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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Root of the matter-Impacts of harvest frequency on soil C and nutrients in switchgrass

We evaluated how harvest frequency affected plant C allocation and soil-water nutrient concentrations in a switchgrass (Panicum virgatumL.) system on the Eastern Shore of Maryland, U.S.A. Switchgrass established in 2023 was harvested once (1Cut), twice (2Cut), or three times (3Cut) during the 2024 growing season to represent potential feedstock-management regimes for anaerobic digestion. Aboveground biomass was measured at each harvest, and root biomass distribution, root C stocks, and soil properties were assessed to 60 cm after the growing season. During 2025, rainfall-synchronized soil water collected with tension lysimeters was analyzed for dissolved inorganic nitrogen (DIN) and inorganic phosphate (Pi) concentrations.

09 BIOMASS FUELS↗
DOE OSTI2024

Adsorption of terbium (III) on DGA and LN resins: Thermodynamics, isotherms, and kinetics

Two commercially available extraction chromatography (EXC) resins containing N,N,N’,N’-tetra-n-octyldiglycolamide (DGA Resin, Normal, 50 – 100 μm) and Bis(2-ethylhexyl) phosphate (LN Resin, 100 – 150 μm) were used as adsorbents to study fundamental adsorption properties such as thermodynamic values, equilibrium isotherms, and kinetic uptake models for terbium(III) adsorption. Weight distribution ratios (D w ) for terbium on DGA and LN resins were measured using a [ 160 Tb]Tb 3+ radiometric tracer in nitric acid as a function of acidity, temperature, initial analyte concentration, and equilibrium time. The D w values showed increasing binding affinity for DGA resin at high nitric acid concentrations and decreasing binding affinity for LN resins. Thermodynamic studies for DGA and LN resins revealed that the Gibbs free energy (ΔG) increased consistently with temperature. To model equilibrium data, increasingly higher parameter equilibrium isotherm models (Henry (1) < Langmuir, Freundlich (2) < Redlich-Peterson (3) < Fritz-Schluender (4)) were compared on their root mean squared errors (RMSE) and adjusted determination coefficients to determine the most applicable model. In all cases, the empirical four-parameter Fritz-Schluender isotherm demonstrated a superior fit. Similar comparisons for reaction-based kinetic models (Pseudo-first-order < Pseudo-second-order < Pseudo-n-order) revealed that the higher-order PNO model yielded a superior fit of kinetic data for both resins. Furthermore, in some cases, adsorption isotherms and kinetic models could also be modeled by a lower-order model with minimal change in error parameters. Weber-Morris plots revealed that two linear sections are observed for each resin, where the first linear segment is attributed to fast (film diffusion) adsorption of terbium, followed by slower intraparticle diffusion of terbium through the pores as the rate-limiting step. Based on the Weber-Morris plot, both film and intraparticle diffusion are involved in controlling the kinetic rate of adsorption for DGA and LN resins.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Identification of a diguanylate cyclase expressed in the presence of plants and its application for discovering candidate gene products involved in plant colonization by Pantoea sp. YR343

Microbial colonization of plant roots is a highly complex process that requires the coordination and regulation of many gene networks, yet the identities and functions of many of these gene products have yet to be discovered. Pantoea sp. YR343, a gamma-proteobacterium isolated from the rhizosphere of Populus deltoides , forms robust biofilms along the root surfaces of Populus and possesses plant growth-promoting characteristics. In this work, we identified three diguanylate cyclases in the plant-associated microbe Pantoea sp. YR343 that are expressed in the presence of plant roots. One of these diguanylate cyclases, DGC2884, localizes to discrete sites in the cells and its overexpression results in reduced motility and increased EPS production and biofilm formation. We performed a genetic screen by expressing this diguanylate cyclase from an inducible promoter in order to identify candidate gene products that may be involved in root colonization by Pantoea sp. YR343. Further, we demonstrate the importance of other domains in DGC2884 to its activity, which in combination with the genes identified by transposon mutagenesis, may yield insights into the mechanisms of plant association as well as the activity and regulation of homologous enzymes in medically and agriculturally relevant microbes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Historical Land Management Alters New Soil Carbon Inputs by Annual and Perennial Bioenergy Crops

