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At least 217 records · Page 12

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NASA NTRS1975

The use of satellite data for regional planning

The experience of the Ohio-Kentucky-Indiana Regional Council of Governments in its development of a regional land use inventory from computer processing of LANDSAT 1 digital tapes and the use of those data in the OKI water quality planning program are discussed. A major part of the planning program is the prediction of water quality in rivers and lakes resulting from existing and future land uses. A model has been developed that can predict the flow of sediment, total phosphorus, total nitrogen, and organic wastes into major streams. An essential input to this model is an accurate map of land use derived from LANDSAT 1 digital tapes.

Hessling, A. H.↗

NASA NTRS1976

Water Hyacinths and Alligator Weeds for Final Filtration of Sewage

The potential of water hyacinths (Eichhornia crassipes) (Mart.) Solms and alligator weeds (Alternanthera philoxerides) (Mart.) Griesb. as secondary and tertiary filtration systems for domestic sewage was demonstrated. These two vascular aquatic plants reduced the suspended solids, total Kjeldahl nitrogen, total phosphorus, BOD sub 5, and total organic carbon levels in domestic sewage from 60 percent to 98 percent within a two week period. These plants grown in domestic sewage were also free of toxic levels of trace heavy metals.

Wolverton, B. C.↗

NASA NTRS1975

Chemical fractionation of the lunar regolith by impact melting

Impact-produced agglutinitic glass in both lunar highland and mare soils is enriched in mafic elements, in potassium, phosphorus, and sulfur, and in most lithophile elements, whereas it is depleted in plagioclase components including europium. It is proposed that the chemical fractionation is the result of a multistage partial-melting mechanism that accompanies micrometeoroid impacts into soils. The process would be expected to occur on solar system bodies that have an impact-produced regolith.

Adams, J. B.↗

NASA NTRS1975

Current status of silicon solar cell technology

Recent advances in solar cell technology have led to the development of laboratory cells with efficiencies above 15% and production cells with efficiencies in the area of 13%. The increased output is largely the result of increases in the short-circuit current. The most significant gain in the amount of light entering the cell has been obtained through surface texturing by chemical etching techniques. Sheet resistances resulting from phosphorus diffusion in the 800 C temperature range yield junction depths on the order of 0.1 micrometer, leading to significant increases in the blue region of the cell spectral response. The inclusion of a back surface field in 10 ohm-cm cells has produced an increase in open-circuit voltage of about 50 mV and an increase in the minority carrier lifetime. It appears that a low emitter efficiency of the diffused region is the cause of poor voltages. Future research will be primarily directed toward correcting this deficiency and toward the development of low cost production methods.

Brandhorst, H. W., Jr.↗

NASA NTRS1976

Mineral and nitrogen balance study observations - The second manned Skylab mission

A metabolic study of important body elements, particularly those of the musculoskeletal system, was carried out on the astronauts of the Skylab 3 mission during the preflight, inflight, and postflight phases. An elevation in the level of urinary calcium similar to that observed in the 28-d Skylab flight continued throughout the flight. Significant nitrogen and phosphorus losses, apparently associated with muscle tissue loss, occurred in spite of inflight exercise programs. On the basis of these results it is predicted that capable musculoskeletal function is likely to occur in flights longer than about 9 months in duration.

Whedon, G. D.↗

NASA NTRS1976

Skylab nutritional studies

Precise nutritional specifications arising from both physiological and experimental requirements necessitated a comprehensive study of the chemical composition of the Skylab food supply. Each of the approximately 70 different food items was analyzed for digestible and nondigestible carbohydrate, and for protein, amino acids, fat, fatty acids, vitamins, and minerals. Menus were formulated to provide at least the National Research Council's Recommended Dietary Allowance of all essential nutrients and, in addition, to provide constant daily intakes of calcium, phosphorus, magnesium, sodium, potassium and protein. In general, the crewmembers adhered to their programmed menus. The ability to swallow and digest food was unaffected by prolonged weightlessness. Taste acuity also appeared to be undiminished inflight. The bone and muscle changes which occurred in previous flights were more pronounced in Skylab. It is concluded that these changes did not develop as a result of nutritional deficit. If such changes are nutritionally related, they point to the existence of nutritional requirements in weightlessness which differ quantitatively from those observed on earth.

