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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 1,261 records · Page 70
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Large-area low-noise flexible organic photodiodes for detecting faint visible light

Silicon photodiodes are the foundation of light-detection technology; yet their rigid structure and limited area scaling at low cost hamper their use in several emerging applications. A detailed methodology for the characterization of organic photodiodes based on polymeric bulk heterojunctions reveals the influence that charge-collecting electrodes have on the electronic noise at low frequency. The performance of optimized organic photodiodes is found to rival that of low-noise silicon photodiodes in all metrics within the visible spectral range, except response time, which is still video-rate compatible. Solution-processed organic photodiodes offer several design opportunities exemplified in a biometric monitoring application that uses ring-shaped, large-area, flexible, organic photodiodes with silicon-level performance.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Gene expression of functionally-related genes coevolves across fungal species: detecting coevolution of gene expression using phylogenetic comparative methods

Researchers often measure changes in gene expression across conditions to better understand the shared functional roles and regulatory mechanisms of different genes. Analogous to this is comparing gene expression across species, which can improve our understanding of the evolutionary processes shaping the evolution of both individual genes and functional pathways. One area of interest is determining genes showing signals of coevolution, which can also indicate potential functional similarity, analogous to co-expression analysis often performed across conditions for a single species. However, as with any trait, comparing gene expression across species can be confounded by the non-independence of species due to shared ancestry, making standard hypothesis testing inappropriate. We compared RNA-Seq data across 18 fungal species using a multivariate Brownian Motion phylogenetic comparative method (PCM), which allowed us to quantify coevolution between protein pairs while directly accounting for the shared ancestry of the species. Our work indicates proteins which physically-interact show stronger signals of coevolution than randomly-generated pairs. Interactions with stronger empirical and computational evidence also showing stronger signals of coevolution. We examined the effects of number of protein interactions and gene expression levels on coevolution, finding both factors are overall poor predictors of the strength of coevolution between a protein pair. Simulations further demonstrate the potential issues of analyzing gene expression coevolution without accounting for shared ancestry in a standard hypothesis testing framework. Furthermore, our simulations indicate the use of a randomly-generated null distribution as a means of determining statistical significance for detecting coevolving genes with phylogenetically-uncorrected correlations, as has previously been done, is less accurate than PCMs, although is a significant improvement over standard hypothesis testing. These methods are further improved by using a phylogenetically-corrected correlation metric. Our work highlights potential benefits of using PCMs to detect gene expression coevolution from high-throughput omics scale data. This framework can be built upon to investigate other evolutionary hypotheses, such as changes in transcription regulatory mechanisms across species.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

MICRO-SEISMOMETERS VIA ADVANCED MESO-SCALE FABRICATION

The Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) seek revolutionary sensing innovations for the monitoring of nuclear detonations. Performance specifications are to be consistent with those obtainable by only an elite few products available today, but with orders of magnitude reduction in size, weight, power, and cost. The proposed commercial innovation calls upon several technologies including the combination of meso-scale fabrication and assembly, photonics-based displacement / motion detection methods, and the use of digital control electronics . Early Phase II development has demonstrated verified and repeatable sub 2ng noise floor from 3Hz to 100Hz, compact integration of 3-axis prototypes, and robust deployment exercises. Ongoing developments are focusing on low frequency challenges, low power consumption, ultra-miniature size, and low cross axis sensitivity. We are also addressing the rigorous set of specifications required for repeatable and reliable long-term explosion monitoring, including thermal stability, reduced recovery time from mass re-centering and large mechanical shocks, sensitivity stability, and transportability. Successful implementation will result in small, hand-held demonstration units with the ability to address national security needs of the DOE/NNSA. Additional applications envisioned include military/defense, scientific instrumentation, oil and gas exploration, inertial navigation, and civil infrastructure monitoring.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Fungal Biodegradative Oxidants in Lignocellulose: Fluorescence Mapping and Correlation With Gene Expression

This work focused on new methods for the detection of oxidation in natural substrates during the deconstruction of lignocellulose by microoganisms. Oxidation was the focus because all known biological systems that degrade lignin are oxidative. The detection methods involved the used of (a) micrometer-scale beads carrying a fluorescent dye that is sensitive to oxidation, (b) 13C-labeled synthetic lignins whose breakdown products can be assessed using mass spectrometry and nuclear magnetic resonance spectroscopy, and (c) a fluorometric stain that is highly sensitive to incipient oxidation during microbial attack. The results showed (a) that one white rot fungus, Phanerochaete chrysosporium, produces diffusible oxidants on wood, and that the onset of oxidation is coincident with the marked up-regulation of genes that encode ligninolytic peroxidases and auxiliary oxidative enzymes; (b) that a more selectively ligninolytic white rot fungus, Ceriporiopsis subvermispora, produces a highly diastereoselective oxidative system for attack on lignin; (c) that a brown rot fungus, Serpula lacrymans, uses extracellular hydroquinone metabolites to drive the production of lignocellulose-oxidizing free radicals; (d) that both white rot and brown rot fungi produce highly diffusible mild oxidants that modify lignocellulose at the earliest stage of substrate deconstruction; and (e) that lignin degradation in a tropical soil is not inhibited as much as expected during periods of flooding-induced hypoxia, which indicates that unknown mechanisms for attack on lignin remain to be discovered.

