Recently, " National Science Review " published online the latest research results of the research team of Professor Zhuhua Zhang and Prof. Wanlin Guo from Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics. The phenomenon of quantum-like Friedel oscillations in one-dimensional confined water was reported.
The researchers found through systematic molecular dynamics simulation calculations that when there is a local perturbation in the one-dimensional nanochannel, the axial density of the confined water in the channel will exhibit significant oscillations. The oscillation moves from the perturbed location away to both channel entrances with a noticeable decay, and it extends as far as ten nanometers in channels of suitable sizes. Further study showed that the pronounced axial density oscillations is a general behavior to different forms of perturbations in the nanochannels, such as charge modification, physical baffles, local collapse, protrusions, and trenches. Furthermore, the density oscillation induced by multiple perturbations can be superimposed together to achieve a more significant behavior. Taking carbon nanotubes with physical baffles as an example, the researchers described the density oscillations of confined water with a mathematical model based on the Fokker-Planck equation. The model shows that the intensity and the decay rate of such quantum-like behavior in the confined systems depend on the perturbation strength and the dipole correlation of water molecules, respectively. In addition, the researchers simulated the carbon nanotube systems under an external pressure and found that the density oscillations of the confined water can unusually repel ions at the distant entrance of the channel, thereby remotely rejecting the ions from entering the channel.
The above research results reveal the rare quantum-like behavior of confined water and its unique regulation of ion transport, shedding light on the mass transport of biological channels and suggesting potential applications in technological fields, such as seawater desalination.
See the article:
An analog of Friedeloscillations in nanoconfined water
https://doi.org/10.1093/nsr/nwab214
National Science Review