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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Electrophoresis tests on STS-3 and ground control experiments - A basis for future biological sample selections

Static zone electrophoresis is an electrokinetic method of separating macromolecules and small particles. However, its application for the isolation of biological cells and concentrated protein solutions is limited by sedimentation and convection. Microgravity eliminates or reduces sedimentation, floatation, and density-driven convection arising from either Joule heating or concentration differences. The advantages of such an environment were first demonstrated in space during the Apollo 14 and 16 missions. In 1975 the Electrophoresis Technology Experiment (MA-011) was conducted during the Apollo-Soyuz Test Project flight. In 1979 a project was initiated to repeat the separations of human kidney cells. One of the major objectives of the Electrophoresis Equipment Verification Tests (EEVT) on STS-3 was to repeat and thereby validate the first successful electrophoretic separation of human kidney cells. Attention is given to the EEVT apparatus, the preflight electrophoresis, and inflight operational results.

Morrison, D. R.↗
NASA NTRS1985

Sample selection and testing of separation processes

Phase partitioning, which has become an important tool for the separation and purification of biological materials, was studied. Instruments available for this technique were researched and a countercurrent distribution apparatus, the Biosheff MK2N, was purchased. Various proteins, polysaccharides and cells were studied as models to determine operating procedures and conditions for this piece of equipment. Results were compared with those obtained from other similar equipment, including a nonsynchronous coil planet centrifuge device. Additionally, work was done with affinity ligands attached to PEG, which can further enhance the separation capabilities of phase partitioning.

Karr, L. J.↗
NASA NTRS1988

Crystal fractionation in the SNC meteorites: Implications for sample selection

Almost all rock types in the SNC meteorites are cumulates, products of magma differentiation by crystal fractionation (addition or removal of crystals). If the SNC meteorites are from the surface of Mars or near subsurface, then most of the igneous units on Mars are differentiated. Basaltic units probably experienced minor to moderate differientation, but ultrabasic units probably experienced extreme differentiation. Products of this differentiation may include Fe-rich gabbro, pyroxenite, periodotite (and thus serpentine), and possibly massive sulfides. The SNC meteorites include ten lithologies (three in EETA79001), eight of which are crystal cumulates. The other lithologies, EETA79001 A and B are subophitic basalts.

Treiman, Allan H.↗
NASA NTRS1990

A catalog of X-ray measurements of selected samples of active galaxies and nuclei

X-ray fluxes or upper limits in the 2-10 keV energy band from the HEAO 1 A-2 experiment are given for well-defined samples of QSOs and of Seyfert galaxies of types 1, 1.5 and 2, and for a list of BL Lac objects (334 sources in total). All on-orbit X-ray measurements of these objects published between 1976 and 1986 from other experiments have also been cataloged.

Della Ceca, R.↗
NASA NTRS1990

Infrared studies of elliptical galaxies. II - A radio-selected sample

An IR survey of radio galaxies in the Bologna B2 catalog is reported. It is found that 40 percent of the sample has IR luminosities of at least one billion solar luminosities, as opposed to about 8 pecent of normal ellipticals. The galaxies are inhomogeneous in their IR properties. The most IR-luminous galaxies are those listed as peculiar by Zwicky. Statistically, these galaxies are strikingly different from Seyfert galaxies in their IR properties in that they show much more radio emission in comparison with their IR emission than do Seyferts, even when the emission from the extended radio lobes has been discounted.

Impey, C. D.↗
NASA NTRS1990

The radio properties of cD galaxies in Abell clusters. I - An X-ray selected sample

The radio and X-ray properties of a sample of 27 cD galaxies in rich clusters are presented. The radio data consist of 6 cm VLA maps at a resolution of 1-2 arcsec. The X-ray data consist of images and surface-brightness profiles from the Einstein IPC and derived quantities such as cooling times, mass-accretion rates, and thermal pressures from Arnaud (1988). These data are used to explore the relationship between X-ray cooling cores, and the power and morphology of the radio emission. It is found that 71 percent of the cD's with X-ray cooling cores are radio loud, whereas a smaller but still significant 23 percent of cD's without cooling cores are detected at 6 cm above 0.2 mJy. Among the radio galaxies in noncooling core clusters are luminous and extended wide-angle tails. There is a weak correlation between the mass-accretion rate and the radio power for cD's. There is also an interesting class of cooling core cluster (e.g., A2052) with small diameter, amorphous radio emission that may be the result of diffusion along radial magnetic fields set up in cooling inflows. Finally, the relationships between optical emission-line luminosity with radio power and mass-accretion rate are examined.

