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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
DOE OSTI2025

CCN Measurements at Urban Site during CoURAGE

Cloud condensation nuclei (CCN) measurements were collected during CoURAGE from March - June 2025 at the BSEC urban atmospheric chemistry supersite (39.32057 N, 76.6246 W). CCN number concentrations (# cm-3) were obtained at a frequency of 1 second using a cloud condensation nuclei counter (CCN-100, Droplet Measurement Technologies). The CCN counter was operated in stepping mode, measuring CCN over a range of supersaturations from 0.2 to 1.0%. The settings of the instrument were set such that the supersaturation increased in increments of 0.2% up to the maximum supersaturation, and then decreased in increments of 0.2% down to the minimum supersaturation in a repeating cycle. The supersaturation of the instrument was calibrated weekly using ammonium sulfate. The weekly calibrated supersaturation values have been applied to the data. Data during transitions between supersaturation values were removed and replaced with a value of -999. Transitions are defined as the first 210 seconds after a new supersaturation value to ensure the instrument has stabilized following a change in supersaturation. Data were also flagged with a value of -999 if there were concerns with the function of the instrument, specifically the presence of alarm codes, fogging of the optical particle counter (1st stage monitor > 0.4 V), or a sheath to sample flow ratio outside the expected range (< 9 or > 11).

CCN number density↗
DOE OSTI2026

AMICE2 measurements of lab-generated and ambient aerosols at BNL from 2025-07-21 to 2025-08-22

From July 21 through August 22, 2025 the Absorption Measurement Inter-Comparison Experiment phase 2 (AMICE2) was conducted at Brookhaven National Laboratory. The experiment included concurrent operation of several filter-based instruments and in situ instruments sampling from a common sample line. The common sample line provided all instruments with either lab-generated aerosols composed of external mixtures of nigrosin, cabojet, and ammonium sulfate, or with ambient aerosol drawn through an external stack. This data set contains measurements from the CAPS PMssa instrument taken as a reference instrument at 532 nm and against which the effectiveness of the filter corrections may be assessed. It also contains attenuation coefficients from all filter-based instruments and filter transmittances in order to permit correction for filter loading, and the SSA and COA to permit corrections for aerosol darkness. Finally, two sets of multiplicative corrections are provided for the AE-33, TAP, and MA-350 instruments: the first one, Corr1, corrects for filter amplification factor and loading, the second one, Corr2, corrects for the aerosol darkness in terms of the natural log of COA.

Aerosol Extinction↗
NASA NTRS1972

The effect of alloying on gamma and gamma prime in nickel-base superalloys

An investigation was conducted to determine the compositional limits of gamma and gamma prime phases in nickel-base superalloys. Fifty-one nickel-base alloys were melted under vacuum and heat treated for 4 hours at 1190 C followed by 1008 hours at 850 C. The alloys had the following composition ranges: A1 4.0 to 13 atomic percent, Cr 6.5 to 20.5 percent, Ti 0.25 to 4.75 percent, Mo 0.0 to 6.0 percent, and W 0.0 to 4.0 percent. The residues from the ammonium sulfate electrolytic extraction for the two-phase alloys were analyzed chemically and by X-ray diffraction. The results of the investigation were used to assemble a mathematical model of the gamma-gamma prime region of the Ni-Al-Cr-Ti-Mo-W system. A computer program was written to analyze the model of the phase diagram. Some of these results are also presented graphically. The resulting model is capable of satisfactorily predicting the compositions of conjugate gamma-gamma prime phases in the alloys investigated and twelve of fifteen commercial superalloys studied.

Dreshfield, R. L.↗
NASA NTRS1973

Physical properties of the stratospheric aerosols

A comparison of the equilibrium vapor pressure over nitric acid solutions with observed water and nitric acid partial pressures in the stratosphere implies that nitric acid cannot be present as an aerosol particle in the lower stratosphere. A similar comparison for sulfuric acid solutions indicates that sulfuric acid aerosol particles are 75% H2SO4 by weight in water, in good agreement with direct observations. The freezing curve of H2SO4 solutions requires that the H2SO4 aerosol particles be solid or supercooled. The equilibrium vapor pressure of H2SO4 in the stratosphere is of the order of 20 picotorr. At stratospheric temperatures, ammonium sulfate is in a ferroelectric phase. As a result, polar molecules may form a surface coating on these aerosols, which may be a fertile ground for further chemical reaction.

