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Electron-Spin Filters Based on the Rashba Effect

Filters would be made from nonmagnetic semiconductors and operated without applied magnetic fields. Semiconductor electron-spin filters of a proposed type would be based on the Rashba effect, which is described briefly below. Electron-spin filters — more precisely, sources of spin-polarized electron currents — have been sought for research on, and development of, the emerging technological discipline of spintronics (spin-based electronics). There have been a number of successful demonstrations of injection of spin-polarized electrons from diluted magnetic semiconductors and from ferromagnetic metals into nonmagnetic semiconductors. In contrast, a device according to the proposal would be made from nonmagnetic semiconductor materials and would function without an applied magnetic field.

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Thermally Insulating, Kinematic Tensioned-Fiber Suspension

Tensioned polymer fibers afford both rigidity and high thermal resistance. Figure 1 shows a salt pill and some parts of a thermally insulating, kinematic suspension system that holds the salt pill rigidly in an adiabatic demagnetization refrigerator (ADR). “Salt pill” in this context denotes a unit comprising a cylindrical container, a matrix of gold wires in the container, and a cylinder of ferric ammonium alum (a paramagnetic salt) that has been deposited on the wires. The structural members used in this system for both thermal insulation and positioning are aromatic polyamide fibers (Kevlar® or equivalent) under tension.

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Back Actuators for Segmented Mirrors and Other Applications

Actuation mechanisms could be simpler. Back actuators have been proposed as alternatives to edge actuators considered previously for use in aligning hexagonal segments of lightweight segmented astronomical mirrors planned for use in outer space. The proposed back actuators could also be useful on Earth as parts of wafer-conveyance systems in the semiconductor industry.

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Mechanism for Self-Reacted Friction Stir Welding

This mechanism performs better than others that have been tried. A mechanism has been designed to apply the loads (the stirring and the resection forces and torques) in self-reacted friction stir welding. This mechanism differs somewhat from mechanisms used in conventional friction stir welding, as described below.

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Simple Systems for Detecting Spacecraft Meteoroid Punctures

A report describes proposed systems to be installed in spacecraft to detect punctures by impinging meteoroids or debris. Relative to other systems that have been used for this purpose, the proposed systems would be simpler and more adaptable, and would demand less of astronauts' attention and of spacecraft power and computing resources. The proposed systems would include a thin, hollow, hermetically sealed panel containing an inert fluid at a pressure above the spacecraft cabin pressure. A transducer would monitor the pressure in the panel. It is assumed that an impinging object that punctures the cabin at the location of the panel would also puncture the panel. Because the volume of the panel would be much smaller than that of the cabin, the panel would lose its elevated pressure much faster than the cabin would lose its lower pressure. The transducer would convert the rapid pressure drop to an electrical signal that could trigger an alarm. Hence, the system would provide an immediate indication of the approximate location of a small impact leak, possibly in time to take corrective action before a large loss of cabin pressure could occur.

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Using Iron To Treat Chlorohydrocarbon Contaminated Soil

Prompt chemical remediation is followed by longer-term enhanced bioremediation. A method of in situ remediation of soil contaminated with chlorinated hydrocarbon solvents involves injection of nanometer-size iron particles. This method should not be confused with a similar method, involving injection of emulsified iron particles, reported in “Treatment To Destroy Chlorohydrocarbon Liquids in the Ground” (KSC-12246), NASA Tech Briefs, Vol. 27, No. 6 (June 2003), page 56. Like that method, this method is implemented in a process that is safe, yields environmentally benign end products, takes less time and costs less than do traditional pump-and-treat processes, and is both less expensive and less environmentally disruptive than are cleanup processes that involve excavation, trans-port to facilities for incineration or other treatment, and reburial in landfills.

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Software For Use With Optoelectronic Measuring Tool

A computer program has been written to facilitate and accelerate the process of measurement by use of the apparatus described in “Optoelectronic Tool Adds Scale Marks to Photographic Images” (KSC-12201), NASA Tech Briefs, Vol. 27, No. 1 (January 2003), page 6a. To recapitulate: The tool contains four laser diodes that generate parallel beams of light spaced apart at a known distance. The beams of light are used to project bright spots that serve as scale marks that become incorporated into photographic images (including film and electronic images). The sizes of objects depicted in the images can readily be measured by reference to the scale marks.

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