RESUMO
The recent pandemic triggered numerous societal efforts aimed to control and limit the spread of SARS-CoV-2. One of these aspects is related on how the virion interacts with inanimate surfaces, which might be the source of secondary infection. Although recent works address the adsorption of the spike protein on surfaces, there is no information concerning the long-range interactions between spike and surfaces, experimented by the virion when is dispersed in the droplet before its possible adsorption. Some descriptors, namely the interaction potentials per single protein and global potentials, were calculated in this work. These descriptors, evaluated for the closed and open states of the spike protein, are correlated to the long-range noncovalent interactions between the SARS-CoV-2 spikes and polymeric surfaces. They are associated with the surface's affinity towards SARS-CoV-2 dispersed in respiratory droplets or water solutions. Molecular-Dynamics simulations were performed to model the surface of three synthetic polymeric materials: Polypropylene (PP), Polyethylene Terephthalate (PET), and Polylactic Acid (PLA), used in Molecular Mechanics simulations to define the above potentials. The descriptors show a similar trend for the three surfaces, highlighting a greater affinity towards the spikes of PP and PLA over PET. For closed and open structures, the long-range interactions with the surfaces decreased in the following order PP â¼ PLA > PET and PLA > PP > PET, respectively. Thus, PLA and PP interact with the virion quite distant from these surfaces to a greater extent concerning the PET surface, however, the differences among the considered surfaces were small. The global potentials show that the long-range interactions are weak compared to classic binding energy of covalent or ionic bonds. The proposed descriptors are useful most of all for a comparative study aimed at quickly preliminary screening of polymeric surfaces. The obtained results should be validated by more accurate method which will be subject of a subsequent work.
RESUMO
In this work, we study the gapped surface electrode (SE), a planar system composed of two-conductor flat regions at different potentials with a gapGbetween both sheets. The computation of the electric field and the surface charge density requires solving Laplace's equation subjected to Dirichlet conditions (on the electrodes) and Neumann boundary conditions over the gap. In this document, the gapless surface electrode is modeled as a two-dimensional classical Coulomb gas having punctual charges +qand -qon the inner and outer electrodes, respectively, interacting with an inverse power law 1/r-potential. The coupling parameter Γ between particles inversely depends on temperature and is proportional toq2. Precisely, the density charge arises from the equilibrium states via Monte Carlo (MC) simulations. We focus on the coupling and the gap geometry effect. Mainly on the distribution of particles in the circular and the harmonically-deformed gapped SE. MC simulations differ from electrostatics in the strong coupling regime. The electrostatic approximation and the MC simulations agree in the weak coupling regime where the system behaves as two interacting ionic fluids. That means that temperature is crucial in finite-size versions of the gapped SE where the density charge cannot be assumed fully continuous as the coupling among particles increases. Numerical comparisons are addressed against analytical descriptions based on an electric vector potential approach, finding good agreement.