Natural calcium minerals as catalysts of oxidative conversion of methane

The studies of the influence of the kind of natural calcium mineral and the kind and amount of sodium promoter on the conversion degree of methane and oxygen, selectivity and yield of the oxidative conversion of methane have shown the usability of limestone as a basic component of the catalyst for this process.     

Anisochronism of large geminal groups in the 1H and 13C nuclear magnetic resonance spectra

The role of steric factors in magnetic non-equivalence anisochronism of complex geminal groups and of their fragments in compounds of the general formula RCH(Ph)CH(COOR′)₂ has been investigated. CMR anisochronism is more sensitive to conformational and other steric changes than is PMR.     

New evidence of the intrinsic chemical shift non-equivalence

Carbinols of the general formulae R·CHOH·C(NO₂)Me₂ exhibit increasing values of chemical shift non-equivalence for the geminal methyl groups with rise of temperature. This phenomenon furnishes indirect evidence for the intrinsic non-equivalence.     

13C n.m.r. chemical shifts in aliphatic alcohols and the γ-shift caused by hydroxyl and methyl groups

Empirical correlations for the prediction of the chemical shifts of the carbon atoms in aliphatic alcohols are presented. Structural and conformational effects contributing to the ¹³C chemical shifts of γ-carbons are discussed.     

Iterative least-squares analysis of dynamic n.m.r. spectra. Hindered rotation of the N-nitroso group in N-nitroso-N-cyanomethylmethylamine

Iterative analysis of dynamic n.m.r. (d.n.m.r.) spectra by the least-squares method was applied to the entire proton spectrum of N-nitroso-N-cyanomethylmethylamine and, separately, to the CH₃ and CH₂CN sub-spectra. Resulting differences in the estimated rates of rotation of the NO group are discussed in terms of systematic errors which may be involved in determining spin exchange rates by d.n.m.r. methods. The most probable explanation is that quadrupolar broadening and then unresolved ¹⁴N? ¹H spin–spin splitting may appear on increasing the temperature. Estimated entropies of activation indicate that the methyl sub-spectrum gives more reliable results.     

Diastereomeric non-equivalence of (−)-ω-camphanic esters of chiral secondary alcohols in 13C NMR spectroscopy

The diastereomeric differences (Δδ) were measured by ¹³C NMR spectroscopy for a series of 11 (?)-ω-camphanic esters of secondary alcohols of known absolute configuration. This method cannot be used for the determination of the absolute configuration, but it can be applied to the estimation of the enantiomeric purity of chiral alcohols.     

Characterization of Ru/CeO2-Al2O3 catalysts and their Performance in CO2 Methanation

Ru/Al₂O₃ and Ru/CeO₂-Al₂O₃ samples were used as catalysts in CO₂ methanation. The catalysts were characterized by temperature-programmed reduction (TPR) and X-ray diffraction. The promoting effect of ceria on the cataytic activity of the catalysts under study in CO₂ methanation was observed.     

Influence of the interaction between adsorbed organic ions and supporting electrolyte ions on the kinetic current of protonation reaction

The paper presents an ionite model of a mercury electrode covered with adsorbed organic ions, and points out that the kinetic current of protonation in the presence of ionic surfactants depends on the process of ion exchange with the participation of the so-called ionite layer formed during the adsorption of organic ions, which have long carbon chains (C10).     

Bellman equations associated to the optimal feedback control of stochastic Navier‐Stokes equations

In this paper we study infinite‐dimensional, second‐order Hamilton‐Jacobi‐Bell‐man equations associated to the feedback synthesis of stochastic Navier‐Stokes equations forced by space‐time white noise. Uniqueness and existence of viscosity solutions are proven for these infinite‐dimensional partial differential equations. © 2005 Wiley Periodicals, Inc.     

Further evidence of the intrinsic chemical shift non-equivalence

The influence of hydrogen bonds on the chemical shift non-equivalence of geminal methyl groups in recently investigated carbinols has been eliminated by using the formyl derivatives of the general formula RCH(OCHO)C(NO₂)Me₂. The observed increasing non-equivalence, with the rise of temperature, provides more convincing evidence of the intrinsic non-equivalence.