Comparison of thermal insulation performance of fibrous materials for the advanced space suit.
The current multi-layer insulation used in the extravehicular mobility unit (EMU) will not be effective in the atmosphere of Mars due to the presence of interstitial gases. Alternative thermal insulation means have been subjected to preliminary evaluation by NASA to attempt to identify a material that will meet the target conductivity of 0.005 W/m-K. This study analyzes numerically the thermal conductivity performance for three of these candidate insulating fiber materials in terms of various denier (size), interstitial void fractions, interstitial void media, and orientations to the applied temperature gradient to evaluate their applicability for the new Mars suit insulation. The results demonstrate that the best conductive insulation is achieved for a high-void-fraction configuration with a grooved fiber cross section, aerogel void medium, and the fibers oriented normal to the heat flux vector. However, this configuration still exceeds the target thermal conductivity by a factor of 1.5.
Investigation of crosslinked silica aerogels for implant applications
Silica-based Aerogels have a number of unique properties that make them suitable for a range of applications. These include superior thermal, acoustic, and electrical insulation capabilities, all associated with the highly-porous nature of this class of materials. Crosslinked (X) silica aerogels have improved mechanical and surface properties making them suitable for biomedical device applications, particularly in the peripheral regions of the body. Aerogel's ability to dampen sounds waves is particularly important since it would allow an external non-invasive imaging technique for aerogel based implants. The biocompatibility of this class of material must be addressed prior to the development of in vivo imaging data. In this work, the authors report on the growth and interaction of Opossum Kidney cells and dorsal root ganglia on crosslinked silica aerogels, paving the way for implant applications.
Cooperative Collection Development
The author discusses cooperative collection development from an historical perspective and examines some of the projects conceived and implemented during the past forty years. In many cases the projects failed even after years of concentrated effort. However, more important than these failures are new efforts that are being made. The major focus of this article is on both current regional projects and the more broadly based ARL-sponsored North American Collections Inventory Project. The author discusses these efforts and offers some specific judgments regarding the possibility that these projects will lead to a truly successful coordinated collection development project on a national basis.