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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Structure and Cathodoluminescent Properties of Y{sub 2}O{sub 3}:Eu Thin Films at Different Activator Concentrations

The surface structure and cathodoluminescence (CL) spectra of thin films of Y{sub 2}O{sub 3}:Eu obtained by HF ion plasma sputtering were investigated by varying the activator concentration in the range of 1.0–7.5 mole%. The possibility of creating irregular solutions of yttrium and europium oxides and the structural features of the small and large crystallites that form the Y{sub 2}O{sub 3}:Eu film were demonstrated on the basis of the shape of the CL spectra at different activator concentrations. The critical distance for interaction between the Eu{sup 3+} ions at nodes with C{sub 2} and C{sub 3i} point symmetry was estimated, and a mechanism of energy migration between these centers was proposed.

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

Data-driven search for promising intercalating ions and layered materials for metal-ion batteries

The rise in demand for lithium-ion batteries has led to a large-scale search for electrode materials and intercalating ion species to meet the demands of next-generation energy technologies. Recent efforts largely focus on searching for cathodes that can accommodate large amounts of intercalating ions, but similar work on anodes is relatively limited. This study utilizes machine learning methods to find alternative two-dimensional (2D) materials and intercalating ions beyond Li for metal-ion batteries with high-power efficiencies. The approach first uses density functional theory (DFT) calculations to estimate the theoretical capacities and voltages of various metal ions on 2D materials. The DFT-generated data also provide insights into the local structural accommodation upon ion intercalation on various 2D materials. Significant changes to the lattice can result in irreversible changes to the bonding environments in the anode material, resulting in poor cycling stability. Next, this study develops a binding energy and structural accommodation-based classification model to screen anode materials for next-generation batteries. The classification model selects intercalating ions and 2D material pairs suitable for batteries based on the calculated voltage and volumetric changes in the 2D material upon intercalation. Finally, this study builds a regression model to accurately predict the binding energies of the various intercalating ions on 2D materials. The approach highlights the importance of different elemental and structural features for classification and regression tasks. In conclusion, the insights gained from this study on the role of involved features, such as electronegativities of the constituent ions and the presence of unfilled electronic levels, will help to streamline further studies towards the search for future layered battery materials.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Synthesis and Characterization of MoNb Films Superconducting at 100-200 mK

We have developed a new transition-edge sensor material with critical temperature (T-c) in the range 100-200 mK. The new material is a solid solution of two superconducting components, MoxNb1-x, co-sputtered from two high-purity single-component targets (Mo and Nb). The T-c has a minimum (dT(c)/dx = 0) at an intermediate concentration of the components. We have optimized the deposition parameters and composition to provide films with a sharp superconducting transition at ~ 150 mK. We investigated structural features of the films and surface morphology using X-ray diffraction (XRD) and scanning electron microscopy. The XRD measurements indicate that the grown films are polycrystalline, with a preferred orientation along the (110) crystal direction and a clear correlation between superconducting properties and film microstructure.

superconducting alloys↗
DOE OSTI2019

Chemical, Morphological, Structural, Optical, and Magnetic Properties of Transition Metal Titanium (Ti)-Doped LaFeO{sub 3} Nanoparticles

In the present work, pure and transition metal titanium (Ti)-doped LaFe{sub 1−x}Ti{sub x}O{sub 3}(x = 0.0, 0.2, 0.4, and 0.6) nanoparticles have been successfully synthesized by hydrothermal synthesis technique for various molar ratios of 0.2, 0.4, and 0.6. The prepared samples were grinned and annealed in furnace at 600 {sup ∘}C/4 h. The X-ray diffraction (XRD) analysis confirms the phase orthorhombic formation of LaFeO{sub 3} and Ti-doped LaFeO{sub 3}. The stoichiometric analysis was performed through energy-dispersive X-ray studies (EDX). The micro-structural features of surface morphology were examined by field emission scanning electron microscopy (FESEM). Further, surface nanocrystalline of the titanium (Ti)-doped LaFe{sub 1−x}Ti{sub x}O{sub 3} was also investigated through high-resolution transmission electron microscopic (TEM) analysis. The enhancement of room temperature magnetization value has been observed from the M–H curve which is measured using vibrating sample magnetometer (VSM).The weak ferromagnetic behavior was observed from hysteresis loop. From hysteresis loop, saturation takes place when the applied magnetic field intensity is 15 kO{sub e}.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Two directions of heterocyclization in the reactions of dimethyl bicyclo[2.2.2]oct-5-ene-endo-2,endo-3-dicarboxylate with hetarenesulfenyl chlorides

