Abstract: A hydrothermal method for forming nanoparticles of a rare earth element, oxygen and fluorine has been discovered. Nanoparticles comprising a rare earth element, oxygen and fluorine are also described. These nanoparticles can exhibit excellent refractory properties as well as remarkable stability in hydrothermal conditions. The nanoparticles can exhibit excellent properties for numerous applications including fiber reinforcement of ceramic composites, catalyst supports, and corrosion resistant coatings for high-temperature aqueous solutions.

Abstract: Exposed lens retroreflective article 10 that comprises a colored layer 14 and a layer of optical elements 12 that are partially embedded in the colored layer 14. The colored layer 14 comprises reflective flakes 16 and a dye that is covalently bonded to a polymer 18. The articles can retain their color after multiple industrial wash cycles. The use of a reactive dye, reflective flakes, and/or polymer precursor during the preparation of the colored layer enables a launderably-durable colored retroreflective article to be made without the use of a solvent and without the use of a temporary carrier.

Abstract: A method of removing particulate solid or liquid aerosol from a gas, which method comprises the step of: passing a particulate solid or liquid aerosol containing gas through an electret filter that comprises a polymer and a performance enhancing additive, wherein the electret filter has a thermally stimulated discharge current (TSDC) spectrum exhibiting a peak having a width at half height of less than about 30° C., as measured by TSDC test procedure 3.

Abstract: A method of predicting the performance of electret filter web involves measuring the level of extractable hydrocarbon material in the web. Electret filters that have low extractable hydrocarbon levels exhibit improved filtration performance.

Abstract: Novel electret articles containing a polymer and a performance-enhancing additive can be identified by their thermally stimulated conductivity characteristics or their filtration properties. Electret articles such as nonwoven filter webs and respirators exhibit superior oily mist loading performance, low penetration and a small pressure drop.

Abstract: The thermally stimulated discharge current of an electret article can be used to identify electret articles that exhibit superior filtration properties. Electret filters that exhibit superior properties not achieved in similarly constructed filters contain fibers that are made from a blend of a polymer and a performance-enhancing additive. The electret filters exhibit an initial detectable DOP penetration of less than 5% and an average Min@Chl of greater than 200 mg DOP as measured by DOP Filter Web Loading Test Procedure 1. These new electrets are particularly useful in a respirator.

Abstract: Electret fibers that contain a polymeric material and a fluorochemical additive. The electret fibers have a low level of extractable hydrocarbon material. Electret filters that have low extractable hydrocarbon levels exhibit improved filtration performance.

Abstract: The position of an object is tracked underwater. Prior to tracking, the object is tagged with an acoustic transmitter. It is important that the transmitter emits sound waves having a frequency of at least 200 kilohertz (kHz) because it has been found that these transmitter frequencies provide better tracking data in noisy environments than conventional transmitters operating at 50-60 kHz. The acoustic transmitter is located by a split-beam transmitter. The position of the object can be accurately tracked by using two split-beam transducers, synchronization of transducer and transmitter, or echo ranging.