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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

A mutagenic analysis of NahE, a hydratase-aldolase in the naphthalene degradative pathway

NahE is a hydratase-aldolase that converts o-substituted trans-benzylidenepyruvates (H, OH, or CO 2 - ) to benzaldehyde, salicylaldehyde, or 2-carboxybenzaldehyde, respectively, and pyruvate. The enzyme is in a bacterial degradative pathway for naphthalene, which is a toxic and persistent environmental contaminant. Sequence, crystallographic, and mutagenic analysis identified the enzyme as a member of the N-acetylneuraminate lyase (NAL) subgroup in the aldolase superfamily. As such, it has a conserved lysine (Lys183) and tyrosine (Tyr155), for Schiff base formation, as well as a GXXGE motif for binding of the pyruvoyl carboxylate group. A crystal structure of the selenomethionine derivative of NahE shows these active site elements along with nearby residues that might be involved in the mechanism and/or specificity. Mutations of five active site amino acids (Thr65, Trp128, Tyr155, Asn157, and Asn281) were constructed and kinetic parameters measured in order to assess the effect(s) on catalysis. Here, the results show that the two Trp128 mutants (Phe and Tyr) have the least effect on catalysis, whereas amino acids with bulky side chains at Thr65 (Val) and Asn281 (Leu) have the greatest effect. Changing Tyr155 to Phe and Asn157 to Ala also hinders catalysis, and the effects fall in between these extremes. These observations are put into a structural context using a crystal structure of the Schiff base of the reaction intermediate. Trapping experiments with substrate, Na(CN)BH 3 , and wild type enzyme and selected mutants mostly paralleled the kinetic analysis, and identified two salicylaldehyde-modified lysines: the active site lysine (Lys183) and one outside the active site (Lys279). The latter could be responsible for the observed inhibition of NahE by salicylaldehyde. Together, the results provide new insights into the NahE-catalyzed reaction.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

A phenology- and trend-based approach for accurate mapping of sea-level driven coastal forest retreat

The rapid replacement of upland forest by encroaching marshland is a striking manifestation of global sea-level rise (SLR). Timely and high-resolution information on the location and extent of transition forest (the ecotone between upland forest and marsh where tree mortality due to seawater intrusion begins) is fundamental to understanding the processes and patterns of SLR-driven landscape reorganization. Despite its significance, accurate characterization of salt-impacted transition forest remains challenging due to the complexity of coastal environments, scarcity of ground-truth data, and the lack of effective mapping algorithms. Here we use the full archive of Landsat images between 1984 and 2021 to investigate the spectral, temporal, and phenological characteristics of transition forest, and develop a robust framework for monitoring coastal vegetation shifts in the mid-Atlantic U.S., a global SLR hotspot. Here, we found that transition forest exhibits strong negative NDVI trends and a deviation of land surface phenology from marsh and upland forest that distinguishes itself from surrounding vegetation. By integrating temporal trends and land surface phenology, our results demonstrate superior discrimination between marsh and coastal forests to existing map products (e.g. NOAA Coastal Change Analysis Program, National Land Cover Database) that allows a reliable identification of the coastal treeline. We applied the approach to map regional land cover in 1985, 2000 and 2020 (overall classification accuracy >92%) and found that the area of coastal forest decreased by 22.0% from 1985 to 2020, the majority of which transitioned to marshland (92.3%, 5.3 × 10 3 ha). Based upon fine-scale patterns of coastal transgression, we created a practical workflow for spatially explicit quantification of forest retreat rates. Concurrent with rising sea level, coastal forests migrated upslope from 0.63 (± 0.27) m above sea level in 1985 to 0.78 (± 0.32) m above sea level in 2020, and horizontal forest retreat rates accelerated from 3.1 (range of 0–36) m yr -1 during 1985–2000 to 4.7 (0–55) m yr -1 during 2001–2020. As SLR continues to accelerate, our study may serve as a scalable solution for consistent tracking of coastal landscape evolution that is urgently needed for sustainable forest and wetland management.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Multi-Messenger In-situ Tolerance Optimization of Mixed Perovskite Photovoltaics. Final Report

The main objectives for this project were to formulate, validate and disseminate a new procedure based on Environmental X-ray Photoelectron Spectroscopy (EXPS) for the accelerated degradation testing of metal hybrid perovskite (MHP) PV materials. With this capability, we can aid US efforts to improve MHP tolerance for illumination in damp heat conditions. This capability will benefit the public by supporting new industry efforts to create stable MHP formulations.