09 BIOMASS FUELS↗
DOE OSTI2026

High Energy Neutrino Physics

Of the twelve subatomic particles that are the building blocks of all the known matter in the universe, three are neutrinos, small neutral particles that interact through the weak interaction with other particles in the Universe. These three neutrinos, paired with the three charged leptons, the familiar electron, the heavier muon, and the still heavier tau, are some of the least well understood particles of these building blocks. Experiments using accelerator beams, like those that are the subject of this grant, can address some of the key questions scientists are posing with respect to the neutrino. Specifically, are there differences between neutrinos and their anti-particles, anti-neutrinos, that could give us some clue to the matter dominated universe, do we understand the spectrum of masses of the three neutrinos, and are there other kinds of neutirnos than the three neutrinos? Coupled with advances in precision neutrino detection, the US is addressing these questions from small scale experiments to the massive DUNE experiment. PI Fleming and her team play critical roles in accelerator based neutrino physics at short and long baseline with participation on MicroBooNE, SBND, and with the group's participation in DUNE. These experiments are at the heart of the US-based high energy physics program.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

A New Field Instrument for Leaf Volatiles Reveals an Unexpected Vertical Profile of Isoprenoid Emission Capacities in a Tropical Forest

Both plant physiology and atmospheric chemistry are substantially altered by the emission of volatile isoprenoids (VI), such as isoprene and monoterpenes, from plant leaves. Yet, since gaining scientific attention in the 1950’s, empirical research on leaf VI has been largely confined to laboratory experiments and atmospheric observations. Here, we introduce a new field instrument designed to bridge the scales from leaf to atmosphere, by enabling precision VI detection in real time from plants in their natural ecological setting. With a field campaign in the Brazilian Amazon, we reveal an unexpected distribution of leaf emission capacities (EC) across the vertical axis of the forest canopy, with EC peaking in the mid-canopy instead of the sun-exposed canopy surface, and moderately high emissions occurring in understory specialist species. Compared to the simple interpretation that VI protect leaves from heat stress at the hot canopy surface, our results encourage a more nuanced view of the adaptive role of VI in plants. We infer that forest emissions to the atmosphere depend on the dynamic microenvironments imposed by canopy structure, and not simply on canopy surface conditions. We provide a new emissions inventory from 52 tropical tree species, revealing moderate consistency in EC within taxonomic groups. We highlight priorities in leaf volatiles research that require field-portable detection systems. Our self-contained, portable instrument provides real-time detection and live measurement feedback with precision and detection limits better than 0.5 nmol VI m -2 leaf s -1 . We call the instrument ‘PORCO’ based on the gas detection method: photoionization of organic compounds. We provide a thorough validation of PORCO and demonstrate its capacity to detect ecologically driven variation in leaf emission rates and thus accelerate a nascent field of science: the ecology and ecophysiology of plant volatiles.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

SUBMILLIMETER OBSERVATION OF JUPITER’S STRATOSPHERIC COMPOSITION: DETECTION OF CARBON MONOSULFIDE (J = 7 − 6) 19 YEARS AFTER THE COMETARY IMPACT

In Jupiter's stratosphere, gaseous carbon monosulfide (CS) was first discovered in 1994 by millimeter and ultraviolet observations as a product induced by the collision of comet Shoemaker–Levy 9 (SL9). To constrain sulfur chemistry, in 2013, 19 years after the SL9 event, we observed Jupiter's stratospheric CS J = 7 − 6 rotational transition at 0.8 mm wavelength by using the Atacama Submillimeter Telescope Experiment 10 m single-dish telescope. The CS molecular line was successfully detected with 120 mK intensity in the antenna temperature scale. The obtained CS total mass shows ∼90% decrease relative to that observed in 1998. From the line shape analysis, CS is suggested to be present above the 0.2{sub −0.15}{sup +0.4} mbar pressure level, which is comparable to that determined in 1998.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

