ABSTRACT
CONTEXT: Electroplated zinc layers have shown excellent corrosion resistance, especially those are stable in the atmosphere after the passivation, and therefore zinc electroplating is widely used in various fields such has mechanical, vehicle, construction, and ironware industries. Benzalacetone (BA) was reported as brighteners for zinc deposition, while polyoxyethylene nonylphenylether (NP) was used as levelers or carriers for zinc electroplating. Sodium benzoate (SB) and dispersant NNO cooperatively act as auxiliary additives. Quantum chemical parameters (QCPs) of four additives were calculated by using DFT, and MD simulations were performed. By comparing binding energies of four additives (benzalacetone (BA), sodium benzoate (SB), polyoxyethylene nonylphenylether (NP) and dispersant NNO), with Zn (001) surface, BA has the lowest binding energy, which is due to the lowest hardness parameter, and NNO has the highest binding energy, which is due to the highest dipole moment despite its small hardness parameter. METHODS: For DFT calculation, NWChem was employed, which uses the Gaussian basis set. The B3LYP functional was used for exchange-correlation interaction between electrons, and the 6-311G+ (d,p) basis sets were used for all the atoms. Solvation effect was considered by using COSMO (COnductor-like Screening MOdel), in which the dielectric constant of solvent was set to 78.54 of water. For dispersion correction, DFT-D method of Tkatchenko and Scheffler (TS) was used. MD simulations were performed by using GULP (General Utility Lattice Program) code with Dreiding forcefield and atomic Hirshfeld charges from DFT calculations. MD simulations were performed on the conditions of NVT ensemble with a step of 1 fs and simulation time of 500 ps at 298 K and 323 K. To consider solvation effect, 1,000 water molecules were inserted into the box.
ABSTRACT
By virtue of their lack of motility, viruses rely entirely on their own temperature (Brownian motion) to position themselves properly for cell attachment. Spiked viruses use one or more spikes (called peplomers) to attach. The coronavirus uses adjacent peplomer pairs. These peplomers, identically charged, repel one another over the surface of their convex capsids to form beautiful polyhedra. We identify the edges of these polyhedra with the most important peplomer hydrodynamic interactions. These convex capsids may or may not be spherical, and their peplomer population declines with infection time. These peplomers are short, equidimensional, and bulbous with triangular bulbs. In this short paper, we explore the interactions between nearby peplomer bulbs. By interactions, we mean the hydrodynamic interferences between the velocity profiles caused by the drag of the suspending fluid when the virus rotates. We find that these peplomer hydrodynamic interactions raise rotational diffusivity of the virus, and thus affect its ability to infect.
