The structure of c sub 2 b sub 5 h sub 7.
Structure of 2,4-dicarbaheptaborane molecule, having pentagonal bipyramid form
CARBON COMPOUND↗
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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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An x-ray diffraction study of nonplanar carbanion structures.
X-ray diffraction of ammonium tricyanomethide and pyridinium dicyanomethylide shows nonplanar carbanion structure
CRYSTAL STRUCTURE↗
Tensile and structural properties of glassy carbon
High temperature tensile strength of glassy carbons in helium atmosphere - mechanical properties
MECHANICAL PROPERTY↗
Survey of thermodynamic properties of the compounds of the elements CHNOPS Sixth preliminary report, 1 Oct. - 31 Dec. 1965
Heat capacity data on polyhydroxy compounds, water, carbon dioxide, and ammonia and vapor pressure data on methane, ammonia, and amino acids
METHANE↗
Dynamics and Characteristics of the Self-trapping of Intense Light Beams
Dynamics and characteristics of self-trapping of intense light beams
TRAPPING↗
Effect of fluroine content, atmosphere, and burnishing technique on the lubricating properties of graphite fluoride
Eight different graphite fluoride compounds with fluorine to carbon ratios varying from x = 0.25 to 1.1 were evaluated as burnished films in order to determine the effect of fluorine content on the solid lubricant properties of graphite fluoride. For comparison, similar experiments were conducted on graphite burnished films. It was found that even a small amount of fluorine in graphite fluoride (CF0.25)n improved the lubricating properties of graphite. However, such factors as burnishing atmosphere, burnishing technique, test atmosphere, and specimen temperature affected the results as much as varying the fluorine to carbon ratio of the compound. Best life was found for films that were machined burnished in moist air and tested in moist air.
Fusaro, R. L.↗
Graphite fluoride lubrication: The effect of fluorine content, atmosphere, and burnishing technique
Eight different graphite fluoride compounds with fluorine to carbon ratios varying from x = 0.25 to 1.1 were evaluated as burnished films in order to determine the effect of fluorine content on the solid lubricant properties of graphite fluoride. For comparison, similar experiments were conducted on graphite burnished films. It was found that even a small amount of fluorine in graphite fluoride (CF sub 0.25) sub n improved the lubricating properties of graphite. Such factors as burnishing atmosphere, burnishing technique, test atmosphere, and specimen temperature affected the results as much as varying the fluorine to carbon ratio of the compound. Best life was found for films that were machine-burnished in moist air and tested in moist air.
Fusaro, R. L.↗
Graphite fluoride lubrication - The effect of fluorine content, atmosphere, and burnishing technique
Eight different graphite fluoride compounds with fluorine to carbon ratios varying from 0.25 to 1.1 were evaluated as burnished films in order to determine the effect of fluorine content on the solid lubricant properties of graphite fluoride. For comparison, similar experiments were conducted on graphite burnished films. It was found that even a small amount of fluorine in graphite fluoride with fluorine to carbon ratio of 0.25 improved the lubricating properties of graphite. However, such factors as burnishing atmosphere, burnishing technique, test atmosphere, and specimen temperature affected the results as much as varying the fluorine to carbon ratio of the compound. Best life was found for films that were machine-burnished in moist air and tested in moist air.
Fusaro, R. L.↗
A versatile system for biological and soil chemical tests on a planetary landing craft. I - Scientific objectives
We describe an approach for the remote detection and characterization of life in planetary soil samples. A mass spectrometer is used as the central sensor to monitor changes in the gas phase in eleven test cells filled with soil. Many biological assays, ranging from general 'in situ' assays to specific metabolic processes (such as photosynthesis, respiration, denitrification, etc.) can be performed by appropriate additions to the test cell via attached preloaded injector capsules. The system is also compatible with a number of chemical assays such as the analysis of atmospheric composition (both chemical and isotopic), the status of soil water, and the determination of compounds of carbon, nitrogen and sulfur in the soil.
Radmer, R. J.↗
Long term impact of anthropogenic emissions of halogenated hydrocarbons on stratospheric ozone level
Reaction kinetics are studied for stratospheric chlorine atoms, OH initiated degradation of carbon-chlorine compounds, the chemical decomposition of stratospheric HCl and ClONO2. A photochemical study is made of the decomposition of O3 over the wavelength range 2935 to 3165 deg A.
Source record↗
Measurement of total organic concentration in water
Instrument for determining total organic concentration in water uses no corrosive reagents or gases. Instead continuous ultraviolet photolysis process converts organic compounds to carbon dioxide (CO2). CO2 electrode is used to measure CO2 content. Only reagent necessary is oxygen, generated in situ by electrolyzing some water. In addition to application in aerospace industry, system has potential uses in pollution monitoring and in laboratory analyses.
Winkler, E.↗
Vertical transport and photochemistry in the terrestrial mesosphere and lower thermosphere /50-120 km/
A study is conducted of the coupled effects of kinetics, solar cycle flux variations, and vertical transport on the distribution of long-lived hydrogen-carbon-oxygen compounds in the terrestrial mesosphere and lower thermosphere, using a one-dimensional aeronomy model. The calculations account for the important chemical reactions and use rocket measurements of the solar flux at solar minimum and maximum. Photodissociation rates appropriate for the mesosphere are determined with a spherical shell atmosphere formalism. Detailed corrections for the O2 Schumann-Runge bands and the temperature dependence of the CO2 cross sections are used. An eddy diffusion profile is derived which is in agreement with the Aladdin 74 mass spectral measurements of atomic O, O2, CO2, and Ar in the lower thermosphere and observations of the O3 minimum at about 80 km.
