Surface impedance of a superconducting slab in the mixed state: Effect of the surface barrier

The effect of the surface barrier on the surface impedance Z of a type-II superconductor slab with a finite thickness is investigated in dc magnetic fields H ₀, which are aligned parallel or perpendicular to the slab plane. It is demonstrated that, in a perpendicular geometry, the surface resistivity ρ_s=ReZ has a maximum when the depth of penetration of the ac magnetic field is of the order of the slab thickness (size effect). For a parallel orientation of the magnetic field H ₀, the effect of the Bean-Livingston surface barrier manifests itself as a decrease in the dissipative loss and a change in the field dependence of the surface resistivity characterized by a magnetic hysteresis. It is shown for the first time that, under the conditions of persistent trapped magnetic flux, the dependence ρ_s(H ₀) is a decreasing function, which is associated, in particular, with a nontrivial suppression of the size effect.     

Kinetics of the Acetic Acid Oxyethylation Catalyzed by Chromium Acetate

The effect of the product of the acetic acid oxyethylation (ethylene glycol monoacetate) on the kinetics of this reaction in the presence of chromium acetate is studied. Compared to base catalysis, catalysis with chromium acetate provided a higher selectivity in the formation of the monoaddition compound. It is found that an increase in the concentration of ethylene glycol monoacetate resulted in a drop in the reaction rate. The hypothetical mechanism of catalysis is proposed. The kinetic equation that adequately describes all experimental data is derived from this mechanism.     

Finite-element solution of a model mechanical problem with friction based on a smoothing Lagrange multiplier method

The convergence of the finite element method in a stable smoothing algorithm for solving a model problem with given friction based on an iterative proximal regularization of the modified Lagrangian functional is analyzed. Numerical results are presented.     

Europium(<Emphasis Type="SmallCaps">iii</Emphasis>) phthalocyanine complexes with 8-oxyquinoline

Europium(iii) phthalocyanine complexes containing 8-oxyquinoline fragments were synthesized. The complexes were identified and structurally characterized by IR and UV-Vis absorption spectroscopy and mass spectrometry.     

Linearized equations of spatial statically determinate states in the theory of ideal plasticity

In the present paper, we consider linearized statically determinate relations in the theory of ideal plasticity for the case in which the full plasticity condition does not hold. We analyze the type of the equations under study. We note that the linearized equations under the full plasticity condition were considered in [1–3].     

Monolithic polymeric sorbents for high-performance chromatography of synthetic polymers

A number of macroporous monolithic materials based on copolymers of butyl methacrylate or lauryl methacrylate with ethylene glycol dimethacrylate is obtained via thermal free-radical polymerization. The effect of polymerization conditions on pore parameters of the synthesized sorbents is studied. Polymer stationary phases obtained for the efficient analysis of synthetic polymers are tested for the separation of a multicomponent mixture containing polystyrene samples of various molecular masses.     

Analysis of the structural interaction of electrically active heterogeneous finely dispersed systems at the interfaces between the solid and liquid phases

Strong electrical forces have been revealed in electrically active heterogeneous finely dispersed systems at the interfaces between the solid and liquid phases. It has been established that these forces give rise to gradients of the potential of an internal self-electric field that can provide circulation of electric currents in the systems under investigation. It has been found that, in these systems, there arises a double electric layer that represents a new structuring phase, which is characteristic of electrically active systems only. The mechanism of formation of a double electric layer includes electrocontact interaction between the surfaces of two heterogeneous liquid and solid polar dielectrics.