The effect of the structure of bonded cyanoalkyl stationary phases on their selectivity in the liquid chromatographic separation of polynuclear aromatic hydrocarbons

Summary The paper discusses the effect of the length and structure of the hydrocarbon chain connecting the nitrile group to the silica gel surface on the chromatographic properties of cyanoalkyl phases.When using non-polar and polar mobile phases, the selectivity of the cyanodecyl phases toward PAHs is higher than of the cyanopropyl phase and of hydroxylated silica gel.Polar additives to the mobile phase drastically decrease the retention on silica gel and on the cyanopropyl phase while affect the properties of cyanodecyl phases only to a considerably less degree. Newly synthesized phases with different structures of the hydrocarbon chain are compared with the commerical cyano-and ODS-phases. The retention mechanism on the cyanoalkyl phases is discussed.     

Generalized killing tensors of arbitrary rank and order

We define Killing tensors and conformal Killing tensors of arbitrary rank and order which generalize in a natural way the notion of a Killing vector. We explicitly derive the corresponding tensors for a flat de Sitter space of dimension p+q=m,m 4, which permits us to calculate complete sets of symmetry operators of arbitrary order n for a scalar wave equation with m independent parameters.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 6, pp. 786–795, June, 1991.     

Adiabatic channel study of the capture of nitrogen and oxygen molecules by an ion: effect of nuclear symmetry and spin-spin interaction

Within the adiabatic channel treatment of ionmolecule capture we have calculated the low temperature capture rate constants of N₂(¹Σ _g ⁺ ) and O₂(³Σ _g ^? )in collisions with positive and negative ions. In both cases, the charge-quadrupole and the anisotropic charge-induced dipole interactions produce noticeable deviations from the Langevin rate constant. The rate constants calculated with account for the anisotropic interaction, in addition, are substantially affected by nuclear symmetry; in the case of O₂(³Σ _g ^? ), the fine-structure spin-spin interaction strongly manifests itself in the rate constants.     

Alkylation of salts ofN-(β-hydroxyalkyl)-N′-hydroxydiazeneN-oxides with alkyl halides and dimethyl sulfate

Salts ofN-(β-hydroxyalkyl)-N′-hydroxydiazeneN-oxides, RCH(OH)CH₂N(O)=NO⁻ M⁺ (R=Me, Prⁱ, or Bu^t; and M=Li, Na, K, Ag, NH₄, or Me₄N), were prepared. Their alkylation with alkyl halides R′X (X=Cl, Br, or I) and dimethyl sulfate was studied. Generally, alkylation afforded mixtures ofN-(β-hydroxyalkyl)-N′-alkoxydiazeneN-oxides RCH(OH)CH₂N(O)=NOR′ andO-alkyl-N-(β-hydroxyalkyl)-N-nitrosohydroxylamines RCH(OH)CH₂N(NO)OR′. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1996–2001, October, 1998.     

Inhibition of the photoinduced ignition of chloromethane–chlorine mixtures by oxygen

The introduction of small amounts of oxygen inhibits the photoinduced ignition of chloromethane–chlorine mixtures. This is accompanied by an increase in the induction period and a decrease in the degree of heating of the reaction mixture. After the consumption of the entire inhibitor, the photochlorination reaction takes place again in the thermal explosion regime but with a lower degree of heating. In the dependence of the mixture temperature on the oxygen concentration, criticality is not pronounced. With an increasing concentration of oxygen, its effect on the induction period weakens.     

Imparting enhanced hydrophobicity to polyester fabrics: Formation of ultrathin water-repelling coatings on the fiber surface

A new technology for hydrophobization of synthetic fiber materials was described. This technological approach is based on formation of nanosized fluoropolymer coatings from solutions of low-molecularweight fraction of ultradispersed polytetrafluoroethylene and tetrafluoroethylene telomers. The mechanism of formation of protective coatings was described, and the properties of polyester materials thus modified were presented.     

Observation of Persistent Currents in Finely Dispersed Pyrolytic Graphite

The trapped magnetic flux in the finely ground pyrolytic graphite sample annealed at 670 K in air has been observed. Flux trapping occurs on cooling of the sample from room temperature to 10 K in a magnetic field of 1 T. The magnitude and sign of the induced trapped moment remain unchanged when the applied magnetic field is varied within ±1 T at T K. The trapped magnetic flux is manifested in the displacement of the magnetization curve relative to that of the sample cooled in zero field. Displacement magnitude gradually decreases with the temperature increase up to 350 K, not reaching zero. The set of experimental observations probably reflects the presence in the sample of a granular high-temperature superconducting phase.     

Interaction of N,N'-Di(4-chlorophenyl)diimide 1,1'-Binaphtyl-4,4',5,5',8,8'-hexacarboxylic Acid with Thiourea Dioxide in Solution and Thin Film

Crystallography Reports - The reactions of interaction of N,N'-di(4-chlorophenyl)diimide 1,1'-binaphtyl-4,4',5,5',8,8'-hexa-carboxylic acid (cubogen red) with thiourea dioxide...