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Shields, A.

Publications and source records attributed to Shields, A..

A review of melt and vapor growth techniques for polydiacetylene thin films for nonlinear optical applications

Methods for the growth of polydiacetylene thin films by melt and vapor growth and their subsequent polymerization are summarized. Films with random orientations were obtained when glass or quartz were used as substrates in the vapor growth process. Oriented polydiacetylene films were fabricated by the vapor deposition of diacetylene monomer onto oriented polydiacetylene on a glass substrate and its subsequent polymerization by UV light. A method for the growth of oriented thin films by a melt-shear growth process as well as a method of film growth by seeded recrstallization from the melt between glass plates, that may be applied to the growth of polydiacetylene films, are described. Moreover, a method is presented for the fabrication of single crystal thin films of polyacetylenes by irradiation of the surface of diacetylene single crystals to a depth between 100 and 2000 angstroms.

Penn, B. G.

Frameworks for the future

NASA is exploring the techniques and technologies which will permit the construction of large structures in space. EASE (Experimental Assembly of Structures in Extravehicular Activity) and ACCESS (Assembly Concept for Construction of Erectable Space Structures) are structures which are carried in the Atlantis bay and are assembled in space by astronauts. The experimental structures were designed to be durable and strong, easily assembled, have removable parts, and be amenable to alterations using specially-designed tools. All space activities are first rehearsed in detail on earth, mainly in the NASA Neutral Buoyancy Facility. Thorough studies are also being done to examine the human factors of space assembly and to gather biomedical data to characterize the capabilities of humans doing construction work in space.

Mcmahan, T.