Allen, M.↗
Atmospheric chemistry of ethane and ethylene
It is shown by a study of ethane and ethylene photochemistry that the loss of ethane is controlled by OH in the troposphere and Cl in the stratosphere. Ethane observations indicating free Cl concentrations below 30 km that are only 10% of the value predicted by the present model calculations cannot be explained by heterogeneous aerosol concentration processes, and contradict current stratospheric photochemistry. The chemical destruction of ethane and ethylene leads to the generation of such compounds as carbon monoxide and formaldehyde, and it is found that the tropospheric concentrations of the latter are enhanced by nearly a factor of three for an ethylene mixing ratio of 2 ppb.
Aikin, A. C.↗
SIRTF: Probing the dark corners of the galaxy
The Space Infrared Telescope Facility (SIRTF) is planned for launch by NASA in the mid-1990's. It will be a cryogenically-cooled observatory for infrared astronomy and will carry several focal plane instruments which will provide a wide range of imaging, photometric, and spectroscopic capabilities. SIRTF will build on the scientific and technical progress of the successful IRAS mission and take the next step in the exploration of the Universe at infrared wavelengths. Most of the observing time during the five-to-ten year SIRTF mission will be available to General Investigators, so there will be ample opportunities for the pursuit of problems originating from within the Space Life Sciences community. Here, a review is given of the capabilities of SIRTF for this style of investigation, using the study of carbon in the Galaxy as a specific example. The very high sensitivity of SIRTF's spectrometers to diffuse emission will allow studies of carbon in both the gaseous and solid phase in the interstellar medium and should be of particular importance for the identification of the carbon-bearing macromolecules believed to be responsible for the emission features identified in the near infrared. SIRTF will also carry out studies of a wide variety of evolved stars which are returning gas and solid phase carbon to the interstellar medium and contribute to our understanding of the carbon budget in the Galaxy. These studies in the area of galactic astronomy will be complemented by detailed investigations of carbon-bearing compounds in solar system objects, including the surfaces of distant asteroids and cometary nuclei which are too faint to be studied in any other way.
Werner, Michael W.↗
A photoautotrophic source for lycopane in marine water columns
Suspended particulate matter and recent sediments from diverse oceanic sites have been investigated for their contents of lycopane. Lycopane was present in all samples, including both oxic and anoxic water column and sediments. The highest concentrations in the water column were found in surface waters of the central Pacific gyre (1.5 ng/L) and in the anoxic waters of the Cariaco Trench (1.1 ng/L) and the Black Sea (0.3 ng/L). Vertical concentration profiles suggest that lycopane is probably algal in origin. Moreover, biogeochemical conditions in anoxic zones apparently result in a secondary production of lycopane from an as yet unidentified precursor. Compound-specific carbon isotopic analyses have been carried out on lycopane from water column and sediment samples. Isotopic compositions of lycopane range between -23.6 and -32.9 percent and are consistent with a photoautotrophic origin. We postulate that some lycopane is produced in surface waters of the ocean, while additional lycopane is produced in anoxic zones by anaerobic microbial action on an algal precursor.
Wakeham, Stuart G.↗
Nondestructive Evaluation of Ceramic Matrix Composite Combustor Components
Combustor liners fabricated from a SiC/SiC composite were nondestructively interrogated before and after combustion rig testing by X-ray, ultrasonic and thermographic techniques. In addition, mechanical test results were obtained from witness coupons, representing the as-manufactured liners, and from coupons machined from the components after combustion exposure. Thermography indications were found to correlate with reduced material properties obtained after rig testing. The thermography indications in the SiC/SiC liners were delaminations and damaged fiber tows, as determined through microstructural examinations. [copyright] 2003 American Institute of Physics
X-ray analysis↗
Laser pyrolysis fabrication of ferromagnetic gamma'-Fe4N and FeC nanoparticles
Using the laser pyrolysis method, single phase gamma'-Fe4N nanoparticles were prepared by a two step method involving preparation of nanoscale iron oxide and a subsequent gas-solid nitridation reaction. Single phase Fe3C and Fe7C3 could be prepared by laser pyrolysis from Fe(CO)5 and 3C2H4 directly. Characterization techniques such as XRD, TEM and vibrating sample magnetometer were used to measure phase structure, particle size and magnetic properties of these nanoscale nitride and carbide particles. c2000 American Journal of Physics.
NASA Discipline Life Sciences Technologies↗
Characterization of silicon-carbon clusters by infrared laser spectroscopy. The nu 1 band of SiC4
The nu 1 fundamental vibration of linear SiC4 has been observed by infrared diode laser spectroscopy of a supersonic cluster beam. Twenty-four rovibrational transitions were measured in the spectral region of 2094.6 to 2097.1 cm-1, the rotational temperature was 10 K. A combined least-squares fit of these transitions with previously reported microwave data yielded the following molecular constants: nu 1 = 2095.45806(37) cm-1, B" = 0.051161131(52) cm-1, and B' = 0.0509157(96) cm-1. These results are compared to vibrational spectroscopy measurements of SiC4 trapped in a solid Ar matrix and to ab initio calculations.
NASA Discipline Exobiology↗