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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Solid state {sup 31}P MAS NMR spectroscopy and conductivity measurements on NbOPO{sub 4} and H{sub 3}PO{sub 4} composite materials

A systematic study of composite powders of niobium oxide phosphate (NbOPO{sub 4}) and phosphoric acid (H{sub 3}PO{sub 4}) has been performed in order to characterize the material's ability to perform as an electrolyte material in medium temperature fuel cells and electrolyzers. Powders of H{sub 3}PO{sub 4} contents between 13.1 and 74.2 M% were produced and characterized with powder X-ray diffraction, {sup 31}P MAS NMR and impedance spectroscopy. NMR revealed that a significant degree of dehydration and vaporization of H{sub 3}PO{sub 4} takes place above 200 °C, and increases with temperature. At 500 °C the NbOPO{sub 4} and H{sub 3}PO{sub 4} has reacted to form niobium pyrophosphate (Nb{sub 2}P{sub 4}O{sub 15}). Impedance spectroscopy showed an increase in conductivity with increasing acid concentration, whereas the conductivity decreased slightly with increasing temperature. The highest conductivity measured was 2.5·10{sup −3} S/cm for a sample containing 74.2 M% of H{sub 3}PO{sub 4}. Lastly, it was shown that NbOPO{sub 4} has no significant conductivity of its own. - Graphical abstract: Conductivity of NbOPO{sub 4}/H{sub 3}PO{sub 4} composites as a function of equivalent P{sub 2}O{sub 5} content. The conductivity is insignificant for pure NbOPO{sub 4}. - Highlights: • Composites have been made from NbOPO{sub 4} and H{sub 3}PO{sub 4}. • The composites composition has been investigated with solid state NMR. • The composites have shown clear signs of acid dehydration upon heating. • The conductivity of the composites increases for increasing acid content. • NbOPO{sub 4} has no significant conductivity of its own.

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

Wake potential in graphene-insulator-graphene composite systems

We study the wake potential produced by an external charged particle that moves parallel to various sy1-Al2O3-sy2 sandwich-like composites, where the system syi (with i=1,2) may be vacuum, pristine graphene, or doped graphene. The effective dielectric function of the composites is obtained using three complementary methods for graphene's electronic response, based on the massless Dirac fermions (MDF) method, the extended hydrodynamic (eHD) model, and the ab initio approach. Three velocity regimes are explored with respect to the threshold for excitations of the Dirac plasmon in graphene, given by its Fermi velocity vF. In the low-velocity regime (below vF), only the transverse optical (TO) phonons in the Al2O3 layer contribute to the wake potential in the surface with sy2 (which is nearest to the charged particle), in a manner that is only sensitive to the composition of that system: if sy2 is vacuum, the TO phonons give rise to intense oscillations in the wake potential, which are strongly suppressed if sy2 is pristine or doped graphene. For intermediate velocities (above vF), the hybridized plasmon-TO phonon modes on both surfaces contribute to the wake potential in the surface with sy2, with the most dominant contribution coming from the hybridized Dirac-like plasmonic modes. In the high-velocity regime (well above vF), the highest-lying hybridized Dirac plasmon gives the dominant contribution to the wake potential, which exhibits a typical V-shaped wave-front pattern that lags behind the charged particle. It is found that the MDF method agrees very well with the results of the ab initio method for small and intermediate velocities. However, in the high-velocity regime, the high-energy π plasmon in graphene introduces new features in the wake potential in the form of fast oscillations, just behind the charged particle. Those oscillations in the wake potential are well described by both the eHD and the ab initio method, proving that the π plasmon indeed behaves as a collective mode.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Initiate test loop irradiations of ALSEP process solvent

