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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Manganese, Metallogenium, and Martian Microfossils

Manganese could easily be considered an abundant element in the Martian regolith, assuming that the composition of martian meteorites reflects the composition of the planet. Mineralogical analyses of 5 SNC meteorites have revealed an average manganese oxide concentration of 0.48%, relative to the 0.1% concentration of manganese found in the Earth's crust. On the Earth, the accumulation of manganese oxides in oceans, soils, rocks, sedimentary ores, fresh water systems, and hydrothermal vents can be largely attributed to microbial activity. Manganese is also a required trace nutrient for most life forms and participates in many critical enzymatic reactions such as photosynthesis. The wide-spread process of bacterial manganese cycling on Earth suggests that manganese is an important element to both geology and biology. Furthermore, there is evidence that bacteria can be fossilized within manganese ores, implying that manganese beds may be good repositories for preserved biomarkers. A particular genus of bacteria, known historically as Metallogenium, can form star-shaped manganese oxide minerals (called metallogenium) through the action of manganese oxide precipitation along its surface. Fossilized structures that resemble metallogenium have been found in Precambrian sedimentary formations and in Cretaceous-Paleogene cherts. The Cretaceous-Paleogene formations are highly enriched in manganese and have concentrations of trace elements (Fe, Zn, Cu, and Co) similar to modern-day manganese oxide deposits in marine environments. The appearance of metallogenium-like fossils associated with manganese deposits suggests that bacteria may be preserved within the minerals that they form. Additional information is contained in the original extended abstract.

Stein, L. Y.↗
NASA NTRS1984

Observations of Gulf Stream-induced and wind-driven upwelling in the Georgia Bight using ocean color and infrared imagery

Ocean color and infrared imagery from U2 aircraft and satellite sensors are used to study upwelling interaction between Gulf Stream and continental shelf waters in the Georgia Bight. The photographic data are combined with in situ measurements of currents, chlorophyll, temperature, salinity, coastal winds, and sea-level in observations of five different upwelling events including a near-short wind-driven upwelling caused by topographic effects, three filament-induced upwellings in the Gulf Stream, and a possible meander-induced upwelling event in the Gulf Stream. Chlorophyll distributions are used to trace the circulation and propagation of filaments along the advective routes by which the water moves offshore. Photographic and mooring array measurements of temperature time series are found to provide nearly identical results for the phase speeds of each event. Field measurements of surface pigments, and Nimbus/7 coastal zone color scanner (CZCS) estimates are found to agree well over the range of concentrations 0.1 to 0.7 mg/m to the third. Examples of U2/Ocean Color Scanner and Nimbus 7 CZCS photographs are provided.

Mcclain, C. R.↗
NASA NTRS1990

The biogeochemical sulfur cycle in the marine boundary layer over the Northeast Pacific Ocean

The major components of the marine boundary layer biogeochemical sulfur cycle were measured simultaneously onshore and off the coast of Washington State, U.S.A. during May 1987. Seawater dimethysulfide (DMS) concentrations on the continental shelf were strongly influenced by coastal upwelling. Concentration further offshore were typical of summer values (2.2 nmol/l) at this latitude. Although seawater DMS concentrations were high on the biologically productive continental shelf (2-12 nmol/l), this region had no measurable effect on atmospheric DMS concentrations. Atmospheric DMS concentrations (0.1-12 nmol/l), however, were extremely dependent upon wind speed and boundary layer height. Although there appeared to be an appreciable input of nonsea-salt sulfate to the marine boundary layer from the free troposphere, the local flux of DMS from the ocean to the atmosphere was sufficient to balance the remainder of the sulfur budget.

Bates, T. S.↗
NASA NTRS2002

Activation of c-Jun N-terminal kinase and apoptosis in endothelial cells mediated by endogenous generation of hydrogen peroxide

Reactive oxygen species have been implicated in the activation of signal transduction pathways. However, extracellular addition of oxidants such as hydrogen peroxide (H2O2) often requires concentrations that cannot be readily achieved under physiological conditions to activate biological responses such as apoptosis. Explanations for this discrepancy have included increased metabolism of H2O2 in the extracellular environment and compartmentalization within the cell. We have addressed this issue experimentally by examining the induction of apoptosis of endothelial cells induced by exogenous addition of H2O2 and by a redox cycling agent, 2,3-dimethoxy-1,4-naphthoquinone, that generates H2O2 in cells. Here we show that low nanomolar steady-state concentrations (0.1-0.5 nmol x min(-1) x 10(6) cells) of H2O2 generated intracellularly activate c-Jun N terminal kinase and initiate apoptosis in endothelial cells. A comparison with bolus hydrogen peroxide suggests that the low rate of intracellular formation of this reactive oxygen species results in a similar profile of activation for both c-Jun N terminal kinase and the initiation of apoptosis. However, a detailed analysis reveals important differences in both the duration and profile for activation of these signaling pathways.

