OGO 5 measurements of the Lyman alpha sky background
Lyman alpha sky background measurements by OGO 5 satellite, discussing absolute emission rate, spatial variations and origin
Krassa, R. F.↗
SEARCH · Engineering Papers
Results for “Alpha 5”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Three-dimensional structure of Schistosoma japonicum glutathione S-transferase fused with a six-amino acid conserved neutralizing epitope of gp41 from HIV
The 3-dimensional crystal structure of glutathione S-transferase (GST) of Schistosoma japonicum (Sj) fused with a conserved neutralizing epitope on gp41 (glycoprotein, 41 kDa) of human immunodeficiency virus type 1 (HIV-1) was determined at 2.5 A resolution. The structure of the 3-3 isozyme rat GST of the mu gene class was used as a molecular replacement model. The structure consists of a 4-stranded beta-sheet and 3 alpha-helices in domain 1 and 5 alpha-helices in domain 2. The space group of the Sj GST crystal is P4(sub 3)2(sub 1)2 with unit cell dimensions of a = b = 94.7 A, and c = 58.1 A. The crystal has 1 GST monomer per asymmetric unit, and 2 monomers that form an active dimer are related by crystallographic 2-fold symmetry. In the binding site, the ordered structure of reduced glutathione is observed. The gp41 peptide (Glu-Leu-Asp-Lys-Trp-Ala) fused to the C-terminus of Sj GST forms a loop stabilized by symmetry-related GSTs. The Sj GST structure is compared with previously determined GST structures of mammalian gene classes mu, alpha, and pi. Conserved amino acid residues among the 4 GSTs that are important for hydrophobic and hydrophilic interactions for dimer association and glutathione binding are discussed.
Lim, Kap↗
Three-dimensional structure of Schistosoma japonicum glutathione S-transferase fused with a six-amino acid conserved neutralizing epitope of gp41 from HIV
The 3-dimensional crystal structure of glutathione S-transferase (GST) of Schistosoma japonicum (Sj) fused with a conserved neutralizing epitope on gp41 (glycoprotein, 41 kDa) of human immunodeficiency virus type 1 (HIV-1) (Muster T et al., 1993, J Virol 67:6642-6647) was determined at 2.5 A resolution. The structure of the 3-3 isozyme rat GST of the mu gene class (Ji X, Zhang P, Armstrong RN, Gilliland GL, 1992, Biochemistry 31:10169-10184) was used as a molecular replacement model. The structure consists of a 4-stranded beta-sheet and 3 alpha-helices in domain 1 and 5 alpha-helices in domain 2. The space group of the Sj GST crystal is P4(3)2(1)2, with unit cell dimensions of a = b = 94.7 A, and c = 58.1 A. The crystal has 1 GST monomer per asymmetric unit, and 2 monomers that form an active dimer are related by crystallographic 2-fold symmetry. In the binding site, the ordered structure of reduced glutathione is observed. The gp41 peptide (Glu-Leu-Asp-Lys-Trp-Ala) fused to the C-terminus of Sj GST forms a loop stabilized by symmetry-related GSTs. The Sj GST structure is compared with previously determined GST structures of mammalian gene classes mu, alpha, and pi. Conserved amino acid residues among the 4 GSTs that are important for hydrophobic and hydrophilic interactions for dimer association and glutathione binding are discussed.
Schistosoma japonicum/enzymology/genetics/immunolo↗
Mariner 5 measurement of Lyman-alpha radiation near Venus.
