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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Electrophoretic separation of proteins in space

Commercially available and synthetic wide range and short range ampholytes used in the isoelectric focusing of proteins was analyzed by ion exchange chromatography. A pH gradient over the pH range 3.8 to 11.0 was used to elute the ampholytes from a column of a sulfonated polystyrene resin. The wide range ampholytes were resolved into some 60 to 70 ninhydrin positive components. The recovery obtained with the method was quantitative. Acid short range ampholytes have approximately 35 components which elute readily from the ion exchange resin. Basic short range ampholytes gave about 50 components, most of which eluted at alkaline pH.

Brown, R. K.↗
NASA NTRS1976

Space processing of chalcogenide glass

The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses was investigated. The following conclusions were reached: (1) Laboratory experiments have established the techniques, processes and equipment necessary for the production of high purity chalcogenide glasses. (2) Processing techniques have been successfully adopted for Ge28Sb12Se60 glass in a 1-g environment. (3) The Ge28Sb12Se60 glasses that have been processed have optical transmission around 63% (5 mm thick). (4) Laboratory experiments have established that the use of precursor materials in powdered form increases the oxygen contamination of the processed glass. This indicates that high purity precursor materials in bar or pellet form should be used. (5) Modifications were made on the MSFC acoustic levitator in an attempt to improve levitation stability during long-time experiments. Room temperature experiments on As2S3 glasses and high temperature experiments on polystyrene were conducted.

Ali, M. A.↗
NASA NTRS1976

The effect of changes in the USF/NASA toxicity screening test method on data from some cellular polymers

Rankings of relative toxicity can be markedly affected by changes in test variables. Revision of the USF/NASA toxicity screening test procedure to eliminate the connecting tube and supporting floor and incorporate a 1.0 g sample weight, 200 C starting temperature, and 800 C upper limit temperature for pyrolysis, reversed the rankings of flexible polyurethane and polychloroprene foams, not only in relation to each other, but also in relation to cotton and red oak. Much of the change is attributed to reduction of the distance between the sample and the test animals, and reduction of the sample weight charged. Elimination of the connecting tube increased the relative toxicity of the polyurethane foams. The materials tested were flexible polyurethane foam, without and with fire retardant; rigid polyurethane foam with fire retardant; flexible polychloroprene foam; cotton, Douglas fir, red oak, hemlock, hardboard, particle board, polystyrene, and polymethyl methacrylate.

Hilado, C. J.↗
NASA NTRS1976

Laser velocimetry applied to transonic and supersonic aerodynamics

As a further demonstration of the capabilities of laser velocity in compressible aerodynamics, measurements obtained in a Mach 2.9 separated turbulent boundary layer and in the transonic flow past a two-dimensional airfoil section are presented and compared to data realized by conventional techniques. In the separated-flow study, the comparisons were made against pitot-static pressure data. Agreement in mean velocities was realized where the pressure measurements could be considered reliable; however, in regions of instantaneous reverse velocities, the laser results were found to be consistent with the physics of the flow whereas the pressure data were not. The laser data obtained in regions of extremely high turbulence suggest that velocity biasing does not occur if the particle occurrence rate is low relative to the turbulent fluctuation rate. Streamwise turbulence intensities are also presented. In the transonic airfoil study, velocity measurements obtained immediately outside the upper surface boundary layer of a 6-inch chord MACA 64A010 airfoil are compared to edge velocities inferred from surface pressure measurements. For free-stream Mach numbers of 0.6 and 0.8, the agreement in results was very good. Dual scatter optical arrangements in conjunction with a single particle, counter-type signal processor were employed in these investigations. Half-micron-diameter polystyrene spheres and naturally occurring condensed oil vapor acted as light scatterers in the two respective flows. Bragg-cell frequency shifting was utilized in the separated flow study.

Johnson, D. A.↗
NASA NTRS1977

Some possible reference materials for fire toxicity tests

Suitable reference materials need to be selected in order to standardize any test method. The evaluation of cotton, polyethylene, polyether sulfone, polycarbonate, polystyrene, and polyurethane flexible and rigid foams as possible reference materials for the University of San Francisco/NASA toxicity screening test method is discussed.

