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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Airborne Measurements of Nitric Oxide, Nitrogen Dioxide, Ozone, and Total Reactive Nitrogen During the NASA Global Tropospheric Experiment

Fabrication of the University of Michigan Multichannel Chemiluminescence Instrument (UMMCI) was completed in early 1996 and the instrument participated in test flights on the NASA P3B at Wallops Island prior to integration and deployment for the PEM- Tropics A Mission. The UMMCI consists of 4 channels for simultaneous measurements of ozone and NO with the option for measurements of NO2 and NOy (total reactive nitrogen) when converters are placed upstream of the NO channels. Each NO channel consists of a zeroing volume and reaction vessel, while the ozone channel consists of an ozone catalyst (or scrubber) trap that is not in line with the reaction vessel. The detectors in all for channels are Hamamatsu photomultiplier tubes, which are followed by pulse amplifier discriminators on the NO channels and an electrometer on the ozone channel. Schematics of the Detector Module and NOx/03 Probe Insert and Diagrams of the Control and Data System, the Power and Ground System, the Gas Flow System, and the Calibration System Flow are attached. Intercomparisons were conducted with G. Gregory, NASA/Langley, during the test flights (following prior calibration of the ozone generator/calibrators at the Wallops Long-Path Absorption facility). Initial test results appeared to be reasonable, and instrument characterization studies proceeded for the ozone channel and the 3 NO channels until deployment for integration for the PEM-Tropics Mission. Ozone data was obtained for Flights #4, and 6-2 1, and finalized data was submitted to the PEM-Tropics Data Archive and to the Science Team during the April 1997 Data Workshop. Although it initially appeared that the instrument sensitivity varied, subsequent tests showed that this was the fault of a leak in the ozone calibrator. In fact; the instrument sensitivity has not been observed to vary in a large number of tests over the years since the PEM-Tropics mission. We have, therefore, a very high degree of confidence in the O3 data that we submitted. NO data was obtained for all flights except the mission out of Christmas Island and the subsequent return to Hawaii, during which time the NO channels were contaminated with back-flushing pure NO from the O3 channel. The NO channels were found to suffer from a varying artifact (7 - 22 pptv) which made the instrument's results unreliable for the marine boundary layer portions of the missions (where conditions were extremely clean with NO typically < 2 pptv and O3 only 8 ppbv). Nonetheless, the NO values were an upper limit and were quite useful in identifying pollution layers and outflow from the Latin American Continent. NO data was submitted to the archive for all flights during which data was obtained. Ozone data from the P3B was among the results presented in several peer-reviewed publications. Notably, the ozone data supported the first published finding of evidence for the occurrence of aerosol nucleation in the marine boundary layer. As well, the ozone data was utilized in a treatment of the wavenumber spectra of winds, temperature and trace gases and to demonstrate the occurrence of layering as observed by the P3B during PEM-Tropics A . O3 and NO data were used in an assessment of the impact of southern hemispheric biomass burning, and in the role of NOx and O3 in HOx photochemistry during the PEM Tropics A mission. These data, along with other species measured during PEM-Tropics A, have also been employed in the generation of climatologies for tropospheric ozone and its precursors by the PI's research group.

Carroll, Mary Anne↗
NASA NTRS1998

Response of potatoes to nitrogen concentrations differ with nitrogen forms

Two separate experiments were conducted to investigate plant growth and mineral composition of potatoes (Solanum tuberosum L.) at varied solution concentrations of nitrate (NO3-) and ammonium (NH4+). Each experiment evaluated five nitrogen (N) concentrations of 0.5, 2, 4, 8, and 12 mM, which were maintained with a non-recirculating nutrient film system in controlled environment. Plants were harvested on day 42 with NO3-; and day 35 with NH4+ after transplanting of tissue culture plantlets, and growth measurements were taken as leaf area, tuber number, and dry weights of different parts. With NO3-, plant growth was greatest and similar at 2, 4, and 8 mM of N whereas with NH4+, plant growth was best only at 2 and 4 mM of N. At 12 mM of N, plants exhibited interveinal ammonium toxicity with NH4+ nutrition, but healthy growth appearance with NO3- nutrition. With either N form, total N concentrations in tissues tended to increase with increased N concentrations, and tissue phosphorus (P) concentrations were reduced at 0.5 and 2 mM of N. Tissue concentrations of calcium (Ca), magnesium (Mg), and sulfur (S) changed only slightly at particular N concentrations, yet changed substantially with different N forms. The data indicate that the optimal ranges of N concentrations in both solution and tissues are wider and higher with NO3- than with NH4+ nutrition, and thus a careful control of NH4+ concentrations is necessary to minimize possible ammonium toxicity to potato plants.