14 SOLAR ENERGY↗
DOE OSTI2026

Automatic Calibration and Health Monitoring of Infrastructure Sensors

Smart transportation infrastructure relies on networks of heterogeneous sensors - cameras, radars, and lidars - continuously monitoring traffic conditions. However, executing the initial spatial calibration of multiple sensors and the subsequent health monitoring presents significant operational challenges. Environmental factors, mechanical vibrations, and gradual drift cause spatial misalignment, degrading fusion performance and tracking accuracy. Traditional calibration approaches require manual intervention with specialized targets or survey equipment, resulting in service interruptions and high maintenance costs. This work presents an automated framework for initial calibration and continuous health monitoring without human intervention or service disruption. Our approach addresses two critical problems: (1) detecting when sensors become miscalibrated during operation, and (2) automatically re-establishing spatial alignment using only operational traffic data. The health monitoring component analyzes measurement innovations - differences between sensor observations and predicted object states - to detect systematic biases indicative of calibration drift. By computing bias magnitude, directional consistency, and rejection rates, the system identifies miscalibrations as small as 0.5 meters. Unlike traditional methods requiring known calibration targets, our diagnostic operates continuously on live traffic observations, enabling early detection before fusion quality degrades. The automatic recalibration algorithm leverages overlapping sensor fields-of-view and temporal correlation of vehicle observations. Using graph-based optimization, the system automatically discovers which sensor pairs observe common regions, estimates pairwise spatial transformations using RANSAC-based robust estimation, and jointly optimizes all sensor poses through bundle adjustment. The framework handles practical deployment challenges, including different sensor sampling rates (1-10 Hz), varying installation positions, unknown orientations, and limited overlap regions (>10%). When approximate sensor positions are available from installation surveys (+/-1m accuracy), the algorithm additionally estimates sensor orientations, refining both position and rotation to sub-meter and sub-degree accuracy. We validate the framework on multi-hour traffic datasets from six heterogeneous sensors with sampling rates ranging from 1 Hz to 10 Hz. Results demonstrate successful calibration even with sparse overlap (<20%) and automatic detection of miscalibrations exceeding 0.8 meters. This work enables a "deploy-and-forget" sensor infrastructure that maintains calibration autonomously, reducing maintenance costs while improving tracking accuracy. The techniques generalize beyond transportation to any multi-sensor monitoring application requiring robust spatial alignment, including smart cities, industrial monitoring, and surveillance systems.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1972

Preliminary design study of a regenerative life support system information management and display system

The instrumentation requirements for a regenerative life support systems were studied to provide the earliest possible indication of a malfunction that will permit degradation of the environment. Four categories of parameters were investigated: environmental parameters that directly and immediately influence the health and safety of the cabin crew; subsystems' inputs to the cabin that directly maintain the cabin environmental parameters; indications for maintenance or repair; and parameters useful as diagnostic indicators. A data averager concept is introduced which provides a moving average of parameter values that is not influenced by spurious changes, and is convenient for detecting parameter rates of change. A system is included to provide alarms at preselected parameter levels.

Parker, C. D.↗
NASA NTRS1982

Evaluation of present thermal barrier coatings for potential service in electric utility gas turbines

The resistance of present-day thermal barrier coatings to combustion gases found in electric utility turbines was assessed. The plasma sprayed coatings, both duplex and graded types, were primarily zirconia-based, although a calcium silicate was also evaluated. Both atmospheric burner rig tests and high pressure tests (135 psig) showed that several present-day thermal barrier coatings have a high potential for service in gas turbines burning the relatively clean GT No. 2 fuel. However, coating improvements are needed for use in turbines burning lower grade fuel such as residual oil. The duplex ZrO2.8Y2O3/NiCrA1Y coating was ranked highest and selected for near-term field testing, with Ca2SiO4/NiCrA1Y ranked second. Graded coatings show potential for corrosive turbine operating conditions and warrant further development. The coating degradation mechanisms for each coating system subjected to the various environmental conditions are also described.