Rambaut, P. C.↗

NASA NTRS1976

Determination of surface recombination velocity in heavily doped silicon

A method was developed and successfully tested for the determination of the effective surface recombination velocity of silicon layers doped by diffusion of phosphorus to a level of 10 to the 19th to 10 to the 21st per cu cm. The effective recombination velocity was obtained from the dependence of the electron-beam-induced current on the penetration of the electron beam of a scanning electron microscope. A special silicon diode was constructed which permitted the collection at the p-n junction of the carriers excited by the electron beam. This diode also permitted the study of the effects of surface preparation on the effective surface recombination velocity.

Watanabe, M.↗

NASA NTRS1977

Response of Selected Microorganisms to Experimental Planetary Environments

Results of studies in anaerobic phosphorus metabolism are presented. Specific topics discussed include: (1) anaerobic utilization of PH3; (2) reduction of phosphate or phosphite; (3) isolation of organisms which utilize phosphite or phosphate anaerobically as a final hydrogen acceptor; and (4) the toxicity of PH3 to the organisms. Techniques of anaerobic microbiology associated with space hardware were also studied. These include: (1) the Brewer anaerobe jar/GasPak system; (2) a new procedure to grow aerobes and anaerobes simultaneously; (3) a culture medium to differentiate oblagate from facultative anaerobes; and (4) a procedure to quantitate O2 sensitivity of anaerobes.

Foster, T. L.↗

NASA NTRS1977

Mineral and nitrogen metabolic studies, experiment M071

The similarity between bed rest test and space flight effects on human mineral and nitrogen metabolisms indicates impairment of capable musculoskeletal functions. A pattern of urinary calcium increases and total calcium shifts suggests that calcium losses continue with time. Significant losses of nitrogen and phosphorus are associated with reduction in muscle tissue. It is concluded that capable musculoskeletal function is likely to be impaired during space flights of 1 1/2 to 3 years duration.

Whedon, G. D.↗

NASA NTRS1976

Biomedical results of the Skylab Program

Skylab, the fourth in a logical sequence of USA manned space flight projects following Mercury, Gemini and Apollo, presented life scientists with their first opportunity for an in-depth study of man's response to the space environment. Extensive medical investigations were undertaken to increase our understanding of man's adaptation to the space environment and his readaptation to gravity upon return to earth. The flight durations of the three Skylab missions were progressively increased from 28 days to 59 days and, finally, 84 days. The results of these investigations of the various body systems clearly denonstrated that man can adapt to zero gravity and perform useful work during long-duration space flight. However, definite changes (some unexpected) in the vestibular, cardiovascular, musculo-skeletal, renal and electrolyte areas were documented. The most significant were: the occurrence of space motion sickness early in the missions; diminished orthostatic tolerance, both in-flight and post-flight; moderate losses of calcium, phosphorus and nitrogen; and decreased tolerance for exercise post-flight. The mechanisms responsible for these physiological responses must be understood and, if necessary, effective countermeasures developed before man can endure unlimited exposure to space flight.

Michel, E. L.↗

NASA NTRS1976

Mineral and nitrogen metabolic studies on Skylab flights and comparison with effects of earth long-term recumbency

A metabolic study of the effects of space flight on various chemical elements, particularly those with special relevance to the musculo-skeletal system, was carried out on the nine astronauts who participated in the three Skylab flights of 28, 59 and 84 days in 1973-1974. The study required of the cooperating crewmen constant dietary intake, continuous 24-hour urine collections and total fecal collections for 21-31 days before each flight, throughout each flight and for 17-18 days post-flight. Increases in urinary calcium and negative calcium balances during space flight were generally similar to those found in previous immobilization and bedrest studies. The persistence of these alterations in calcium metabolism throughout the flights suggested that calcium losses would continue in weightlessness for a very long time. Significant losses of nitrogen and phosphorus occurred, associated with observed reduction in muscle tissue. Both mineral and muscle losses occurred despite rigorous exercise regimens in flight. It was concluded that unless protective measures can be developed, capable musculo-skeletal function is likely to be impaired in space flights, ultimately to be conducted to Mars, of 1-1/2 to 3 years duration.

