The columbium-hydrogen system and hydrogen embrittlement of columbium

Columbium specimens are charged uniformly with hydrogen allowing accurate measurement of the hydrogen content by a procedure involving the removal of hydrogen from flowing argon at 2000 degrees F. Hydrogen content effects on the ductile-to-transition temperature are determined for temperatures between 200 and 600 degrees F

Purification train produces ultrapure hydrogen gas

Three-stage purification train produces ultrapure hydrogen gas at 1000 psi from K-bottles of high-purity hydrogen. The continuous process incorporates deoxidation and dehydration units and a molecular sieve

Probing clumpy stellar winds with a neutron star

INTEGRAL, the European Space Agency's gamma-ray observatory, tripled the number of super-giant high-mass X-ray binaries (sgHMXB) known in the Galaxy by revealing absorbed and fast transient (SFXT) systems. In these sources, quantitative constraints on the wind clumping of the massive stars could be obtained from the study of the hard X-ray variability of the compact accreting object. Hard X-ray flares and quiescent emission of SFXT systems have been characterized and used to derive wind clump parameters. A large fraction of the hard X-ray emission is emitted in the form of flares with a typical duration of 3 ks, frequency of 7 days and luminosity of 1E36 erg/s. Such flares are most probably emitted by the interaction of a compact object orbiting at ~10 R* with wind clumps (1E(22-23) g) representing a large fraction of the stellar mass-loss rate. The density ratio between the clumps and the inter-clump medium is 1E(2-4) in SFXT systems. The parameters of the clumps and of the inter-clump medium, derived from the SFXT flaring behavior, are in good agreement with macro-clumping scenario and line driven instability simulations. SFXT have probably a larger orbital radius than classical sgHMXB.Comment: 8 page

Low-temperature embrittlement of Ti-6Al-4V and Inconel-718 by high pressure hydrogen

Notched specimens of titanium alloy and Inconel-718 exhibit little reduction of notch strength at certain low temperatures under 2000 lb/sq in. hydrogen, unnotched specimens are not embrittled at these temperatures. The degree of Inconel-718 embrittlement is lower than earlier observations under 1000 lb/sq in. hydrogen

Coaxial cable connector

A coaxial cable connector is provided, which resists radio frequency breakdown in coaxial cables used in the vacuum of outer space. The connector body surrounds an insulator which includes an easily compressible elastomeric portion. An insulated coaxial cable is prepared so that its insulation projects beyond the outer conductor and compresses the elastomeric portion of the connector insulator

Changes in banking concentration in selected Fifth district SMSAs, 1970-1976

An abstract for this article is not availableBanks and banking ; Federal Reserve District, 5th

Neutron star masses from hydrodynamical effects in obscured sgHMXBs

A population of obscured supergiant High Mass X-ray Binaries (sgHMXBs) has been discovered by INTEGRAL. X-ray wind tomography of IGR J17252-3616 inferred a slow wind velocity to account for the enhanced obscuration. The main goal of this study is to understand under which conditions high obscuration could occur. We have used an hydrodynamical code to simulate the flow of the stellar wind around the neutron star. A grid of simulations was used to study the dependency of the absorbing column density and of the X-ray light-curves on the model parameters. A comparison between the simulation results and the observations of IGR J17252-3616 provides an estimate on these parameters. We have constrained the wind terminal velocity to 500-600 km/s and the neutron star mass to 1.75-2.15 solar masses. We have confirmed that the initial hypothesis of a slow wind velocity with a moderate mass loss rate is valid. The mass of the neutron star can be constrained by studying its impact on the accretion flow.Comment: A&A in pres

Decorrelating a compressible turbulent flow: an experiment

Floating particles that are initially distributed uniformly on the surface of a turbulent fluid, subsequently coagulate, until finally a steady state is reached. This being so, they manifestly form a compressible system. In this experiment, the information dimension D_1, and the Lyapunov exponents of the coagulated floaters, are measured. The trajectories and the velocity fields of the particles are captured in a sequence of rapidly acquired images. Then the velocity sequence is randomly shuffled in time to generate new trajectories. This analysis mimics the Kraichnan ensemble and yields properties of a velocity correlation function that is delta-correlated in time (but not in space). The measurements are compared with theoretical expectations and with simulations of Boffetta et al., that closely mimic the laboratory experiment reported here.Comment: 6 pages, 5 figure

UV spectral analysis of very hot H-deficient [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6, and Sand 3

We analysed UV FUSE, IUE, and HST/STIS spectra of five of the hottest [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6, and Sand 3. The analysis leveraged on our grid of CMFGEN synthetic spectra, which covers the parameter regime of hydrogen deficient central stars of planetary nebulae and allows a uniform and systematic study of the stellar spectra. The stellar atmosphere models calculated by us include many elements and ionic species neglected in previous analyses, which allowed us to improve the fits to the observed spectra considerably and provided an additional diagnostic line: the Ne VII $\lambda$ 973 $\mathrm{\AA}$, which had not been modelled in [WCE] spectra and which presents, in these stars, a strong P-Cygni profile. We report newly derived photospheric and wind parameters and elemental abundances. The central stars of NGC 2867, NGC 5189, and Pb 6 had their temperatures revised upward in comparison with previous investigations and we found the carbon to helium mass ratio of the sample objects to span a wide range of values, 0.42$\leq$C:He$\leq$1.96. Modelling of the Ne VII $\lambda$ 973 $\mathrm{\AA}$ P-Cygni profile indicated strong neon overabundances for the central stars of NGC 2867, NGC 5189, NGC 6905, and Pb 6, with Ne mass fractions between 0.01 and 0.04. Nitrogen abundances derived by us for the central stars of NGC 5189, Pb 6, and Sand 3 are higher than previous determinations by factors of 3, 10, and 14, respectively.Comment: Accepted on MNRA