Toon, O. B.↗
NASA NTRS1977

Microphysical processes affecting stratospheric aerosol particles

Physical processes which affect stratospheric aerosol particles include nucleation, condensation, evaporation, coagulation and sedimentation. Quantitative studies of these mechanisms to determine if they can account for some of the observed properties of the aerosol are carried out. It is shown that the altitude range in which nucleation of sulfuric acid-water solution droplets can take place corresponds to that region of the stratosphere where the aerosol is generally found. Since heterogeneous nucleation is the dominant nucleation mechanism, the stratospheric solution droplets are mainly formed on particles which have been mixed up from the troposphere or injected into the stratosphere by volcanoes or meteorites. Particle growth by heteromolecular condensation can account for the observed increase in mixing ratio of large particles in the stratosphere. Coagulation is important in reducing the number of particles smaller than 0.05 micron radius. Growth by condensation, applied to the mixed nature of the particles, shows that available information is consistent with ammonium sulfate being formed by liquid phase chemical reactions in the aerosol particles. The upper altitude limit of the aerosol layer is probably due to the evaporation of sulfuric acid aerosol particles, while the lower limit is due to mixing across the tropopause.

Hamill, P.↗
NASA NTRS1980

Analysis and interpretation of lidar observations of the stratospheric aerosol

Data obtained with a 48 in. telescope lidar system are compared with results obtained using a one-dimensional stratospheric aerosol model to analyze various microphysical processes influencing the formation of this aerosol. Special attention is given to the following problems: (1) how lidar data can help determine the composition of the aerosol particles and (2) how the layer corresponds to temperature profile variations. The lidar record during the period 1974 to 1979 shows a considerable decrease of the peak value of the backscatter ratio. Seasonal variations in the aerosol layer and a gradual decrease in stratospheric loading are observed. The aerosol model simulates a background stratospheric aerosol layer, and it predicts stratospheric aerosol concentrations and compositions. Numerical experiments are carried out by using the model and by comparing the theoretical results with the experimentally obtained lidar record. Comparisons show that the backscatter profile is consistent with the composition when the particles are sulfuric acid and water; it is not consistent with an ammonium sulfate composition. It is shown that the backscatter ratio is not sensitive to the composition or stratospheric loading of condensation nuclei such as meteoritic debris.

Hamill, P.↗
NASA NTRS1980

Lidar determination of the composition of atmosphere aerosols

Theoretical and experimental studies of the feasibility of using DIfferential SCatter (DISC) lidar to measure the composition of atmospheric aerosols are described. This technique involves multiwavelength measurements of the backscatter cross section of aerosols in the middle infrared, where a number of materials display strong restrahlen features that significantly modulate the backscatter spectrum. The theoretical work indicates that a number of materials of interest, including sulfuric acid, ammonium sulfate, and silicates, can be discriminated among with a CO2 lidar. An initial evaluation of this procedure was performed in which cirrus clouds and lower altitude tropospheric aerosols were developed. The observed ratio spectrum of the two types of aerosol displays structure that is in crude accord with theoretical expectations.

Wright, M. L.↗
NASA NTRS1981

Neurotrophic factor - Characterization and partial purification

Recent evidence suggests that neurotrophic activity is required for the normal proliferation and development of muscle cells. The present paper reports a study of the purification and characterization of a neurotrophic factor (NTF) from adult chicken ischiatic-peroneal nerves using two independent quantitative in vitro assay systems. The assays were performed by the measurement of the incorporation of tritiated thymidine or the sizes of single-cell clones by chick muscle cells grown in culture. The greatest amount of neutrotrophic activity is found to be extracted at a pH of 8; aqueous suspensions of the activity are stable to long-term storage at room temperature. The specific activity of the substance is doubled upon precipitation with ammonium sulfate or after gel filtration, and increase 4 to 5 fold after salt gradient elution from DEAE cellulose columns. The active fraction obtained after gel filtration and rechromatography on DEAE cellulose exhibits a 7 to 10-fold increase in specific activity. Electrophoresis of the most highly purified material yields a greatly concentrated band at around 80,000 daltons. Although NTF is purified almost 10-fold as indicated by the increase in specific activity, the maximum activity of the partially purified material is greatly reduced, possibly due to a requirement for a cofactor for the expression of maximum activity.

Popiela, H.↗
NASA NTRS1984

On archaebacterial ATPase from Halobacterium saccharovorum

The energy transducing ATPase from Halobacterium saccharovorum was studied in order to define the origin of energy transducing systems. The ATPase required high salt concentration (4M NaCl) for activity; activity was rapidly lost when NaCl was below 1 Molar. At low salt concentration, the membrane bound ATPase activity could be stabilized in presence of spermine. However, following solubilization spermine was ineffective. Furthermore, F1 ATPase activity was stabilized by ammonium sulfate even when the NaCl concentration was less than 1 Molar. These studies suggest that stabilization by hydrophobic interactions preceded ionic ones in the evolution of the energy transducing ATPases.

Kristjansson, H.↗
NASA NTRS1984

Atmospheric aerosol backscatter measurements using a tunable coherent CO2 lidar

Measurements of atmospheric aerosol backscatter coefficients, using a coherent CO2 lidar at 9.25- and 10.6-micron wavelengths, are described. Vertical profiles of the volume backscatter coefficient beta have been measured to a 10-km altitude over the Pasadena, CA, region. These measurements indicate a wide range of variability in beta both in and above the local boundary layer. Certain profiles also indicate a significant enhancement in beta at the 9.25-micron wavelength compared with beta at the 10.6-micron wavelength, which possibly indicates a major contribution to the volume backscatter from ammonium sulfate aerosol particles.

