X-ray counterparts for 35 galaxy clusters contained in the PF catalog of galaxy clusters and groups were found in XMM-Newton archive. 22 ones (all from ACO catalogue) have extended elliptic Xray haloes appropriate for determination of orientation. Position angles and eccentricities were calculated and compared with cluster orientations optical band.

We study relations between hydrodynamical (H) and scalar field (SF) models of the dark energy in the homogeneous isotropic Universe. The focus is on SF described by the Lagrangian with the canonical kinetic term within spatially flat cosmology. We analyze requirements that guarantee the same cosmological history for the SF and H models at least for special solutions. The differential equation for the SF potential is obtained that ensures such equivalence of the SF and H-models. However, if the "equivalent" SF potential is found for given equation of state (EOS) of the H-model, this does not mean that all solutions of this SF-model have corresponding H-model analogs. In this view we derived a condition that guarantees an "approximate equivalence", when there is a small difference between energy-momentum tensors of the models. The "equivalent" SF potentials and corresponding SF solutions for linear EOS are found in an explicit form; we also present examples with more complicated EOSs.

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We study solutions of the Friedmann equations in case of the homogeneous isotropic Universe filled with a perfect fluid. The main points concern the monotony properties of the solutions, the possibility to extend the solutions on all times and occurrence of singularities. We present a qualitative classification of all possible solutions in case of the general smooth barotropic equation of state of the fluid, provided the speed of sound is finite. The list of possible scenarios includes analogues of the "Big Rip" in the future and/or in the past as well as singularity free solutions and oscillating Universes. Extensions of the results to the multicomponent fluids are discussed.