13 research outputs found
Triple molybdates one-, one - and three(two)valence metals
The authors thank Ph. D. M. K. Alibaeva, Ph. D. I. A. Gudkova and Ph. D. I. V. Korolkova for participation in the research.The review summarizes experimental data on the phase formation, structure and properties of new complex oxide compounds group - triple molybdates containing tetrahedral molybdate ion, two different singly charged cation, together with tri- or divalent cation. The several structural families of these compounds were distinguished and it shown that many of them are of interest as luminescent, laser, ion-conducting or nonlinear optical materials.The work is executed at partial support of the Russian Foundation for basic research (projects No. 08-03-00384, 13-03-01020 and 14-03-00298)
Horizon effects with surface waves on moving water
Surface waves on a stationary flow of water are considered, in a linear model
that includes the surface tension of the fluid. The resulting gravity-capillary
waves experience a rich array of horizon effects when propagating against the
flow. In some cases three horizons (points where the group velocity of the wave
reverses) exist for waves with a single laboratory frequency. Some of these
effects are familiar in fluid mechanics under the name of wave blocking, but
other aspects, in particular waves with negative co-moving frequency and the
Hawking effect, were overlooked until surface waves were investigated as
examples of analogue gravity [Sch\"utzhold R and Unruh W G 2002 Phys. Rev. D 66
044019]. A comprehensive presentation of the various horizon effects for
gravity-capillary waves is given, with emphasis on the deep water/short
wavelength case kh>>1 where many analytical results can be derived. A
similarity of the state space of the waves to that of a thermodynamic system is
pointed out.Comment: 30 pages, 15 figures. Minor change