This report describes the initial results of the study of the impacts of gamma radiolysis upon the efficacy of the ALSEP process and is written in completion of milestone M3FT-14IN030202. Initial irradiations, up to 100 kGy absorbed dose, of the extraction section of the ALSEP process have been completed. The organic solvent used for these experiments contained 0.05 M TODGA and 0.75 M HEH[EHP] dissolved in n-dodecane. The ALSEP solvent was irradiated while in contact with 3 M nitric acid and the solutions were sparged with compressed air in order to maintain aerated conditions. The irradiated phases were used for the determination of americium and europium distribution ratios as a function of absorbed dose for the extraction and stripping conditions. Analysis of the irradiated phases in order to determine solvent composition as a function of absorbed dose is ongoing. Unfortunately, the failure of analytical equipment necessary for the analysis of the irradiated samples has made the consistent interpretation of the analytical results difficult. Continuing work will include study of the impacts of gamma radiolysis upon the extraction of actinides and lanthanides by the ALSEP solvent and the stripping of the extracted metals from the loaded solvent. The irradiated aqueous and organic phases will be analyzed in order to determine the variation in concentration of solvent components with absorbed gamma dose. Where possible, radiolysis degradation product will be identified.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2012

Structural phase transitions in the Ag{sub 2}Nb{sub 4}O{sub 11}-Na{sub 2}Nb{sub 4}O{sub 11} solid solution

The phase transitions between various structural modifications of the natrotantite-structured system xAg{sub 2}Nb{sub 4}O{sub 11}-(1-x)Na{sub 2}Nb{sub 4}O{sub 11} have been investigated and a phase diagram constructed as a function of temperature and composition. This shows three separate phase transition types: (1) paraelectric-ferroelectric, (2) rhombohedral-monoclinic and (3) a phase transition within the ferroelectric rhombohedral zone between space groups R3c and R3. The parent structure for the entire series has space group R3{sup Macron }c. Compositions with x>0.75 are rhombohedral at all temperatures whereas compositions with x<0.75 are all monoclinic at room temperature and below. At x=0.75, rhombohedral and monoclinic phases coexist with the phase boundary below room temperature being virtually temperature-independent. The ferroelectric phase boundary extends into the monoclinic phase field. No evidence was found for the R3-R3c phase boundary extending into the monoclinic phase field and it is concluded that a triple point is formed. - Graphical abstract: Phase diagram for xAg{sub 2}Nb{sub 4}O{sub 11}-(1-x)Na{sub 2}Nb{sub 4}O{sub 11} solid solution showing changes in crystal symmetry as a function of temperature and composition. The crystal structure is depicted. Highlights: Black-Right-Pointing-Triangle Ferroelectric, rhombohedral Ag{sub 2}Nb{sub 4}O{sub 11} in solid solution with monoclinic Na{sub 2}Nb{sub 4}O{sub 11}. Black-Right-Pointing-Triangle Three phase boundaries were studied as a function of composition and temperature. Black-Right-Pointing-Triangle Both rhombohedral and monoclinic variants exhibit ferroelectricity. The parent phase of the series has space group R3{sup Macron }c.

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

Metaproteomics reveals persistent and phylum-redundant metabolic functional stability in adult human gut microbiomes of Crohn’s remission patients despite temporal variations in microbial taxa, genomes, and proteomes