Non-NASA Center↗
NASA NTRS2000

Fibroblast growth factor-2 promotes keratan sulfate proteoglycan expression by keratocytes in vitro

Keratocytes of the corneal stroma produce a specialized extracellular matrix responsible for corneal transparency. Corneal keratan sulfate proteoglycans (KSPG) are unique products of keratocytes that are down-regulated in corneal wounds and in vitro. This study used cultures of primary bovine keratocytes to define factors affecting KSPG expression in vitro. KSPG metabolically labeled with [(35)S]sulfate decreased during the initial 2-4 days of culture in quiescent cultures with low serum concentrations (0.1%). Addition of fetal bovine serum, fibroblast growth factor-2 (FGF-2), transforming growth factor beta, or platelet derived growth factor all stimulated cell division, but only FGF-2 stimulated KSPG secretion. Combined with serum, FGF-2 also prevented serum-induced KSPG down-regulation. KSPG secretion was lost during serial subculture with or without FGF-2. Expression of KSPG core proteins (lumican, mimecan, and keratocan) was stimulated by FGF-2, and steady state mRNA pools for these proteins, particularly keratocan, were significantly increased by FGF-2 treatment. KSPG expression therefore is supported by exogenous FGF-2 and eliminated by subculture of the cells in presence of serum. FGF-2 stimulates KSPG core protein expression primarily through an increase in mRNA pools.

NASA Discipline Developmental Biology↗
NASA NTRS1996

Protein phosphatase 2A in stretch-induced endothelial cell proliferation

We previously proposed that activation of protein kinase C is a key mechanism for control of cell growth enhanced by cyclic strain [Rosales and Sumpio (1992): Surgery 112:459-466]. Here we examined protein phosphatase 1 and 2A activity in bovine aortic endothelial cells exposed to cyclic stain. Protein phosphatase 2A activity in the cytosol was decreased by 36.1% in response to cyclic strain for 60 min, whereas the activity in the membrane did not change. Treatment with low concentration (0.1 nM) of okadaic acid enhanced proliferation of both static and stretched endothelial cells in 10% fetal bovine serum. These data suggest that protein phosphatase 2A acts as a growth suppressor and cyclic strain may enhance cellular proliferation by inhibiting protein phosphatase 2A as well as stimulating protein kinase C.

NASA Discipline Cell Biology↗
NASA NTRS1998

A search for endogenous amino acids in martian meteorite ALH84001

Trace amounts of glycine, serine, and alanine were detected in the carbonate component of the martian meteorite ALH84001 by high-performance liquid chromatography. The detected amino acids were not uniformly distributed in the carbonate component and ranged in concentration from 0.1 to 7 parts per million. Although the detected alanine consists primarily of the L enantiomer, low concentrations (<0.1 parts per million) of endogenous D-alanine may be present in the ALH84001 carbonates. The amino acids present in this sample of ALH84001 appear to be terrestrial in origin and similar to those in Allan Hills ice, although the possibility cannot be ruled out that minute amounts of some amino acids such as D-alanine are preserved in the meteorite.