Whedon, G. D.↗

NASA NTRS1977

17-25 micrometer spectra of Jupiter and Saturn

Ground-based spectra of Jupiter and Saturn in the region from 17 to 25 microns are compared with intensities computed from current thermal-structure models. Good agreement with the continuum of Jupiter is obtained for models which incorporate a temperature inversion, but published models give disagreement with the continuum of Saturn. Upper-limit abundances for sulfur and phosphorus in the Jovian atmosphere, as thermodynamically stable species S8 and P4, are found to be 0.04 and 2.1 times the solar abundance, respectively.

Tokunaga, A.↗

NASA NTRS1977

The metallic microstructures and thermal histories of severely reheated chondrites

The metallographic structures of eight severely reheated chondrites - Farmington, Ramsdorf, Orvinio, Wickenburg, Lubbock, Rose City, Arapahoe, and Tadjera - were studied using optical, SEM and electron microprobe techniques. The following metallographic criteria were used to estimate the post-shock residual temperature of the chondrites: melted metal-troilite appearance, presence of martensite, phosphorus enrichment of metal and averaging of central metal grain compositions. The presence of phosphides and secondary kamacite are due to slow post-shock cooling rates. Ni rim gradients indicate both extensive remelting of metal grains and relatively fast cooling.

Smith, B. A.↗

NASA NTRS1977

Determination of minority-carrier lifetime and surface recombination velocity with high spacial resolution

Quantitative analysis of the electron beam induced current in conjunction with high-resolution scanning makes it possible to evaluate the minority-carrier lifetime three dimensionally in the bulk and the surface recombination velocity two dimensionally, with a high spacial resolution. The analysis is based on the concept of the effective excitation strength of the carriers which takes into consideration all possible recombination sources. Two-dimensional mapping of the surface recombination velocity of phosphorus-diffused silicon diodes is presented as well as a three-dimensional mapping of the changes in the minority-carrier lifetime in ion-implanted silicon.

Watanabe, M.↗

NASA NTRS1978

Fire-retardant epoxy polymers

Phosphorus atoms in molecular structure of epoxies make them fire-retardant without degrading their adhesive strength. Moreover, polymers are transparent, unlike compounds that contain arsenic or other inorganics. They have been used to bond polyvinylfluoride and polyether sulfone films onto polyimide glass laminates.

Akawie, R. I.↗

NASA NTRS1978

Solar silicon via the Dow Corning process

Carbon, as a reductant for quartz, must be made available so as to have suitable reactivity in conjunction with high purity, especially with respect to boron and phosphorus. A detailed experimental plan was developed to do this. Different sources of carbon were selected to be subjected to various purification methods and reactivity-enhancement processes. A developmental scale arc furnace was installed to perform quartz-carbon reactivity testing.

Hunt, L. P.↗

NASA NTRS1978

Cornell University remote sensing program

The author has identified the following significant results. Available aerial photographs were used to characterize mosquito breeding sites in Oswego County, New York. Numerous wetlands are contained within this county; this area is the only inland area in North America to have confirmed outbreaks of eastern equine encephalitis. This photocharacterization of primary mosquito breeding sites will be used to develop effective spraying. Large scale color and color infrared aerial photographs were used to assess changes in aquatic vegetation that accompanied phosphorus reduction in an eutrophic lake in New York.

Liang, T.↗

NASA NTRS1978

Anaerobic utilization of phosphite and hypophosphite by Bacillus sp.

A Bacillus species capable of using phosphite and hypophosphite under anaerobic conditions was isolated from Cape Canaveral soil samples and grown on a glucose-mineral salts medium with phosphate omitted. The optimum hypophosphite concentration was 60 microg/ml, while the optimum phosphite concentration was greater than 1000 microg/ml. P-32-labeled hypophosphite was incorporated into the cell as organic phosphate, and little or no phosphate appeared in the medium when either hypophosphite or phosphite was the phosphorus source. When phosphate was present in the medium, phosphite was not metabolized. When both phosphite and hypophosphite were present, phosphite was used first and then hypophosphite.

Foster, T. L.↗