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Molecules for Fluorescence Detection of Specific Chemicals

These molecules could be used in the detection of chemical warfare agents. A family of fluorescent dye molecules has been developed for use in “on-off” fluorescence detection of specific chemicals. By themselves, these molecules do not fluoresce. However, when exposed to certain chemical analytes in liquid or vapor forms, they do fluoresce (see figure). These compounds are amenable to fixation on or in a variety of substrates for use in fluorescence-based detection devices: they can be chemically modified to anchor them to porous or non-porous solid supports or can be incorporated into polymer films. Potential applications for these compounds include detection of chemical warfare agents, sensing of acidity or alkalinity, and fluorescent tagging of proteins in pharmaceutical research and development. These molecules could also be exploited for use as two-photon materials for photodynamic therapy in the treatment of certain cancers and other diseases.

Posted in: Briefs, TSP

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Nature Vs. Nurture



Posted in: Blog

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LiGa(OTf)4 as an Electrolyte Salt for Li-Ion Cells

This salt could improve rechargeable lithiumion cell performance. Lithium tetrakis(trifluoro- methanesulfonato) gallate [abbreviated “LiGa(OTf)4” (wherein “OTf” signifies trifluoro- methanesulfonate)] has been found to be promising as an electrolyte salt for incorporation into both liquid and polymer electrolytes in both rechargeable and non-rechargeable lithium-ion electro- chemical cells. This and other ingredients have been investigated in continuing research oriented toward improving the performances of rechargeable lithium-ion electrochemical cells, especially at low temperatures.

Posted in: Briefs

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Refractory Ceramic Foams for Novel Applications

Properties could be tailored for specific uses as insulators, filters, or catalyst supports. Workers at NASA Ames Research center are endeavoring to develop durable, oxidation- resistant, foam thermal protection systems (TPSs) that would be suitable for covering large exterior spacecraft surfaces, would have low to moderate densities, and would have temperature capabilities comparable to those of carbon- based TPSs [reusable at 3,000 °F (≈1,650 °C)] with application of suitable coatings. These foams may also be useful for repairing TPSs while in orbit. Moreover, on Earth as well as in outer space, these foams might be useful as catalyst supports and filters.

Posted in: Materials, Briefs, TSP

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Self-Deploying Trusses Containing Shape-Memory Polymers

Compacted structures can be used in shelters for hostile environments. Composite truss structures are being developed that can be compacted for stowage and later deploy themselves to full size and shape. In the target applications, these “smart” structures will precisely self-deploy and support a large, lightweight space-based antenna. Self-deploying trusses offer a simple, light, and affordable alternative to articulated mechanisms or inflatable structures. The trusses may also be useful in such terrestrial applications as variable-geometry aircraft components or shelters that can be compacted, transported, and deployed quickly in hostile environments.

Posted in: Briefs

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Compact, Highly Stable Ion Atomic Clock

This high-precision clock is designed for navigation and radio science applications. A mercury-ion clock now at the breadboard stage of development (see figure) has a stability comparable to that of a hydrogen-maser clock: In tests, the clock exhibited an Allan deviation of between 2 × 10–13 and 3 × 10–13 at a measurement time of 1 second, averaging to about 10–15 at 1 day. However, the clock occupies a volume of only about 2 liters — about a hundredth of the volume of a hydrogen- maser clock. The ion- handling parts of the apparatus are housed in a sealed vacuum tube, wherein only a getter pump is used to maintain the vacuum. Hence, this apparatus is a prototype of a generation of small, potentially portable high-precision clocks for diverse ground- and space-based navigation and radio science applications. Furthermore, this new ion-clock technology is about 100 times more stable and precise than the rubidium atomic clocks currently in use in the NAVSTAR GPS Earth-orbiting satellites.

Posted in: Briefs

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System Estimates Radius of Curvature of a Segmented Mirror

A system that estimates the global radius of curvature (GRoC) of a segmented telescope mirror has been developed for use as one of the subsystems of a larger system that exerts precise control over the displacements of the mirror segments. This GRoC-estimating system, when integrated into the overall control system along with a mirror-segment- actuation subsystem and edge sensors (sensors that measure displacements at selected points on the edges of the segments), makes it possible to control the GROC mirror-deformation mode, to which mode contemporary edge sensors are insufficiently sensitive. This system thus makes it possible to control the GRoC of the mirror with sufficient precision to obtain the best possible image quality and/or to impose a required wavefront correction on incoming or outgoing light.

Posted in: Briefs

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