U-Pu-Zr fuel, new data have shown it is more complex than our current understanding and predictive capabilities. The size and composition of redistributed rings evolve as a function of pin composition, burnup, geometry, and irradiation temperature. In this work, we extract microstructural information from optical microscopy conducted on U-19Pu-10Zr pins (irradiated between 1.9 at. % and 11.6 at. % peak burnup). Both manual image analysis techniques and machine learning-assisted segmentation are used to quantify the thicknesses of the cladding, fuel-cladding interaction layers, and rings of fuel constituent redistribution in addition to pore distribution. These microstructural features and individual redistributed regions affect local thermomechanical properties, and identifying the relationship between burnup and constituent redistribution will improve accurate prediction of advanced reactor fuel performance.

Constituent Redistribution↗
DOE OSTI2013

Ammonium–cobalt–nickel phosphates, NH{sub 4}[Co{sub 1−x}Ni{sub x}PO{sub 4}]·H{sub 2}O

The ammonium–cobalt–nickel phosphates, NH{sub 4}[Co{sub 1−x}Ni{sub x}PO{sub 4}]·H{sub 2}O (x=0.00, 0.34, 0.59, 0.70, 1.00), and the deuterated forms, ND{sub 4}[Co{sub 1−x}Ni{sub x}PO{sub 4}]·D{sub 2}O (x=0.00, 0.38, 0.48, 0.69, 0.85), have been synthesized under mild hydrothermal conditions and characterised using X-ray and neutron diffraction, chemical and thermal analysis, and magnetic measurements. Their crystal structures, including hydrogen positions, were determined by Rietveld refinement using single-crystal X-ray and neutron powder diffraction data. The space group of these orthorhombic crystals modifies as a function of their composition. The magnetic susceptibility and magnetization measurements of these ammonium–cobalt–nickel phosphates show antiferromagnetic behaviour, and the Neel temperature evolves from 5.5 K (x=0.00) up to 13.2 K (x=1.00). - Graphical abstract: We obtained single crystals for all the members of the family. In this series, although all crystals are orthorhombic, the space group changes as a function of the composition, showing how the single-crystal diffraction data is capable to manifest structural subtleties that had not been described before for this group of materials. All the investigated materials behave antiferromagnetically with ordering temperatures from 5.5 K up to 13.2 K. Display Omitted - Highlights: • The ammonium–cobalt–nickel phosphates, NH{sub 4}[Co{sub 1−x}Ni{sub x}PO{sub 4}]·H{sub 2}O (x=0.00, 0.34, 0.59, 0.70, 1.00) and the deuterated forms ND4[Co1-xNixPO4]·D{sub 2}O (x=0.00, 0.38, 0.49, 0.68, 0.85) have synthesized by hydrothermal synthesis. • The structural studies of these compounds are introduced as a function of the composition. • The magnetic studies show an antiferromagnetically behavior with ordering temperatures from 5.5 K to 13.2 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Interplay between experiments and calculations for organometallic clusters and caged clusters

Clusters consisting of 10-1000 atoms exhibit size-dependent electronic and geometric properties. In particular, composite clusters consisting of several elements and/or components provide a promising way for a bottom-up approach for designing functional advanced materials, because the functionality of the composite clusters can be optimized not only by the cluster size but also by their compositions. In the formation of composite clusters, their geometric symmetry and dimensionality are emphasized to control the physical and chemical properties, because selective and anisotropic enhancements for optical, chemical, and magnetic properties can be expected. Organometallic clusters and caged clusters are demonstrated as a representative example of designing the functionality of the composite clusters. Organometallic vanadium-benzene forms a one dimensional sandwich structure showing ferromagnetic behaviors and anomalously large HOMO-LUMO gap differences of two spin orbitals, which can be regarded as spin-filter components for cluster-based spintronic devices. Caged clusters of aluminum (Al) are well stabilized both geometrically and electronically at Al{sub 12}X, behaving as a “superatom”.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