A reaction of dimethyl bicyclo[2.2.2]oct-5-ene-endo-2,endo-3-dicarboxylate with 1,3-benzо- thiazole-2- and 3-methoxycarbonylpyridine-2-sulfenyl chlorides leads to two types of heterocyclization products, which are formed through the ring closure by the oxygen atom of the carbоmethoxy group and/or by the nitrogen atom of the hetaryl fragment of the sulfenylating agent. The product ratio is affected by the medium nature and structural features of sulfenyl chlorides.

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

Fabrication and physicochemical characterization of graphene oxide derived from thermally expanded graphite

Graphene oxide was obtained from expanded graphite according to the modified Hummers method. The reaction time was significantly reduced (from 24 to 8 h) by applying the expanded graphite in the oxidation process. The interlayer distance in obtained samples was equal to 0.70–0.74 nm. Structural features of the material were studied by the powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, XPS spectroscopy, and NMR spectroscopy.

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

Electronic and Vibrational Properties of LiBO{sub 2} Crystals

On the basis of the density functional theory using the CRYSTAL code, electronic and vibrational properties of lithium metaborate in the monoclinic and tetragonal phases are studied. The band spectra, elastic moduli, long-wave vibrational frequencies at the point Г, dynamic charges, and acoustic velocities are calculated for both phases. The influence of structural features and short-range order in trigonal BO{sub 3}- and tetragonal BO{sub 4}- groups on the significant difference in physical properties in the low-temperature and high-temperature phases of LiBO{sub 2} crystal is established.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Use of Solvatochromism to Assay Preferential Solvation of a Prototypic Catalytic Site

The composition of the reaction medium near photoactive catalytic sites can be inferred from the solvatochromism of the absorption and emission spectra of the wetted sites, which depend on the polarizability of the fluid. In brief, solvatochromism measures the interaction of the dipole moments of the ground and excited states with the electric field imposed by the solvent shell: a field, which does not relax on the time scale of the absorption or emission events. As a first step in establishing the utility of the technique for inorganic catalysts that operate in complex reaction media, such as encountered in the upgrading of biogenic fuels, we have measured the solvatochromism of a common, structural feature of metal oxide catalysts. In toluene, cyclohexene, chloroform and tetrahydrofuran, POSS-ligated oxometalates exhibit strong ligand-to-metal charge-transfer bands in their UV-visible absorption and emission spectra. The magnitudes of the solvatochromic effects agreed well with the calculated changes in dipole moments that accompany the electronic transitions. From the solvatochromism of the chromophores dissolved in toluene-chloroform mixtures we inferred an unexpectedly strong, preferential solvation of the chromophore even when all three components (oxometalate and the two solvents) were highly miscible. This research was supported in part by the Laboratory Directed Research & Development program at Pacific Northwest National Laboratory. PNNL is operated by Battelle for the US Department of Energy under contract DE-AC05-76RL01830. A portion of the research was performed at EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at PNNL.

chromium↗
DOE OSTI2018

A stable metal-covalent-supramolecular organic framework hybrid: enrichment of catalysts for visible light-induced hydrogen production

Cubic metal-covalent-supramolecular organic framework (MCSOF-1) hybrid has been created from the reaction of two molecular components and subsequent co-assembly with cucurbit[8]uril (CB[8]) in water. In the presence of CB[8], [Ru(bpy) 3 ] 2+ -based acylhydrazine 1·2Cl reacted with aldehyde 2·Cl to quantitatively yield six-armed precursor 3·8Cl through the generation of MCSOF-1. MCSOF-1 combines the structural features of metal-, covalent- and supramolecular organic frameworks. Its periodicity in water and in the solid state was confirmed by synchrotron X-ray scattering and diffraction experiments. Finally, MCSOF-1 could enrich discrete anionic polyoxometalates (POMs), maintain periodicity in acidic medium, and remarkably facilitate visible light-induced electron transfer from its [Ru(bpy) 3 ] 2+ units to enriched POMs, leading to enhanced catalysis of the POMs for the reduction of proton to H 2 in both aqueous (homogeneous) and organic (heterogeneous) media.

