Gas phase photoreaction of SO2 with n-pentane in the presence of NO

The spectrum of an intermediate, ascribed to nitrosopentane, has been detected in the photolysis of SO₂-pentane-NO mixtures. This may be explained by a radical photolysis mechanism involving an initial H-atom abstraction from the pentane molecule by SO₂.

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SO₂--NO , . , H .

     

Nature of the activity and the kinetics of cyclohexene hydrogenation by the catalytic system (C5H5)2 TiCl2?LiC4H9

The reaction of tributylphosphine with the catalytic system (C₅H₅)₂ TiCl₂–LiC₄H₉ prepared in an atmosphere of H₂ has been investigated in toluene solution. By using the ESR technique, a hydride complex Cp₂Ti(H) (PBu₃) has been detected. The proportionality between the rate of cyclohexene hydrogenation and the complex concentration has been established. The kinetics of cyclohexene hydrogenation has been investigated and a reaction mechanism is proposed.

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Cp₂TiCl₂–LiC₄H₉ (Cp–C₅H₅), H₂, Cp₂Ti(H) (PBu₃). Ti (III). .

     

Difference schemes for the dirichlet problem for an elliptical equation with discontinuous coefficients in an arbitrary region on a regular grid

Exact difference scheme operators are used to construct a difference scheme for a second-order elliptical equation with discontinuous coefficients. The solution of the scheme converges to the solution of the original problem at a rate O(h^1/2) in the grid norm W₂ ¹().Translated from Vychislitel'naya i Prikladnaya Matematika, No. 56, pp. 3–7, 1985     

Dirichlet norms,capacities and generalized isoperimetric inequalities for Markov operators

We define the notion of p-capacity for a reversible Markov operator on a general measure space and prove that uniform estimates for the ratio of capacity and measure are equivalent to certain imbedding theorems for the Orlicz and Dirichlet norms. As a corollary we get results on connections between embedding theorems and isoperimetric properties for general Markov operators and, particularly, a generalization of the Kesten theorem on the spectral radius of random walks on amenable groups for the case of arbitrary graphs with non-finitely supported transition probabilities.     

Point interactions with inner structure as a limit of separable potentials

Interactions of zero radius with an additional inner channel are considered. The corresponding generalized Krein resolvents in a functional sector are approximated in the weak sense with the aid of interactions of rank 1. The cut-off procedure of the interaction is explicitly described in prepresentation.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 182, pp. 113–122, 1990.     

Reduction of 4-fluoro-5-(1,1,2,2-tetrafluoroethyl)-3H-1,2-dithiole-3-thione with sodium sulfide: Synthesis of fluoro-containing sulfur-rich heterocycles

Treatment of 4-fluoro-5-(1,1,2,2-tetrafluoroethyl)-3H-1,2-dithiole-3-thione with 2 equivalents of sodium sulfide gives after acidification 3,4-difluoro-2-mercapto-1,6,6aλ⁴-trithiapentalene, which can be further reduced by sodium sulfide to 3,5-difluoro-4-mercapto-thiopyran-2-thione.     

Magnetic fluorescence and phosphorescence quenching of gas-phase sulfur dioxide

Sulfur dioxide fluorescence and phosphorescence are quenched by a magnetic field. A model is suggested for the qualitative interpretation of the results.

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. , - .

     

Laser-selective enrichment of 3d-states of the Ca II ion for detecting rare radioactive isotope calcium-41

For the detection of the rare radioactive isotope⁴¹Ca, the possibilities of the earlier-proposed initial-state enrichment by continuous-wave laser radiation are examined. It is shown that the enrichment 10¹⁴ of 3d-states of the ion Ca II can be reached. As the method of enriched-state detection, the process of resonant charge exchange is analysed. For a further increase of the selectivity, the repetition of the cycle initial state enrichment plus resonant charge exchange is discussed.     

Modification of sturgeon protamines with succinic anhydride

The modification of the - and -NH₂ groups of sturins A and B — protamines fromAcipenser güldenstadti — with succinic anhydride has been studied. Succinylation was carried out at 20°C, pH from 7.5 to 10.5, using a 50 to 180-fold excess of succinic anhydride. The modification products were separated by reversed-phase HPLC on a Zorbax ODS column. A linear relationship has been established between the retention times of the succinyl derivatives and the number of succinyl groups introduced. The influence of the pH and of the excess of succinic anhydride on the modification of the sturins has been studied by the method of experimental planning and mathematical modeling. The optimum conditions have been found for the succinylation of the proteins: a 150- to 180-fold excess of succinic anhydride and pH values of 9.8–10.2 for sturin A and of 8.4–9.4 for sturin B.Moscow Technological Institute of the Meat and Dairy Industry. All-Union Scientific-Research Institute for the Search for New Antibiotics, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 238–243, March–April, 1989.     

Synthesis of a new polyfluorinated vinylogue of tetrathiafulvalene through 1,3-dipolar cycloaddition of ethyl beta-bromoperfluorodithiocrotonate with dimethyl acetylenedicarboxylate

The ethyl ester of beta-bromoperfluorodithiocrotonic acid reacts with dimethyl acetylenedicarboxylate to give 1,4-difluoro-2,3-bis(trifluoromethyl)-but-2-ene-1,4-diylidene-2,2'-bis(4',5'-dicarbomethoxy-1',3'-dithiole) (4), a new type of vinylogue of tetrathiafulvalene. The thermal transformations of this compound lead, depending on the temperature, to the formation of the cyclization products: 11,14-difluoro-2,3,8,9-tetra(carbomethoxy)-12,13-bis(trifluoromethyl)-1,4,7,10-tetrathiadispiro[4.0.4.4]tetradeca-2,8,11,13-tetraene (8) or 5,8-difluoro-6,7-bis(trifluoromethyl)-2,3-bis(carboxymethyl)-1,4-benzodithiine (11).