Abstract: The present application relates to a hydrogel. The hydrogel includes polyvinyl alcohol, sodium carboxymethyl cellulose and Huangshui polysaccharide, and the mass ratio of the mass sum of the polyvinyl alcohol and the sodium carboxymethyl cellulose to the Huangshui polysaccharide is 100:(1.8-8.2). The present application further relates to use of the hydrogel as an adsorbent for a dye. The present application further relates to a method for preparing a hydrogel.

Abstract: A system and method for preparing epoxy chloropropane is provided in that by coupling three stages of high gravity reactors, the product epoxy chloropropane and water vapor are distilled from a reaction system in form of an azeotrope by adopting a water vapor steam stripping method. Further, by combining the azeotrope with the multiples stages of high gravity reactors, the gas phase mass transfer and the liquid phase mass transfer of the azeotrope are improved aiming at the features of the azeotrope in the reaction system, thus making the overall conversion rate higher. In addition, by combining steam stripping and high gravity, dichloropropanol and alkali solution are rapidly mixed for mass transfer, and the product epoxy chloropropane is rapidly distilled from the reaction system in the form of the azeotrope, such that the reaction proceeds continuously towards the direction of producing epoxy chloropropane, thus significantly improving the conversion rate.

Abstract: An optical imaging apparatus having a variable focal length is disclosed. A plurality of holographic polymer dispersed liquid crystal (“H-PDLC”) lenses are arranged in a stack, each lens having a unique focal length. A controller is configured to program a plurality of voltages applied to the plurality of H-PDLC lenses to achieve a plurality of focal lengths, the plurality of focal lengths higher than the plurality of H-PDLC lenses.