The gut microbiome plays a fundamental role in the human host’s overall health by contributing key biological functions such as expanded metabolism and pathogen defense/immune control. In a healthy individual, the gut microbiome co-exists within the human host in a symbiotic, non-inflammatory relationship that enables mutual benefits, such as microbial degradation of indigestible food products into small molecules that the host can utilize, and enhanced pathogen defense. In abnormal conditions, such as Crohn’s disease, this favorable metabolic relationship breaks down and a variety of undesirable activities result, including chronic inflammation and other health-related issues. It has been difficult, however, to elucidate the overall functional characteristics of this relationship because the microbiota can vary substantially in composition for healthy humans and possibly even more in individuals with gut disease conditions such as Crohn’s disease. Overall, this suggests that microbial membership composition may not be the best way to characterize a phenotype. Alternatively, it seems to be more informative to examine and characterize the functional composition of a gut microbiome. Towards that end, this study examines 25 metaproteomes measured in several Crohn’s disease patients’ post-resection surgery across the course of 1 year, in order to examine persistence of microbial taxa, genes, proteins, and metabolic functional distributions across time in individuals whose microbiome might be more variable due to the gut disease condition. As a result, the measured metaproteomes were highly personalized, with all the temporally-related metaproteomes clustering most closely by individual. In general, the metaproteomes were remarkably distinct between individuals and to a lesser extent within individuals. This prompted a need to characterize the metaproteome at a higher functional level, which was achieved by annotating identified protein groups with KEGG orthologous groups to infer metabolic modules. At this level, similar and redundant metabolic functions across multiple phyla were observed across time and between individuals. Tracking through these various metabolic modules revealed a clear path from carbohydrate, lipid, and amino acid degradation to central metabolism and finally the production of fermentation products. In conclusion, the human gut metaproteome can vary quite substantially across time and individuals. However, despite substantial intra-individual variation in the metaproteomes, there is a clear persistence of conserved metabolic functions across time and individuals. Additionally, the persistence of these core functions is redundant across multiple phyla but is not always observable in the same sample. Finally, the gut microbiome’s metabolism is not driven by a set of discrete linear pathways but a web of interconnected reactions facilitated by a network of enzymes that connect multiple molecules across multiple pathways.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Density Measurement of NaCl-MgCl 2 -PuCl 3 and NaCl-UCl 3 -PuCl 3 Molten Salt Systems by Neutron Radiographic Dilatometry

A novel neutron radiographic technique was developed and implemented to measure the change in volume as a function of temperature of select plutonium-containing liquid chloride mixtures from melt to 1250 K. These measurements were performed at Los Alamos National Laboratory by members of the molten salt research group under support from Gateway for Accelerated Innovation in Nuclear (GAIN) voucher NE-21-25117: “Density Measurements of Plutonium Bearing Salts via Neutron Beam Dilatometry”. This technical report contains a description of the experimental method and a summary of the results. Initial characterization of the {NaCl, MgCl 2 , UCl 3 , PuCl 3 } salts used in this experiment includes a combination of x-ray diffraction, differential scanning calorimetry, gamma ray spectroscopy, and inductively coupled plasma mass spectrometry. Four samples of NaCl + MgCl 2 + x mol% PuCl 3 and four samples of NaCl + UCl 3 + x mol% PuCl 3 were prepared at the Plutonium Facility, shipped to the Los Alamos Neutron Science Center (LANSCE), and radiographed with the density via neutron radiography (DvNR) apparatus. Density data in the form of meniscus heights were recorded as a function of temperature. The results show a linear dependence of density with temperature and a third order polynomial dependence of density with composition as a function of PuCl 3 addition in the corresponding halide salt mixture. Additions of PuCl 3 result in a significant increase in density of the salt mixture and a slight reduction in the coefficient of volumetric expansion. These results represent a first measurement of the density of plutonium chloride salt mixtures and, in combination with additional measurements, may lead to a generalized description of the density of such salt systems for arbitrary compositions and temperature.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Local Structure Analysis and Modelling of Lignin‐Based Carbon Composites through the Hierarchical Decomposition of the Radial Distribution Function

Abstract Carbonized lignin has been proposed as a sustainable and domestic source of activated, amorphous, graphitic, and nanostructured carbon for many industrial applications as the structure can be tuned through processing conditions. However, the inherent variability of lignin and its complex physicochemical structure resulting from feedstock and pulping selection make the Process‐Structure‐Property‐Performance (PSPP) relationships hard to define. In this work, radial distribution functions (RDFs) from synchrotron X‐ray and neutron scattering of lignin‐based carbon composites (LBCCs) are investigated using the Hierarchical Decomposition of the Radial Distribution Function (HDRDF) modelling method to characterize the local atomic environment and develop quantitative PSPP relationships. PSPP relationships for LBCCs defined by this work include crystallite size dependence on lignin feedstock as well as increasing crystalline volume fraction, nanoscale composite density, and crystallite size with increasing reduction temperature.

