Growth and study of single crystals of (Na,K)NbO<Subscript>3</Subscript> solid solutions

(Na, K)NbO₃ crystals with a perovskite structure and a KNbO₃ content up to 40 mol % were grown from flux with the use of the solvent NaBO₂. The dielectric measurements of the crystals grown revealed phase transitions that had never been observed before in ceramic samples.     

Arene sulfenylation by arenesulfenamides and arenesulfenylacetates

Two systems for arene sulfenylation were investigated: arenesulfenamides in the presence of SO₃ and sulfenylacetate complexes with AlBr₃. A preference for the second reagent was demonstrated for sulfenylation of substrates bearing donor substituitents.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 324–326, February, 1995.     

Inconsistency of a metatheory of Nudel''man

A metatheory of Nudel'man outlined in [1] is proved inconsistent. The groundwork for the proof is the method of arithmetization of metamathematics.Translated fromAlgebra i Logika, Vol. 34, No. 1, pp. 41–43, January–February, 1995.     

Multistep numerical methods for functional-differential-algebraic equations

This paper deals with constructing multistep numerical methods for differential delay equations under additional algebraic constraints. Theorems on the orders of convergence of these methods are proved both for functional-differential equations with algebraic constraints and for singular functional-differential equations.     

The double exponential map and covariant derivation

We study the double exponential map which is a composition of a special form of two exponential maps on a manifold with connection. We relate this map and the composition of covariant derivations as well as the composition of pseudodifferential operators on these manifolds.     

On the conditions under which a satellite orbit intersects the surface of a central body of finite radius in the restricted double-averaged three-body problem

This paper is concerned with the applied problem of choosing long-living orbits of artificial Earth satellites whose evolution under the influence of gravitational perturbation from the Moon and the Sun may result in the collision of the satellite with the central body, as was shown by M.L. Lidov for the well-known example of “Vertical Moon.” We use solutions of the completely integrable system of evolution equations obtained by Lidov in 1961 by averaging twice the spatial circular restricted three-body problem in the Hill approximation. In order to apply the integrability of this problem in practice, we study the foliation of the manifold of levels of first integrals and the change of motion under crossing the bifurcation manifolds separating the foliated cells. As a result, we describe the manifold of initial conditions under which the orbit evolution leads to an inevitable collision of the satellite with the central body. We also find a lower bound for the practical applicability of the results, which is determined by the presence of gravitational perturbations caused by a polar flattening of the central body. Original Russian Text ? V.I. Prokhorenko, 2007, published in Trudy Matematicheskogo Instituta imeni V.A. Steklova, 2007, Vol. 259, pp. 156–173.     

Ultrashort pulse laser osteotomy

Laser treatment of bone tissue has already been the subject of many studies to find substitutes for mechanical instruments that are nowadays used in implantology and orthopaedics. Mainly lasers with pulse durations in the μs region have been tested leaving surface features that are not always satisfactory. Therefore, in the present study laser osteotomy has been performed with a 330 fs Yb:glass laser, λ = 1040 nm, at a pulse repetition rate of 1 kHz. For bovine spongiosa, compacta, and cartilage, the ablation thresholds as well as the ablation rates for various pulse energies have been determined. Additionally, quadratic areas have been ablated in bone tissue. The remaining morphology has been analyzed via scanning electron microscopy. Laser ablation has also been performed with an Er, Cr:YSGG laser, λ = 2780 nm, PRR = 20 Hz, τ ～ 50 μs. The results of USPL and Erbium laser ablation are compared.