Burns, Jack O.↗
NASA NTRS2013

High-Resolution Near-Infrared Spectroscopy of an Equivalent Width-Selected Sample of Starbursting Dwarf Galaxies

Spectroscopic observations from the Large Binocular Telescope and the Very Large Telescope reveal kinematically narrow lines (approx. 50 km/s) for a sample of 14 Extreme Emission Line Galaxies (EELGs) at redshifts 1.4 < zeta < 2.3. These measurements imply that the total dynamical masses of these systems are low ( 3 × 10(exp 9) M). Their large [O III]5007 equivalent widths (500 − 1100 A) and faint blue continuum emission imply young ages of 10−100 Myr and stellar masses of 10(exp 8)−10(exp 9) M, confirming the presence of a violent starburst. The stellar mass formed in this vigorous starburst phase thus represents a large fraction of the total (dynamical) mass, without a significantly massive underlying population of older stars. The occurrence of such intense events in shallow potentials strongly suggests that supernova-driven winds must be of critical importance in the subsequent evolution of these systems.

Spectroscopy↗
NASA NTRS1980

Mars sample return: Site selection and sample acquisition study

Various vehicle and mission options were investigated for the continued exploration of Mars; the cost of a minimum sample return mission was estimated; options and concepts were synthesized into program possibilities; and recommendations for the next Mars mission were made to the Planetary Program office. Specific sites and all relevant spacecraft and ground-based data were studied in order to determine: (1) the adequacy of presently available data for identifying landing sities for a sample return mission that would assure the acquisition of material from the most important geologic provinces of Mars; (2) the degree of surface mobility required to assure sample acquisition for these sites; (3) techniques to be used in the selection and drilling of rock a samples; and (4) the degree of mobility required at the two Viking sites to acquire these samples.

Nickle, N.↗
NASA NTRS1973

Effects of cesium ions and cesium vapor on selected ATS-F samples

Thermal control coating samples were subjected to cesium ion beam and vapor exposures. Degradation of solar absorptance and infrared emittance were measured. Solar cells and samples selected from surfaces on the ATS-F spacecraft likely to experience ion or vapor impingement were bombarded by 10-volt cesium ions. Other samples were subjected to high levels of cesium vapor. Aluminum and white paint were backsputtered by 550-volt cesium ions onto selected samples. For direct bombardment, the threshold for ion-induced property changes was above five-thousand trillion ions/sq cm. With material sputtered from a 450-sq cm target onto samples 36 cm distant, the threshold for noticeable effects was above 5 times 10 to the 17-th power ions/sq cm.

Kemp, R. F.↗
NASA NTRS1986

The Medium Sensitivity Survey and the X-ray selected quasar sample

Statistical investigations of X-ray-emitting quasars are reviewed, focusing on the possible incompleteness of the Einstein IPC Medium Sensitivity Survey (MSS) (Maccacaro et al., 1982; Stocke et al., 1983; Gioia et al., 1984). The criteria used in constructing the MSS and calculating the source parameters are discussed, and the corrections determined for each line of sight by Maccacaro and Gioia (1986) on the basis of the H I measurements of Stark et al. (1986) are shown to have no effect on the completeness of the MSS extragalactic sample as a whole and of the quasar sample in particular. Other possible reasons for inconsistencies between the MSS sample and optically selected quasar samples are considered; ongoing efforts to expand the MSS sample are described; and some preliminary results are presented in graphs.

Gioia, Isabella M.↗
NASA NTRS1975

X-ray reflection and scatter measurements on selected optical samples

The results from an experimental program to determine the reflection efficiency and scatter parameters of selected optical samples are presented. The measurements were made using 8.34A X-rays at various angles of incidence. Selected samples were contaminated after being measured and then remeasured to determine the effects of contamination. The instrumentation involved in taking the data, including the X-ray reflectometer and data processing equipment, is discussed in detail. The condition of the optical surfaces, the total reflection measurements, the scatter measurements, and the analysis are discussed.

