A unified theoretical treatment is given of longitudinal (or compressional) and transverse modes in Yukawa crystals, including the effects of damping. Dispersion relations are obtained for hexagonal lattices in two dimensions and bcc and fcc lattices in three dimensions. Theoretical predictions are compared with two recent experiments.

NixCo2x(OH)6x, as a precursor of intensively studied NiCo2O4, has been directly deposited into self-standing titanium nitride nanotube array (TiN NTA) grid monolithic supports to form a coaxial nanostructured electrode for supercapacitors. With TiN NTA substrates providing a large surface area, fast electron transport, and enhanced structure stability, this NixCo2x(OH)6x/TiN electrode exhibits superior pseudocapacitive performance with a high specific capacitance of 2543 F g(-1) at 5 mV s(-1), remarkable rate performance of 660 F g(-1) even at 500 mV s(-1), and promising cycle performance (about 6.25% capacitance loss for 5000 cycles). Interestingly, the NixCo2x(OH)6x/TiN NTA electrode outperforms the NiCo2O4/TiN NTA electrode, indicating that this self-standing NixCo2x(OH)6x/TiN NTA monolith is a promising candidate for high-performance supercapacitor applications.

Graphene nanosheet has exhibited an increasing prospect in various biomedical applications because of its extraordinary properties. Meanwhile, recent experiments have shown that graphene has antibacterial activity or cytotoxicity and can cause cell membrane damage. Therefore, it is necessary to understand the interactions between graphene and cell membrane to avoid its adverse effects. Here, we use molecular dynamics simulation to explore these interactions. The results show that pristine graphene (PG) can readily penetrate into the bilayer and has no effect on the integrity of membrane. When graphene oxide (GO) is embedded in the membrane, several lipids are pulled out of the membrane to the surface of GO, resulting in the pore formation and water molecules flowing into the membrane. The difference between PG and GO in the membrane originates from GO's oxygen-contained groups, which enhance the adsorption of the lipids on GO surface. However, the main interactions between GO and membrane are still determined by the strong dispersion interactions between its hydrophobic domains and the lipid tails of the bilayer. Therefore, the toxicity of coated GO can be weakened, since its hydrophobic domains are screened by polymers. The findings may offer new perspective for better designing GO based nanocarrier or antibiotics and other biomedical applications.

The scaling of the reconnection electric field in a collisionless plasma is determined analytically for a model of forced reconnection. In particular, the dependence of the length of the reconnection layer on the ion skin depth and the boundary conditions is calculated explicitly. Analytical results are tested by Hall magnetohydrodynamics simulations.