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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

The relative line strength and intensity of the N II 2143 doublet

The doublet emission from N II at 2139.7 A and 2143.6 A was observed by a 1.4-m scanning spectrometer with 3.1 A resolution in the daytime, high-altitude thermosphere during moderate levels of solar activity. The spectrometer viewed the earth's limb 5 deg below the local horizontal to give a nominal tangent height of 152 km. Both sub band heads of the nitric oxide gamma band system were resolved in the data at the resolution used. The emission features from N II are clearly evident on the short wavelength shoulder of the (1, 0) band. Synthetic profiles of the (1, 0) gamma band and the (0, 3) delta band of nitric oxide were fitted to the data using a chi-square analysis. These contributions were removed from the data leaving a residual emission, considered to be the N II doublet. A chi-square minimization of the data relative to a synthetic intensity profile was done. The minimum was for a line strength ratio between the 2139 A and 2143 A lines of 0.58 + or - 0.08. The mean solar EUV flux deduced from the intensity of the N II emission in this experiment is lower than other reported observations, consistent with a lower solar activity level.

Bucsela, Eric J.↗
NASA NTRS2002

Mechanical Signal Transduction in Countermeasures to Muscle Atrophy

We have shown that modifications in muscle use result in changes in the expression and activity of calpains and nitric oxide synthase (NOS). Although muscle unloading for 10 days produced no change in the concentrations of calpain 1 or 2 and no change in calpain activation, muscle reloading produced a 90% increase in calpain 2 concentration. We developed an in vitro model to test our hypothesis that nitric oxide can inhibit cytoskeletal breakdown in skeletal muscle cells by inhibiting calpain cleavage of talin. Talin was selected because it is a well-characterized calpain substrate and it is codistributed with calpain in muscle cells. We found that intermittant loading during hindlimb suspension that is sufficient to prevent muscle mass loss that occurs during muscle unloading is also sufficient to prevent the decrease in NOS expression that normally occurs during hindlimb unloading. These findings indicate that therapeutics directed toward regulating the calpain/calpastatin system may be beneficial in preventing muscle mass loss in muscle injury, unloading and disease.

Tidball, James G.↗
NASA NTRS1981

Tunguska meteor fall of 1908 - Effects on stratospheric ozone

The Tunguska meteor, whose disintegration over Siberia in 1908 may have generated as much as 30 million metric tons of nitric oxide (NO) in the stratosphere and mesosphere, is discussed. The photochemical aftereffects of the event are simulated using a comprehensive model of atmospheric trace composition. Calculations are made which indicate that up to 45% of the ozone in the Northern Hemisphere may have been depleted by the meteor's nitric oxide cloud early in 1909 and that large ozone reductions may have persisted until 1912. Measurements of atmospheric transparency by the Smithsonian Astrophysical Observatory for the years 1909-1911 reveal evidence of a steady ozone recovery from unusually low levels in early 1909, implying a total ozone deficit of 30 + or - 15%. The coincidence in time between the observed ozone recovery and the Tunguska meteor fall suggests that the event may provide a test of current ozone depletion theories.

Turco, R. P.↗
NASA NTRS2001

Mars Flyer Rocket Propulsion Risk Assessment Kaiser Marquardt Testing

This report describes the investigation of a 10-N, bipropellant thruster, operating at -40 C, with monomethylhydrazine (MMH) and 25% nitric oxide in nitrogen tetroxide (MON-25). The thruster testing was conducted as part of a risk reduction activity for the Mars Flyer, a proposed mission to fly a miniature airplane in the Martian atmosphere. Testing was conducted using an existing thruster, designed for MMH and MON-3 propellants. The nitric oxide content of MON-3 was increased to 25%, to lower its freezing point to -55 C. The thruster was conditioned, along with the propellants, to temperature prior to hot firing. Thruster operating parameters included oxidizer-to-fuel mixture ratios of 1.6 to 2.7 and inlet pressure ranging from 689 to 2070 kPa. The test matrix consisted of many 10-second firings and several 60-, 300-, 600-, and 1200-second firings, as well as pulse testing. The thruster successfully accumulated nearly 10,000 seconds of operation without failure, at temperatures ranging from -40 C to 22 C. At nominal inlet pressures, the ignition delay was comparable to MMH/MON-3 operation. The optimal performance for the 8.9-N thruster was determined to be at a mixture ratio of 1.93 with an average specific impulse of 298 sec.