Bratton, R. J.↗
NASA NTRS1994

Isothermal Damage and Fatigue Behavior of SCS-6/Timetal 21S [0/90](Sub S) Composite at 650 Deg C

The isothermal fatigue damage and life behaviors of SCS-6/Timetal 21S (0/90)s were investigated at 650 C. Strain ratcheting and degradation of the composite's static elastic modulus were carefully monitored as functions of cycles to indicate damage progression. Extensive fractographic and metallographic analyses were conducted to determine damage/failure mechanisms. Resulting fatigue lives show considerable reductions in comparison to (0) reinforced titanium matrix composites subjected to comparable conditions. Notable stiffness degradations were found to occur after the first cycle of loading, even at relatively low maximum stress levels, where cyclic lives are greater than 25,000 cycles. This was attributed to the extremely weak fiber/matrix bond which fails under relatively low transverse loads. Stiffness degradations incurred on first cycle loadings and degradations thereafter were found to increase with increasing maximum stress. Environmental effects associated with oxidation of the (90) fiber interfaces clearly played a role in the damage mechanisms as fracture surfaces revealed environment assisted matrix cracking along the (90) fibers. Metallographic analysis indicated that all observable matrix fatigue cracks initiated at the (90) fiber/matrix interfaces. Global de-bonding in the loading direction was found along the (90) fibers. No surface initiated cracks were evident and minimal if any (0) fiber cracking was visible.

Castelli, Michael G.↗
NASA NTRS2017

Materials Science Corrosion Internship Overview

The overarching purpose of this semester-long internship at the National Aeronautics and Space Administration's (NASA) John F. Kennedy Space Center (KSC) was to study the impacts of corrosion regarding the development of ground support equipment (GSE), launch support structures, and flight hardware in aid of the Space Launch System (SLS) and Orion program. Environmental corrosion is known as one of the largest material degradation issues for any structure comprised of metal on the Space Coast and requires the initiation of special protective measures for proper corrosion mitigation. The four (4) projects to be described were conducted with NASA Civil Servants and NASA Contractors who provided necessary resources to ensure the highest quality of data acquisition and knowledge transfer. The main objective shared between all four (4) of the following projects was to assess the modes by which corrosion takes place in multiple environments as well as the methods by which these modes of corrosion can be reduced for the enhancement of the mechanical, structural, and chemical compatibility of those respective environments with different candidate metals. A multitude of test methods were performed over the duration of this internship to assess the corrosive properties of these different candidate metals.

Ground Systems Development and Operations↗
NASA NTRS2022

Tracing PAH Emission in λ-Orionis Using COBE/DIRBE Data

We use archival COBE/DIRBE data to construct a map of polycyclic aromatic hydrocarbon (PAH) emission in the λ-Orionis region. The presence of the 3.3 μm PAH feature within the DIRBE 3.5 μm band and the corresponding lack of significant PAH spectral features in the adjacent DIRBE bands (1.25, 2.2, and 4.9 μm) enable estimation of the PAH contribution to the 3.5 μm data. Having the shortest wavelength of known PAH features, the 3.3 μm feature probes the smallest PAHs, which are also the leading candidates for carriers of anomalous microwave emission (AME). We use this map to investigate the association between the AME and the emission from PAH molecules. We find that the spatial correlation in λ-Orionis is higher between AME and far-infrared dust emission (as represented by the DIRBE 240 μm map) than it is between our PAH map and AME. This finding, in agreement with previous studies using PAH features at longer wavelengths, is in tension with the hypothesis that AME is due to spinning PAHs. However, the expected correlation between mid-infrared and microwave emission could potentially be degraded by different sensitivities of each emission mechanism to local environmental conditions even if PAHs are the carriers of both.

David T. Chuss↗
NASA NTRS2023

Drought-Tolerant Succulent Plants as an Alternative Crop Under Future Global Warming Scenarios in Sub-Saharan Africa

Globally, we are facing an emerging climate crisis, with impacts to be notably felt in semiarid regions across the world. Cultivation of drought-adapted succulent plants has been suggested as a nature-based solution that could: (i) reduce land degradation, (ii) increase agricultural diversification and provide both economic and environmentally sustainable income through derived bioproducts and bioenergy, (iii) help mitigate atmospheric CO 2 emissions and (iv) increase soil sequestration of CO 2 . Identifying where succulents can grow and thrive is an important prerequisite for the advent of a sustainable alternative ‘bioeconomy’. Here, we first explore the viability of succulent cultivation in Africa under future climate projections to 2100 using species distribution modelling to identify climatic parameters of greatest importance and regions of environmental suitability. Minimum temperatures and temperature variability are shown to be key controls in defining the theoretical distribution of three succulent species explored, and under both current and future SSP5 8.5 projections, the conditions required for the growth of at least one of the species are met in most parts of sub-Saharan Africa. These results are supplemented with an analysis of potentially available land for alternative succulent crop cultivation. In total, up to 1.5 billion ha could be considered ecophysiologically suitable and available for succulent cultivation due to projected declines in rangeland biomass and yields of traditional crops. These findings may serve to highlight new opportunities for farmers, governments and key stakeholders in the agriculture and energy sectors to invest in sustainable bioeconomic alternatives that deliver on environmental, social and economic goals.

