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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Extraordinary phylogenetic diversity and metabolic versatility in aquifer sediment

Microorganisms in the subsurface represent a substantial but poorly understood component of the Earth’s biosphere. Subsurface environments are complex and difficult to characterize; thus, their microbiota have remained as a ‘dark matter’ of the carbon and other biogeochemical cycles. Here we deeply sequence two sediment-hosted microbial communities from an aquifer adjacent to the Colorado River, CO, USA. No single organism represents more than ~1% of either community. Remarkably, many bacteria and archaea in these communities are novel at the phylum level or belong to phyla lacking a sequenced representative. The dominant organism in deeper sediment, RBG-1, is a member of a new phylum. On the basis of its reconstructed complete genome, RBG-1 is metabolically versatile. Its wide respiration-based repertoire may enable it to respond to the fluctuating redox environment close to the water table. We document extraordinary microbial novelty and the importance of previously unknown lineages in sediment biogeochemical transformations.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Synthesis, crystal structures, and physical properties of the new Zintl phases A{sub 21}Zn{sub 4}Pn{sub 18} (A=Ca, Eu; Pn=As, Sb)—Versatile arrangements of [ZnPn{sub 4}] tetrahedra

Four new Zintl phases, Ca{sub 21}Zn{sub 4}As{sub 18}, Ca{sub 21}Zn{sub 4}Sb{sub 18}, Eu{sub 21}Zn{sub 4}As{sub 18} and Eu{sub 21}Zn{sub 4}Sb{sub 18} have been synthesized by metal flux reactions. Their structures have been established from single-crystal X-ray diffraction. Despite the similar chemical makeup and the identical formulae, the structures of the four compounds are not the same—Ca{sub 21}Zn{sub 4}As{sub 18}, Ca{sub 21}Zn{sub 4}Sb{sub 18} and Eu{sub 21}Zn{sub 4}As{sub 18} crystallize in the monoclinic space group C2/m (No. 12, Z=4) with the β-Ca{sub 21}Mn{sub 4}Sb{sub 18} structure type, while Eu{sub 21}Zn{sub 4}Sb{sub 18} adopts the Ba{sub 21}Cd{sub 4}Sb{sub 18} structure type with the orthorhombic space group Cmce (No. 64, Z=8). Both structures are based on ZnAs{sub 4} or ZnSb{sub 4} tetrahedra, linked in slightly different ways, and Ca{sup 2+} and Eu{sup 2+} cations that fill the space between them. The structural relationships between the title compounds and other known ternary phases with intricate structures are discussed. Electrical resistivity measurement on single-crystalline Eu{sub 21}Zn{sub 4}Sb{sub 18} suggests an intrinsic semiconductor behavior with a band gap of ca. 0.2 eV. The temperature dependent DC magnetization measurement on the same material indicates Curie–Weiss paramagnetism in the high-temperature regime, and a spontaneous antiferromagnetic ordering below 8 K. The calculated effective moments of Eu confirm the divalent Eu{sup 2+} ground state, as expected from the Zintl–Klemm concept. - Graphical abstract: The four new Zintl phases—Ca{sub 21}Zn{sub 4}As{sub 18}, Ca{sub 21}Zn{sub 4}Sb{sub 18}, Eu{sub 21}Zn{sub 4}As{sub 18}, and Eu{sub 21}Zn{sub 4}Sb{sub 18}—crystallize in two structure types, showing the versatility in the arrangements of ZnAs{sub 4} and ZnSb{sub 4} tetrahedra. - Highlights: • Ca{sub 21}Zn{sub 4}As{sub 18}, Ca{sub 21}Zn{sub 4}Sb{sub 18}, Eu{sub 21}Zn{sub 4}As{sub 18}, and Eu{sub 21}Zn{sub 4}Sb{sub 18} are new compounds in the respective ternary phase diagrams. • They form with structure types, showing the versatility in the arrangements of ZnAs{sub 4} and ZnSb{sub 4} tetrahedra. • For both structures, the valence electron count follows the Zintl–Klemm rules.