Marquardt, Kaiser↗
NASA NTRS1988

The Amazon Boundary Layer Experiment (ABLE 2A) - Dry season 1985

The Amazon Boundary Layer Experiment (ABLE 2A) used data from aircraft, ground-based, and satellite platforms to characterize the chemistry and dynamics of the lower atmosphere over the Amazon Basin during the early-to-middle dry season, July and August 1985. This paper reports the conceptual framework and experimental approach used in ABLE 2A and serves as an introduction to the detailed papers which follow in this issue. The results of ABLE 2A demonstrate that isoprene, methane, carbon dioxide, nitric oxide, dimethylsulfide, and organic aerosol emissions from soils and vegetation play a major role in determining the chemical composition of the atmospheric mixed layer over undisturbed forest and wetland environments. As the dry season progresses, emissions from both local and distant biomass burning become an important source of carbon monoxide, nitric oxide and ozone in the atmosphere over the central Amazon Basin.

Harriss, R. C.↗
NASA NTRS1973

Emission calculations for a scramjet powered hypersonic transport

Calculations of exhaust emissions from a scramjet powered hypersonic transport burning hydrogen fuel were performed over a range of Mach numbers of 5 to 12 to provide input data for wake mixing calculations and forecasts of future levels of pollutants in the stratosphere. The calculations were performed utilizing a one-dimensional chemical kinetics computer program for the combustor and exhaust nozzle of a fixed geometry dual-mode scramjet engine. Inlet conditions to the combustor and engine size was based on a vehicle of 227,000 kg (500,000 lb) gross take of weight with engines sized for Mach 8 cruise. Nitric oxide emissions were very high for stoichiometric engine operation but for Mach 6 cruise at reduced equivalence ratio are in the range predicted for an advanced supersonic transport. Combustor designs which utilize fuel staging and rapid expansion to minimize residence time at high combustion temperatures were found to be effective in preventing nitric oxide formation from reaching equilibrium concentrations.

Lezberg, E. A.↗
NASA NTRS2017

TPSAS-NF1676L-28217-DND

The climate of the thermosphere is controlled in part by cooling to space driven by infrared radiation from nitric oxide (NO, 5.3μm), carbon dioxide (CO2, 15μm), and atomic oxygen (O, 63μm). The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite measures the vertical distribution of infrared radiation emitted by various atmospheric gases (ozone, water vapor, as well as nitric oxide, and carbon dioxide), providing important information about the radiation budget in the upper atmosphere. SABER was launched in December 2001 and began making measurements in January 2002. From these radiance measurements, we have more than 15 years of derived scan fluxes and global daily infrared power and energy radiated by NO and CO2 in the thermosphere.

L A Hunt↗
NASA NTRS1979

Launch vehicle effluent measurements during the September 5, 1977, Titan 3 launch at Air Force eastern test range

Airborne effluent measurements and cloud physical behavior data are presented. The monitoring program included airborne effluent measurements in situ in the launch cloud, visible and infrared photography of cloud growth and physical behavior, and limited surface collection of rain samples. Effluent measurements included concentrations of HCl, Cl2, NO, nitric oxide, and particles as a function of time in the exhaust cloud. In situ particle mass concentration and number density were measured as a function of time and size in the range of 0.05 micron m to 30 micron m diameter. Measurement results were similar to those of previous launch monitorings. Maximum HCl and nitric oxide concentrations of Cl2 were maximum about 2 minutes after launch and by 10 to 15 minutes had decayed to less than 10 ppb (detection limit). Particle measurements showed most of the particles present to be below about 3-micron m diameter. Postlaunch analyses of collected particle samples showed significant amounts of Al (some cases Cl) from about 3-micron m to 0.04-micron m diameter.

