POWER FLATTENING STUDIES FOR RADIOISOTOPE-THERMOELECTRIC GENERATORS. Final Report

The natural exponential decay of a radioisotope used as a heat source for a thermoelectric generator makes the use of a power flattening'' device highly desirable, especially when the duration of the mission is large compared to the half life of the radioisotope. Power-flattening devices are considered which either dump excess heat outside the thermoelectric generator or use the characteristics of the generator to absorb the excess heat and thereby regulate the hot junction temperature. A number of power-flattening devices were studied both analytically and experimentally with a view toward operability in space. The most promising concepts are (a) to utilize a secondary radiator of variable area; (b) to provide thermal shunts that are sequentially removed during the mission; (c) to use a secondary radiator coupled to the heat source through a slowly evaporating thermal connection. (auth

Atomic Energy Commission Report NYO-9783

"The natural exponential decay of a radioisotope used as a heat source for a thermoelectric generator makes the use of a power flattening'' device highly desirable, especially when the duration of the mission is large compared to the half-life of the radioisotope. Power-flattening devices are considered which either dump excess heat outside the thermoelectric generator or use the characteristics of the generator to absorb the excess heat and thereby regulate the hot junction temperature. A number of power-flattening devices were studied both analytically and experimentally with a view toward operability in space. The most promising concepts are (a) to utilize a secondary radiator of variable area; (b) to provide thermal shunts that are sequentially removed during the mission; (c) to use a secondary radiator coupled to the heat source through a slowly evaporating thermal connection.

Cottoquinazoline A and Cotteslosins A and B, metabolites from an australian marine-derived strain of aspergillus versicolor

An Australian marine-derived isolate of Aspergillus versicolor (MST-MF495) yielded the known fungal metabolites sterigmatocystin, violaceol I, violaceol II, diorcinol, (−)-cyclopenol, and viridicatol, along with a new alkaloid, cottoquinazoline A (1), and two new cyclopentapeptides, cotteslosins A (2) and B (3). Structures for 1−3 and the known compounds were determined by spectroscopic analysis. The absolute configurations of 1−3 were addressed by chemical degradation and application of the C3 Marfey’s method. The use of “cellophane raft” high-nutrient media as a device for up-regulating secondary metabolite diversity in marine-derived fungi is discussed. The antibacterial properties displayed by A. versicolor (MST-MF495) were attributed to the phenols violaceol I, violaceol II, and diorcinol, while cotteslosins 2 and 3 were identified as weak cytotoxic agents