agriculture↗
NASA NTRSDate not supplied

Tensor Decomposition Analysis for UAV Anomaly Detection

Vibrational anomalies can provide valuable insights into the health status of an unmanned aerial vehicle, potentially indicating system degradation including propeller, motor, or sensor damage, as well as environmental anomalies such as strong wind gusts and turbulence. However, many causes for vibrational anomalies are not related to vehicle health, such as sharp shifts in velocity or direction of flight. Thus, depending strictly on vibration signals to detect anomalies can result in false positives for failures. Hence, it is important to include additional telemetries in detecting and diagnosing in-flight anomalies. This paper considers an approach to anomaly detection based on tensor decompositions that incorporates information from vibration signals, as well as additional flight data such as velocity, current draw, voltage drop, and attitude. Using experimental flight data collected by the University of Notre Dame, we construct third-order tensors then apply the CANDECOMP/PARAFAC decomposition to identify trends within each flight and classify flights as nominal or anomalous.

unmanned aviation↗
DOE OSTI2021

BETO 2021 Peer Review - Bio-Insecticides from Thermochemical Biomass Conversion

This work is developing a sustainable and inexpensive bioinsecticide that leverages the inherent chemical functionality created from thermochemical biomass conversion. The impact of this project lies at the intersection of energy and agricultural sustainability. Thermochemical conversion of biomass to fuels remains an attractive pathway, and bioinsecticides, isolated from a fraction of upgraded bio-oils, are a high-valued coproduct that can increase biorefinery profitability. Existing insecticide products are facing significant pressure from regulators and consumers due to negative health and environmental impacts. Bioinsecticides, produced through the deconstruction of biomass, can offer a safer more environmentally benign alternative due to the chemical homology with biologically degraded lignin. To enable thermochemical coproduction of bioinsecticides insecticidal activity must be competitive with existing products, separations of the bioinsecticide must be technically viable, and the overall process economics must be improved. Using vacuum distillation, we have separated a bioinsecticide active ingredient that has similar activity to current commercial products, and technoeconomic modeling has shown it can be produced at market competitive prices. This work has established a bioinsecticide fraction that is ready for further, more resource intensive development by addressing early technical, economic, and toxicological risks.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Activity assays of NnlA homologs suggest the natural product N -nitroglycine is degraded by diverse bacteria

Linear nitramines (R–N(R′)NO 2 ; R′ = H or alkyl) are toxic compounds, some with environmental relevance, while others are rare natural product nitramines. One of these natural product nitramines is N -nitroglycine (NNG), which is produced by some Streptomyces strains and exhibits antibiotic activity towards Gram-negative bacteria. An NNG degrading heme enzyme, called NnlA, has recently been discovered in the genome of Variovorax sp. strain JS1663 ( Vs NnlA). Evidence is presented that NnlA and therefore, NNG degradation activity is widespread. To achieve this objective, we characterized and tested the NNG degradation activity of five Vs NnlA homologs originating from bacteria spanning several classes and isolated from geographically distinct locations. E. coli transformants containing all five homologs converted NNG to nitrite. Four of these five homologs were isolated and characterized. Each isolated homolog exhibited similar oligomerization and heme occupancy as Vs NnlA. Reduction of this heme was shown to be required for NnlA activity in each homolog, and each homolog degraded NNG to glyoxylate, NO 2 − and NH 4 + in accordance with observations of Vs NnlA. It was also shown that NnlA cannot degrade the NNG analog 2-nitroaminoethanol. The combined data strongly suggest that NnlA enzymes specifically degrade NNG and are found in diverse bacteria and environments. These results imply that NNG is also produced in diverse environments and NnlA may act as a detoxification enzyme to protect bacteria from exposure to NNG.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1990

Scientific Assessment of Stratospheric Ozone: 1989, volume 2. Appendix: AFEAS Report

The results are presented of the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS), which was organized to evaluate the potential effects on the environment of alternate compounds targeted to replace fully halogenated chlorofluorocarbons (CFCs). All relevant current scientific information to determine the environmental acceptability of the alternative fluorocarbons. Special emphasis was placed on: the potential of the compounds to affect stratospheric ozone; their potential to affect tropospheric ozone; their potential to contribute to model calculated global warming; the atmospheric degradation mechanisms of the compounds, in order to identify their products; and the potential environmental effects of the decomposition products. The alternative compounds to be studied were hydrofluorocarbons (HFCs) with one or two carbon atoms and one or more each of fluorine and hydrogen.

