Thermal shock and erosion resistant tantalum carbide ceramic material

Ceramic tantalum carbide artifacts with high thermal shock and mechanical erosion resistance are provided by incorporating tungsten-rhenium and carbon particles in a tantalum carbide matrix. The mix is sintered by hot pressing to form the ceramic article which has a high fracture strength relative to its elastic modulus and thus has an improved thermal shock and mechanical erosion resistance. The tantalum carbide is preferable less than minus 100 mesh, the carbon particles are preferable less than minus 100 mesh, and the tungsten-rhenium particles are preferable elongate, having a length to thickness ratio of at least 2/1. Tungsten-rhenium wire pieces are suitable as well as graphite particles

Determination of elevated-temperature fatigue data on refractory alloys in ultra- high vacuum fourth quarterly report, 1 apr. - 1 jul. 1965

High temperature fatigue data on refractory alloys in ultrahigh vacuum - tests on titanium- zirconium-molybdenu

Determination of elevated-temperature fatigue data on refractory alloys in ultra-high vacuum Fifth quarterly report, 1 Jul. - 1 Oct. 1965

Elevated-temperature fatigue data on notched and smooth specimens of refractory alloys in ultrahigh vacuum environment

Combined high vacuum/high frequency fatigue tester

Apparatus permits application of significantly greater number of cycles or equivalent number of cycles in shorter time than conventional fatigue test machines. Environment eliminates problems associated with high temperature oxidation and with sensitivity of refractory alloy behavior to atmospheric contamination

Out of Sight, Out of Mind: Including Group Quarters Residents with Household Residents Can Change What We Know About Working-Age People with Disabilities

Information about residents of institutional and noninstitutional group quarters (GQ), particularly those with disabilities, has been limited by gaps in survey data, and statistics based on data that exclude some or all GQ residents are biased as estimates of total population statistics. We used the 2006 and 2007 American Community Survey (ACS) to identify the distribution of working-age populations with and without disabilities by major residence type, and to assess the sensitivity of disability statistics to GQ residence. Our findings showed that (1) of those with disabilities, about one in 13 males and one in 33 females live in GQ; (2) younger males with disabilities are more likely to reside there, particularly at institutional GQ; (3) individuals with and without disabilities who are black, American Indian, never married, or have less than a high school education had higher GQ residence rates; (4) 40% of male and 62% of female GQ residents have a disability; (5) adding GQ residents to household residents increases estimated disability prevalence for males by 6% and the estimated difference between disability prevalence rates by gender nearly disappears; and (6) inclusion of the GQ population substantively lowers employment rate estimates for males with disabilities—especially young blacks and American Indians

Effect of protective coatings on the stress- corrosion properties of supersonic-transport skin materials eleventh quarterly status report, 1 jun. - 31 aug. 1965

Protective coatings effect on stress corrosion properties of supersonic transport skin material

Effect of protective coatings on the stress- corrosion properties of supersonic-transport skin materials tenth quarterly status report, 1 mar. - 31 may 1965

Protective coating effect on stress corrosion properties of supersonic transport skin materials - bending-ductility evaluatio

Determination of elevated-temperature fatigue data on refractory alloys in ultra- high vacuum third quarterly report, 1 jan. - 1 apr. 1965

Fatigue data for refractory alloys at elevated temperatures in ultrahigh-vacuum environment

Soil Freeze-Thaw Processes: Implications for Nutrient Cycling

Soil freeze-thaw processes can regulate nutrient availability to plants by influencing nutrient leakage from plant tissues, nutrient release from soil organisms, mineral weathering, various inorganic nutrient transformations, and nutrient transport in both soil solution and sediment. These aspects of freeze-thaw processes are given in this review. A frequently reported observation is that soil water content controls the extent of freeze-thaw impacts on several chemical, physical, and biological processes and components important for nutrient cycling. Practices affecting soil water content, such as tillage and crop residue management, may therefore provide opportunities for managing freeze-thaw impacts on nutrient use efficiency in crop production

Observations of V592 Cas -— an Outflow at Optical Wavelengths

We present new red optical spectra of V592 Cas aimed at exploring the properties of the outflow of this system in a spectral region where the underlying white dwarf and the accretion disk do not contribute significantly to the observed absorption components of the Hα and He I line profiles. We use the Hα emission line to study the wind, which appears as pronounced blueshifted P Cygni absorption troughs whose low velocity end contaminates the blue side of the emission line profile. The wind appears to be episodic in nature, with multiple events reaching velocities of 5000 km s^–1 in Hα. Similar (but weaker) wind signatures appear in the He I 5876 Å line but are absent in He I 6678 Å. Our data suggest that during wind episodes the wind is phase dependent and is visible for half of the orbit of the system. Considering that V592 Cas is viewed almost face-on, the symmetry axis of the outflow cannot be orthogonal to the disk and/or the outflow must have some other inherent asymmetry in outflow geometry. A possible origin of the wind is in a disk hotspot, either at the initial impact point of the accretion stream on the disk edge or as a result of disk overflow (similar to SW Sextantis stars). Simultaneous optical photometry during one night of our spectroscopic observations indicate that there is no clear relationship between the optical brightness variations and the strength of the outflow in this system