Equilibrium conditions for the minimum coke formation during the dehydrogenation of propane

The equilibrium distribution of propane conversion products over temperature and pressure range of 700–1000 K and 0.05–0.25 MPa was determined. Calculations of the quasi-equilibrium composition of the gas phase without taking into account C_s formation demonstrated that, along with CH₄ and H₂, high-boiling C₁₄–C₃₆ aromatic hydrocarbons can be formed. The effect of H₂ on the composition was examined; it was shown that its excess with respect to propane required to ensure the zero yield of C_s increases with the temperature. Water vapor was demonstrated to influence the equilibrium composition of the products; conditions for the most effective reduction of the C_s yield were determined.     

Polariton dynamics of a one-dimensional gyrotropic magnetic photonic crystal in a dc electric field: II. Surface waves

Localization and dispersion of collective magnetic TE and TM polaritons are analyzed for a semi-infinite, one-dimensional, magnetic photonic crystal of the compensated antiferromagnetic-nonmagnetic dielectric type in the presence of orthogonal magnetic and electric fields. The case where easy magnetization axis is orthogonal to the external electric field is considered.     

9α-hydroxylation of 25-fluoroponasterone a diacetonide in lithium-ammonia solution

25-Fluoroponasterone A diacetonide reacted with lithium in liquid ammonia to give 25-fluoro-9α,20-dihydroxyecdysone diacetonide whose hydrolysis afforded 25-fluoro-9α,20-dihydroxyecdysone 20,22-acetonide. Nonfluorinated analog of the latter was isolated previously from Silene italica ssp. nemoralis.     

Interaction of Alkyl Radicals with Dihydric Phenol Derivatives in Hexane Solutions under γ-Radiolysis

The influence of structurally different dihydric phenols on the radical reactions of hexane in deaerated solutions under -irradiation was studied. It was found that 4-tert-butylpyrocatechol (I), 3,5-diisopropylpyrocatechol (II), 2,5-di-tert-butylhydroquinone (III), and 4,6-di-tert-butylresorcinol (IV) effectively inhibited the formation of hexyl radical combination products. Using the chromatography–mass spectrometry technique, it was shown that the adducts of alkyl radicals with I–III have the structure of a monoalkyl ether. Phenol IV gave a mixture of dimers with O- and C-alkylation products.     

Method for mild trimethylsilylation of the 14α-hydroxy group in ecdysteroids

In the reactions of poststerone derivatives and 20-hydroxyecdysone with (trifluoromethyl)trimethylsilane catalyzed by tetrabutylammonium fluoride, the 14-hydroxy group is readily subjected to trimethylsilylation.     

Determination of stresses in fiberglass blades of shaft fans,induced by aerodynamic pressure and centrifugal forces

Mechanics of Composite Materials -