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

Research on Bulk-metallic Glasses and High-entropy Alloys in Peter K. Liaw’s Group and with His Colleagues

Bulk-metallic glasses (BMGs) and high-entropy alloys (HEAs) have attracted extensive attention in the field of metallic materials research for several decades due to their extraordinary properties. Many scientists and researchers have significantly contributed to developing new classes of metallic alloys, such as BMGs and HEAs, for various applications. Liaw’s group and his colleagues have focused on the fundamental understanding of unique features, structures, and properties in BMGs and HEAs as well as the development of new types of metallic materials. Here, we summarized the research work of Liaw’s group and his colleagues by reviewing relevant papers. The goal is to provide an understanding of the current research progression in BMGs and HEAs while further encouraging young and junior researchers to be involved in the field of structural materials research pertaining to these classes of exotic alloy systems.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Influence of Structure and Mineral Association of Tuyere-Level Coke on Gasification Process

The gasification properties of feed coke and tuyere coke were investigated by non-isothermal thermogravimetric method under CO{sub 2} atmosphere. The physical and chemical structure features were also systematically tested, as well as the mineral composition. The pore characteristics, graphitization degree of carbon matrix, and ash content were the main factors determining the reactivity of coke. Higher L{sub c} decreases the reactivity of tuyere coke in low temperature, while larger porosity increases the reactivity in high temperature, forming an intersection with the gasification process of the feed coke. The high content of Fe{sub 2}O{sub 3} in 25 to 20 mm tuyere coke made a rapid gasification reaction. The SiC produced in the tuyere area increased the porosity of coke especially the 5 to 1 mm coke at the edge of BF, which promoted the gasification process of coke in the area.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2018

Application of Al-2La-1B Grain Refiner to Al-10Si-0.3Mg Casting Alloy

This paper reports the application and microstructure refining effect of an Al-2La-1B grain refiner in Al-10Si-0.3Mg casting alloy. Compared with the traditional Al-5Ti-1B refiner, Al-2La-1B refiner shows better performances on the grain refinement of Al-10Si-0.3Mg alloy. Transmission electron microscopy analysis suggests that the crystallite structure features of LaB6 are beneficial to the heterogeneous nucleation of α-Al grains. Regarding the mechanical performances, tensile properties of Al-10Si-0.3Mg casting alloy are prominently improved, due to the refined microstructures.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Analysis of Proteins, Protein Complexes, and Organellar Proteomes Using Sheathless Capillary Zone Electrophoresis - Native Mass Spectrometry

Native mass spectrometry (MS) is a rapidly advancing field in the analysis of proteins, protein complexes, and macromolecular species of various types. The majority of native MS experiments reported to-date has been conducted using direct infusion of purified analytes into a mass spectrometer. In this study, capillary zone electrophoresis (CZE) was coupled online to Orbitrap mass spectrometers using a commercial sheathless interface to enable high-performance separation, identification, and structural characterization of limited amounts of purified proteins and protein complexes, the latter with preserved non-covalent associations under native conditions. The performance of both bare-fused silica and polyacrylamide-coated capillaries was assessed using mixtures of protein standards known to form non-covalent protein–protein and protein–ligand complexes. High-efficiency separation of native complexes is demonstrated using both capillary types, while the polyacrylamide neutral-coated capillary showed better reproducibility and higher efficiency for more complex samples. The platform was then evaluated for the determination of monoclonal antibody aggregation and for analysis of proteomes of limited complexity using a ribosomal isolate from E. coli. Native CZE-MS, using accurate single stage and tandem-MS measurements, enabled identification of proteoforms and non-covalent complexes at femtomole levels. This study demonstrates that native CZE-MS can serve as an orthogonal and complementary technique to conventional native MS methodologies with the advantages of low sample consumption, minimal sample processing and losses, and high throughput and sensitivity. This study presents a novel platform for analysis of ribosomes and other macromolecular complexes and organelles, with the potential for discovery of novel structural features defining cellular phenotypes (e.g., specialized ribosomes). .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

