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At least 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

A monolithic lead sulfide-silicon MOS integrated-circuit structure

A technique is developed for directly integrating infrared photoconductive PbS detector material with MOS transistors. A layer of chromium, instead of aluminum, is deposited followed by a gold deposition in order to ensure device survival during the chemical deposition of the PbS. Among other devices, a structure was fabricated and evaluated in which the PbS was directly coupled to the gate of a PMOS. The external bias, load, and source resistors were connected and the circuit was operated as a source-follower amplifier. Radiometric evaluations were performed on a variety of different MOSFETs of different geometry. In addition, various detector elements were simultaneously fabricated to demonstrate small element capability, and it was shown that elements of 25 x 25 microns could easily be fabricated. Results of room temperature evaluations using a filtered 700 K black body source yielded a detectivity at peak wavelength of 10 to the 11th cm (root Hz)/W at 100 Hz chopping frequency.

Jhabvala, M. D.↗
NASA NTRS1985

Microbial colonization and growth on metal sulfides and other mineral surfaces

To determine whether a bacterial film forms on sulfur minerals in situ, various sulfur containing and other minerals were incubated in Penitencia Creek. The rate of cell growth and attachment within the surface microenvironment of mineral surfaces was also determined. To determine whether surfaces enriched with soluble sulfur substrates (cysteine, glutathione, thioglycolate, sulfite, and thiosulfate) increased the rate of growth or attachment of natural communities, membrane enrichments were incubated. These rates were determined as described by Caldwell et al. (1981, 1983). The growth of Pseudomonas fluorescens, a heterotrophic sulfur oxidizer, was studied in batch cell suspensions and in continuous culture. In batch culture the cells were oxygen limited (growth rate 0.33 per hour under oxygen limitations and 0.52 per hour when vigorously aerated). Growth within the film was glucose limited. Several behavioral phenomena were observed for cells growing within the hydrodynamic boundary layer. Despite a flow of 10 cm per second in the environment, the bacteria were able to move freely in both directions within the hydrodynamic boundary layer.

Caldwell, D.↗
NASA NTRS1985

Sulfide and sulfate saturation in hydrous silicate melts

A series of hydrothermal experiments was performed over a wide range of pressures, temperatures, oxygen fugacities, and melt FeO content, in order to examine the effects of physical changes on sulfur solubility in fractionated hydrous silicate melts. On the basis of the experimental results, it is concluded that upper crustal oxidation-reduction reactions and crystal fractionation processes may exert considerable influence on the amount of sulfur contained in magmas erupted at the surface. The application of the experimental results to investigations of volatile transport and volcanic degassing processes on the earth, Venus, and Mars is discussed

Carroll, M. R.↗
NASA NTRS1985

Thermoelectric properties of lanthanum sulfide

The Seebeck coefficient, electrical resistivity, thermal conductivity, and Hall effect have been studied in gamma-phase La(3-x)S4(LaS/y/) for compositions with x in the range from 0.04 to 0.3 (y in the range from 1.35 to 1.48) in order to ascertain its suitability for high-temperature (300 to 1400 K) thermoelectric energy conversion. In this temperature and composition range the material behaves as an extrinsic semiconductor whose degenerate carrier concentration is controlled by the stoichiometric ratio of La to S. A maximum figure-of-merit (Z) of approximately 0.0005 per K at a composition x = 0.3, y = 1.48 (LaS/1.48/) was obtained.

Wood, C.↗
NASA NTRS1987

Pb, Sr, and Nd isotopes in basalts and sulfides from the Juan de Fuca Ridge

Isotopic Pb, Sr, and Nd data were collected by the Alvin submersible from seven basalt glasses in the southern Juan de Fuca Ridge (JFR), giving similar ratios for Pb-206/Pb-204 of about 18.45, for Pb-207/Pb-204 of about 15.47, for Pb-208/Pb-204 of about 37.81, for Sr-87/Sr-86 of about 0.70249, and for Nd-143/Nd-144 of about 0.51315. Data suggest that the basalts are all cogenetic, and that four of the samples are also comagmatic. It is concluded that isotopic data for the JFR and seamount basalts provide additional support for the mantle blob cluster model (Allegre et al., 1984), suggesting the involvement of multiple components in the genesis of ridge basalts, and including an unusual end-member that has nonradiogenic Sr and variable Pb-206/Pb-204 isotopic compositions.

Hegner, E.↗
NASA NTRS1988

Ejection of sodium from sodium sulfide by the sputtering of the surface of Io

The mechanism by which Na is removed from the surface of Io prior to its injection into the plasma torus is investigated experimentally. Na2S films of thickness 3-8 microns were produced by spray coating an Ni substrate in a dry N2 atmosphere and subjected to sputtering by 34-keV Ar(+), Ne(+), Kr(+), or Xe(+) ions up to total doses of about 5 x 10 to the 18th ions/sq cm. The sputtering yields and mass spectra are found to be consistent with ejection of only small amounts of atomic Na and somewhat larger amounts of Na-containing molecules. It is concluded that the amount of Na ejected by magnetospheric-ion sputtering of Na2S would be insufficient to account for the amounts observed in the Io neutral cloud. A scenario involving sputtering of larger polysulfide molecules is considered.