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

Chemical Framework to Design Linear-like Relaxors toward Capacitive Energy Storage

ABO 3 -type perovskite relaxor ferroelectrics (RFEs) have emerged as the preferred option for dielectric capacitive energy storage. However, the compositional design of RFEs with high energy density and efficiency poses significant challenges owing to the vast compositional space and the absence of general rules. Here, we present an atomic-level chemical framework that captures inherent characteristics in terms of radius and ferroelectric activity of ions. By categorizing A/B-site ions as host framework, rattling, ferroelectrically active, and blocking ions and assembling these four types of ions with specific criteria, linear-like relaxors with weak locally correlated and highly extendable unit-cell polarization vectors can be constructed. As example, we demonstrate two new compositions of Bi 0.5 K 0.5 TiO 3- based and BaTiO 3- based relaxors, showing extremely high recoverable energy densities of 17.3 and 12.1 J cm –3 , respectively, both with a high efficiency of about 90%. Further, the role of different types of ions in forming heterogeneous polar structures is identified through element-specific local structure analysis using neutron total scattering combined with reverse Monte Carlo modeling. Further, our work not only opens up new avenues toward rational compositional design of high energy storage performance lead-free RFEs but also sheds light on atomic-level manipulation of functional properties in compositionally complex ferroelectrics.

25 ENERGY STORAGE↗
DOE OSTI2017

Influence of surface morphology and UFG on damping and mechanical properties of composite reinforced with spinel MgAl{sub 2}O{sub 4}-SiC core-shell microcomposites

Interface between ceramic particulate and matrix is known to control the response of the materials and functionality of the composite. Among numerous physical properties, grain structure of the materials has also played a significant role in defining the behaviour of metal matrix composites. Usually, silicon carbide (SiC) particles show poor interfacial wettability in aluminium melt. Herein, we were successfully synthesized magnesium oxide (MgO) and nanocrystalline magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel coated silicon carbide (SiC) core-shell micro-composites through sol-gel technique to improve the wettability of dispersoids. Core-shell structures of submicron size were thoroughly investigated by various characterization techniques. Further, aluminium matrix composites incorporated with pristine SiC, MgO grafted SiC and MgAl{sub 2}O{sub 4} grafted SiC particles were fabricated by stir casting technique, respectively. Additionally, as-cast composites were processed via friction stir processing (FSP) technique to observe the influence of grain refinement on mechanical and damping properties. Electron back scattered diffraction (EBSD), Field emission scanning electron microscopy (FE-SEM) and X-ray energy dispersion spectroscopy (EDX) analysis were conducted for investigating grain size refinement, adequate dispersion, stability and de-agglomeration of encapsulated SiC particles in aluminium matrix. The mechanical as well as thermal cyclic (from − 100 to 400 °C) damping performance of the as-cast and friction stir processed composites were studied, respectively. Finally, the enhanced properties were attributable to reduced agglomeration, stabilization and proper dispersion of the tailored SiC particles Al matrix. - Highlights: •Synthesizing a novel coating layer of MgO and MgAl{sub 2}O{sub 4} spinel onto SiC particles •Significant improvement in UTS and hardness by reinforcing tailored SiC in Al •Significant grain refinements were obtained through FSP •SiC/MgAl{sub 2}O{sub 4}/Al exhibits ~ 61% higher storage modulus as compare to pure Al after FSP.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Correlation between the critical viscosity and ash fusion temperatures of coal gasifier ashes

Coal gasification yields synthesis gas, an important intermediate in chemical manufacturing. It is also vital to the production of liquid fuels through the Fischer-Tropsch process and electricity in Integrated Gasification Combined Cycle power generation. Minerals naturally present in coal become molten in entrained-flow slagging gasifiers. Molten coal ash slag penetrates and dissolves refractory bricks, leading to costly plant shutdowns. The extent of coal ash slag penetration and refractory brick dissolution depends on the slag viscosity, the gasification temperature, and the composition of slag and bricks. We measured the viscosity of several synthetic coal ash slags with a high-temperature rotary viscometer and their ash fusion temperatures through optical image analysis. All measurements were made in a carbon monoxide-carbon dioxide reducing atmosphere that approximates coal gasification conditions. Empirical correlation models based on ash fusion temperatures were used to calculate critical viscosity temperatures based on the coal ash compositions. These values were then compared with those obtained from thermodynamic phase-transition models. An understanding of slag viscosity as a function of ash composition is important to reducing refractory wear in slagging coal gasifiers, which would help to reduce the cost and environmental impact of coal for chemical and electricity production.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2010