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

A Versatile Thin-Film Deposition Method for Multidimensional Semiconducting Bismuth Halides

Despite the significant progress in fabricating hybrid organic-inorganic lead halide perovskite solar cells, their toxicity and low stability remain as major drawbacks, thereby hindering large-scale commercialization. Given the isoelectronic nature of lead(II) and bismuth(III) ions, potentially stable and non-toxic alternatives for efficient light absorption in thin-film photovoltaic (PV) devices may be found among bismuth-based halide semiconductors. However, high-quality polycrystalline films of many of these systems have not been demonstrated. In this work, we present a versatile and facile two-step co-evaporation approach to fabricate A 3 Bi 2 I 9 (A = Cs, Rb) and AgBi 2 I 7 polycrystalline films with smooth, pin-hole-free morphology and average grain size of > 200 nm. The process involves an initial two-source evaporation step (involving CsI, RbI or AgI, and BiI 3 sources), followed by an annealing step under BiI3 vapor. The structural, optical and electrical characteristics of the resulting thin films are studied by X-ray diffraction, optical spectroscopy, X-ray/UV photoelectron spectroscopy and scanning electron microscopy.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Versatile Synthetic Platform for Polymer Membrane Libraries Using Functional Networks

Poly(ethylene glycol) (PEG) diacrylate copolymer networks containing pentafluorophenyl active esters can be quantitatively substituted with a wide variety of primary amines, enabling the development of a versatile synthetic platform for the preparation of polymer hydrogel and membrane libraries. Here, by tuning the starting network, a high degree of control over cross-linking density, water uptake, and functional group incorporation can be reproducibly achieved, which is vital for elucidating structure–property relationships in ion transporting membranes. From the same cross-linked scaffold, a diversity of basic, acidic, and solute-chelating moieties were obtained through functionalization, which allows for tailored uptake of basic and acidic organic dyes and metal chloride salts. Ion permeation and sorption measurements for a series of polymer networks with controlled cross-linking density and varied imidazole grafting densities illustrate the ability of this platform to isolate the effect of chemical functionality on ion transport from the effects of cross-linking density and water content.

36 MATERIALS SCIENCE↗
DOE OSTI2012

The AMPIX electrochemical cell: a versatile apparatus for in situ X-ray scattering and spectroscopic measurements

This article presents a versatile easy-to-use electrochemical cell suitable for in operando , in situ measurements of battery materials during electrochemical cycling using a variety of X-ray techniques. Argonne's multi-purpose in situ X-ray (AMPIX) cell provides reliable electrochemical cycling over extended periods owing to the uniform stack pressure applied by rigid X-ray windows and the formation of a high-fidelity hermetic seal. The suitability of the AMPIX cell for a broad range of synchrotron-based X-ray scattering and spectroscopic measurements has been demonstrated with studies at eight Advanced Photon Source beamlines to date. Compatible techniques include pair distribution function analysis, high-resolution powder diffraction, small-angle scattering and X-ray absorption spectroscopy. These techniques probe a broad range of electronic, structural and morphological features relevant to battery materials. The AMPIX cell enables experiments providing greater insight into the complex processes that occur in operating batteries by allowing the electrochemical reactions to be probed at fine reaction intervals with greater consistency (within the charge–discharge cycle and between different methodologies) with potential for new time-dependent kinetic studies or studies of transient species. Representative X-ray and electrochemical data to demonstrate the functionality of the AMPIX cell are presented.

energy storage (including batteries and capacitors↗
DOE OSTI2018

Comparative genomics and transcriptomics depict ericoid mycorrhizal fungi as versatile saprotrophs and plant mutualists