Bioenergy and bioproduct markets are expanding to meet demand for climate-friendly goods and services. Perennial biomass crops are particularly well suited for this goal because of their high yields, low input requirements, and potential to increase soil carbon (C). However, it is unclear how much C is allocated into belowground pools by perennial bioenergy crops and whether the belowground benefits vary with nitrogen (N) fertilizer inputs. Using in situ 13 C pulse-chase labeling, we tested whether the sterile perennial grass Miscanthus × giganteus (miscanthus) or annual maize transfers more photosynthetic C to belowground pools. The experiment took place at two sites in Central and Northwest (NW) Iowa with different management histories and two nitrogen (N) fertilizer rates (0 and 224 kg N ha −1 year −1 ) to determine if the fate of plant-derived soil C depends on soil fertility and crop type (perennial or annual). Maize allocated a greater percentage of total new 13 C to roots than miscanthus, but miscanthus had greater new 13 C in total and belowground plant biomass. We found strong interactions between site and most soil measurements—including new 13 C in mineral and particulate soil organic matter (SOM) pools—which appears to be driven by differences in historical fertilizer management. The NW Iowa site, with a history of manure inputs, had greater plant-available nutrients (phosphorus, potassium, and ammonium) in soils, and resulted in less 13 C from miscanthus in SOM pools compared to maize (approximately 64% less in POM and 70% less in MAOM). In more nutrient-limited soils (Central site), miscanthus transferred 4.5 times more 13 C than maize to the more stable mineral-associated SOM pool. Our results suggest that past management, including historical manure inputs that affect a site's soil fertility, can influence the net C benefits of bioenergy crops.

13C↗
NASA NTRS2000

A mutation in the Arabidopsis HYL1 gene encoding a dsRNA binding protein affects responses to abscisic acid, auxin, and cytokinin

Both physiological and genetic evidence indicate interconnections among plant responses to different hormones. We describe a pleiotropic recessive Arabidopsis transposon insertion mutation, designated hyponastic leaves (hyl1), that alters the plant's responses to several hormones. The mutant is characterized by shorter stature, delayed flowering, leaf hyponasty, reduced fertility, decreased rate of root growth, and an altered root gravitropic response. It also exhibits less sensitivity to auxin and cytokinin and hypersensitivity to abscisic acid (ABA). The auxin transport inhibitor 2,3,5-triiodobenzoic acid normalizes the mutant phenotype somewhat, whereas another auxin transport inhibitor, N-(1-naph-thyl)phthalamic acid, exacerbates the phenotype. The gene, designated HYL1, encodes a 419-amino acid protein that contains two double-stranded RNA (dsRNA) binding motifs, a nuclear localization motif, and a C-terminal repeat structure suggestive of a protein-protein interaction domain. We present evidence that the HYL1 gene is ABA-regulated and encodes a nuclear dsRNA binding protein. We hypothesize that the HYL1 protein is a regulatory protein functioning at the transcriptional or post-transcriptional level.

NASA Discipline Plant Biology↗
NASA NTRS1982

Closed-form solutions of supersonic wing-body interference

Closed-form formulas are presented for the interference factors of a body in the presence of a wing at supersonic speeds, when a finite afterbody is introduced. In addition, formulas are obtained for those cases in which the base of the body is forward of the trailing edge of the exposed root chord. These formulas are shown to be valid, subject to the restrictions inherent in the formulation given by Pitts, Nielsen and Kaattari (1959).

Vira, N. R.↗
DOE OSTI2021

Tradeoffs and Synergies in Tropical Forest Root Traits and Dynamics for Nutrient and Water Acquisition: Field and Modeling Advances

