Conformational changes of membrane proteins are accompanied by deformation in the surrounding lipid bilayer. To gain insight into the energetics of membrane deformation, the phase behavior of dimyristoylphosphatidylcholine (DMPC) membranes in the presence of the dipole potential, ψ d , modifiers was investigated by differential scanning calorimetry. 7-Ketocholesterol, which weakens ψ d and reduces membrane-perpendicular dipole–dipole repulsion, causes a discrete second peak on the high-temperature side of the main transition, whereas 6-ketocholestanol, which strengthens ψ d and increases membrane-perpendicular dipole–dipole repulsion, merely produces a shoulder. Measurements on pure DMPC vesicles showed that the observed temperature profile could not be explained by a single endothermic process, that is, breaking of van der Waals forces between hydrocarbon chains alone. Removal of NaCl from the buffer caused an increase in the main transition temperature and the appearance of an obvious shoulder, implicating polar interactions. Consideration of the phosphatidylcholine (PC) head group dipole moment indicates direct interactions between PC dipoles that are unlikely to account for the additional process. It seems more likely that the breaking of an in-plane hydrogen-bonded network consisting of hydrating water dipoles together with zwitterionic lipid head groups is responsible. The evidence presented supports the idea that the breaking of van der Waals forces between lipid tails required for the main phase transition of PC membranes is coupled to partial breaking of a hydrogen-bonded network at the membrane surface.

Wireless mesh network (WMN), as a new generation of wireless network technology, has raised increasing concerns in recent years. Due to the strong mobility nature of the clients in WMNs, the handover events frequently occur. Therefore, taking into consideration the openness of the wireless communication channel, the handover authentication protocols for WMNs have to be both efficient and secure, which remains a challenge. In this paper, an anonymous batch handover authentication protocol is proposed using group signature technique to pre-distribute handover keys. Unlike existing protocols based on group signature, the proposed protocol does not involve group signature correlation operations in the handover authentication phase, hence achieving a better performance.

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