Cholesterol-induced deformation of the gramicidin A channel inhibiting potassium ion binding and transport

Gramicidin A(gA)is a kind of antibiotic peptide produced by bacillus brevis and it can dimerize across lipid bilayers to form a monovalent cation channel.In this work,we investigate the impact of cholesterol in the lipid bilayer on the binding of potassium ions with the gA channel and the transport of the ions across the channel.The results indicate that cholesterol can significantly influence the conformational stability of the gA channel and cause the channel deformation which inhibits the potassium ion binding with the channel and transport across the channel.The work provides some molecular insights into understanding of influence of lipids on the activity of gA channel in both model membranes and plasma membranes of intact cells.

Valley filtering and valley-polarized collective modes in bulk graphene monolayers

The presence of two sublattices in hexagonal graphene brings two energetically degenerate extremes in the conduction and valence bands, which are identified by the valley quantum number. Recently, this valley degree of freedom has been suggested to encode and process information, which develops a new carbon-based electronics named graphene valleytronics. In this topical review, we present and discuss valley-related transport properties in bulk graphene monolayers,which are due to strain-induced pseudomagnetic fields and associated vector potential, sublattice-stagger potential, and the valley-Zeeman effect. These valley-related interactions can be utilized to obtain valley filtering, valley spatial separation, valley-resolved guiding modes, and valley-polarized collective modes such as edge or surface plasmons. The present challenges and the perspectives on graphene valleytronics are also provided in this review.

Thermal analysis and Joule-Thomson expansion of black hole exhibiting metric-affine gravity

This study examines a recently hypothesized black hole,which is a perfect solution of metric-affine gravity with a positive cosmological constant,and its thermodynamic features as well as the Joule-Thomson expansion.We develop some thermodynamical quantities,such as volume,Gibbs free energy,and heat capacity,using the entropy and Hawking temperature.We also examine the first law of thermodynamics and thermal fluctuations,which might eliminate certain black hole instabilities.In this regard,a phase transition from unstable to stable is conceivable when the first law order corrections are present.In addition,we study the efficiency of this system as a heat engine and the effect of metric-affine gravity for the physical parameters q_(e),q_(m),κ_(s),κ_(d),and κ_(sh).Further,we study the Joule-Thomson coefficient and inversion temperature,and observe the isenthalpic curves in the Ti−Pi plane.In metric-affine gravity,a comparison is made between a van der Waals fluid and a black hole to study their similarities and differences.