Controlling the work function of a diamond-like carbon surface by fluorination with XeF{sub 2}

Thin diamond-like carbon films were subjected to fluorination with gaseous XeF{sub 2} under ultrahigh vacuum conditions in order to increase the work function of the diamond-like carbon surface. Changes in the work function and surface composition were monitored with UV photoemission spectroscopy and x-ray photoemission spectroscopy, respectively. Successive XeF{sub 2} exposures raised the work function by as much as 1.55 eV. Surprisingly, approximately half of the increase in the work function occurred while the coverage of fluorine remained below 0.02 monolayers (ML). This suggests that initial doses of XeF{sub 2} remove extrinsic adsorbates from the diamond-like carbon film and that fluorine desorbs with the reaction products. Increasing the exposure of the diamond-like carbon to XeF{sub 2} leads to the expected covalent fluorination of the surface, which saturates at fluorine coverages of 6 F atoms/nm{sup 2} ({approx}0.3 ML). Annealing of the diamond-like carbon to temperatures above 850 K was required to reduce the surface fluorine concentration to undetectable levels. This did not, however, cause the work function to return to its original, prefluorination value.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Shrub Expansion Simulations at Trail Valley Creek Tundra site using E3SM Land Model (ELM) Arctic-focused Version

The warming of the Arctic is causing substantial compositional, structural, and functional changes in tundra vegetation including shrub and densification in parts of the Arctic. Assessing the impact of these changes in vegetation composition on the Arctic’s carbon and energy budgets is important to constrain projected local and global surface-atmosphere exchanges. We conduct a sensitivity analysis of the projected surface energy fluxes, soil carbon pools, and carbon dioxide fluxes (net ecosystem exchange, gross primary production, and ecosystem respiration) between present day and 2100 to different shrub expansion rates and air temperature increases under future emission scenarios (intermediate – RCP4.5, and high – RCP8.5) using the Arctic-focused version of the Energy Exascale Earth System Model (E3SM) Land Model (ELM). We focus on Trail Valley Creek (TVC), a mineral upland tundra site located in the western Canadian Arctic, which is experiencing tall shrub densification and expansion. In this study, we run TVC under two different warming scenarios RCP4.5 and RCP 8.5 and simulate different shrubification rates projected until year 2100. In this repository, we include all the forcing, input, parameters, and output data corresponding to all the simulations performed. flmd.csv includes a detailed description of the datasets files.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Prediction of the influence of strain magnitude and strain path on the resulting microstructure and post-forming mechanical behavior of RA containing high formability steels

In third generation advanced high strength steels (AHSS) there is considerable potential to alter the transformation characteristics through variation of process parameters and through changes in chemical composition. This proposal aims to utilize this known phenomenon to develop microstructure-based transformation models to predict austenite stability as a function of chemical composition, strain level, deformation mode. The ultimate intent is to predict microstructure and performance during room temperature forming to produce automotive structural components with superior strength and failure resistance.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Structural and photoelectrochemical properties in the thin film system Cu–Fe–V–O and its ternary subsystems Fe–V–O and Cu–V–O