ESTIMATING THE GeV EMISSION OF MILLISECOND PULSARS IN DWARF SPHEROIDAL GALAXIES

We estimate the conventional astrophysical emission from dwarf spheroidal satellite galaxies (dSphs) of the Milky Way (MW), focusing on millisecond pulsars (MSPs), and evaluate the potential for confusion with dark matter (DM) annihilation signatures at GeV energies. In low-density stellar environments, such as dSphs, the abundance of MSPs is expected to be proportional to stellar mass. Accordingly, we construct the γ -ray luminosity function (LF) of MSPs in the MW disk, where >90 individual MSPs have been detected with the Fermi Large Area Telescope (LAT), and scale this LF to the stellar masses of 30 dSphs to estimate the cumulative emission from their MSP populations. We predict that MSPs within the highest stellar mass dSphs, Fornax and Sculptor, produce a γ -ray flux >500 MeV of ∼10{sup −11} ph cm{sup −2} s{sup −1}, which is a factor ∼10 below the current LAT sensitivity at high Galactic latitudes. The MSP emission in ultra-faint dSphs, including targets with the largest J-factors, is typically several orders of magnitude lower, suggesting that these targets will remain clean targets for indirect DM searches in the foreseeable future. For a DM particle of mass 25 GeV annihilating to b quarks at the thermal relic cross section (consistent with DM interpretations of the Galactic Center excess), we find that the expected γ -ray emission due to DM exceeds that of MSPs in all of the target dSphs. Using the same MW MSP population model, we also estimate the Galactic foreground MSP coincidence probability along the same sightlines to the dSphs.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects

The apparent clustering in longitude of perihelion piv and ascending node Ω of extreme trans-Neptunian objects (ETNOs) has been attributed to the gravitational effects of an unseen 5–10 Earth-mass planet in the outer solar system. To investigate how selection bias may contribute to this clustering, we consider 14 ETNOs discovered by the Dark Energy Survey, the Outer Solar System Origins Survey, and the survey of Sheppard and Trujillo. Using each survey's published pointing history, depth, and TNO tracking selections, we calculate the joint probability that these objects are consistent with an underlying parent population with uniform distributions in $\bar{w}$ and Ω. We find that the mean scaled longitude of perihelion and orbital poles of the detected ETNOs are consistent with a uniform population at a level between 17% and 94% and thus conclude that this sample provides no evidence for angular clustering.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1973

California coast nearshore processes study

The author has identified the following significant results. Large scale sediment plumes from intermittent streams and rivers form detectable seasonal patterns on ERTS-1 imagery. The ocean current systems, as plotted from three California coast ERTS mosaics, were identified. Offshore patterns of sediment in areas such as the Santa Barbara Channel are traceable. These patterns extend offshore to heretofore unanticipated ranges as shown on the ERTS-1 imagery. Flying spot scanner enhancements of NASA tapes resulted in details of subtle and often invisible (to the eye) nearshore features. The suspended sediments off San Francisco and in Monterey Bay are emphasized in detail. These are areas of extremely changeable offshore sediment transport patterns. Computer generated contouring of radiance levels resulted in maps that can be used in determining surface and nearsurface suspended sediment distribution. Tentative calibrations of ERTS-1 spectral brightness against sediment load have been made using shipboard measurements. Information from the combined enhancement and interpretation techniques is applicable to operational coastal engineering programs.

Pirie, D. M.↗
NASA NTRS1974

The application of ERTS imagery to monitoring Arctic sea ice

The author has identified the following significant results. Because of the effect of sea ice on the heat balance of the Arctic and because of the expanding economic interest in arctic oil and minerals, extensive monitoring and further study of sea ice is required. The application of ERTS data for mapping ice is evaluated for several arctic areas, including the Bering Sea, the eastern Beaufort Sea, parts of the Canadian Archipelago, and the Greenland Sea. Interpretive techniques are discussed, and the scales and types of ice features that can be detected are described. For the Bering Sea, a sample of ERTS-1 imagery is compared with visual ice reports and aerial photography from the NASA CV-990 aircraft. The results of the investigation demonstrate that ERTS-1 imagery has substantial practical application for monitoring arctic sea ice. Ice features as small as 80-100 m in width can be detected, and the combined use of the visible and near-IR imagery is a powerful tool for identifying ice types. Sequential ERTS-1 observations at high latitudes enable ice deformations and movements to be mapped. Ice conditions in the Bering Sea during early March depicted in ERTS-1 images are in close agreement with aerial ice observations and photographs.

Barnes, J. C.↗
NASA NTRS1974

Monitoring Arctic Sea ice using ERTS imagery

Because of the effect of sea ice on the heat balance of the Arctic and because of the expanding economic interest in arctic oil and other minerals, extensive monitoring and further study of sea ice is required. The application of ERTS data for mapping ice is evaluated for several arctic areas, including the Bering Sea, the eastern Beaufort Sea, parts of the Canadian Archipelago, and the Greenland Sea. Interpretive techniques are discussed, and the scales and types of ice features that can be detected are described. For the Bering Sea, a sample of ERTS imagery is compared with visual ice reports and aerial photography from the NASA CV-990 aircraft.

