Chemical kinetic performance losses for a hydrogen laser thermal thruster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77288/1/AIAA-25927-132.pd

Effect of Magnetic-Field on the Microstructure and Macrosegregation in Directionally Solidified Pb-Sn Alloys

An investigation into the influence of a transverse magnetic field (0.45 T) on the mushy zone morphology and macrosegregation in directionally solidified hypoeutectic Pb-Sn alloy shows that the field has no influence on the morphology of dendritic arrays. The field does, however, cause severe distortion in the cellular array morphology. Cellular arrayed growth with the magnetic field results in an extensive channel formation in the mushy zone, as opposed to the well-aligned and uniformly distributed cells formed in the absence of the field. The channels are produced due to the anisotropy in the thermosolutal convection caused by the magnetic field. Macrosegregation, however, along the length of the directionally solidified samples is not influenced by this magnetic field for either the cellular or dendritic arrays

High performance materials in coal conversion utilization. Final report, October 1, 1993--September 30, 1996

This report describes the research conducted at the University of Tennessee Space Institute on high performance materials for use in corrosive environments. The work was supported by a US Department of Energy University Coal Research grant. Particular attention was given to the silicon carbide particulate reinforced alumina matrix ceramic composite manufactured by Lanxide Corporation as a potential tubular component in a coal-fired recuperative high-temperature air heater. Extensive testing was performed to determine the high temperature corrosion effects on the strength of the material. A computer modeling of the corrosion process was attempted but the problem proved to be too complex and was not successful. To simplify the situation, a computer model was successfully produced showing the corrosion thermodynamics involved on a monolithic ceramic under the High Performance Power System (HIPPS) conditions (see Appendix A). To seal the material surface and thus protect the silicon carbide particulate from corrosive attack, a dense non porous alumina coating was applied to the material surface. The coating was induced by a defocused carbon dioxide laser beam. High temperature corrosion and strength tests proved the effectiveness of the coating. The carbon dioxide laser was also used to successfully join two pieces of the Lanxide material, however, resources did not allow for the testing of the resulting joint

Adult-limited dietary restriction slows gompertzian aging in Caenorhabditis elegans

Dietary restriction (DR) delays the onset of age-related deterioration and extends the life span in a variety of model organisms. In many species, age changes in mortality obey the Gompertz equation, which describes an exponential increase with age in age-specific mortality rate. Recently, this model has been used in fruitflies and rodents to investigate the mechanism by which DR reduces adult mortality. We report that food restriction imposed by axenic culture reduces the exponential increase of age-specific mortality of Caenorhabditis elegans. Furthermore, the life span appears largely independent of nutritional status during development, as shown by shifting worms to different food concentrations shortly before adulthood. When DR was exerted after reproduction, a smaller reduction in Gompertzian aging was seen. Thus, the demographic changes exerted by DR in C. elegans resemble those seen in rats, yet are different to those seen in Drosophila and mice