Source record↗
DOE OSTI2022

In-situ Characterizations of Microstructural Degradation of Perovskite Solar Cells

Rapid progress has been achieved in perovskite solar cells (PSCs), and their efficiencies have improved from 3.8 % to 24.2 % in less than a decade. With low-cost processing, PSCs have shown exciting photovoltaic (PV) properties, such as effective optical absorption, a long carrier lifetime, and unique defect tolerance. While recent studies demonstrated improved stability up to 100 days, PSC technology is still challenged to meet the stringent industry requirements for commercialization. Despite considerable efforts, the underlying physical mechanisms for the inferior stability of PSCs are not well understood. One reason for this divergence is that many established measurement techniques (e.g., quantum efficiency, photoluminescence) probe the properties on length scales far greater than that of electronic and/or structural inhomogeneity (i.e., < 1 μm near grain boundaries) and therefore characterize convoluted and/or averaged properties. Ion/electron beam-based techniques have been extensively used to access the microstructures of PSCs, enabling atomic/nanoscale structural, chemical, optical, and electrical characterizations. For example, focused ion beam (FIB) milling produces an atomically smooth surface that minimizes the artifacts attributed to the surface roughness. FIB techniques can also create a well-defined cross-section of PSCs without mechanical damage in a physical cleaving sample preparation. While powerful, there are some concerns about possible beam damage of inorganic-organic perovskites via chemical-bond breakage and local heating. This project aims to comprehensively understand how the microstructural/interfacial properties of PSCs (e.g., Methylammonium Lead Iodide [MAPbI 3 ]) are modified under the irradiating ion beams. Specifically, we investigate the sub-surface properties of PSCs before and after Ar-ion beam injections. Kelvin probe force microscopy (KPFM) measures the contact potential differences (CPDs). Photoluminescence (PL) microscopy in conjunction with Finite-Difference Time-Domain (FDTD) simulations infers the formation of a “dead layer” (< 15 nm) on the subsurface of MAPbI 3 during Ar+ milling processes while preserving the initial bulk properties. The x-ray photoemission spectroscopy (XPS) confirms this modified surface is a lead-rich and iodine-deficient surface. We initiate customizing in-situ measurement setup while measuring the local optical and electrical properties of PSC under thermal (cooling, heating) and light stressors. Our results provide in-depth knowledge of the ion-beam impact on metal-halide perovskites and how this modified sub-surface impacts their properties under accelerated stressors of light and heat. Intensive Monte Carlo simulations of an electron beam interacting with PSCs provide the beam energy distribution in PSCs, proposing possible measurement conditions of using e-beam with minimizing beam damage. Our in-situ measurement platform can accommodate the diverse architecture of PSC devices for studying deterioration mechanisms under mixed environmental stressors.

14 SOLAR ENERGY↗
DOE OSTI2023

A review of emerging photoinduced degradation methods for per- and polyfluoroalkyl substances in water

The remediation of per- and polyfluoroalkyl substances (PFAS) in water continues to garner significant attention due to their environmental persistence and adverse health effects. Among the various PFAS remediation methods, photoinduced approaches have recently emerged as promising techniques for the degradation of these persistent contaminants. However, many questions remain unanswered regarding the detailed mechanisms in these photoinduced methods as well as the best ways to leverage these approaches for PFAS degradation. In this review, we provide an update on recent experimental and theoretical developments in photoinduced PFAS degradation techniques over the past 2–5 years. We conclude with a perspective of promising research directions in this vibrant area and give recommendations on future experimental and computational approaches needed to further advance these photoinduced remediation capabilities.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1989

Probabilistic constitutive relationships for material strength degradation models

In the present probabilistic methodology for the strength of aerospace propulsion system structural components subjected to such environmentally-induced primitive variables as loading stresses, high temperature, chemical corrosion, and radiation, time is encompassed as an interacting element, allowing the projection of creep and fatigue effects. A probabilistic constitutive equation is postulated to account for the degradation of strength due to these primitive variables which may be calibrated by an appropriately curve-fitted least-squares multiple regression of experimental data. The resulting probabilistic constitutive equation is embodied in the PROMISS code for aerospace propulsion component random strength determination.

Boyce, L.↗