Atomic hydrogen density and Venus upper atmosphere temperature measured by Mariner 5 observation of Lyman-alpha radiation
Barth, C. A.↗
In situ measurement of low-Z material coating thickness on high Z substrate for tokamaks
Rutherford backscattering of energetic particles can be used to determine the thickness of a coating of a low-Z material over a heavier substrate. Simulations indicate that 5 MeV alpha particles from an {sup 241}Am source can be used to measure the thickness of a Li coating on Mo tiles between 0.5 and 15 μm thick. Using a 0.1 mCi source, a thickness measurement can be accomplished in 2 h of counting. This technique could be used to measure any thin, low-Z material coating (up to 1 mg/cm{sup 2} thick) on a high-Z substrate, such as Be on W, B on Mo, or Li on Mo. By inserting a source and detector on a moveable probe, this technique could be used to provide an in situ measurement of the thickness of Li coating on NSTX-U Mo tiles. A test stand with an alpha source and an annular solid-state detector was used to investigate the measurable range of low-Z material thicknesses on Mo tiles.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Experimental investigation of the flowfield of an oscillating airfoil
The flowfield of an airfoil oscillated periodically over a wide range of reduced frequencies, 0 less than or = k less than or = 1.6 is studied experimentally at chord Reynolds numbers of R sub c = 22,000 and 44,000. The NACA0012 airfoil is pitched sinusoidally about one quarter chord between angles of attack (alpha) of 5 and 25 degrees. Detailed flow visualization and phase averaged vorticity measurements are carried out for k = 0.2 to document the evolution and the shedding of the dynamic stall vortex (DSV). In addition to the DSV, an intense vortex of opposite sign originates from the trailing edge just when the DSV is shed. After being shed into the wake, the two together take the shape of a large 'mushroom' while being convected away from the airfoil. The unsteady circulation around the airfoil and, therefore, the time varying component of the lift is estimated in a novel way from the shed vorticity flux and is found to be in good agreement with the lift variation reported by others. The delay in the shedding of the DSV with increasing k, as observed by previous researchers, is documented for the full range of k. The DSV, for example, is shed nearly at the maximum alpha of 25 degrees at k = 0.2, but is shed at the minimum alpha of 5 degrees at k = 0.8. At low k, the flowfield appears quasi-steady and the bluff body shedding corresponding to the maximum alpha (25 degrees) dominates the unsteady fluctuations in the wake.
Panda, J.↗
Experimental investigation of the flowfield of an oscillating airfoil
The flow field of an airfoil oscillated periodically over a wide range of reduced frequencies, 0 less than k less than 1.6, is studied experimentally at chord Reynolds numbers of R sub c = 22,000 and 44,000. The NACA0012 airfoil is pitched sinusoidally about one quarter chord between alpha of 5 deg and 25 deg. Detailed flow visualization and phase averaged vorticity measurements are carried out for k = 0.2 to document the evolution and the shedding of the dynamic stall vortex (DSV). In addition to the DSV, an intense vortex of opposite sign originates from the trailing edge just when the DSV is shed. After being shed into the wake, the two together take the shape of a large 'mushroom' while being convected away from the airfoil. The unsteady circulation around the airfoil and, therefore, the time varying component of the lift is estimated in a novel way from the shed vorticity flux and is found to be in good agreement with the lift variation reported by others. The delay in the shedding of the DSV with increasing k, as observed by previous researchers, is documented for the full range of k. The DSV, for example, is shed nearly at the maximum alpha of 25 deg at k = 0.2, but is shed at the minimum alpha of 5 deg at k = 0.8. At low k, the flowfield appears quasi-steady and the bluff body shedding corresponding to the maximum alpha (25 deg) dominates the unsteady fluctuations in the wake.
Panda, J.↗
The X-Ray, Optical and Infrared Counterpart to GRB 980703
We report on our X-ray, optical and infrared follow-up observations of GRB980703. A previously unknown X-ray source in the GRB error box displays a powerlaw decline with index alpha= -1.0,5(exp +0.24 sub -0.29), fairly consistent with the average optical/infrared decay index alpha = -1.61 plus or minus 0.12. We invoke host galaxy extinction to match the observed spectral slope with the slope expected from 'fireball' models. The hypothesis that between 1998 July 4.4 and 8.4 UT no spectral breaks are present in the infrared to X-ray spectral range is in good agreement with the observations. For these two epochs we obtain an extinction of A(sub v) = 1.50 +/- 0.11 (July 4.4) and A(sub v) = 0.85 +/- 0.26 (July 8.4). From the X-ray data we estimate the optical extinction to be A(sub v) = 20.2(+12.3/-7.3), inconsistent with the former value. Optical spectra we took confirm the redshift of z=0.966 found by Djorgovski et al. We compare the afterglow of GRB 980703 with that of GRB 970508 and find that the fraction of the energy in the magnetic field is much lower in the case of GRB 980703.