Vegetation processes are fundamentally limited by nutrient and water availability, the uptake of which is mediated by plant roots in terrestrial ecosystems. While tropical forests play a central role in global water, carbon, and nutrient cycling, we know very little about tradeoffs and synergies in root traits that respond to resource scarcity. Tropical trees face a unique set of resource limitations, with rock-derived nutrients and moisture seasonality governing many ecosystem functions, and nutrient versus water availability often separated spatially and temporally. Root traits that characterize biomass, depth distributions, production and phenology, morphology, physiology, chemistry, and symbiotic relationships can be predictive of plants’ capacities to access and acquire nutrients and water, with links to aboveground processes like transpiration, wood productivity, and leaf phenology. In this review, we identify an emerging trend in the literature that tropical fine root biomass and production in surface soils are greatest in infertile or sufficiently moist soils. We also identify interesting paradoxes in tropical forest root responses to changing resources that merit further exploration. For example, specific root length, which typically increases under resource scarcity to expand the volume of soil explored, instead can increase with greater base cation availability, both across natural tropical forest gradients and in fertilization experiments. Also, nutrient additions, rather than reducing mycorrhizal colonization of fine roots as might be expected, increased colonization rates under scenarios of water scarcity in some forests. Efforts to include fine root traits and functions in vegetation models have grown more sophisticated over time, yet there is a disconnect between the emphasis in models characterizing nutrient and water uptake rates and carbon costs versus the emphasis in field experiments on measuring root biomass, production, and morphology in response to changes in resource availability. Closer integration of field and modeling efforts could connect mechanistic investigation of fine-root dynamics to ecosystem-scale understanding of nutrient and water cycling, allowing us to better predict tropical forest-climate feedbacks.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Ectomycorrhizal effects on decomposition are highly dependent on fungal traits, climate, and litter properties: A model-based assessment

It has been proposed that competition between ectomycorrhizal (ECM) fungi and free-living saprotrophs for resources like nitrogen (N) slows decomposition and increases the soil carbon storage in ECM ecosystems compared to arbuscular (AM) ecosystems. However, empirical evidence for the generality of such ECM effects is equivocal, and confounding mechanisms have been proposed that affect the magnitude and direction of ECM effects on soil carbon. Here, for this work, we conduct a theoretical modeling experiment, where we explicitly incorporate mycorrhizal processes into the Carbon, Organisms, Rhizosphere, and Protection in the Soil Environment (CORPSE) model. We use the model to explore the conditions under which ECM N acquisition processes can induce stronger saprotrophic N limitation and result in slower decomposition rates and greater soil organic carbon accumulation compared to AM processes. We found that the ECM fungi more strongly inhibited decomposition when litter inputs were N-depleted and relatively recalcitrant and when ECM fungi possessed a strong capacity to mine N from both recalcitrant soil organic matter and microbial necromass. Climate and seasonality also played a role as the ECM competition effect was strongest at low mean annual temperatures and when litterfall peaked seasonally. Priming effects driven by high root exudation rates in ECM-dominated systems could overwhelm the competition effect and reduce soil carbon under some circumstances. The ECM effect on decomposition in our simulations was highly context dependent. Based on our model results, we expect to see a strong ECM competition effect in temperate deciduous and boreal forests with relatively recalcitrant litter inputs, and with ECM fungi that produce oxidases and necromass-degrading enzymes. However, even a relatively strong ECM competition effect on decomposition only increased soil organic carbon accumulation by ~10%.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Improving Stratocumulus Cloud Amounts in a 200‐m Resolution Multi‐Scale Modeling Framework Through Tuning of Its Interior Physics

Abstract High‐Resolution Multi‐scale Modeling Frameworks (HR)—global climate models that embed separate, convection‐resolving models with high enough resolution to resolve boundary layer eddies—have exciting potential for investigating low cloud feedback dynamics due to reduced parameterization and ability for multidecadal throughput on modern computing hardware. However low clouds in past HR have suffered a stubborn problem of over‐entrainment due to an uncontrolled source of mixing across the marine subtropical inversion manifesting as stratocumulus dim biases in present‐day climate, limiting their scientific utility. We report new results showing that this over‐entrainment can be partly offset by using hyperviscosity and cloud droplet sedimentation. Hyperviscosity damps small‐scale momentum fluctuations associated with the formulation of the momentum solver of the embedded large eddy simulation. By considering the sedimentation process adjacent to default one‐moment microphysics in HR, condensed phase particles can be removed from the entrainment zone, which further reduces entrainment efficiency. The result is an HR that can produce more low clouds with a higher liquid water path and a reduced stratocumulus dim bias. Associated improvements in the explicitly simulated sub‐cloud eddy spectrum are observed. We report these sensitivities in multi‐week tests and then explore their operational potential alongside microphysical retuning in decadal simulations at operational 1.5° exterior resolution. The result is a new HR having desired improvements in the baseline present‐day low cloud climatology, and a reduced global mean bias and root mean squared error of absorbed shortwave radiation. We suggest it should be promising for examining low cloud feedbacks with minimal approximation.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1986