Some soil fungi in the Leotiomycetes form ericoid mycorrhizal (ERM) symbioses with Ericaceae. In the harsh habitats in which they occur, ERM plant survival relies on nutrient mobilization from soil organic matter (SOM) by their fungal partners. The characterization of the fungal genetic machinery underpinning both the symbiotic lifestyle and SOM degradation is needed to understand ERM symbiosis functioning and evolution, and its impact on soil carbon (C) turnover. We sequenced the genomes of the ERM fungi Meliniomyces bicolor, M. variabilis, Oidiodendron maius and Rhizoscyphus ericae, and compared their gene repertoires with those of fungi with different lifestyles (ecto- and orchid mycorrhiza, endophytes, saprotrophs, pathogens). Here we also identified fungal transcripts induced in symbiosis. The ERM fungal gene contents for polysaccharide-degrading enzymes, lipases, proteases and enzymes involved in secondary metabolism are closer to those of saprotrophs and pathogens than to those of ectomycorrhizal symbionts. The fungal genes most highly upregulated in symbiosis are those coding for fungal and plant cell wall-degrading enzymes (CWDEs), lipases, proteases, transporters and mycorrhiza-induced small secreted proteins (MiSSPs). The ERM fungal gene repertoire reveals a capacity for a dual saprotrophic and biotrophic lifestyle. This may reflect an incomplete transition from saprotrophy to the mycorrhizal habit, or a versatile life strategy similar to fungal endophytes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Sulfur in oleylamine as a powerful and versatile etchant for oxide, sulfide, and metal colloidal nanoparticles: Sulfur in oleylamine as a powerful and versatile etchant

Understanding of crystal growth is essential to the design of materials with improved properties. Unfortunately, still very little is understood about the basic growth mechanisms of nanostructures, even in the most established colloidal synthetic routes. Etching is one of the most important mechanisms to consider during particle growth, but it is rarely considered in the syntheses of oxide or chalcogenide nanostructures. Here in this paper, we report that the most common precursor for the synthesis of sulfide nanostructures – the mixture of sulfur and oleylamine – acts as a very powerful etchant for oxide, chalcogenide, and metal nanostructures. Specifically, we discuss its effect on several nanoparticle compositions (PbS, Cu 2 S, Fe 3 O 4 , and Au) and compare it to control conditions in which only oleylamine is present. Our experiments suggest that the etching results from the evolution of H 2 S from the sulfur–oleylamine precursor. We predict that the simultaneous role of this precursor as both etchant and ligand stabilizer will make it a useful tool for the chemical post-processing (e.g., size reduction, focusing of size distributions, faceting) of nanocrystal dispersions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

A Versatile Approach for Quantification of Surface Site Fractions using Reaction Kinetics: The Case of CO Oxidation on Supported Ir Single Atoms and Nanoparticles

Supported metal single atom catalysts have shown unique activity and selectivity for several reactions. Investigating the reaction mechanism on single atom catalysts and unambiguous assignment of the activity and selectivity requires catalysts with exclusively single atoms. However, it is challenging to prepare pure single atom catalysts with conventional impregnation methods, which typically result in a mixture of single atoms and nanoparticles. Here, we show that owing to different reaction mechanisms on single atoms and nanoparticles, reaction kinetics can serve as a surface sensitive characterization technique for quantifying their surface site fractions. As a case study, we use CO oxidation kinetics on Ir/MgAl2O4 to quantify the surface site fractions of single atoms and nanoparticles and the results are consistent with aberration-corrected scanning transmission electron microscopy, X-ray absorption fine structure and infrared spectroscopies. Additionally, by carefully choosing the reaction conditions, the activity of single atoms (or nanoparticles) can be made dominant, enabling detection of a small fraction, or allowing a study of their reaction mechanism on a catalyst containing a mixture of single atoms and nanoparticles. These results are general and could be applied to other systems where two types of sites have different reaction mechanisms.

Single atom catalyst, Kinetics, CO oxidation, x-ra↗