Materials

Silk Microneedles Deliver Controlled-Release Drugs Painlessly

Tiny needles deliver precise amounts of drugs over time without need for refrigeration. Bioengineers have developed a new silk-based microneedle system able to deliver precise amounts of drugs over time and without need for refrigeration. The tiny needles can be fabricated under normal temperature and pressure and from water, so they can be loaded with sensitive biochemical compounds and maintain their activity prior to use. They are also biodegradable and biocompatible.

Posted in: Bio-Medical, Drug Delivery & Dispensing, Treatment Devices, Materials, Medical, Drug Delivery & Fluid Handling, Briefs, MDB

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Resin-Impregnated Carbon Ablator: A New Ablative Material for Hyperbolic Entry Speeds

From surface temperatures as high as ≈3,000 °C, the measured back temperature is only 50 °C Ablative materials are required to protect a space vehicle from the extreme temperatures encountered during the most demanding (hyperbolic) atmospheric entry velocities, either for probes launched toward other celestial bodies, or coming back to Earth from deep space missions. To that effect, the resinimpregnated carbon ablator (RICA) is a high-temperature carbon/phenolic ablative thermal protection system (TPS) material designed to use modern and commercially viable components in its manufacture. Heritage carbon/phenolic ablators intended for this use rely on materials that are no longer in production (i.e., Galileo, Pioneer Venus); hence the development of alternatives such as RICA is necessary for future NASA planetary entry and Earth re-entry missions. RICA’s capabilities were initially measured in air for Earth re-entry applications, where it was exposed to a heat flux of 14 MW/m2 for 22 seconds. Methane tests were also carried out for potential application in Saturn’s moon Titan, with a nominal heat flux of 1.4 MW/m2for up to 478 seconds. Three slightly different material formulations were manufactured and subsequently tested at the Plasma Wind Tunnel of the University of Stuttgart in Germany (PWK1) in the summer and fall of 2010. The TPS’ integrity was well preserved in most cases, and results show great promise.

Posted in: Materials, Briefs, TSP

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Self-Cleaning Particulate Prefilter Media

This technology has application for air filter manufacturers for self-cleaning particulate prefilters. A long-term space mission requires efficient air revitalization performance to sustain the crew. Prefilter and particulate air filter media are susceptible to rapid fouling that adversely affects their performance and can lead to catastrophic failure of the air revitalization system, which may result in mission failure. For a long-term voyage, it is impractical to carry replacement particulate prefilter and filter modules due to the usual limitations in size, volume, and weight. The only solution to this problem is to reagentlessly regenerate prefilter and filter media in place. A method was developed to modify the particulate prefilter media to allow them to regenerate reagentlessly, and in place, by the application of modest thermocycled transverse or reversed airflows. The innovation may allow NASA to close the breathing air loop more efficiently, thereby sustaining the vision for manned space exploration missions of the future.

Posted in: Materials, Briefs

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Polyurea-Based Aerogel Monoliths and Composites

These aerogels can be used in portable apparatus for warming, storing, and/or transporting food and medicine, and can be recycled for fillers for conventional plastics. A flexible, organic polyurea-based aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection for government and commercial applications. The rubbery polyurea-based aerogel exhibits little dustiness, good flexibility and toughness, and durability typical of the parent polyurea polymer, yet with the low density and superior insulation properties associated with aerogels. The thermal conductivity values of polyurea-based aerogels at lower temperature under vacuum pressures are very low and better than that of silica aerogels.

Posted in: Materials, Briefs, TSP

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Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell Membranes

Polymer electrolyte membrane fuel cells can be used for portable power sources. Polymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrenebased quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells.

Posted in: Materials, Briefs, TSP

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Blocking Filters With Enhanced Throughput for X-Ray Microcalorimetry

Polyimide replaces the standard metal mesh. New and improved blocking filters (see figure) have been developed for microcalorimeters on several mission payloads, made of high-transmission polyimide support mesh, that can replace the nickel mesh used in previous blocking filter flight designs. To realize the resolution and signal sensitivity of today’s x-ray microcalorimeters, significant improvements in the blocking filter stack are needed.

Posted in: Materials, Briefs, TSP

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High-Thermal-Conductivity Fabrics

Applications include cooling garments for firefighters, hazmat personnel, soldiers, and in cooling vests for multiple sclerosis patients. Heat management with common textiles such as nylon and spandex is hindered by the poor thermal conductivity from the skin surface to cooling surfaces. This innovation showed marked improvement in thermal conductivity of the individual fibers and tubing, as well as components assembled from them.

Posted in: Materials, Briefs, TSP

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