Menzies, R. T.↗
NASA NTRS1988

Protein-crystal growth experiment (planned)

To evaluate the effectiveness of a microgravity environment on protein crystal growth, a system was developed using 5 cubic feet Get Away Special payload canister. In the experiment, protein (myoglobin) will be simultaneously crystallized from an aqueous solution in 16 crystallization units using three types of crystallization methods, i.e., batch, vapor diffusion, and free interface diffusion. Each unit has two compartments: one for the protein solution and the other for the ammonium sulfate solution. Compartments are separated by thick acrylic or thin stainless steel plates. Crystallization will be started by sliding out the plates, then will be periodically recorded up to 120 hours by a still camera. The temperature will be passively controlled by a phase transition thermal storage component and recorded in IC memory throughout the experiment. Microgravity environment can then be evaluated for protein crystal growth by comparing crystallization in space with that on Earth.

Fujita, S.↗
NASA NTRS1988

Backscatter laser depolarization studies of simulated stratospheric aerosols: Crystallized sulfuric acid droplets

The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystallization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

Sassen, Kenneth↗
NASA NTRS1989

Backscatter laser depolarization studies of simulated stratospheric aerosols - Crystallized sulfuric acid droplets

The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystalization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

Sassen, Kenneth↗
NASA NTRS1990

Preliminary crystallographic examination of a novel fungal lysozyme from Chalaropsis

The lysozyme from the fungus of the Chalaropsis species has been crystallized. This lysozyme displays no sequence homology with avian, phage, or mammalian lysozymes, however, preliminary studies indicate significant sequence homology with the bacterial lysozyme from Streptomyces. Both enzymes are unusual in possessing beta-1,4-N-acetylmuramidase and beta-1,4-N,6-O-diacetylmuramidase activity. The crystals grow from solutions of ammonium sulfate during growth periods from several months to a year. The space group is P2(1)2(1)2(1) with a = 34.0 A, b = 42.6 A, c = 122.1 A. Preliminary data indicate that there is 1 molecule/asymmetric unit.

Carter, Daniel C.↗
NASA NTRS1990

Cirrus cloud model parameterizations: Incorporating realistic ice particle generation

Recent cirrus cloud modeling studies have involved the application of a time-dependent, two dimensional Eulerian model, with generalized cloud microphysical parameterizations drawn from experimental findings. For computing the ice versus vapor phase changes, the ice mass content is linked to the maintenance of a relative humidity with respect to ice (RHI) of 105 percent; ice growth occurs both with regard to the introduction of new particles and the growth of existing particles. In a simplified cloud model designed to investigate the basic role of various physical processes in the growth and maintenance of cirrus clouds, these parametric relations are justifiable. In comparison, the one dimensional cloud microphysical model recently applied to evaluating the nucleation and growth of ice crystals in cirrus clouds explicitly treated populations of haze and cloud droplets, and ice crystals. Although these two modeling approaches are clearly incompatible, the goal of the present numerical study is to develop a parametric treatment of new ice particle generation, on the basis of detailed microphysical model findings, for incorporation into improved cirrus growth models. For example, the relation between temperature and the relative humidity required to generate ice crystals from ammonium sulfate haze droplets, whose probability of freezing through the homogeneous nucleation mode are a combined function of time and droplet molality, volume, and temperature. As an example of this approach, the results of cloud microphysical simulations are presented showing the rather narrow domain in the temperature/humidity field where new ice crystals can be generated. The microphysical simulations point out the need for detailed CCN studies at cirrus altitudes and haze droplet measurements within cirrus clouds, but also suggest that a relatively simple treatment of ice particle generation, which includes cloud chemistry, can be incorporated into cirrus cloud growth.

Sassen, Kenneth↗
NASA NTRS1990

Adiabatic demagnetization refrigerator for space use

An Adiabatic Demagnetization Refrigerator (ADR) for space use is under development at NASA's Goddard Space Flight Center (GSFC). The breadboard ADR operated at 100 mK for 400 minutes. Some significant changes to that ADR, designed to eliminate shortcomings revealed during tests, are reported. To increase thermal contact, the ferric ammonium sulfate crystals were grown directly on gold-plated copper wires which serve as the thermal bus. The thermal link to the X-ray sensors was also markedly improved. To speed up the testing required to determine the best design parameters for the gas gap heat switch, the new heat switch has a modular design and is easy to disassemble.

Serlemitsos, A. T.↗
NASA NTRS1990

Crystallization of highly supersaturated solutions - An experimental study

The crystallization of ammonium sulfate solutions under very high supersaturation is investigated. The results imply that high saturation ratios can exist at least to 30 +/- 5 and possibly higher in smaller drops. Under certain atmospheric conditions highly supersaturated drops can persist at even lower temperatures and humidities.

Queen, Brian↗