Disclosed are particles that have an exterior surface coated with a thin polymeric coating, such as a coating that includes a sulfur-containing polymer. Also disclosed are compositions, such as fuel-resistant sealant and coating compositions, which include such particles. Aerospace vehicles having an aperture at least partially sealed with a sealant deposited from such a sealant composition are also disclosed.

Particles that have an exterior surface coated with a thin polymer coating, such as a coating that includes a sulfur-containing polymer can be used as lightweight fillers in compositions, such as fuel resistant sealant and coating compositions. The compositions can be used to seal apertures on aerospace vehicles.

The present invention provides a method of producing core/shell-type fluorescent dye-containing nanoparticles for immunohistochemical staining or live cell imaging, the method including: the step 1 of polymerizing monomers for thermoplastic resin synthesis in the presence of a fluorescent dye and thereby preparing core particles composed of a thermoplastic resin containing the fluorescent dye; and the step 2 of coating the core particles each with a shell layer composed of a thermosetting resin. By the method of producing fluorescent dye-containing nanoparticles according to the present invention, fluorescent dye-containing nanoparticles having a high brightness, whose dye does not elutes into water, physiological saline, culture medium and the like, can be produced, and the fluorescent dye-containing nanoparticles can be effectively utilized in immunohistochemical staining and live cell imaging.

A sound-absorbing material includes an open-cell, filled silicone foam having a density of less than 155 kg/m.sup.3 and a porosity of at least 70%, wherein the silicone foam has an average cell size of less than 2300 micrometers, determined in a direction parallel to the rise direction, and an average cell size of less than 800 micrometers, determined in a direction perpendicular to the rise direction, each determined by optical microscopy.