Thin-film material libraries in the ternary and quaternary metal oxide systems Fe–V–O, Cu–V–O, and Cu–Fe–V–O were synthesized using combinatorial reactive co-sputtering with subsequent annealing in air. Their compositional, structural, and functional properties were assessed using high-throughput characterization methods. Prior to the investigation of the quaternary system Cu–Fe–V–O, the compositions (Fe 61 V 39 )O x and (Cu 52 V 48 )O x with promising photoactivity were identified from their ternary subsystems Fe–V–O and Cu–V–O, respectively. Two Cu–Fe–V–O material libraries with (Cu 29-72 Fe 4-27 V 22-57 )O x and (Cu 11-55 Fe 27-73 V 12-34 )O x composition spread were investigated. Seven mixed ternary and quaternary phase regions were identified: I (α-Cu 3 FeV 6 O 26 /FeVO 4 ), II (Cu 5 V 2 O 10 /FeVO 4 /α-Cu 3 Fe 4 V 6 O 26 ), III (Cu 5 V 2 O 10 ), IV (Cu 5 V 2 O 10 /FeVO 4 , V (FeVO 4 /γ-Cu 2 V 2 O 7 /α-Cu 3 Fe 4 V 6 O 26 ), VI (β-Cu 2 V 2 O 7 /α-Cu 3 Fe 4 V 6 O 26 /FeVO 4 ), and VII (β-Cu 3 Fe 4 V 6 O 26 /FeVO 4 ). Furthermore, in the investigated composition range, two photoactive regions, (Cu 53 Fe 7 V 40 )O x and (Cu 45 Fe 21 V 34 )O x , were identified, exhibiting 103 μ A/cm 2 and 108 μ A/cm 2 photocurrent density for the oxygen evolution reaction at 1.63 V vs reversible hydrogen electrode, respectively. The highest photoactive region (Cu 45 Fe 21 V 34 )O x comprises the dominant α-Cu 3 Fe 4 V 6 O 24 phase and minor FeVO 4 phase. This photoactive region corresponds to having an indirect bandgap of 1.87 eV and a direct bandgap of 2.58 eV with an incident photon-to-current efficiency of 30% at a wavelength of 310 nm.

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

Functional variability in specific root respiration translates to autotrophic differences in soil respiration in a temperate deciduous forest

CO 2 release from forest soils (R s ) is a prominent flux in the global carbon cycle. Rs is derived from roots (autotrophic respiration, R a ) and microbial (heterotrophic) respiration and is highly dynamic, as it depends on edaphic and environmental conditions as well as root functional traits and microbial community composition. It is unclear how root functional traits affect root and microbial respiration rates; however, their consideration may help parse out the relative contributions of root and microbial respiration to R s . At a temperate forest site, root systems of 3–4 functional root orders and their surrounding surface soil were carefully excavated and placed into custom trays designed to repeatedly measure R s in situ on eight temperate tree species that varied in their root functional strategies and mycorrhizal affinity. R s was measured bi-weekly to monthly for nearly one year using a custom chamber attached to a gas exchange system. R s varied over time, ranging from 0.3 to 12 µmol m -2 s -1 . Comparable root systems of the same species were excised from the soil and specific root respiration rates (R r ) were measured. Rr ranged from 2.5 to 9.0 nmol g -1 s -1 and was negatively correlated with root tissue density and positively related to root tissue nitrogen concentration. Using R r to estimate R a , we estimate that R a accounts for <10%, on average 2–3%, of R s for individual root systems (averaging 1.2 g dry biomass) housed in surrounding soil (average 1.3 kg dry mass) in situ; thus, Ra was roughly 20 times greater than Rh per unit mass. The contribution of R a peaked in the fall and coincided with leaf senescence of the forest canopy. A soil-sterilizing experimental treatment designed to help isolate R a in situ reduced bacterial biomass and shifted fungal community composition, but there was no reduction in Rs of the in-situ root-soil tray systems. The relative R a to R s ratio increased with root functional strategies characterized by greater specific root length and tip abundance, but also to greater root tissue density. The ratio of R a to R s also increased with warmer soil temperatures and decreased slightly with increasing soil moisture. We discuss how incorporating root functional traits as modulators of the autotrophic contribution to R s could be considered when modeling total soil CO 2 efflux from forests.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Composition Driven, Statistical Review of Cast Stone Screening Matrix Results

