No abstract

No abstract

Covert communication is designed for hiding the subliminal communication which takes place between both of the speakers and their relationship. The traditional covert communication utilizes the centralized channel and the third-party central node or authority to distribute messages which leads to a lack of undetectability, antitraceability, and robustness. In recent years, there have been attempts to apply the blockchain to covert communication solutions, for the characteristics of blockchain such as decentralization, openness, and trustworthiness. In this paper, based on the analysis of the literature and the classification according to the hiding position, we identify four kinds of covert communication: Address Channel, Value Channel, DSA (Digital Signature Algorithm) Channel, and Script Channel, which will help inform future research agenda.

To date, there has been little attention focused on jade powder, the leftover of the jade polishing process, although jade has been long considered precious and valuable. Herein, jade powder was characterized, followed by an investigation on its biocompatibility and bactericidal effects. Characterization conducted by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy showed that the main component of jade powder is tremolite, which is in good crystallization with no typical peaks of possible impurities observed. Tremolite’s main elements are oxygen, calcium, magnesium, and silicon, all of which exist in the form of oxides. Water contact angle, trace element content, and in vitro cytotoxicity analyses demonstrated that jade powder is of hydrophilicity and good cytocompatibility and contains only parts-per-million-level heavy metals. Meanwhile, antibacterial evaluation proved that the jade powder had excellent antimicrobial effects against both gram positive and negative microbes such as Escherichia coli and Staphylococcus aureus. This study suggested that jade powder is a promising material that could be used in the fields of biological and medical applications.