Vreeswijk, P. M.↗
Evaluation of radiation hardness of semiconductor materials against alpha particles for an API detector
An Associated Particle Imaging (API) system consists of a high vacuum chamber where deuterium ions are accelerated on a tritium-loaded target, resulting in alpha particles and neutrons emitted back-to-back, the latter escaping the chamber and used, for example, for tomography of a high-Z sample. An accurate determination of the alpha position is crucial to determine the trajectory of the neutron. Existing API systems have several limitations which a semiconductor-based API detector placed inside the vacuum chamber should not present. The semiconductor material can be either silicon or diamond. In particular, large and fast signals are generated by the alpha interactions in these materials. A pixelated API detector will measure the time and hit position of the alphas produced in the reaction. However, during the lifetime of the generator, the semiconductor detector will be exposed to an intense flux of alpha particles that will degrade its performance over time. To assess the radiation hardness of silicon and diamond against the alpha particles, we exposed single diodes made of either of the two materials to a 5 MeV alpha flux generated by an 241Am radioactive source. During irradiation, the diodes were biased and mounted on current-sensitive preamplifier boards. We have therefore been able to measure insitu the evolution of the waveforms as the damage was accumulating in their substrates.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
X-ray spectra of a complete sample of extragalactic core-dominated radio sources
We present ROSAT soft X-ray spectra for the members of a complete sample of 13 core-dominated, flat radio spectrum sources. The sample comprises all radio sources from a flux-limited radio catalog (S(sub 5GHz) greater than 1 Jy; Kuehr et al. 1981) which are north of delta = 70 deg, at galactic latitudes b greater than 10 deg, and have a flat radio spectrum between 1.4 and 5 GHz (alpha(sub r) less than 0.5; f approximately nu(sup -alpha)). The sources have already undergone much study at radio and optical wavelengths and are classified in broad terms as quasars (8 sources) and BL Lac objects (5 sources). We find mean X-ray power-law energy indices of alpha(sub x) = 0.59 +/- 0.19 for the quasars and 1.36 +/- 0.27 for the BL Lac objects (68% confidence range for two parameters of interest as determined by a maximum likelihood method), supporting earlier Einstein Observatory results for heterogeneous samples of sources (Worrall & Wilkes 1990). A non-zero dispersion on alpha(sub x) is found for both the quasars and the BL Lac objects. When we incorporate published radio, mm, and optical measurements and compare the X-ray and broad-band spectral indices alpha(sub x), alpha(sub rx), alpha(sub mm,x), and alpha(sub ox), the most obvious difference between the quasar and BL Lac subsamples lies within the X-ray band. We have fitted the multi-wavelength data to inhomogeneous synchotron-self-Compton models and find that, for the BL Lac objects with steep X-ray spectra, synchotron emission can account for the radio to soft X-ray measurements, whereas the BL Lac objects with hard X-ray spectra and the quasars require significant Compton emission to model the spectral flattening indicated by alpha(sub x) less than alpha(sub ox).
Brunner, H.↗
Alpha radioactivity of the lunar surface at the Surveyor 5, 6, and 7 landing sites
Alpha radioactivity of lunar surface at Surveyor 5, 6, and 7 landing sites
Economou, T. E.↗
Materials Data on MnC5IO5 by Materials Project
IMn(CO)5 is alpha U structured and crystallizes in the orthorhombic Cmcm space group. The structure is zero-dimensional and consists of four IMn(CO)5 clusters. Mn3+ is bonded in a 6-coordinate geometry to five C+1.60+ and one I1- atom. There is one shorter (1.84 Å) and four longer (1.88 Å) Mn–C bond length. The Mn–I bond length is 2.76 Å. There are two inequivalent C+1.60+ sites. In the first C+1.60+ site, C+1.60+ is bonded in a distorted single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.15 Å. In the second C+1.60+ site, C+1.60+ is bonded in a single-bond geometry to one Mn3+ and one O2- atom. The C–O bond length is 1.15 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+1.60+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+1.60+ atom. I1- is bonded in a single-bond geometry to one Mn3+ atom.
36 MATERIALS SCIENCE↗
Materials Data on Cr(NO3)5 by Materials Project
Cr(NO3)5 is alpha Selenium structured and crystallizes in the trigonal P3_221 space group. The structure is zero-dimensional and consists of three Cr(NO3)5 clusters. Cr5+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Cr–O bond distances ranging from 2.04–2.07 Å. There are three inequivalent N5+ sites. In the first N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.24 Å) and one longer (1.31 Å) N–O bond length. In the second N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of N–O bond distances ranging from 1.24–1.30 Å. In the third N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.21 Å) and two longer (1.31 Å) N–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one N5+ atom. In the second O2- site, O2- is bonded in an L-shaped geometry to one Cr5+ and one N5+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one N5+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cr5+ and one N5+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one N5+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one N5+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Cr5+ and one N5+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one N5+ atom.