Hilado, C. J.↗
NASA NTRS1977

Studies with the Arapahoe smoke chamber

Samples of polymethyl methacrylate, polyvinyl chloride, polyester, and polystyrene were evaluated using the Arapahoe smoke chamber. These same materials had been previously evaluated using the National Bureau of Standards (NBS) smoke chamber. The percent smoke based on initial weight as determined using the Arapahoe smoke chamber appeared to correlate with the maximum specific optical density under flaming conditions as determined using the NBS smoke chamber. In addition, the percent smoke based on weight loss as determined using the Arapahoe smoke chamber appeared to correlate with the maximum specific optical density under nonflaming conditions as determined using the NBS smoke chamber. The Arapahoe smoke chamber also offers the advantage of high sample throughput and the possibility of related studies of smoke particulates.

Hilado, C. J.↗
NASA NTRS1977

A simple laboratory method for determining flash fire propensity of materials

A simple laboratory method for determining flash fire propensity of materials is described. The apparatus consists of a tube furnace and a combustion tube. The ignition source can be a wooded match but the hot pyrolysis tube itself may be the most suitable ignition source. Test results are presented for various materials including polyethylene, polystyrene, polycarbonate, and polyurethane and polychloroprene flexible foams.

Hilado, C. J.↗
NASA NTRS1977

Toxicity of pyrolysis gases from synthetic polymers

The screening test method was used to investigate toxicity in polyethylene, polystyrene, polymethyl methacrylate, polyaryl sulfone, polyether sulfone, polyphenyl sulfone, and polyphenylene sulfide. Changing from a rising temperature program to a fixed temperature program resulted on shorter times to animal responses. This effect was attributed in part to more rapid generation of toxicants. The toxicants from the sulfur containing polymers appeared to act more rapidly than the toxicants from the other polymers. It was not known whether this effect was due primarily to difference in concentration or in the nature of the toxicants. The carbon monoxide concentration found did not account for the results observed with the sulfur containing polymers. Polyphenyl sulfone appeared to exhibit the least toxicity among the sulfur containing polymers evaluated under these test conditions.

Hilado, C. J.↗
NASA NTRS1978

Calibration of longwavelength exotech model 20-C spectroradiometer

A brief description of the Exotech model 20-C field spectroradiometer which measures the spectral radiance of a target in the wavelength ranges 0.37 to 2.5 microns (short wavelength unit), 2.8 to 5.6 microns and 7.0 to 14 microns (long wavelength unit) is given. Wavelength calibration of long wavelength unit was done by knowing the strong, sharp and accurately known absorption bands of polystyrene, atmospheric carbon dioxide and methyl cyclohexane (liquid) in the infrared wavelength region. The spectral radiance calibration was done by recording spectral scans of the hot and the cold blackbodies and assuming that spectral radiance varies linearly with the signal.

Kumar, R.↗
NASA NTRS1977

Effect of test conditions on relative toxicity rankings of fifteen materials

Fifteen materials were evaluated for relative toxicity of pyrolysis effluents, using different test conditions in the USF methodology. Wool fabrics were consistently among the most toxic materials, and polystyrene and polychloroprene flexible foam were consistently among the least toxic materials.

Hilado, C. J.↗
NASA NTRS1977

Effect of heating rate on toxicity of pyrolysis gases from some synthetic polymers

The effect of heating rate on the toxicity of the pyrolysis gases from some synthetic polymers was investigate, using a screening test method. The synthetic polymers were polyethylene, polystyrene, polymethyl methacrylate, polycarbonate, ABS, polyaryl sulfone, polyether sulfone, and polyphenylene sulfide. The toxicants from the sulfur-containing polymers appeared to act more rapidly than the toxicants from the other polymers. It is not known whether this effect is due primarily to differences in concentration or in the nature of the toxicants. The carbon monoxide concentrations found do not account for the observed results.

Hilado, C. J.↗
NASA NTRS1979

Improved flight-simulator viewing lens

Triplet lens system uses two acrylic plastic double convex lenses and one polystyrene plastic single convex lens to reduce chromatic distortion and lateral aberation, especially at large field angles within in-line systems of flight simulators.

Kahlbaum, W. M.↗
NASA NTRS1978

Water system virus detection

The performance of a waste water reclamation system is monitored by introducing a non-pathogenic marker virus, bacteriophage F2, into the waste-water prior to treatment and, thereafter, testing the reclaimed water for the presence of the marker virus. A test sample is first concentrated by absorbing any marker virus onto a cellulose acetate filter in the presence of a trivalent cation at low pH and then flushing the filter with a limited quantity of a glycine buffer solution to desorb any marker virus present on the filter. Photo-optical detection of indirect passive immune agglutination by polystyrene beads indicates the performance of the water reclamation system in removing the marker virus. A closed system provides for concentrating any marker virus, initiating and monitoring the passive immune agglutination reaction, and then flushing the system to prepare for another sample.