NASA Discipline Exobiology↗
NASA NTRS1986

Calcium dependence of rapid auxin action in maize roots

We investigated the interaction of Ca2+ and auxin on root elongation in seedlings of Zea mays L. The seedlings were raised either in the presence of Ca2+ (high calcium; HC = imbibed and raised in 10 millimolar CaCl2), in the absence of additional Ca2+ (intermediate calcium; IC = imbibed and raised in distilled H2O, calcium supply from seed only), or without additional Ca2+ and subsequently depleting them of Ca2+ (low calcium; LC = imbibed and raised in distilled H2O and subsequently treated with 1 millimolar ethyleneglycol-bis-[beta-aminoethylether]-N,N,N',N'-tetraacetic acid [EGTA]). Exposure of roots of either HC or IC seedlings to auxin concentrations from 0.1 to 10 micromolar resulted in strong inhibition of elongation. In roots of LC seedlings, on the other hand, auxin concentrations as high as 10 micromolar caused only slight inhibition of elongation. Adding 0.5 millimolar Ca2+ to LC roots in the presence of IAA allowed normal expression of the inhibitory action of the hormone. Inhibition of elongation in IC roots by indoleacetic acid was reversible upon treatment of the roots with 1 millimolar EGTA. The inhibitory action of auxin could then be re-established by supplying 0.5 millimolar Ca2+. The data indicate that Ca2+ may be necessary to the growth-regulating action of auxin. The significance of this finding is discussed with respect to the potential role of Ca2+ as a second messenger of auxin action and the relevance of this model to recent evidence for gravi-induced redistribution of Ca2+ and its role in establishing gravitropic curvature.

Non-NASA Center↗
NASA NTRS1994

Au/Zn Contacts to rho-InP: Electrical and Metallurgical Characteristics and the Relationship Between Them

The metallurgical and electrical behavior of Au/Zn contacting metallization on p-type InP was investigated as a function of the Zn content in the metallization. It was found that ohmic behavior can be achieved with Zn concentrations as small as 0.05 atomic percent Zn. For Zn concentrations between 0.1 and 36 at. percent, the contact resistivity rho(sub c) was found to be independent of the Zn content. For low Zn concentrations the realization of ohmic behavior was found to require the growth of the compound Au2P3 at the metal-InP interface. The magnitude of rho(sub c) is shown to be very sensitive to the growth rate of the interfacial Au2P3 layer. The possibility of exploiting this sensitivity to provide low resistance contacts while avoiding the semiconductor structural damage that is normally attendant to contact formation is discussed.

Weizer, Victor G.↗
NASA NTRS2003

Properties of the Hermean Regolith: New Optical Reflectance Spectra, Comparison with Lunar Anorthosites and Mineralogical Modelling - 5

We present new optical (0.4-0.65 micron) spectra of Mercury and lunar pure anorthosite locations, obtained quasi-simultaneously with the Nordic Optical Telescope (NOT) in 2002. A comparative study is performed with the model of Lucey et al. between iron-poor, mature, pure anorthosite (less than 90% plagioclase feldspar) Clementine spectra from the lunar farside and a combined 0.4-1.0 micron mercurian spectrum, obtained with the NOT, calculated for standard photometric geometry. Mercury is located at more extreme locations in the Lucey ratio-reflectance diagrams than any known lunar soil, specifically with respect to the extremely iron-poor mature anorthosites. Though quantitative prediction of FeO and TiO2 abundances cannot be made without a more generally applicable model, we find qualitatively that the abundances of both these oxides must be near zero for Mercury. We utilize the theory of Hapke, with realistic photometric parameters, to model laboratory spectra of matured mineral powders and lunar soils, and remotely sensed spectra of lunar anorthosites and Mercury. An important difference between fabricated and natural powders is the high value for the internal scattering parameter necessary to interpret the spectra for the former, and the requirement of rough and non-isotropically scattering surfaces in the modelling of the latter. The mature lunar anorthosite spectra were well modelled with binary mixtures of calcic feldspars and olivines, grain sizes of 25-30 micron and a concentration of submicroscopic metallic iron (SMFe) of 0.12-0.15% in grain coatings. The mercurian spectrum is not possible to interpret from terrestrial mineral powder spectra without introducing an average particle scattering function for the bulk soil that increases in backscattering efficiency with wavelength. The observed spectrum is somewhat better predicted with binary mixture models of feldspars and pyroxenes, that single-component regoliths consisting of either albite or diopside. Correct spectral reflectance values were predicted with a concentration of 0.1 wt% SMFe in coatings of 15-30 micron sized grains. Since reasonable cosmogonical formation scenarios for Mercury, or meteoritic infall, predict iron concentrations at least this high, we draw the conclusion that the average grain size of Mercury is about a factor of two smaller than for average returned lunar soil samples. The 0.6-2.5 micron spectrum of McCord and Clark is used to further limit the possible range of mineralogical composition of Mercury. It is found that an intimately mixed and matured 3 : 1 labradorite-to-enstatite regolith composition best matches both the optical and near-infrared spectra, yielding an abundance of approx. 1.2 wt% FeO and -approx. 0 wt% TiO2.

