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Fibers of Aligned Single-Wall Carbon Nanotubes and Process for Making the Same

This invention imparts properties such as reinforcement, enhanced tensile strength, and/or electrical and thermal conductivity to composites. Lyndon B. Johnson Space Center, Houston, Texas Single-wall carbon nanotubes (SWNTs) are fullerenes of closed-cage carbon molecules typically arranged in hexagons and pentagons. Commonly known as “buckytubes,” these cylindrical carbon structures have extraordinary properties, including high electrical and thermal conductivity, as well as high strength and stiffness. With intrinsic strength estimated to be on the order of 100 times that of steel, SWNTs are a possible strengthening reinforcement in composite materials. The intrinsic electronic properties of SWNTs also make them electrical conductors and useful in applications involving field mission devices such as flat-panel displays, and in polymers used for radio frequency interference and electromagnetic shielding that require electrical conductance properties.

Posted in: Briefs, Materials

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Enhancing MRI Contrast by Geometrical Confinement of Small Imaging Agents Within Nanoporous Particles

Lyndon B. Johnson Space Center, Houston, Texas Magnetic resonance imaging (MRI) has evolved into one of the most powerful, non-invasive diagnostic imaging techniques in medicine and biomedical research. The superior resolution and in-depth anatomical details provided by MRI are essential for early diagnosis of many diseases. Chemical contrast agents (CAs) have been widely used for improving the sensitivity and diagnostic confidence in MRI.

Posted in: Briefs, Materials

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Purifying Nanomaterials by Dissolving Excess Reactants and Catalysts in Ferric Chloride

Liquid phase temperature salts dissolve metallic catalysts like Fe, Co, or Ni, and “wash” them away. John H. Glenn Research Center, Cleveland, Ohio Physical and chemical properties of nanomaterials are known to be significantly different from those having larger crystallites (i.e. bigger than nano), but with the same chemical compositions. Optimal uses of these new nanomaterial properties will likely result in engineering materials that are better than what is available today. Before this can happen, characterization of the physical and chemical properties of nanomaterials is needed.

Posted in: Briefs, Materials, Nanotechnology

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White, Electrically Conductive, Radiation-Stable, Thermal Control Coating

Goddard Space Flight Center, Greenbelt, Maryland A highly reflective, white conductive coating system was developed using a layered approach with a combination of commercially available white conductive pigments within a conductive binder system. The top coating is a space-stable, radiation-resistant, highly reflective coating that has been tailored to provide optimum reflectance properties and meet vacuum thermal surface resistivities. The combined layer is a mixture of a highly reflective, electrically dissipative coating and a moderately reflective but highly conductive pigment in a conductive binder. A second, underlying layer of conductive white coating offers optimum adhesion to metal substrates and the topcoat. The system vacuum resistivity at room temperature is approximately 1 × 109 ohms/sq, and has a solar absorptance of less than 0.13 as measured on a Cary 5000 spectrophotometer.

Posted in: Briefs, TSP, Thermoelectrics, Coatings & Adhesives, Materials

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Plasma-Assisted Thin Film Coatings to Create Highly Hydrophobic Porous Structures

Multiple samples can be coated in this manner. John H. Glenn Research Center, Cleveland, Ohio Gas-distribution layers (GDLs) are water-management structures used in fuel cells and electrolyzers. GDLs are critical components that prevent flooding of the fuel cell electrode by product water, thus preserving open channels for reactant gas to reach the electrode. Typically, GDLs are electrically conductive papers (metal or carbon) having a fine pore structure. Extremely fine pores in some GDL materials are difficult to fully infiltrate with Teflon (PTFE). These materials are typically wet-proofed by coating with hydrophobic materials (e.g. PTFE). This is usually accomplished by immersing the raw paper in a PTFE emulsion. Completeness of wet-proofing by immersion in emulsion can be limited, because fine pores will filter out the PTFE particles.

Posted in: Briefs, TSP, Coatings & Adhesives, Materials

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High-Performance Photocatalytic Oxidation Reactor System

Airborne volatile organic chemicals are oxidized using blue LEDs, fiber optics, and visible light-activated catalysts for space and terrestrial air purification. Marshall Space Flight Center, Alabama As crewed space missions extend beyond low Earth orbit, the need to reliably recover potable water is critical. Aboard the International Space Station (ISS), the water is recycled from cabin humidity condensate, urine distillate, and hygiene wash wastes. In spacecraft cabin air environments, off-gassing from equipment, human metabolism, and human personal care products contributes to significant airborne concentrations of volatile organic compounds (VOCs). These polar and water-soluble compounds ultimately dissolve into the humidity condensate and stress the process load, logistics costs, and lifecycle requirements of the water processing systems. The aim of this effort was to develop the High Performance Photocatalytic Oxidation Reactor System (HPPORS) technology for the destruction of airborne VOCs prior to reaching the water processing systems. This innovation will reduce the logistics costs and lifecycle requirements of water processing systems, and help extend NASA missions to include long-duration space habitation and lunar and Mars colonization missions.

Posted in: Briefs, Aerospace, Green Design & Manufacturing, Recycling Technologies, Remediation Technologies, LEDs, Lighting, Materials, Fiber Optics, Photonics

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Optical Fiber for Solar Cells

These materials enable new solar-powered devices that are small, lightweight, and can be used without connection to existing electrical grids. Ames Research Center, Moffett Field, California Polymeric and inorganic semiconductors offer relatively high quantum efficiencies, and are much less expensive and versatile to fabricate than non-amorphous silicon wafers. An optical fiber and cladding can be designed and fabricated to confine light for transport within ultraviolet and near-infrared media, using evanescent waves, and to transmit visible wavelength light for direct lighting.

Posted in: Briefs, Energy, Energy Storage, Solar Power, Materials, Fiber Optics, Physical Sciences

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