  The existence and stability of domain walls (DWs) and bubble-droplet (BD)
states in binary mixtures of quasi-one-dimensional ultracold Bose gases with
inter- and intra-species repulsive interactions is considered. Previously, DWs
were studied by means of coupled systems of Gross-Pitaevskii equations (GPEs)
with cubic terms, which model immiscible binary Bose-Einstein condensates
(BECs). We address immiscible BECs with two- and three-body repulsive
interactions, as well as binary Tonks--Girardeau (TG) gases, using systems of
GPEs with cubic and quintic nonlinearities for the binary BEC, and coupled
nonlinear Schr\"{o}dinger equations with quintic terms for the TG gases. Exact
DW\ solutions are found for the symmetric BEC mixture, with equal intra-species
scattering lengths. Stable asymmetric DWs in the BEC mixtures with dissimilar
interactions in the two components, as well as of symmetric and asymmetric DWs
in the binary TG gas, are found by means of numerical and approximate
analytical methods. In the BEC system, DWs can be easily put in motion by phase
imprinting. Combining a DW and anti-DW on a ring, we construct BD states for
both the BEC and TG models. These consist of a dark soliton in one component
(the "bubble"), and a bright soliton (the "droplet") in the other. In the BEC
system, these composite states are mobile too.