On Energy Storage Chemistry of Aqueous Zn-Ion Batteries: From Cathode to Anode

Rechargeable aqueous zinc-ion batteries (ZIBs) have resurged in large-scale energy storage applications due to their intrinsic safety, affordability, competitive electrochemical performance, and environmental friendliness. Extensive efforts have been devoted to exploring high-performance cathodes and stable anodes. However, many fundamental issues still hinder the development of aqueous ZIBs. Here, we critically review and assess the energy storage chemistries of aqueous ZIBs for both cathodes and anodes. First, this review presents a comprehensive understanding of the cathode charge storage chemistry, probes the existing deficiencies in mechanism verification, and analyzes contradictions between the experimental results and proposed mechanisms. Then, a detailed summary of the representative cathode materials and corresponding comparative discussion is provided with typical cases encompassing structural features, electrochemical properties, existing drawbacks, and feasible remedies. Subsequently, the fundamental chemical properties, remaining challenges, and improvement strategies of both Zn metal and non-Zn anodes are presented to thoroughly explore the energy storage chemistry of ZIBs and pursue the development of high-performance ZIBs. Furthermore, the progress of mechanistic characterization techniques and theoretical simulation methods used for ZIBs is timely reviewed. Finally, here we provide our perspectives, critical analysis, and insights on the remaining challenges and future directions for development of aqueous ZIBs.

25 ENERGY STORAGE↗
DOE OSTI2018

Identification and structural characterization of a novel myeloperoxidase inhibitor from Staphylococcus delphini

Staphylococcus aureus and related species are highly adapted to their hosts and have evolved numerous strategies to evade the immune system. S. aureus shows resistance to killing following uptake into the phagosome, which suggests that the bacterium evades intracellular killing mechanisms used by neutrophils. We recently discovered an S. aureus protein (SPIN for Staphylococcal Peroxidase INhibitor) that binds to and inhibits myeloperoxidase (MPO), a major player in the oxidative defense of neutrophils. To allow for comparative studies between multiple SPIN sequences, we identified a panel of homologs from species closely related to S. aureus . Characterization of these proteins revealed that SPIN molecules from S. agnetis, S. delphini, S. schleiferi , and S. intermedius all bind human MPO with nanomolar affinities, and that those from S. delphini, S. schleiferi , and S. intermedius inhibit human MPO in a dose-dependent manner. A 2.4 Å resolution co-crystal structure of SPINdelphini bound to recombinant human MPO allowed us to identify conserved structural features of SPIN proteins, and to propose sequence-dependent physical explanations for why SPIN-aureus binds human MPO with higher affinity than SPIN-delphini. Overall, these studies expand our understanding of MPO binding and inhibition by a recently identified component of the staphylococcal innate immune evasion arsenal.

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

Snow-corrected vegetation indices for improved gross primary productivity assessment in North American evergreen forests

North American evergreen forests cover large areas and influence the global carbon cycle. Satellite remote sensing has been used to track the phenology of ecosystem photosynthesis of these forests by detecting variation in vegetation optical properties associated with physiological and structural features, and most of these methods have been closely tied to vegetation greenness. However, in evergreens, the application of satellite data to monitor photosynthetic phenology is often limited by the lack of sensitivity of greenness-based indices. In this study, we identified 47 evergreen forest flux sites in North America that had MODIS observation overlapping with the flux tower records. We then calculated four vegetation indices using MODIS MAIAC data (MCD19A1), including NDVI, CCI, NIRv, and kNDVI, for the 47 flux sites and evaluated relationships between gross primary productivity (GPP) and vegetation indices across the North American evergreen forests. Our results showed that snow had substantial effects on the performance of all vegetation indices in tracking GPP phenology, particularly in the early spring when rapid changes occurred to both GPP and snow cover. Furthermore, different vegetation indices were affected differently, indicating contradictory and confounding effects of snow on these indices. After correcting for the snow effects, both CCI and NIRv performed well in tracking GPP phenology, albeit for different reasons. CCI is sensitive to seasonal changes in the relative levels of chlorophyll and carotenoid pigments, which are closely tied to GPP phenology in evergreens. NIRv is sensitive to the absorbed photosynthetically active radiation and to the contribution of deciduous components to the overall optical properties. We also found that correlations between GPP and vegetation indices varied among ecoregions and climate classes. In general, regions with pronounced seasonal GPP patterns had stronger correlations between GPP and greenness-based indices than regions with weaker seasonal GPP patterns. These biome differences were less pronounced for CCI. The snow artifacts and complementary vegetation index effects reported here should be considered in any large-scale studies of GPP using reflectance-based indices from optical satellites.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Growth, total lipid, and omega-3 fatty acid production by Nannochloropsis spp. cultivated with raw plant substrate