Recent studies in support of Cast Stone development for the Hanford Site were designed to screen the effects of mix components on properties and performance of the waste form. Dry blend components, including portland cement, blast furnace slag, and Class F fly ash, sourced from both southeastern and northwestern suppliers, were included in the screening matrix. Multiple decontaminated salt solutions (simulated) were combined with the dry blend components at various liquid to solid ratios following a statistically designed matrix of compositions. Properties of the resulting mixes and performance of the cured materials were then measured and related to the dry blend components and salt solutions that were used for each mix. At the conclusion of the screening matrix work, SRNL felt that additional insight into the study might be obtained by relating the properties and performance of the materials to the composition of each Cast Stone mix, as opposed to just the dry blend – salt solution combination. This memorandum provides the results of a statistically driven review of the screening matrix data as a function of the composition of each mix. It is meant to augment the results obtained by reviewing the screening matrix data as a function of the dry blend and salt solution combination.

Edwards, T. B.↗
DOE OSTI2019

Atmo-ecometabolomics: A novel atmospheric particle chemical characterization methodology for ecological research

Aerosol particles play important roles in processes controlling the composition of the atmosphere and function of ecosystems. A better understanding of the composition of aerosol particles is beginning to be recognized as critical for ecological research to further comprehend the link between aerosols and ecosystems. While chemical characterization of aerosols has been practiced in the atmospheric science community, detailed methodology tailored to the needs of ecological research does not exist yet. In this study, we describe an efficient methodology (atmo-ecometabolomics), in step-by-step details, from the sampling to the data analyses, to characterize the chemical composition of aerosol particles, namely atmo-metabolome. This method employs mass spectrometry platforms such as liquid and gas chromatography mass spectrometries (MS) and Fourier transform ion cyclotron resonance MS (FT-ICR-MS). For methodology evaluation, we analyzed aerosol particles collected during two different seasons (spring and summer) in a low-biologicalactivity ecosystem. Additionally, to further validate our methodology, we analyzed aerosol particles collected in a more biologically active ecosystem during the pollination peaks of three different representative tree species. Our statistical results showed that our sampling and extraction methods are suitable for characterizing the atmo-ecometabolomes in these two distinct ecosystems with any of the analytical platforms. Datasets obtained from each mass spectrometry instrument showed overall significant differences of the atmo-ecometabolomes between spring and summer as well as between the three pollination peak periods. Furthermore, we have identified several metabolites that can be attributed to pollen and other plant-related aerosol particles.We additionally provide a basic guide of the potential use ecometabolomic techniques on different mass spectrometry platforms to accurately analyze the atmoecometabolomes for ecological studies. Our method represents an advanced novel approach for future studies in the impact of aerosol particle chemical compositions on ecosystem structure and function and biogeochemistry.

Rivas-Ubach, Albert (ORCID:0000000312937127)↗
DOE OSTI2020

Discerning the thermodynamic feasibility of the spontaneous coexistence of multiple functional vegetation groups

Can the Second Law of Thermodynamics explain why ecosystems naturally organize into a complex structure composed of multiple vegetation species and functional groups? Ecosystem structure, which refers to the number and type of plant functional groups, is the result of self-organization, or the spontaneous emergence of order from random fluctuations. By considering ecosystems as open thermodynamic systems, we model and study these fluctuations of throughput signatures on short timescales to determine the drivers and characteristics of ecosystem structure. This diagnostic approach allows us to use fluxes of energy and entropy to calculate an ecosystem’s estimated work and understand the thermodynamic behavior of the system. We use a multi-layer canopy-root-soil model to calculate the energy and entropy fluxes of different scenarios for field sites across various climates. At each site, scenarios comprised of native individual plant functional groups and a coexisting multi-group composition scenario including all functional groups observed at the site are compared. Ecosystem-scale calculations demonstrate that entropy fluxes and work efficiency—the work performed for the amount of radiation entering the ecosystem—are greatest in the multi-group scenario when its leaf area is significantly larger than each of its individual functional groups. Thus, we conclude that ecosystems self-organize towards the vegetation structure with the greatest outgoing entropy flux and work efficiency, resulting in the coexistence of multiple functional groups and performing the maximum amount of work within the constraints of locally available energy, water, and nutrients.

54 ENVIRONMENTAL SCIENCES↗