It is shown that the attractive force between ions in a degenerate quantum plasma, recently predicted by Shukla and Eliasson [Shukla, Eliasson, PRL 108, 165007 (2012), arXiv:1112.5556] using a generalized quantum hydrodynamical model, is dwarfed by t
he attractive force due to kinetic effects that cannot be accounted for in the previous model. This suggests that the problem of charge shielding in a degenerate quantum plasma should necessarily be a kinetic one, providing the dominant part of the attractive force.
Surface plasmons (SP) in a semi-bounded quantum plasma with degenerate electrons (e.g., a metal) is considered, and some interesting consequences of electron Pauli blocking for the SP dispersion and temporal attenuation are discussed. In particular,
it is demonstrated that a semi-bounded degenerate plasma with a sharp boundary supports two types of SP with distinct frequencies and qualitatively different temporal attenuation, in contrast to a non-degenerate plasma that only supports one type of SP citep{Guernsey_1969}.
