Simulation of the physical process of neural electromagnetic signal generation based on a simple but functional bionic Na^(+)channel

The physical processes occurring at open Na^(+) channels in neural fibers are essential for the understanding of the nature of neural signals and the mechanism by which the signals are generated and transmitted along nerves.However,there is a less generally accepted description of these physical processes.We studied changes in the transmembrane ionic flux and the resulting two types of electromagnetic signals by simulating the Na^(+) transport across a bionic nanochannel model simplified from voltage-gated Na^(+) channels.The results show that the Na^(+) flux can reach a steady state in approximately 10 ns due to the dynamic equilibrium of the Na^(+) ion concentration difference between both sides of the membrane.After characterizing the spectrum and transmission of these two electromagnetic signals,the low-frequency transmembrane electric field is regarded as the physical quantity transmitting in the waveguide-like lipid dielectric layer and triggering the neighboring voltage-gated channels.Factors influencing the Na^(+) flux transport are also studied.The impact of the Na^(+) concentration gradient is found to be higher than that of the initial transmembrane potential on the Na^(+) transport rate,and introducing the surface-negative charge in the upper third channel could increase the transmembrane Na^(+) current.This work can be further studied by improving the simulation model;however,the current work helps to better understand the electrical functions of voltage-gated ion channels in neural systems.

A semi-classical model for the charge exchange and energy loss of slow highly charged ions in ultrathin materials

We present a simple and reliable method,based on the over-barrier model and Lindhard’s formula,to calculate the energy loss,charge transfer,and normalized intensity of highly charged ions penetrating through 2D ultrathin materials,including graphene and carbon nanomembranes.According to our results,the interaction between the ions and the 2D material can be simplified as an equivalent two-body collision,and we find that full consideration of the charge exchange effect is key to understanding the mechanism of ion energy deposition in an ultrathin target.Not only can this semiclassical model be used to evaluate the ion irradiation effect to a very good level of accuracy,but it also provides important guidance for tailoring the properties of 2D materials using ion beams.