Henan Normal University

About: Henan Normal University is a education organization based out in Xinxiang, China. It is known for research contribution in the topics: Catalysis & Ionic liquid. The organization has 10863 authors who have published 11077 publications receiving 166773 citations.

Reversible data hiding in encrypted images using cross division and additive homomorphism

Abstract: There are three problems in the existing reversible data hiding (RDH) algorithms in encrypted images: one is that some algorithms are not processed in the encrypted domain; another is that the reversibility which implies exact data extraction and perfect image recovery cannot be ensured in some cases; the last is that data expansion occurs when probabilistic public-key cryptosystem is used for image encryption in some homomorphic schemes. In this paper, a complete RDH in encrypted images is proposed. By using the idea of cross division and additive homomorphism, we solve all of the problems. Experimental results verify the superiority of the proposed method, which will have a good potential for practical applications of multimedia privacy protection. HighlightsHost image is divided into crosses.Homomorphic encryption is with no data expansion.Data hiding is directly processed in encrypted domain.Real reversibility is realized.Difference histogram is shifted several rounds.

Efficient Ionic-Liquid-Promoted Chemical Fixation of CO2 into α-Alkylidene Cyclic Carbonates.

Abstract: The efficient conversion of CO2 into value-added chemicals under metal-free conditions is of significant importance from the viewpoint of sustainable chemistry In this work, ionic liquids (ILs) with different properties were used to promote the reaction between CO2 and propargylic alcohol for the synthesis of α-alkylidene cyclic carbonates The protic IL 1,8-diazabicyclo-[540]-7-undecenium 2-methylimidazolide ([DBUH][MIm]) was prepared by simple neutralization of the superbase with a weak proton donor and could efficiently promote the reactions in high yields After the reactions, the IL was separated from the reaction mixtures by simply adding water, and then reused after drying without an observable decrease in the catalytic activity and selectivity NMR spectroscopy and detailed density functional theory analysis were used to propose a reaction mechanism Both the cation and anion of the IL played a key synergistic role in promoting the reaction These findings may be useful for the rational design of novel metal-free and recyclable routes for the reaction between CO2 and propargylic alcohols