NASA Discipline Life Support Systems↗
NASA NTRS2004

Influence of nitrogen nutrition management on biomass partitioning and nitrogen use efficiency indices in hydroponically grown potato

The National Aeronautics and Space Administration (NASA) has been conducting controlled environment research with potatoes (Solanum tuberosum L.) in recirculating nutrient film technique (NFT)-hydroponic systems as a human life support component during long-duration spaceflight. Standard nutrient solution management approaches include constant pH regulation with nitric acid (HNO3) and daily adjustment of electrical conductivity (EC) equivalent to half-strength modified Hoagland's solution, where nitrate (NO3-) is the sole nitrogen (N) source. Although tuber yields have been excellent with such an approach, N use efficiency indices are expected to be low relative to tuber biomass production. Furthermore, the high amount of N used in NFT-hydroponics, typically results in high inedible biomass, which conflicts with the need to minimize system mass, volume, and expenditure of resources for long-duration missions. More effective strategies of N fertilization need to be developed to more closely match N supply with demand of the crop. Hence, the primary objective of this study was to identify the optimal N management regime and plant N requirement to achieve high yields and to avoid inefficient use of N and excess inedible biomass production. In separate 84-day cropping experiments, three N management protocols were tested. Treatments which decreased NO3(-)-N supply indirectly through lowering nutrient solution EC (Expt. I), or disabling pH control, and/or supplying NH4(+)-N (Expt. III) did not significantly benefit tuber yield, but did influence N use efficiency indices. When supplied with an external 7.5 mM NO3(-)-N for the first 42 days after planting (DAP), lowered to 1.0 mM NO3(-)-N during the final 42 days (Expt. II), plants were able to achieve yields on par with plants which received constant 7.5 mM NO3(-)-N (control). By abruptly decreasing N supply at tuber initiation in Expt. II, less N was taken up and accumulated by plants compared to those which received high constant N (control). However, proportionately more plant accumulated N was used (N use efficiency) to produce tuber biomass when N supply was abruptly lowered at tuber initiation in Expt. II. Hence, a hydroponic nutrient solution N management system may be modified to elicit greater plant N-use while maintaining overall high tuber yield as opposed to achieving high tuber yields through excess N supply and shoot growth.

NASA Discipline Life Support Systems↗
DOE OSTI2020

Method for forming a nitrogenation barrier and machine formed using a body having the nitrogenation barrier

A method includes forming one or more oxide barrier layers on one or more protected portions of a magnetic, metallic body, and converting one or more unprotected portions of the magnetic, metallic body to a less magnetic material by exposing the magnetic metallic body having the one or more oxide barrier layers formed thereon to nitrogen. One or more protected portions of the magnetic, metallic body that are beneath the one or more oxide barrier layers are not converted to the less magnetic material. The method can be used to form one or more layers of a laminated electric motor.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Nitrogen uptake by wheat seedlings, interactive effects of four nitrogen sources: NO3-, NO2-, NH4+, and urea

The net influx (uptake) rates of NO3-, NH4+, NO2-, and urea into roots of wheat (Triticum aestivum cv Yecora Rojo) seedlings from complete nutrient solutions containing all four compounds were monitored simultaneously. Although urea uptake was too slow to monitor, its presence had major inhibitory effects on the uptake of each of the other compounds. Rates of NO3-, NH4+, and NO2- uptake depended in a complex fashion on the concentration of all four N compounds. Equations were developed which describe the uptake rates of each of the compounds, and of total N, as functions of concentrations of all N sources. Contour plots of the results show the interactions over the range of concentrations employed. The coefficients of these equations provide quantitative values for evaluating primary and interactive effects of each compound on N uptake.

NASA Discipline Number 61-10↗
DOE OSTI2024

Nitrogen‐Nitrogen Bond Breaking in Irradiation Products of Hexanitrohexaazaisowurtzitane (CL‐20)

While the primary result of an interaction of ionizing radiation with an organic material is the ejection of electrons from molecular orbitals producing cations, the free electrons can further interact, yielding excited states; and, potentially, anions. In this work, we computed reaction barriers and energies for N−N bond breaking in the CL-20 cation, anion, and excited state to investigate if CL-20 degradation is accelerated after radiation exposure. We focused on N−N bond dissociation because it is the rate-determining step in the thermal degradation of CL-20. We found that N−N cleavage rapidly takes place in the CL-20 cation and anion with greatly reduced reaction energies as compared to CL-20. We also outlined a potential path for photodissociation of the N−N bond. While CL-20 is kinetically stable, initial degradation occurs readily in its irradiation products. In conclusion, this is of importance for the performance of the explosive after high-dose exposure and influences aging if CL-20 is irradiated at a low dose over extended periods of time.

CL-20 anion↗