Fraser, A. S.↗
NASA NTRS1979

Development of stable low-electroosmotic mobility coatings

Long-time rinsings of the Z6040-methlycellulose coating used successfully on the ASTP MA=011 experiment indicate the permanency of this coating is inadequate for continuous flowing systems. Two approaches are described for developing coatings which are stable under continuous fluid movement and which exhibit finite and predictable electroosmotic mobility values while being effective on different types of surfaces, such as glass, plastics, and ceramic alumina, such as is currently used as the electrophoresis channel in the GE-SPAR-CPE apparatus. The surface charge modification of polystyrene latex, especially by protein absorption, to be used as model materials for ground-based electrophoresis experiments, and the preliminary work directed towards the seeded polymerization of large-particle-size monodisperse latexes in a microgravity environment are discussed.

Vanderhoff, J. W.↗
NASA NTRS1979

Preparative cell electrophoresis at 1 and 0 gravity

It is attempted to show that the use of heavy water (D2O) as starting cushion for the cells combines the advantages of the required density difference, with no lasting biochemical or physiochemical influence on the cells. Phosphate buffers of low ionic strength were prepared in distilled water or heavy water. A vertical starch gel electrophoresis was used to support a cylindrical polystyrene electrophoresis tube used for lymphocyte separations, 25 cm in length and 0.75 cm I.D., prepared from a 10 ml disposable pipet. Erythrocyte separations were carried out in a jacketed rectangular plexiglas chamber. It is pointed out that the described preparative D2O gradient electrophoresis method cannot be readily used for the measurement of electrophoretic mobilities for analytical purposes. However, for the preparative separation of cells with only slightly different electrokinetic properties the method appears promising, simple, and entirely inocuous to the cells.

Van Oss, C. J.↗
NASA NTRS1978

Annual Conference on Nuclear and Space Radiation Effects, 15th, University of New Mexico, Albuquerque, N. Mex., July 18-21, 1978, Proceedings

Radiation effects in MOS devices and circuits are considered along with radiation effects in materials, space radiation effects and spacecraft charging, SGEMP, IEMP, EMP, fabrication of radiation-hardened devices, radiation effects in bipolar devices and circuits, simulation, energy deposition, and dosimetry. Attention is given to the rapid anneal of radiation-induced silicon-sapphire interface charge trapping, cosmic ray induced errors in MOS memory cells, a simple model for predicting radiation effects in MOS devices, the response of MNOS capacitors to ionizing radiation at 80 K, trapping effects in irradiated and avalanche-injected MOS capacitors, inelastic interactions of electrons with polystyrene, the photoelectron spectral yields generated by monochromatic soft X radiation, and electron transport in reactor materials.

Simons, M.↗
NASA NTRS1979

Concentration-time data in toxicity tests and resulting relationships

Periodic analyses for carbon monoxide and methane in the animal exposure chamber during pyrolysis of polyethylene at 800 C without forced air flow showed that the concentrations of these compounds increased with exposure time. These observations, and similar observations for polyurethane flexible foam, permitted the calculation of carbon monoxide toxicity in terms of a DP (Death Product Concentration) value, in addition to flammability in terms of HC (Hydro Carbon) value. Observed DP values exceeding the critical DP(CO) value of 47,200 ppm-min for carbon monoxide may indicate that lethal exposures were reached earlier but not immediately manifested because of the time delay involved in physiological processes. On the basis of this DP(CO) value, carbon monoxide could have been the sole toxicant in the case of polyethylene, polypropylene, polyoxymethylene, polystyrene, polycarbonate, ethylene propylene diene rubber, and wood.

Hilado, C. J.↗
NASA NTRS1979

Calibration of long wavelength Exotech model 20C spectroradiometer

A brief description of the Exotech model 20C field spectroradiometer, which measures the spectral radiance of a target in the wavelength ranges from 0.37 to 2.5 microns (short wavelength unit), 2.8 to 5.6 microns, and 7.0 to 14 microns (long wavelength unit) is given. It is a rugged field instrument which uses four circular-variable-filters to get wavelength scan. Wavelength calibration of the long wavelength unit was done by use of the strong, sharp, and accurately known absorption bands of polystyrene, atmospheric carbon dioxide, and methyl cyclohexane (liquid) in the IR wavelength region. The spectral radiance calibration was done by recording spectral scans of the hot and the cold blackbody targets and assuming that spectral radiance varies linearly with the signal.

Kumar, R.↗