Wornom, D. E.↗
NASA NTRS2010

Characterizing Methods of Measuring Flow-Mediated Dilation in the Brachial Artery

Regulation of vascular tone is one of the many important functions of the vascular endothelium. Endothelial dysfunction is a critical early event in the pathogenesis of atherosclerosis and occurs in the absence of angiographic disease. Flow-Mediated Dilation (FMD) is a noninvasive technique commonly used to evaluate endothelium-dependent vasodilation in humans and gauge the health of the cardiovascular system. Reductions in brachial artery FMD have been strongly correlated with disease progression and are predictive of future cardiac events. The flow stimulus for brachial artery FMD occurs as a result of the increased shear stress following deflation of an occlusion cuff around the upper arm. Using 2-dimensional ultrasound, changes in arterial diameter up to 5-minutes following cuff deflation are calculated from baseline image measurements. Along with pulsed Doppler measures of flow velocity through the artery, flow-mediated, endothelium-dependent vasodilation can be assessed. There is debate among investigators, however, about the proper positioning of the occlusion cuff during FMD testing. It is thought that placement of the cuff around the upper arm may not accurately reflect the impact of nitric oxide, a critically important molecule released as a result of the increased shear stress created by the FMD technique. Data suggest that the production of other endogenous metabolites may also contribute to FMD-related changes when positioning the cuff around the upper arm. To overcome the potential influence of such molecules, researchers now suggest that the occlusion cuff be placed below the elbow allowing a more precise estimate of nitric oxide mediated dilation. The purpose of this study is to compare the differences in FMD between the two methodologies of occlusion cuff placement. In addition, this study will determine the method that is easier for ultrasound technicians to perform and will produce a low coefficient of variance between technicians. Ultimately, the results of this study will help in tracking any adverse cardiovascular effects of spaceflight.

Callender, Ariane R.↗
NASA NTRS1979

Advanced catalytic combustors for low pollutant emissions, phase 1

The feasibility of employing the known attractive and distinguishing features of catalytic combustion technology to reduce nitric oxide emissions from gas turbine engines during subsonic, stratospheric cruise operation was investigated. Six conceptual combustor designs employing catalytic combustion were defined and evaluated for their potential to meet specific emissions and performance goals. Based on these evaluations, two parallel-staged, fixed-geometry designs were identified as the most promising concepts. Additional design studies were conducted to produce detailed preliminary designs of these two combustors. Results indicate that cruise nitric oxide emissions can be reduced by an order of magnitude relative to current technology levels by the use of catalytic combustion. Also, these combustors have the potential for operating over the EPA landing-takeoff cycle and at cruise with a low pressure drop, high combustion efficiency and with a very low overall level of emission pollutants. The use of catalytic combustion, however, requires advanced technology generation in order to obtain the time-temperature catalytic reactor performance and durability required for practical aircraft engine combustors.

Dodds, W. J.↗
NASA NTRS2015

Investigation of Gas Seeding for Planar Laser-Induced Fluorescence in Hypersonic Boundary Layers