Fields, S. A.↗
NASA NTRS1974

Selection of sampling rate for digital control of aircrafts

The considerations in selecting the sample rates for digital control of aircrafts are identified and evaluated using the optimal discrete method. A high performance aircraft model which includes a bending mode and wind gusts was studied. The following factors which influence the selection of the sampling rates were identified: (1) the time and roughness response to control inputs; (2) the response to external disturbances; and (3) the sensitivity to variations of parameters. It was found that the time response to a control input and the response to external disturbances limit the selection of the sampling rate. The optimal discrete regulator, the steady state Kalman filter, and the mean response to external disturbances are calculated.

Katz, P.↗
NASA NTRS1993

A neutral hydrogen survey of the Hydra 1 cluster

We are undertaking a project to image the entire volume of the Hydra 1 cluster of galaxies in neutral hydrogen using the VLA. This involves making a series of pointings spaced 30 min. (the half power beam width) apart, each observed at three velocity settings in order to span the whole velocity range of the cluster. The purpose of this survey is to determine the true distribution, both in space and velocity, of gas-rich systems and hence, to deduce what effects a dense environment may have on the evolution of these systems. Most surveys of clusters to date have been performed on optically selected samples. However, optically selected samples may provide misleading views of the distribution of gas-rich systems, since many low surface brightness galaxies have an abundance of neutral gas (Bothun et al. 1987, Giovanelli & Haynes 1989). The Hydra project is providing the first unbiased view of the HI distribution in a cluster of galaxies. Our 5 sigma sensitivity is 4.1 x 10(exp 7) solar M/beam, (assuming H(sub 0) = 75 km s(exp -1) Mpc(exp -1)) and our velocity resolution is 42 km s(exp -1). We have a spatial resolution of 45 sec., which means that only the largest galaxies are spatially resolved enough to determine HI disk size. Our coverage is about 50 percent of the central region plus eight other fields centered on bright spirals within about 2 deg. of the center.

Mcmahon, Pauline↗
NASA NTRS1978

The effect of prefilter design on sample rate selection in digital flight control systems

The effect of prefilters on sample rate selection is examined and design procedures are determined for obtaining the best combination of prefilter breakpoint and sample rate. The employed approach involves a quantitative comparison of the output noise response of systems originating from the same basic plant and designed over a wide range of prefilters and sample rates. Each system design was carefully tailored so that it exhibited approximately identical responses to commands. The results presented augment the criteria for sample rate selection which have been discussed by Powell and Katz (1975). Attention is given to system characteristics, an integrator as a plant, and the short period motion of the F-8 aircraft.

Peled, U.↗
NASA NTRS2000

The Quasar Fraction in Low-Frequency Selected Complete Samples and Implications for Unified Schemes

Low-frequency radio surveys are ideal for selecting orientation-independent samples of extragalactic sources because the sample members are selected by virtue of their isotropic steep-spectrum extended emission. We use the new 7C Redshift Survey along with the brighter 3CRR and 6C samples to investigate the fraction of objects with observed broad emission lines - the 'quasar fraction' - as a function of redshift and of radio and narrow emission line luminosity. We find that the quasar fraction is more strongly dependent upon luminosity (both narrow line and radio) than it is on redshift. Above a narrow [OII] emission line luminosity of log(base 10) (L(sub [OII])/W) approximately > 35 [or radio luminosity log(base 10) (L(sub 151)/ W/Hz.sr) approximately > 26.5], the quasar fraction is virtually independent of redshift and luminosity; this is consistent with a simple unified scheme with an obscuring torus with a half-opening angle theta(sub trans) approximately equal 53 deg. For objects with less luminous narrow lines, the quasar fraction is lower. We show that this is not due to the difficulty of detecting lower-luminosity broad emission lines in a less luminous, but otherwise similar, quasar population. We discuss evidence which supports at least two probable physical causes for the drop in quasar fraction at low luminosity: (i) a gradual decrease in theta(sub trans) and/or a gradual increase in the fraction of lightly-reddened (0 approximately < A(sub V) approximately < 5) lines-of-sight with decreasing quasar luminosity; and (ii) the emergence of a distinct second population of low luminosity radio sources which, like M8T, lack a well-fed quasar nucleus and may well lack a thick obscuring torus.

Willott, Chris J.↗