Three materials containing Ni 2 P, Ni 12 P 5 , and Ni 3 P phases on silica gel with surface area 320 m 2 /g at loadings of 32-37 wt % and the crystal size of Ni x P phases 30, 9, and 13 nm, respectively, were prepared by a combination of impregnation and TPR methods and tested in hydrodesulfurization (HDS) and adsorptive desulfurization (ADS) of diesel fuel. There were established opposite trends in changing the DS efficiency in two processes: The HDS rate constant decreased while the ADS sulfur capacity (breakthrough at 1 ppmw) increased with increasing the Ni to P ratio in Ni x P from 2 to 3. The observed behavior was attributed to the specific features of the densities of states (DOS) obtained from the density functional theory calculations of total and partial DOS for Ni and P in Ni x P phases and revealed in XPS measurements of binding energy of Ni 2p 3/2 -and P 2p-electrons. This attribution was consistent with the analysis of the relative part of d-electrons of Ni participating in bonding with p-electrons of phosphorus in these phases.

The linear instability of two equilibrium configurations with either poloidal (I) or toroidal (II) dominant magnetic field components are studied in thin vertically isothermal Keplerian discs. Solutions of the stability problem are found explicitly by asymptotic expansions in the small aspect ratio of the disc. In both the equilibrium configurations the perturbations are decoupled into in‐plane and vertical modes. For equilibria of type I those two modes are the Alfvén–Coriolis and sound waves, while for equilibria of type II they are the inertia–Coriolis and magnetosonic waves. Exact expressions for the growth rates as well as the number of unstable modes for type I equilibria are derived. Those are the discrete counterpart of the continuous infinite homogeneous cylinder magnetorotational (MRI) spectrum. It is further shown that the axisymmetric MRI is completely suppressed by dominant toroidal magnetic fields (i.e. equilibria of type II). This renders the system prone to either non‐axisymmetric MRI or non‐modal algebraic growth mechanisms. The algebraic growth mechanism investigated in the present study occurs exclusively due to the rotation shear, generates the inertia–Coriolis driven magnetosonic modes due to non‐resonant or resonant coupling that induces, respectively, linear or quadratic temporal growth of the perturbations.

Mechanical deformations of a magnetostrictive-piezoelectric bilayer result in the interaction between the magnetic and electric subsystems. This review reports the models for describing the distinctive features of magnetoelectric (ME) interactions in ferrite-piezoelectric nanostructures at low-frequencies and in electromechanical resonance region. Expressions for ME coefficients are obtained using the solution of elastostatic/elastodynamic and electrostatic and magnetostatic equations. The ME voltage coefficients are estimated from known material parameters. The models take into account the clamping effect of substrate, flexural deformations, and the contribution of lattice mismatch between composite phases and substrate to ME coupling. Lattice mismatch effect has been taken into account by using the classical Landau–Ginsburg–Devonshire phenomenological thermodynamic theory. For a nickel ferrite-lead zirconate titanate nanobilayer on SrTiO3 substrates, the strength of low-frequency ME interactions is shown to be weaker than for thick film bilayers due to the strong clamping effects of the substrate. However, flexural deformations result in the considerably lower rate of change in ME voltage coefficient with substrate thickness compared to the case when neglecting the flexural strains. To avoid the strong clamping effects of the substrate, nanopillars of a magnetostrictive material in a piezoelectric matrix can be used as an alternative. The further methods of increasing the ME coupling in nanostructures are discussed.

A new nondissipative mechanism is proposed for the saturation of the axisymmetric magnetorotational (MRI) instability in thin Keplerian disks that are subject to an axial magnetic field. That mechanism relies on the energy transfer from the MRI to stable magnetosonic waves. Such mode interaction is enabled due to the vertical stratification of the disk that results in the discretization of its MRI spectrum, as well as by applying the appropriate boundary conditions. A second order Duffing-like amplitude equation for the initially unstable MRI modes is derived. The solutions of that equation exhibit bursty nonlinear oscillations with a constant amplitude that signifies the saturation level of the MRI. Those results are verified by a direct numerical solution of the full nonlinear reduced set of thin disk magnetohydrodynamics equations.

The nonlinear mean-field dynamo due to a shear-current effect in a nonhelical homogeneous turbulence with a mean velocity shear is discussed. The transport of magnetic helicity as a dynamical nonlinearity is taken into account. The shear-current effect is associated with the W×J term in the mean electromotive force, where W is the mean vorticity due to the large-scale shear motions and J is the mean electric current. This effect causes the generation of large-scale magnetic field in a turbulence with large hydrodynamic and magnetic Reynolds numbers. The dynamo action due to the shear-current effect depends on the spatial scaling of the correlation time τ (k) of the background turbulence, where k is the wave number. For Kolmogorov scaling, τ (k) ∝ k −2/3 , the dynamo instability occurs, while when τ (k) ∝ k −2 (small hydrodynamic and magnetic Reynolds numbers) there is no the dynamo action in a sheared nonhelical turbulence. The magnetic helicity flux strongly affects the magnetic field dynamics in the nonlinear stage of the dynamo action. Numerical solutions of the nonlinear mean-field dynamo equations which take into account the shear-current effect, show that if the magnetic helicity flux is not small, the saturated level of the mean magnetic field is of the order of the equipartition field determined by the turbulent kinetic energy. Turbulence with a large-scale velocity shear is a universal feature in astrophysics, and the obtained results can be important for elucidation of origin of the large-scale magnetic fields in astrophysical sheared turbulence.