Warell, J.↗
NASA NTRS1991

Recovery of precious metals from space

The overall objective is to develop efficient and economical separation and recovery methods for the platinum group and other precious metals. The separation of Pd(II) from Pt(II), Ir(III), and Rh(III) with trioctylphosphine oxide (TOPO) in heptane using centrifugal partition chromatography (CPC) was investigated. Activities to achieve this objective focussed on selection and evaluation of extraction systems for the PGM and modification of selected systems for multistage operation with a view to scaling up to desired macro levels. On the basis of preliminary evaluation of a series of simple metal complexing agents and chelating agents, the TOPO in heptane was selected as a likely system for isolating of Pd(II) and Pt(II) from the other PGM. A multistage apparatus capable of configuration as a simple rugged device, a centrifugal partition chromatograph (CPC), was shown to be effective. The extraction of Pd(II) was studied by CPC and batch solvent extraction. The distribution ratios for Pd(II) determined by both methods agree well. In low HCl concentrations (less than 0.1 M), the extracted species was PdCl2.(TOPO)2, irrespective of the chloride concentration, while at acid concentrations above 0.1 M, the Pd was extracted as the ion pair, 2(TOPO.H+).(PdCl4)2-. Base line separation of Pd(II) and Pt(II) in CPC was obtained under a variety of chloride and HCl concentration. It was demonstrated that the efficiency of CPC for metal separation was limited by chemical kinetic factors rather than instrumental factors, strongly suggesting that dramatic improvements can be achieved by studying reaction kinetics of formation and dissociation of the extractable metal complex.

Freiser, Henry↗
NASA NTRSDate not supplied

The UV Aerosol Extinction Coefficients Retrieval Using the Ground-Based Ozone Lidar

NASA Langley Mobile Ozone Lidar (LMOL) has capability to measure the O3 concentration from 0.1 to 8 km. A new method is proposed to retrieve the aerosol backscatter and extinction coefficients from the LMOL attenuated backscatter signals. The LMOL attenuated backscatter data are corrected by the O3 concentration determined by LMOL system. The aerosol extinction coefficients are retrieved by using Fernald-type method. The retrieved aerosol extinction coefficient profiles are compared with the coincident aerosol extinction coefficient profiles provided by overflights of the airborne High Altitude Lidar Observatory (HALO) system during the 2018 LISTOS campaign. Results show the new method has the capability to retrieve aerosol extinction coefficients from 0.1-8 km at night and 0.1-4 km during the day for 5 minute temporal averaging. The profile time series of the retrieved aerosol extinction coefficient are also compared with co-located ceilometer data, showing general agreement with aerosol features and dynamics. The impact of lidar extinction to backscatter ratios on the retrievals is also presented.This new method extends LMOL’s ability to quantitatively determine the vertical distribution of aerosol optical properties. This is expected to contribute to further understanding of the relationship between the ozone and aerosol in the wildfire emissions transport and impact on local air quality during the LISTOS campaign.

Liqiao Lei↗
NASA NTRS1982

Effect of some nitrogen compounds thermal stability of jet A

The effect of known concentrations of some nitrogen containing compounds on the thermal stability of a conventional fuel, namely, Jet A was investigated. The concentration range from 0.01 to 0.1 wt% nitrogen was examined. Solutions were made containing, individually, pyrrole, indole, quinoline, pyridine, and 4 ethylpyridine at 0.01, 0.03, 0.06, and 0.1 wt% nitrogen concentrations in Jet A. The measurements were all made by using a standard ASTM test for evaluating fuel thermal oxidation behavior, namely, ASTM D3241, 'thermal oxidation stability of turbine fuels (JFTOT procedure).' Measurements were made at two temperature settings, and 'breakpoint temperatures' were determined. The results show that the pyrrole and indole solutions have breakpoint temperatures substantially lower than those of the Jet A used.

Antoine, A. C.↗
NASA NTRS1995

On Lateral Viscosity Contrast in the Mantle and the Rheology of Low-Frequency Geodynamics

