Methodology of using expert systems for structure elucidation of organic molecules by their spectra

Major axioms underlying structure elucidation of molecules by their characteristic spectral data are considered. The amount of information obtained by solving the problem on structure elucidation of molecules serves as a basis to evaluate the quality of solution. Conditions for computer-aided solution of problems using expert systems (ES) are analyzed. Reasons for incorrect or zero solutions and for inconsistencies leading to negative results are examined. The role of additional information as a necessary condition for correct solution is discussed. On the basis of this analysis, a general strategy for structure elucidation of molecules by their spectra using ES is suggested. The principal idea is to use the iteration method, gradually increasing the rigidity of constraints. Strategies named ARCHEOLOGIST and SCULPTOR are discussed. Examples are given. Russian Scientific Research Institute of Organic Synthesis. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 3, pp. 548–558, May–June, 1995. Translated by L. Smolina     

Algebra with polynomial commutation relations for the Zeeman effect in the Coulomb-Dirac field

We consider a model of particle motion in the field of an electromagnetic monopole (in the Coulomb-Dirac field) perturbed by homogeneous and inhomogeneous electric fields. After quantum averaging, we obtain an integrable system whose Hamiltonian can be expressed in terms of the generators of an algebra with polynomial commutation relations. We construct the irreducible representations of this algebra and its hypergeometric coherent states. We use these states to represent the eigenfunctions of the original problem in terms of the solutions of the model ordinary differential equation. We also present the asymptotic approximations of the eigenvalues in the leading term of the perturbation theory, where the degeneration of the spectrum is removed completely.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 142, No. 1, pp. 127–147, January, 2005.     

Tverberg-Type Theorems for Intersecting by Rays

In this paper we consider some results on intersection between rays and a given family of convex, compact sets. These results are similar to the central point theorem, and Tverberg’s theorem on partitions of a point set.     

Algebra with Quadratic Commutation Relations for an Axially Perturbed Coulomb–Dirac Field

The motion of a particle in the field of an electromagnetic monopole (in the Coulomb–Dirac field) perturbed by an axially symmetric potential after quantum averaging is described by an integrable system. Its Hamiltonian can be written in terms of the generators of an algebra with quadratic commutation relations. We construct the irreducible representations of this algebra in terms of second-order differential operators; we also construct its hypergeometric coherent states. We use these states in the first-order approximation with respect to the perturbing field to obtain the integral representation of the eigenfunctions of the original problem in terms of solutions of the model Heun-type second-order ordinary differential equation and present the asymptotic approximation of the corresponding eigenvalues.     

The effect of a longitudinal magnetic field on the plasma-dust structures in strata in a glow discharge

The plasma-dust structures in strata in a glow discharge exposed to a longitudinal magnetic field are studied in detail. In a weakly ordered structure, the angular velocity has a vertical gradient. A reversal of rotation of the structure in a magnetic field corresponding to the magnetization of electrons is found. With the help of the pair distribution function of particles, changes in the degree of order of the structure in the magnetic field are revealed. These changes correlate with changes in the angular velocity of rotation. To explain this effect, it is assumed that the dust structure is subjected to the action of ions in crossed electric and magnetic fields.     

Mechanochemical synthesis of nanosized europium nitrate with 1,10-phenanthroline

Mechanochemically synthesized europium nitrate with 1,10-phenanthroline (Phen) is formed into globules with sizes of 100–300 nm, which are assembled into larger globular aggregates or packed into layers. The increasing mechanical activation time induces sintering, generating porous aggregates with micro-and nanopores. Eu²⁺ paramagnetic centers, detectable by ESR, are generated by mechanical grinding. Possibly, they are positioned on the surfaces of nanoglobules. The complex Eu(NO₃)₃ · 2Phen synthesized conventionally from aqueous ethanol consists of needle-shaped microcrystallites. They do not give rise to ESR spectra.     

The dispersity and distribution of luminophors in high-pressure polyethylene

Polymers based on high-pressure polyethylene were prepared and activated with europium(III) complexes with carboxylic acids and compositions based on europium-anthranilic acid compounds. According to the electron scanning, atomic, and fluorescence spectroscopic data, luminophor particles showed a heterophase distribution in films. The particles had an average size of 3–30 μm and were shaped as globules.     

The luminescent properties of polyethylene films with admixtures of luminophores based on europium compounds

Polyethylene films activated with europium(III) complexes with carboxylic acids and Eu(L)₃ · nD · xH₂O + ANT compositions, where L is the trifluoroacetic, toluyl, or cinnamic acid anion and ANT is anthranilic acid, were prepared. The intensity of luminescence of the polymeric compositions depended on the content of luminophores (molar ratio between europium compounds and anthranilic acid). An analysis of the excitation spectra showed that, in polymer—Eu(L)₃ · nPhen · xH₂O + ANT compositions, there was effective energy transfer from phenanthroline to anthranilic acid levels.     

Dimension of maps,universal spaces,and homotopy

This paper is a survey of some recent results in dimension theory. The main topics under consideration are: dimension of maps in the classical and extension dimension theories, universal spaces (in particular, universal compacta) in extension dimension theory, and [L]-homotopy. A number of theorems included in the survey are accompanied by proofs. __________ Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 48, General Topology, 2007.     

Columinescence effect in macromolecular complexes of Eu(III) and Tb(III)

The effect of Y(III) and Gd(III) coactivator ions on the intensity of Eu(III) and Tb(III) luminescence in monomer and polymer mixed-metal complexes was studied. Isomorphic replacement of Eu(III) and Tb(III) ions by Y(III) and Gd(III) ions in macromolecular complexes led to sensitization of Eu(III) and Tb(III) ion luminescence. A mechanism of columinescence was suggested. It involves a charge transfer and the ligand orbitals and the vacant orbitals of Eu(III) and Tb(III) ions and coactivators.