Barnes, J. C.↗
NASA NTRS1976

Trends in modern system theory

The topics considered are related to linear control system design, adaptive control, failure detection, control under failure, system reliability, and large-scale systems and decentralized control. It is pointed out that the design of a linear feedback control system which regulates a process about a desirable set point or steady-state condition in the presence of disturbances is a very important problem. The linearized dynamics of the process are used for design purposes. The typical linear-quadratic design involving the solution of the optimal control problem of a linear time-invariant system with respect to a quadratic performance criterion is considered along with gain reduction theorems and the multivariable phase margin theorem. The stumbling block in many adaptive design methodologies is associated with the amount of real time computation which is necessary. Attention is also given to the desperate need to develop good theories for large-scale systems, the beginning of a microprocessor revolution, the translation of the Wiener-Hopf theory into the time domain, and advances made in dynamic team theory, dynamic stochastic games, and finite memory stochastic control.

Athans, M.↗
NASA NTRS1983

H0323 + 022 - A puzzling high-latitude X-ray/optical/radio source

HEAO 1 has located a flaring X-ray source, H0323 + 022, at high galactic latitude. This source is identified with a V = 16.5 UV-excess object. While the counterpart has been observed on two occasions to have zero redshift absorption lines, these features have been absent on at least five other occasions. The high IR flux of the object indicates a multicomponent source. Einstein Observatory observations indicate that the X-ray source has two components, a steady soft component and a variable hard one which exhibits a pronounced 60-sec dip, as well as flaring activity, on time scales as small as six hours. A 5 GHz detection of the source, with a flux density of 41 + or - 1 mJy, has also been made by Feigelson et al (1982).

Doxsey, R.↗
NASA NTRS1986

Observations of the seasonal variability of soil moisture and vegetation cover over Africa using satellite microwave radiometry

Multispectral passive microwave data from the scanning multichannel microwave radiometer (SMMR) on the Nimbus-7 satellite were processed selectively for a 1 yr period over Africa. The data show a wide dynamic range of brightness temperature (180 to 290 K), corresponding to variations in surface features such as moisture, temperature, vegetation, roughness, and large-scale topography. It appears that soil moisture variability is detectable with the SMMR over large regions of Africa. To what extent roughness and vegetation affect this capability is not clear. The lowest SMMR frequency is C-band (6.6 GHz), thus any soil moisture sensitivity at this frequency would be much improved by a sensor at L-band (1 to 2 GHz) less affected by roughness and vegetation.

Njoku, Eni G.↗
NASA NTRS1986

Vertical motions in the quiescent prominences observed in the He I Lambda10830Angstrom line

The observations contain two-dimensional spectral scans of a total of 17 different prominences on the solar disk from the period 3 to 9 May 1981, using the main spectrograph of the solar vacuum telescope at Sacramento Peak. The following conclusions may be drawn from the data: (1) Blue shifts are much more common than red shifts. In many cases more than 90 per cent of the projected prominence area is associated with blue shifts. (2) The darkest prominence regions show the largest blue shift (v less than 3 km s-1). (3) Red shifts are most commonly seen at prominence edges. (4) The general pattern of prominence velocity persists for several hours. On the scale of about 10 arcsec and less, changes are detectable in the course of 2 to 5 minutes. The observed predominance of the blue shifts is largely in agreement with earlier results from H alpha (cf. Martres et al. 1981). It cannot, however, be concluded definitely that the observed shift really represents a net flow of matter. The situation could possibly be analogous to that of the solar transition region where lines such as C IV lambda 1548 angstroms seem to indicate a net inflow, which can hardly be true, at velocities greater than 4 km s(-1) in the quiet Sun (Athay et al. 1983; Gurman and Athay 1983). If the typical structure element of the prominence is sub-resolution, i.e., 2 to 3 arcsec or worse, as in the present case, an apparent net shift could result if the ascending and the decending elements have different temperature and/or pressure. Different lines could then indicate different flow velocities and even opposite directions.

Engvold, Oddbjorn↗
NASA NTRS1987

Floating frame grounding system

The development of a floating frame grounding system (FFGS) for the 40- by 80-foot low speed wind tunnel facility at the NASA Ames Research Center National Full Scale Aerodynamics Complex is addresssed. When electrical faults are detected, the FFGS ensures a ground path for the fault current. In addition, the FFGS alerts the tunnel operator when a mechanical foul occurs.

Forsyth, T. J.↗
NASA NTRS1991

Thermocouple-Signal-Conditioning Circuit

Thermocouple-signal-conditioning circuit acting in conjunction with thermocouple, exhibits electrical behavior of voltage in series with resistance. Combination part of input bridge circuit of controller. Circuit configured for either of two specific applications by selection of alternative resistances and supply voltages. Includes alarm circuit detecting open circuit in thermocouple and provides off-scale output to signal malfunctions.

Simon, Richard A.↗