a b s t r a c tA new image encryption scheme based on DNA sequence addition operation and chaos is presented. First, a DNA sequence matrix is obtained by encoding the original image, then, divide the DNA sequence matrix into some equal blocks and use the DNA sequence addition operation to add these blocks. Next, perform the DNA sequence complement operation to the result of the added matrix by using two Logistic maps. Finally, decode the DNA sequence matrix from the third step, and we can get the encrypted image. The simulation experimental results and security analysis show that our scheme not only can achieve good encryption, but can also resist exhaustive attack, statistical attack and differential attack.

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Iron carbodiimide ( FeNCN) is a high-reactivity anode material for sodiumion batteries. However, strict synthesis technology and poor electrochemical stability limit its application. FeNCN polyhedrons are prepared using a facile one-step pyrolysis process. In these polyhedrons, many "anchor-like" structures are in situ constructed with FeC bonds. These FeC bonds connect the FeNCN polyhedrons closely. The FeNCN polyhedrons with "anchor-like" structures exhibit good electrochemical stability, that is, high capacity retention of 79.9% (408 mAh g −1 ) at 0.5 A g −1 after 300 cycles. Further analysis suggests that the FeC bond plays an important role to improve the structural stability of FeNCN polyhedrons. The "anchor-like" structures with FeC bonds can hold FeNCN polyhedrons closely when Na + intercalates, avoiding structural breakage with obvious capacity loss. This work provides a novel synthesis technology of FeNCN and helps related researcher to deepen the understanding of this material, as well as provide inspirations as to improving the electrochemical stability of related materials.