Solar wind control of the Geomagnetic Mass Spectrometer

Evidence from Dynamics Explorer retarding-ion mass-spectrometer data collected between 1981 and 1983 for the mass dispersion of ionospheric plasma in the polar cap, known as the Geomagnetic Mass Spectrometer, is discussed, and implications of this new source of ionospheric ions for the magnetosphere are considered. A localized source of energization of ionspheric H(+), He(+), O(+) and N(+) ions in the polar cusp yields a source of upswelling plasma that is transported into the magnetosphere, and equal heating of the ion species results in field-aligned flow velocities which are inversely proportional to the square root of the ion mass. The present phenomenon is produced by the resulting velocity filter effect of solar-driven ExB ion convection. The influence of solar wind conditions on the outflow via the polar cap ExB convection pattern is also discussed.

Waite, J. H., Jr.↗
NASA NTRS1998

Biocompatibility of sweetpotato and peanut in a hydroponic system

'Georgia Red' peanut (Arachis hypogaea L.) and TU-82-155 sweetpotato [Ipomoea batatas (L.) Lam] were grown in monocultured or intercropped recirculating hydroponic systems in a greenhouse using the nutrient film technique (NFT). The objective was to determine whether growth and subsequent yield would be affected by intercropping. Treatments were sweetpotato monoculture (SP), peanut monoculture (PN), and sweetpotato and peanut grown in separate NFT channels but sharing a common nutrient solution (SP-PN). Greenhouse conditions ranged from 24 to 33 degrees C, 60% to 90% relative humidity (RH), and photosynthetic photon flux (PPF) of 200 to 1700 micromoles m-2 s-1. Sweetpotato cuttings (15 cm long) and 14-day-old seedlings of peanuts were planted into growth channels (0.15 x 0.15 x 1.2 m). Plants were spaced 25 cm apart within and 25 cm apart between growing channels. A modified half-Hoagland solution with a 1 N: 2.4 K ratio was used. Solution pH was maintained between 5.5 and 6.0 for treatments involving SP and 6.4 and 6.7 for PN. Electrical conductivity (EC) ranged between 1100 and 1200 microS cm-1. The number of storage roots per sweetpotato plant was similar for both SP and SP-PN. Storage root fresh and dry mass were 29% and 36% greater, respectively, for plants in the SP-PN treatment than for plants in the SP treatment. The percent dry mass of the storage roots, dry mass of fibrous and pencil roots, and the length-to-diameter ratio of storage roots were similar for SP and SP-PN sweetpotato plants. Likewise, foliage fresh and dry mass and harvest index were not significantly influenced by treatment. Total dry mass was 37% greater for PN than for SP-PN peanut plants, and pod dry mass was 82% higher. Mature and total seed dry mass and fibrous root dry mass were significantly greater for PN than for SP-PN plants. Harvest index (HI) was similar for both treatments. Root length tended to be lower for seedlings grown in the nutrient solution from the SP-PN treatment.

Non-NASA Center↗
NASA NTRS1986

The uptake of NO3-, NO2-, and NH4+ by intact wheat (Triticum aestivum) seedlings. I. Induction and kinetics of transport systems

The inducibility and kinetics of the NO3-, NO2-, and NH4+ transporters in roots of wheat seedlings (Triticum aestivum cv Yercora Rojo) were characterized using precise methods approaching constant analysis of the substrate solutions. A microcomputer-controlled automated high performance liquid chromatography system was used to determine the depletion of each N species (initially at 1 millimolar) from complete nutrient solutions. Uptake rate analyses were performed using computerized curve-fitting techniques. More precise estimates were obtained for the time required for the extent of the induction of each transporter. Up to 10 and 6 hours, respectively, were required to achieve apparent full induction of the NO3- and NO2- transporters. Evidence for substrate inducibility of the NH4+ transporters requiring 5 hours is presented. The transport of NO3- was mediated by a dual system (or dual phasic), whereas only single systems were found for transport of NO2- and NH4+. The Km values for NO3-, NO2-, and NH4+ were, respectively, 0.027, 0.054, and 0.05 millimolar. The Km for mechanism II of NO3- transport could not be defined in this study as it exhibited only apparent first order kinetics up to 1 millimolar.

NASA Program CELSS↗