Mantle-wide heterogeneity is largely controlled by deeply penetrating thermal convective currents. These thermal currents are likely to produce significant lateral variation in rheology, and this can profoundly influence overall material behaviour. How thermally related lateral viscosity variations impact models of glacio-isostatic and tidal deformation is largely unknown. An important step towards model improvement is to quantify, or bound, the actual viscosity variations that characterize the mantle. Simple scaling of viscosity to shear-wave velocity fluctuations yields map-views of long- wavelength viscosity variation. These give a general quantitative description and aid in estimating the depth dependence of rheological heterogeneity throughout the mantle. The upper mantle is probably characterized by two to four orders of magnitude variation (peak-to-peak). Discrepant time-scales for rebounding Holocene shorelines of Hudson Bay and southern Iceland are consistent with this characterization. Results are given in terms of a local average viscosity ratio, (Delta)eta(bar)(sub i), of volumetric concentration, phi(sub i). For the upper mantle deeper than 340 km the following reasonable limits are estimated for (delta)eta(bar) approx. equal 10(exp -2): 0.01 less than or equal to phi less than or equal to 0.15. A spectrum of ratios (Delta)eta(bar)(sub i) less than 0.1 at concentration level eta(sub i) approx. equal 10(exp -6) - 10(exp -1) in the lower mantle implies a spectrum of shorter time-scale deformational response modes for second-degree spherical harmonic deformations of the Earth. Although highly uncertain, this spectrum of spatial variation allows a purely Maxwellian viscoelastic rheology simultaneously to explain all solid tidal dispersion phenomena and long-term rebound-related mantle viscosity. Composite theory of multiphase viscoelastic media is used to demonstrate this effect.

Ivins, Erik R.↗
NASA NTRS2002

Enzyme-based CO2 capture for advanced life support

Elevated CO2 levels in air can lead to impaired functioning and even death to humans. Control of CO2 is critical in confined spaces that have little physical or biological buffering capacity (e.g., spacecraft, submarines, or aircraft). A novel enzyme-based contained liquid membrane bioreactor was designed for CO2 capture and certain application cases are reported in this article. The results show that the liquid layer accounts for the major transport resistance. With addition of carbonic anhydrase, the transport resistance decreased by 71%. Volatile organic compounds of the type and concentration expected to be present in either the crew cabin or a plant growth chamber did not influence carbonic anhydrase activity or reactor operation during 1-day operation. Alternative sweep method studies, examined as a means of eliminating consumables, showed that the feed gas could be used successfully in a bypass mode when combined with medium vacuum pressure (-85 kPa) to achieve CO2 separation comparable to that with an inert sweep gas. The reactor exhibited a selectivity for CO2 versus N2 of 1400:1 and CO2 versus O2 is 866:1. The CO2 permeance was 1.44 x 10(-7) mol m-2 Pa-1 s-1 (4.3 x 10(-4) cm3 cm-2 s-1 cmHg-1) at a feed concentration of 0.1% CO2. These data show that the enzyme-based contained liquid membrane is a promising candidate technology that may be suitable for NASA applications to control CO2 in the crew or plant chambers.

NASA Discipline Life Support Systems↗
NASA NTRS1973

Using computers to analyze continuous data.

Dynamic field measurements often involve large quantities of continuous data, which must be analyzed and interpreted to obtain meaningful information. The processing can often be accomplished by tape-recording the data in analog form, performing off-line digitalization, and using the result as an input to statistical programs on a digital computer. A time series analysis was used to obtain power spectral density (PSD) curves to identify dominant frequencies. Representative PSD plots were obtained for STOL aircraft during cruise. Vibrational energy was clearly concentrated below 0.1 Hz, and was much higher in the vertical than in the lateral direction.

Catherines, J. J.↗
NASA NTRS1974

Estimate of contribution of jet aircraft operations to trace element concentration at or near airports

Samples of ASTM type A jet fuel were analyzed for trace-element content by instrumental neutron activation techniques. Forty-nine elements were sought. Only ten, aluminum, gold, indium, lanthanum, titanium, vandium, barium, dysprosium, tellurium, and uranium, were observed at levels above the detection limits encountered; of these only aluminum, titanium, and barium were present at concentrations greater than 0.1 ppm. Estimates of exhaust gas concentrations are made, and the ambient contribution at or near airports is calculated by using the Los Angeles International Airport dispersion model. It is shown that the ambient contribution is about an order of magnitude below typical urban levels for virtually all elements sought.

Fordyce, J. S.↗
NASA NTRS1975

The role of large particles in the formation of the radio echo

The contribution to the total reflectivity of separate parts of a particle spectrum described by a gamma distribution is estimated. It is shown that the largest individual particles, whose percent concentration is 0.1 - 1, originate approximately 60 - 70% of the total reflectivity of the spectrum. Explanations are given of a number of effects which confirm the dominant role of large particles in the formation of the echo.

Salman, Y. M.↗