Numerical simulations of the gas-seeding strategies required for planar laser-induced fluorescence in a Mach 10 (approximately Mach 8.2 postshock) airflow were performed. The work was performed to understand and quantify the adverse effects associated with gas seeding and to assess various types of seed gas that could potentially be used in future experiments. In prior experiments, NO and NO2 were injected through a slot near the leading edge of a flatplate wedge model used in NASA Langley Research Center's 31 in. Mach 10 air tunnel facility. In this paper, nitric oxide, krypton, and iodine gases were simulated at various injection rates. Simulations showing the deflection of the velocity boundary layer for each of the cases are presented. Streamwise distributions of velocity and concentration boundary-layer thicknesses, as well as vertical distributions of velocity, temperature, and mass distributions, are presented for each of the cases. A comparison between simulated streamwise velocity profiles and experimentally obtained molecular tagging velocimetry profiles using a nitric oxide seeding strategy is performed to verify the influence of such a strategy on the boundary layer. The relative merits of the different seeding strategies are discussed. The results from a custom solver based on OpenFOAM version 2.2.1 are compared against results obtained from ANSYS® Fluent version 6.3.

Arisman, C. J.↗
NASA NTRS2010

Hydrogen peroxide catalytic decomposition

Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated through the use of concentrated hydrogen peroxide fed as a monopropellant into a catalyzed thruster assembly. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50%-70% by volume, and may be increased in concentration in a continuous process preceding decomposition in the thruster assembly. The exhaust of the thruster assembly, rich in hydroxyl and/or hydroperoxy radicals, may be fed into a stream containing oxidizable components, such as nitric oxide, to facilitate their oxidation.

Parrish, Clyde F.↗
NASA NTRS1976

Measurements of air pollutants over a Los Angeles freeway with a bistatic laser system

Nitric oxide, ozone, and ethylene were monitored over roads during periods of heavy traffic by transmitting several known laser wavelengths over an atmospheric path and measuring the differential absorption of the wavelengths. Heavy afternoon traffic between four and five o'clock over a 3.75 km path produced a noticeable increase in ethylene and a decrease in ozone. The changes occurred on a short time scale and correlated with the sudden traffic density increase. The ozone decrease occurs because of the sudden presence of large quantities of nitric oxide. Although the laboratory laser equipment used is rather cumbersome, the measurements did point out the potential of the laser absorption technique for monitoring large areas from one location.-

Menzies, R. T.↗
NASA NTRS1977

The production and treatment of gaseous pollutants in an electrostatic precipitator

The production of ozone and nitric oxides and the oxidation of two organic contaminants, methane and acetylene, were studied in the corona discharge of a model cylindrical electrostatic precipitator. Both air and oxygen streams were passed through the discharge while current, voltage, electrode/wall radius ratio, residence time and wall temperature were varied. Under all conditions using air, much more ozone was produced in the negative than in the positive corona, in agreement with qualitative data reported in the literature. However, using oxygen, as much as three to four times more ozone is produced by the positive corona. Over a wide range of conditions ozone production is proportional to current. Limited analyses of nitric oxides formation in air indicated that levels were higher in the negative than in the positive corona. In contrast to previous work using an RF discharge, methane contamination was not removed by the corona discharge. However, the oxidation of acetylene was affected by the discharge and could not be accounted for by homogeneous ozonation alone.

Flamm, D. L.↗
DOE OSTI2020

Buckybowls as gas adsorbents: binding of gaseous pollutants and their electric-field induced release

Here, the adsorption of nitric oxide and nitrogen dioxide (NO x ) to the Buckybowls sumanene and corannulene was investigated. Binding energies were up to 1.8x larger than for coronene as the planar analogue, demonstrating the advantages of Buckybowls for gas adsorption. In agreement with previous reports on carbon dioxide and methane adsorption, the favorable binding energies for NO x were shown to be associated with the curvature of the Buckybowls. It is shown that applying an electric field along the bowl symmetry axis modifies the bowl curvatures and impacts adsorbate binding energies, including the potential to desorb adsorbates. As a proof of concept, it is shown that applying electric fields of different strengths and orientations selectively controls sumanene's preference to bind nitric oxide, nitrogen dioxide, and carbon dioxide, suggesting potential applications for dynamically tunable gas adsorption. Moreover, it is demonstrated that adsorbates can be desorbed by applying suitable electric field strengths, allowing cleaning of the Buckybowls for renewed usage.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