the gap between gases and liquids, and their transparency and solid state, making them easier to use than cryogenic liquids or compressed gases. Resorcinol–formaldehyde aerogels (polymers chemically similar to phenol formaldehyde resins) are used as precursors for manufacture of carbon aerogels, or when an organic insulator with large surface is desired. Metal–aerogel nanocomposites prepared by impregnating the hydrogel with solution containing ions of a transition metal and irradiating the result with gamma rays, precipitates nanoparticles of the metal. Such composites can be used as catalysts, sensors, electromagnetic shielding, and in waste disposal. A prospective use of platinum-on-carbon catalysts is in fuel cells. As a drug delivery system owing to its biocompatibility. Due to its high surface area and porous structure, drugs can be adsorbed from supercritical . The release rate of the drugs can be tailored by varying the properties of the aerogel. Carbon aerogels are used in the construction of small electrochemical double layer supercapacitors. Due to the high surface area of the aerogel, these capacitors can be 1/2000th to 1/5000th the size of similarly rated electrolytic capacitors. According to Hindawi's Journal of Nanomaterials, "Aerogel supercapacitors can have a very low impedance compared to normal supercapacitors and can absorb or produce very high peak currents. At present, such capacitors are polarity-sensitive and need to be wired in series if a working voltage of greater than about 2.75 V is needed." Dunlop Sport uses aerogel in some of its racquets for sports such as tennis. In water purification, chalcogels have shown promise in absorbing the heavy metal pollutants mercury, lead, and cadmium from water. Aerogels may be used to separate oil from water, which could for example be used to respond to oil spills. Aerogels may be used to disinfect water, killing bacteria. Aerogel can introduce disorder into superfluid helium-3. In aircraft de-icing, a new proposal uses a carbon nanotube aerogel. A thin filament is spun on a winder to create a 10 micron-thick film. The amount of material needed to cover the wings of a jumbo jet weighs . Aerogel heaters could be left on continuously at low power, to prevent ice from forming. Thermal insulation transmission tunnel of the Chevrolet Corvette (C7). CamelBak uses aerogel as insulation in a thermal sport bottle. 45 North uses aerogel as palm insulation in its Sturmfist 5 cycling gloves. Silica aerogels may be used for sound insulation, such as on windows or