Chrisey, D. B.↗
NASA NTRS1989

Detection of interstellar hydrogen sulfide in cold, dark clouds

Interstellar H2S has been detected toward the cold, dark clouds L134N and TMC 1. Total column densities at the SO peak of L134N and the NH3 peak of TMC 1 are found to be about 2.6 X 10 to the 13th/sq cm and 7.0 X 10 to the 12th/sq cm, respectively. The results suggest that grain surface reactions may play a major role in the synthesis of H2S in cold, dark clouds.

Minh, Y. C.↗
NASA NTRS1991

Abundances of hydrogen sulfide in star-forming regions

Interstellar H2S and its isotopic variant H2(S-34) have been observed toward several star-forming regions via their 1(10)-1(01) transitions at 2 mm, using the FCRAO telescope. In sources where both isotopic species were observed, column densities of about 10 to the 16th/sq cm were measured. Column density lower limits of about 10 to the 14th/sq cm for H2S were found for other sources, where only the main isotopic line was observed. The fractional abundances of H2S relative to molecular hydrogen appear to be enhanced by at least an order of magnitude relative to quiescent cloud values (about 10 to the -9th) for many of the observed sources.

Minh, Y. C.↗
NASA NTRS1992

Mineralization on the moon? Theoretical considerations of Apollo 16 'rusty rocks', sulfide replacement in 67016, and surface-correlated volatiles on lunar volcanic glass

Theoretical considerations of vapor-rock interactions in the lunar environment are a useful supplement to petrologic studies of mineralization or alteration in rocks from the moon. They also provide insights into the potential for the existence of more extensive mineralization on the moon than is found in the limited sample set. Discussed in this paper are the coexistence and textural association in 66095 of the phases lawrencite, troilite, schreibersite, iron metal, and sphalerite; the replacement of olivine in certain clasts of 67016 by troilite and enstatite; and the existence of Zn + S deposits on the surfaces of volcanic glass beads. Particular attention is given in each case to whether the observed mineralization implies that metals, as well as S, P, or Cl, have been mobilized in the vapor. Vapor species that might mobilize metals in the absence of H2O are considered. Most importantly, the suggestion is made that in the dry lunar environment carbonyl species may be important carriers of S and metals. The implications of this possibility are discussed.

Colson, Russell O.↗
NASA NTRS1992

Use of cobalt sulfide (black dye) anodize for thermal control of the Space Station Freedom airlock

This paper presents six thermal design options of the Space Station Freedom (SSF) airlock and shows the important role that exterior coatings had in minimizing heater power. Options included using anodized coatings separately or in combination, employing fans to circulate interior air, and using a solar shade that eliminates the adverse effect of degrading optical properties. The design that is most efficient, in terms of cost and minimum heater power, and that meets all temperature requirements, has a black anodized exterior finish and uses a maximum of 410 watts of heater power.

Saiz, John↗
NASA NTRS1952

Velocity of action of oxygen, hydrogen sulfide, and halogens on metals

This report discusses a method of determining the rate of surface oxidation of a metal by the change in the color of the surface film produced by reactions with oxygen, chlorine, or iodine. The metals studied included iron, nickel, copper, zinc, cadmium, tin, lead, cobalt, and manganese. Tables are given for surface film thickness versus color for various times.

TIN↗
NASA NTRS1993

Cronstedtite and iron sulfide mineralogy of CM-type carbonaceous chondrites from cryogenic Moessbauer spectra

Determinations of oxidation states and the crystal chemistry of iron-bearing minerals in CM meteorites by Moessbauer spectroscopy are complicated by thermally-induced electron hopping in cronstedtite and by ill-defined contributions from the hydrous iron sulphide phase believed to be tochilinite. Moessbauer spectral measurements at 30 K of several cronstedtite and tochilinite specimens have enabled modal proportions of these minerals, as well as Fe(3+)/Fe(2+) ratios, to be determined quantitatively for a suite of CM-type carbonaceous chondrites that included Murchison, Murray, Cold Bokkeveld, ALH 83100, and LEW 90500.

Fisher, Duncan S.↗
NASA NTRS2007

Mars Sulfate Formation Sourced in Sulfide-Enriched Subsurface Fluids: The Rio Tinto Model

The extensive evidence for sulfate deposits on Mars provided by analyses of MER and Mars Express data shows that the sulfur played an essential role in the geochemical cycles of the planet, including reservoirs in the atmosphere, hydro-sphere and geosphere. Overall the data are consistent with a fluvial/lacustrine-evaporative origin of at least some of the sulfate deposits, with mineral precipitation through oversaturation of salty acidic fluids enriched in sulfates. This scenario requires reservoirs of sulfur and associated cations, as well as an acidic and oxidizing hydrochemistry which could be provided by surface and subsurface catching of meteoric waters resulting in the presence of sulfur-bearing gases and steam photochemistry. In this work we suggest a new scenario for the extensive generation of sulfates in Mars based on the observation of seasonal changes in the redox and pH of subsurface waters enriched in sulfur that supply the acidic Mars process analog of Rio Tinto. This model considers the long-term subsurface storage of sulfur during most of Noachian and its release from the late Noachian to Hesperian time through weathering by meteoric fluids that would acidify and oxidize the sulfur bearing compounds stored in the subsurface.

Fernandez-Remolar, D. C.↗