Improving productivity and lipid concentration in microalgae is important for the economic success of both biofuel and microalgae coproducts production. Nannochloropsis spp. are marine microalgae currently being grown at large-scale for the production of biofuel and lipid coproducts. In this work, we demonstrate improvements of growth and omega-3 production in Nannochloropsis gaditana CCMP526 and Nannochloropsis oceanica CCAP849/10 with plant substrate addition, a potentially economical option for increasing microalgal productivity. Furthermore, we examine growth in the presence of corn stover, switchgrass, sugarcane bagasse, and yard waste. By examining the microbial ecology of N. gaditana cultures with and without plant substrate and with and without antibiotics, we discovered a potential bacterial interaction in these cultures, but its presence is not necessary for algal growth improvements in the presence of plant substrate. Analysis of plant substrate morphology by scanning electron microscopy (SEM) after cultivation in media with and without N. gaditana shows a degradation of specific plant structural features and a colonization of the plant phloem by N. gaditana. An examination of N. gaditana in a Congo red plate assay indicates potential cellulolytic activity, but a preliminary examination of the potential cellulase transcripts does not reveal differential expression of a candidate in the presence of plant. This evidence demonstrates potential raw plant utilization by a marine microalga for increased productivity and provides a potentially economical option for increasing coproduct concentration at industrial scale without genetic engineering.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

Structural and biophysical characterization of Rv3716c, a hypothetical protein from Mycobacterium tuberculosis

Highlights: • The dimeric MtbRv3716c has a “tweezers” like structure with a head and two tails. • The spacing between the tails is appropriate to accommodate double helical DNA. • The N- and the proline rich C-terminal ends exhibit flexibility. • Packing of molecules in the crystal structure is mediated by Cd{sup 2+} ions. • The {sup 25}QQQ{sup 27} motif might be important for divalent metal ion binding. Latent tuberculosis (TB) is the main hurdle in reaching the goal of “Stop TB 2050”. Tuberculin skin and Interferon-gamma release assay tests used currently for the diagnosis of TB infection cannot distinguish between active disease and latent tuberculosis infection (LTBI) and hence new and sensitive protein markers need to be identified for the diagnosis. A protein Rv3716c from Mycobacterium tuberculosis (MtbRv3716c) has been identified as a potential surrogate marker for the diagnosis of LTBI. Here, we present characterization of MtbRv3716c (∼13 kDa) using both biophysical and X-Ray crystallographic methods. EMSA study showed that MtbRv3716c binds to double stranded DNA. X-ray diffraction data collected on a crystal of MtbRv3716c at 1.9 Å resolution was used for structure determination using the molecular replacement method. Significant electron density was not observed for the N-terminal 21 and C-terminal 41 residues in the final electron density map. The C- terminal disordered region is proline rich and displays characteristics of intrinsically disordered proteins. Although the crystal asymmetric unit contained a protomer, a tight dimer could be generated by the application of the crystal two-fold symmetry parallel to the b axis. Packing of dimers in the crystal is mediated by a cadmium ion (Cd{sup 2+}) occurring at the interface of two dimers. Molecular packing analysis reveals large cavities that are probably occupied by the disordered segments of the N- and C-termini. Structural comparison with other homologous hypothetical DNA binding proteins (PDB codes: 1PUG, 1YBX) highlights structural features that might be significant for DNA binding.

60 APPLIED LIFE SCIENCES↗