Characteristic features of carbazole phosphorescence quenching by benzophenone molecules in toluene at 77 K

We have studied the characteristic features of carbazole phosphorescence quenching by benzophenone in toluene at 77 K. We have shown that the decrease in the relative phosphorescence intensity for carbazole (energy donor) by a greater factor than we see for the relative change in its decay time is due to the fact that a change in the phosphorescence decay time occurs only for carbazole molecules participating in triplet-triplet energy transfer, while the substantial decrease in the phosphorescence intensity for carbazole with no change in the phosphorescence decay time is connected with quenching of its singlet states. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 554–556, July–August, 2006.     

Recognition of the structural-functional organization of genetic sequences

The analysis problem for genetic sequences is formulated from the viewpoint of modern mathematical and information approaches. Statistical, correlative, entropic, and spectral approaches are considered. A brief introduction into the background of the problem is given. Genesis of a new interdisciplinary subject area, bioinformatics, a science considering application of computer methods in biological studies, is analyzed. New approaches to studying macromolecular systems on the basis of combined spectral-analytic technologies are proposed. Estimates of the algorithmic complexity of implementation of the proposed approaches are presented.     

Reactions of epoxides of the pyran series involving ring expansion. Reaction of 4-methyl-3,4-epoxytetrahydropyran with potassium thiocyanate

The reaction of 4-methyl-3,4-epoxytetrahydropyran with potassium thiocyanate occurs with expansion of the oxirane ring and leads to 6-methyl-8-amino-3,7-dioxa-9-thiabicyclo[4,3,0]nonane, the formation of which has been proven by the fact that products of its acylation by acid chlorides of 2-R-cinchonic acids are obtained, and also by the formation of Mannich bases when it is treated with formaldehyde and secondary amines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1039–1042, August, 1992.     

Tandem cleavage of 2,3,5-trimethyl 7-trifluoroacetyl-1,2,3,4-tetrahydro-pyrrolo[1,2-<Emphasis Type="Italic">c</Emphasis>]pyrimidine by activated alkynes,caused by Michael addition of a tertiary nitrogen atom to a triple bond

The interaction of 7-trifluoroacetyltetrahydropyrrolo[1,2-c]pyrimidine with acetylenedicarboxylic ester (DMAD) and ethyl propiolate in acetonitrile and alcohols has been studied. It was established that DMAD splits pyrrolopyrimidine at the aminal fragment in acetonitrile and methanol with the formation of 1-H-and 2-(N-dimethoxycarbonylvinyl-N-methyl)aminoethyl-1-methoxymethyl-3-methyl-5-trifluoroacetylpyrroles. In acetonitrile ethyl propiolate splits pyrrolopyrimidine both at the aminal fragment and at the C₍₃₎-N₍₂₎ bond (Hofmann reaction), but in ethanol only at the C₍₃₎-N₍₂₎ bond with the formation of 2-propenylpyrroles. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1082–1087, July, 2007.     

Synthesis of 6α-methyl-16α,17α-cyclohexano-19-norprogesterone from a 19-methyl-6-desmethyl precursor

After prolonged refluxing of 19-tosyloxy-16α,17α-cyclohexanopregn-5-en-3β-ol-20-one (3) with NaI in 2-propanol, the initially formed 19-iodo derivative (4) undergoes supraface migration of the CH₂I group from the C(10) atom to the C(6) atom, probably through involvement of a homoallyl cation. The resulting 6β-iodomethyl-16α,17α-cyclohexano-19-norpregn-5(10)-en-3β-ol (5) was transformed in three steps into 6α-methyl-16α,17α-cyclohexano-19-norprogesterone (6α-methyl-19-nor-D′ ₆-pentarane,8). The transformation of compound5 into the target product8 also gave a side product, a pentarane with aromatic ringA (10), which was isolated and characterized by spectroscopic methods. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1688–1691, September, 1997.     

On the dissociation mechanism of carbonates and their isomorphous mixture

The thermal decomposition processes of carbonate minerals are analyzed by comparison of the notions on chemical bonds in crystals and modern concepts on solid-phase reactions. It is shown that depending on the mechanism of thermal dissociation, the carbonate minerals most widespread in nature may be divided into two groups: first, CaCO₃, SrCO₃ and BaCO₃, characterized by decomposition temperatures close to the equilibrium values and undergoing recombination on cooling; and second, MgCO₃, MnCO₃, FeCO₃ and ZnCO₃, with dissociation temperatures exceeding the equilibrium values by 250° and recombining only at high partial pressures of CO₂ (above 1000 bar).

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Zusammenfassung Die thermischen Zersetzungsprozesse von Carbonatmineralien wurden auf der Basis der Vorstellungen über die chemischen Bindungen in Kristallen und moderner Konzeptionen über Festphasenreaktionen analysiert. Es wird gezeigt, dass die in der Natur weitverbreitetsten Carbonatmineralien, abhängig vom Mechanismus der thermischen Zersetzung, in zwei Gruppen unterteilt werden können: die erste umfasst CaCO₃, SrCO₃ und BaCO₃ und ist durch Zersetzungstemperaturen nahe den Gleichgewichtswerten und durch Rekombination beim Abkühlen charakterisiert, zur zweiten gehören MgCO₃, MnCO₃, FeCO₃ und ZnCO₃ mit Dissoziationstemperaturen, die die Gleichgewichtswerte um etwa 250° überschreiten, und die nur bei hohen CO₂-Partialdrücken (über 1000 bar) rekombinieren.

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, . , , . CaCO₃, SrCO₃, BaCO₃ , . MgCO₃, MnCO₃, FeCO₃, ZnCO₃ , 250°, ( 1000 .).

     

The acidity functionsH 0 s of HCl solutions in EtOH with low water content

The acidity functionsH ₀ ^s of HCl solutions in EtOH-H₂O solvents containing 1.09, 3.0, and 5.0% water have been measured at 25 and 40 °C by the indicator method. The concentration of HCl changes from 10^–2 to 36m. Nitroanilines, for which a protonation mechanism is realized in the studied systems, were used as indicators.For each solvent,H ₀ ^s is temperature independent atm _HCl < 4, and acidity atm _HCl > 4 mol L^–1 increases more rapidly at 25 °C than at 40 °C. The acidity functions of aqueous and water-ethanol solutions of HCl were compared, and the concentrations of proton solvates of different compositions and their relative protonating ability were evaluated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1722–1725, October, 1994.This work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-18356).     

Comparison of the efficiency of titanium(IV) and iron(III) oxide nanoparticles as mediators in suppression of bacterial growth by radiation of a blue (405 nm) light-emitting diode

The effect of blue (405 nm) radiation of a light-emitting diode in combination with titanium(IV) and iron(III) oxide nanoparticles on S. aureus 209 P, S. simulans, and D. hominis bacteria is studied. It is shown that, upon irradiation of bacteria by blue (405 nm) light, Fe₂O₃ nanoparticles have a stronger (by 5–30%) antibacterial effect than TiO₂ nanoparticles.     

Unusual stereoselectivity of methionine-γ-lyase from Citrobacterfreundii toward diastereomeric (S)-methionine S-oxide

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