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Nanoporous carbons play an important role in different electrochemical applications such as being utilized as electrodes in supercapacitors. Application of electric potential to a porous electrode in electrolyte solution stimulates adsorption or desorption of ions on the electrode surface. Electrosorption causes appearance of solvation pressure in the pores and results in electrode deformation. In this work, using molecular dynamics simulations and the continuum theory based on the modified Poisson-Boltzmann equation, we studied the structure of the electrical double layer in slit graphitic micropores filled with a NaCl aqueous solution, and solvation pressure in these pores. We focused on the behavior of the solvation pressure as a function of pore width and surface charge density. Within molecular dynamics simulations, two different water models were used -- an explicit model based on SPC/E water molecules and an implicit model, i.e., structureless background with fixed dielectric permittivity. The latter allows us to relate molecular dynamics simulations to the continuum theory. Simulations with explicit water show a qualitatively different behavior of the solvation pressure in the 1 and 2 nm pores as a function of the surface charge density. We demonstrated that the value of the solvation pressure is defined by a delicate balance between Van der Waals and electrostatic contributions. We demonstrated that the theory predicts the dependence of the solvation pressure on the pore width, which matches the results of simulations using the implicit water model. Finally, we adapted the continuum theory, developed for adsorption-induced deformation to estimate the deformation of a carbon electrode due to electrosorption. Our results can be used in the further development of nanoporous actuators working based on electrosorption-induced deformation. 

Bacterial spores have outstanding properties from the materials science perspective, which allow them to survive extreme environmental conditions. Recent work by [S. G. Harrellsonet al.,Nature619, 500–505 (2023)] studied the mechanical properties ofBacillus subtilisspores and the evolution of these properties with the change of humidity. The experimental measurements were interpreted assuming that the spores behave as water-filled porous solids, subjected to hydration forces. Here, we revisit their experimental data using literature data on vapor sorption on spores and ideas from polymer physics. We demonstrate that upon the change of humidity, the spores behave like rubber with respect to their swelling, elasticity, and relaxation times. This picture is consistent with the knowledge of the materials comprising the bacterial cell walls—cross-linked peptidoglycan. Our results provide an interpretation of the mechanics of bacterial spores and can help in developing synthetic materials mimicking the mechanical properties of the spores.