On properties of infimal topology of a map space

We study properties of the infimal topology τ_inf which is the infimum of the family of all topologies of uniform convergence defined on the set C(X, Y) of continuous maps into a metrizable space Y. One of the main results of the research consists in obtaining necessary and sufficient condition for the topology τ_inf to have the Fréchet–Urysohn property. We also establish necessary and sufficient conditions for coincidence of the topology τinf and a topology of uniform convergence τ_μ (“attaining” the infimum). We prove that for this coincidence it is sufficient for the topology τ_inf to satisfy the first axiom of countability.     

Reactions of terpene alcohols and diols with chlorine dioxide in dimethylformamide

The system chlorine dioxide–dimethylformamide in combination with or without a catalytic amount of MoCl₅, CeCl₃, ZrOCl₂, or VO(acac)₂ induces oxidative chlorination of a number of bicyclic terpene alcohols and vicinal diols. 2α-Chloropinan-3-one, 3α-chloro-10β-pinan-4-one, 5α-chloro-3α-hydroxycaran-4-one, 5β-chloro-3β-hydroxycaran-4-one, and 4α-chloro-2α-hydroxypinan-3-one were thus synthesized in good preparative yields.     

Nature and conditions of formation of structural defects in zirconium(IV) oxide in the course of its preparation from zirconium hydroxide

The nature of paramagnetic defects in nanosized ZrO₂ samples prepared by the sol-gel method was studied by ESR. Conditions of formation of different centers (Zr³⁺, F centers, O^?, O ₂ ^? ) in ZrO₂ were elucidated. The Zr³⁺ and O^? centers arise in the course of thermal dehydration of Zr(OH)₄ under the conditions when the formation of a Zr-O-Zr bridging bond is hindered. The F centers are formed in ZrO₂ on heating in a reducing atmosphere or as a result of structural rearrangements accompanied by a decrease in the amount of lattice oxygen in the coordination surrounding of Zr(IV).     

Ion Beam Generation in a Vacuum Arc Ion Source with a Multicomponent Cathode

Russian Physics Journal - Vacuum arc ion sources are widely used for modifying the properties of various surfaces using ion implantation. The use of cathodes consisting of multicomponent compounds...     

Modification of the Material Surface by Boron Ions Based on Vacuum Arc Discharge Systems and a Planar Magnetron

Russian Physics Journal - The principle of operation and the characteristics of the experimental equipment intended for the generation of boron ion plasma and beams are presented. The equipment...     

Reaction of 2-(alkenylsulfanyl)pyrimidin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones with hydrochloric acid

Hydrochloric acid reacts with 5-ethyl-2-methallylsulfanyl-6-methylpyrimidin-4(3H)-ones to protonate the nitrogen atom; it adds to the double bond of 2-prenylsulfanyl-6-(trifluoromethyl)pyrimidin-4(3H)-one and gives the addition and heterocyclization products in the case of 2-prenylsulfanyl-6-methylpyrimidin-4(3H)-one.     

Edge absorption spectra of crystalline and glassy PbGeS<Subscript>3</Subscript>

Edge absorption spectra of crystalline and glassy lead thiogermanate (PbGeS₃) have been measured in the temperature range from 77 to 470 K. It is shown that the dependence of the absorption coefficient on the photon energy for the glassy and crystalline states in the polarization E ∥ c is described by the Urbach rule. For the crystal in the polarization E ∥ b, at T < 300 K, an almost parallel shift of the intrinsic absorption edge to lower energies occurs with an increase in temperature, whereas at T ≥ 300 K, the Urbach absorption edge is observed. The parameter σ₀, related to the electron-phonon coupling constant, and the energy ?ω_ph of the effective phonons involved in the formation of the absorption edge of crystalline PbGeS₃ are determined from the temperature dependence of the parameter of the absorption edge slope. The contributions of the dynamic and static disorders to the diffusion of the absorption edge of crystalline PbGeS₃, as well as the topological disorder of glassy PbGeS₃, have been estimated.     

Lattice dynamics and phase diagram of aluminum at high temperatures

The dispersion of phonons in the fcc, hcp, and bcc phases of aluminum is calculated at ultrahigh pressures by the method of small displacements in a supercell. The stability of the phonon subsystem is studied. The thermodynamic characteristics are calculated in the quasi-harmonic approximation, and a phase diagram of aluminum is plotted. As compared to the Debye model, the use of a phonon spectrum calculated in the quasi-harmonic approximation significantly broadens the hcp phase field and strongly shifts the phase boundary between the fcc and bcc phases. The normal isentrope is calculated at megabar pressures. It is shown to intersect the fcc-hcp and hcp-bcc phase boundaries. The sound velocity along the normal isentrope is calculated. It is shown to have a nonmonotonic character.     

Shock compression of some porous media in conical targets: numerical study

Axially symmetric flows in conical solid targets filled by porous aluminum, graphite or polytetrafluoroethylene under impact of an aluminum plate with the velocity of 2.5 km/s are simulated numerically within the framework of the model of the hypoelastic ideal-plastic solid. The porosity of the samples is taken into account by conservation laws at the leading shock wave; the medium behind that is supposed to be nonporous. Equations of state for all materials in question are used to describe thermodynamic properties of the impactor and target over a wide range of pressures and temperatures taking into account phase transformations. The maximal over space and time pressure as a function of the initial relative density is presented and discussed.     

One-pot multicomponent synthesis of diversely substituted 2-aminopyrroles. A short general synthesis of rigidins A, B, C, and D

Privileged medicinal scaffolds based on the structures of tetra- and pentasubstituted 2-aminopyrroles were prepared via one-pot multicomponent reactions of structurally diverse aldehydes and N-(aryl-, hetaryl-, alkylsulfonamido)acetophenones with activated methylene compounds. This methodology was used in a four-step synthesis of alkaloids rigidins A, B, C, and D in overall yields of 61%, 58%, 60%, and 53%, respectively. Of these, rigidins B, C, and D were synthesized for the first time.