36 MATERIALS SCIENCE↗
Alpha radioactivity of the lunar surface at the landing sites of Surveyors 5, 6, and 7
Lunar surface alpha radioactivity at Surveyor 5, 6 and 7 landing sites
Economou, T. E.↗
Materials Data on K2(CuTe)5 by Materials Project
K2(CuTe)5 is alpha bismuth trifluoride-derived structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight Te2- atoms. There are a spread of K–Te bond distances ranging from 3.59–3.78 Å. There are three inequivalent Cu+1.60+ sites. In the first Cu+1.60+ site, Cu+1.60+ is bonded to four Te2- atoms to form a mixture of edge and corner-sharing CuTe4 tetrahedra. There are two shorter (2.57 Å) and two longer (2.60 Å) Cu–Te bond lengths. In the second Cu+1.60+ site, Cu+1.60+ is bonded to four Te2- atoms to form a mixture of edge and corner-sharing CuTe4 tetrahedra. There are two shorter (2.61 Å) and two longer (2.66 Å) Cu–Te bond lengths. In the third Cu+1.60+ site, Cu+1.60+ is bonded to four Te2- atoms to form a mixture of edge and corner-sharing CuTe4 tetrahedra. There are a spread of Cu–Te bond distances ranging from 2.65–2.74 Å. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 8-coordinate geometry to four equivalent K1+ and four Cu+1.60+ atoms. In the second Te2- site, Te2- is bonded in a 8-coordinate geometry to four equivalent K1+ and four Cu+1.60+ atoms. In the third Te2- site, Te2- is bonded in a 6-coordinate geometry to two equivalent K1+ and four Cu+1.60+ atoms.
36 MATERIALS SCIENCE↗
Materials Data on ReC5IO5 by Materials Project
ReI(CO)5 is alpha carbon monoxide-derived structured and crystallizes in the orthorhombic Cmcm space group. The structure is zero-dimensional and consists of twenty formaldehyde molecules and four iodorhenium molecules.
36 MATERIALS SCIENCE↗
Radial widths, optical depths, and eccentricities of the Uranian rings
Observations of the stellar occultation by the Uranian rings of 15/16 August 1980 are used to estimate radial widths and normal optical depths for segments of rings 6, 5, 4, alpha, beta, eta, gamma, and delta. Synthetic occultation profiles are generated to match the observed light curves. A review of published data confirms the existence of width-radius relations for rings alpha and beta, and indicates that the optical depths of these two rings vary inversely with their radial widths. Masses are obtained for rings alpha and beta, on the assumption that differential precession is prevented by their self-gravity. A quantitative comparison of seven epsilon-ring occultation profiles obtained over a period of 3.4 yr reveals a consistent structure, which may reflect the presence of unresolved gaps and subrings.
Nicholson, P. D.↗
CO mapping of the Orion molecular cloud: The influence of star formation on cloud structure
Regions of massive star formation have long been believed to have a profound influence on the structure of their surrounding molecular clouds. The ways in which massive star formation has altered the structure and kinematics of the Orion Molecular Cloud are discussed. The data to be discussed consists of a large scale map of the CO J=1-0 emission from approximately 3 square degrees of OMC-1. During 1985, the Five College Radio Astronomy Observatory 14M antenna was used to map a 2 deg x 1 deg region centered on alpha(1950) = 5(h)33(m)00(s) delta(1950) = -5 deg 30 min. The region mapped in 1985 covers the well known HII regions M42, M43, and NGC1977, and the CO map contains abundant evidence of the interaction between these regions and the molecular cloud. Indeed, the global structure of the cloud appears to have been strongly influenced by the continuous formation of massive stars within the cloud. Individual instances of some of these features are discussed. There appear to be two classes of features which are indicative of this interaction: CO bright rims and CO holes. During 1986, we have undertaken further mapping of OMC-1 to the south of the region covered by the 1985 map. This portion of the cloud contains significant regions of star formation, but O star formation has not occured and large HII regions have not developed to alter the appearance of the cloud. A detailed map of this region is thus an opportunity to view the structure of the molecular cloud before it has been altered by massive star formation. Preliminary analysis of data obtained in this region suggests that the structure and kinematics of the southern portion of the Orion cloud are indeed dramatically different from those of the region previously mapped. Comparison of the two regions thus supports models of the development of structure in molecular clouds through interaction with the HII regions formed within them.
Schloerb, F. P.↗