Abstract: A method for determining whether an item has been exposed to an environmental condition during a monitoring period. The method includes placing a sensor at least in proximity to the item at the beginning of the monitoring period so that the sensor will be exposed to a level of an environmental condition that can be correlated to an exposure level of the item to the environmental condition; reading the sensor; and determining from reading the sensor whether the item has been exposed to the environmental condition. The sensor includes a detecting material comprising a photochromic or photothermochromic material, the detecting material selected so that upon exposure to the environmental condition the detecting material exhibits a detectable color change.

Abstract: A method for determining whether an item has been exposed to an environmental condition during a monitoring period. The method includes placing a sensor at least in proximity to the item at the beginning of the monitoring period so that the sensor will be exposed to a level of an environmental condition that can be correlated to an exposure level of the item to the environmental condition; reading the sensor; and determining from reading the sensor whether the item has been exposed to the environmental condition. The sensor includes a detecting material comprising a photochromic or photothermochromic material, the detecting material selected so that upon exposure to the environmental condition the detecting material exhibits a detectable color change.

Abstract: Disclosed is a composition which comprises silica particles containing a water soluble dye entrapped therein, said silica particles being coated with a surfactant. The particles can be prepared by a process which comprises preparing a mixture of a surfactant and an organic solvent immiscible with water and capable of forming a stable microemulsion with water, adding to the mixture a solution of a water-soluble dye, a hydrolyzing reagent, and water to form a microemulsion of water domains within a continuous phase of the organic solvent, and adding to the microemulsion a tetraalkoxysilane, wherein the tetraalkoxysilane reacts with the hydrolyzing agent to form in each water domain a silica particle containing the water-soluble dye and coated with the surfactant. The particles are useful as colorants for various organic materials, such as dry electrostatic toners, liquid electrostatic toners, plastics, oil based inks, hot melt ink jet inks, and the like.