Parametric Optimization of Metal Rod Structures Using the Modified Gradient Projection Method

International Applied Mechanics - Problems of parametric optimization of rod structure stated in terms of the nonlinear programming problem are considered. Use is made of the method of projection...     

GIPKh catalysts

In the Russian Scientific Center Applied Chemistry catalysts have been developed for the gas-phase fluorination of organics, including chlorine-containing substances, hydrogenation and reductive amination of organic substances, decomposition of liquid substances to gases, complete oxidation and reduction, suitable for environment at protection.     

Adsorption and thermodynamic properties of active sites of a pyrogenic aluminium oxide surface

Differential isosteric adsorption heats and entropies of adsorption of both n-pentane and diethyl ether on hydrated and dehydrated surfaces of pyrogenic alumina (S=140 m²/g) in the coverage range of 0.15–1.0 have been calculated from the adsorption isotherms.     

Electronic structure and properties of heteropoly anions with the formula [PM12O40]n− [M=V(V), Mo(VI), W(VI)]

Institute of Catalysis, Academy of Sciences of the USSR. Central Institute of Physical Chemistry, Academy of Sciences of the German Democratic Republic. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 1, pp. 29–33, January–February, 1989.     

A study of deuterium exchange in adamantane carboxylic acids and alcohols under electron impact

The mass spectra of 1-adamantyl substituted carboxylic acids and alcohols with and without deuterated hydroxyl groups were studied. Deuterium exchange between functional group and adamantane nucleus was observed and a possible explantation of the phenomenon is given.     

Synthesis of fluorous fullerene adducts: reversible solubilization of fullerenes in perfluorinated solvents

Fullerene (C60) Diels-Alder adducts with perfluoroalkylated 1,3-cyclopentadiene (1a,b) were synthesized and studied. The perfluoroalkylated cyclopentadiene was found to be less reactive toward C60 than cyclopentadiene itself, possibly because of the electron-withdrawing effect of the side chain. Because of the same effect, the temperature of the retro-Diels-Alder reaction for the fluorinated adducts was lower (70 degrees C) than the reported value (95 degrees C) for the cyclopentadiene adducts of C60. Higher adducts of the fluorous diene and C60 were found to be soluble in perfluorohexane and to show visible partitioning between organic (toluene) and fluorous phases. Also, the Diels-Alder addition of the fluorous diene was accompanied by extensive oxidation of the fullerene core, as revealed by MALDI-TOF data.     

Interaction of phosphomolybdovanadium heteropolyacids with hydrazine hydrate studied by a calorimetric method

The heats of interaction of VO ₂ ⁺ and of heteropolyacids H_3+nPMo_12−nV_nO₄₀ (n=1,2,3,6) with N₂H₄ have been measured.

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Измерены теплоты взаимодействия VO ₂ ⁺ и гетерополикислот H_3+nPMo_12−nV_nO₄₀ (n=1,2,3,6) с N₂H₄.

     

Direct transformations of ketones to gamma-unsaturated thiols via

The reaction of a series of ketones with dimsylsodium in dimethyl sulfoxide resulting in the formation of gamma-unsaturated thiols was studied experimentally. [2,3]-Sigmatropic rearrangements of beta-unsaturated sulfinyl carbanions are involved at the key step of those transformations. DFT computations at the B3LYP/6-31+G level indicated that such rearrangements, as well as some typical [2, 3]-sigmatropic rearrangements, e.g., thermal rearrangements of allyl sulfoxides and Wittig rearrangements of sulfur ylides and lithiated allyloxy methyl anions, are concerted and moderately synchronous processes. Negative (diatropic) nucleus-independent chemical shifts (NICS) and high diamagnetic susceptibility exaltations indicate that the transition structures of these [2,3]-sigmatropic migrations are aromatic.     

Potential-energy surface for the electronic ground state of NH3 up to 20,000 cm-1 above equilibrium

Ab initio coupled cluster calculations with single and double substitutions and a perturbative treatment of connected triple excitations [CCSD(T)] with the augmented correlation-consistent polarized valence triple-zeta aug-cc-pVTZ basis at 51 816 geometries provide a six-dimensional potential-energy surface for the electronic ground state of NH3. At 3814 selected geometries, CBS+ energies are obtained by extrapolating the CCSD(T) results for the aug-cc-pVXZ(X=T,Q,5) basis sets to the complete basis set (CBS) limit and adding corrections for core-valence correlation and relativistic effects. CBS** ab initio energies are generated at 51,816 geometries by an empirical extrapolation of the CCSD(T)/aug-cc-pVTZ results to the CBS+ limit. They cover the energy region up to 20,000 cm-1 above equilibrium. Parametrized analytical functions are fitted through the ab initio points. For these analytical surfaces, vibrational term values and transition moments are calculated by means of a variational program employing a kinetic-energy operator expressed in the Eckart-Sayvetz frame. Comparisons against experiment are used to assess the quality of the generated potential-energy surfaces. A "spectroscopic" potential-energy surface of NH3 is determined by a slight empirical adjustment of the ab initio potential to the experimental vibrational term values. Variational calculations on this refined surface yield rms deviations from experiment of 0.8 cm-1 for 24 inversion splittings and 0.4 (3.0) cm-1 for 34 (51) vibrational term values up to 6100 (10,300) cm-1.