The Hopf Property for Subgroups of Hyperbolic Groups

A group is said to be Hopfian if every surjective endomorphism of the group is injective. We show that finitely generated subgroups of torsion-free hyperbolic groups are Hopfian. Our proof generalizes a theorem of Sela (Topology 35 (2) 1999, 301–321).     

Reactions of benzothiazole-2-thione and benzothiazole-2-one with acetylene

Reaction of benzothiazole-2-thione and benzothiazole-2-one with acetylene in the presence of potassium hydroxide or cadmium acetate gives 2-vinylthiobenzothiazole and 3-vinylbenzothiazol-2-one, respectively. Benzothiazole-2-thione is partially convened to benzothiazol-2-one by the action of Cd(OAc)₂. Under vinylation conditions the latter also forms 2-vinylthioaniline.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 270–271, February, 1991.     

Kinetics of the acidic hydrolysis of vinyl derivatives of benzimidazole-2-thione and benzoxazol-2-one and -2-thione

The kinetics of the acidic hydrolysis of seven vinyl derivatives of benzimidazole-2-thione and benzoxazol-2-one and -2-thione were studied by means of polarography. The rate constants and energies of activation of the reaction were determined. The hydrolytic stabilities of the compounds depend on the nature of the heteroring and the site to which the vinyl group is attached.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1532–1535, November, 1982.     

Surface solid-state interactions in copper-nickel-cement catalysts for hydrogenation of oxygen

The surface phase composition of alumocalcium cement-supported CuO and CuO-NiO catalysts prepared by chemical mixing has been studied using the method of thermo-vacuum curves of electric conductivity. The deactivation of these catalysts due to overheating to 800 °C under conditions of hydrogenation of oxygen is rationalized by the partial extraction of CuO (and NiO) from the stabilizing structure of the support solid solutions and by sintering of the extracted oxides and the reduced metallic phase. Complete regeneration of the CuO-NiO-talum catalysts can be achieved if a considerable amount (20%) of copper hydroxocarbonate is added.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1559–1562, September, 1994.     

Experimental and theoretical study of the pyrolysis of trichlorosilane

Pyrolysis of trichlorosilane (TCS) and copyrolysis of TCS with 1,3-butadiene were studied. The enthalpies and activation energies for the reactions of the products of TCS pyrolysis were found by quantum-chemical calculations. A direct study of the pyrolysis of TCS by mass spectrometry was carried out. Based on the thermochemical parameters found by quantum-chemical calculations and on the results of GLC and mass spectrometry concerning the composition of the pyrolysis products, it was concluded that the pyrolysis of TCS follows a scheme that includes formation of radicals and silylenes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1659–1662, September, 1997.     

Synthesis and properties of a number of salts of N-succinylmethionine

A comparative study has been made of the radioprotector activity of cystamine and the synthesized cobalt and copper salts of N-succinylmethionine. Activity falls in the sequence cystamine-copper salt-cobalt salt.Khar'kov Scientific-Research Institute of Endocrinology and Hormone Chemistry. Khar'kov Medical Institute. Khar'kov Scientific-Research Institute of Medical Radiology. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 86–88, January–February, 1990.     

Enantioselective, chirally templated sol-gel thin films

Enantioselective surfactant-templated thin films were fabricated through the sol-gel (SG) process. The enantioselectivity is general in the sense that it discriminates between pairs of enantiomers not used for the imprinting process. The chiral cationic surfactant (-)-N-dodecyl-N-methylephedrinium bromide (1) was used as the surfactant template, and after its extraction chiral domains were created. The chiral discriminative feature of these films was examined by challenging with pure enantiomer solutions for rebinding. Selective adsorption was shown using (R)- and (S)-propranolol, (R)-2 and (S)-2, respectively, and (R)- and (S)-2,2,2-trifluoro-1-(9-anthryl)ethanol, (R)-3 and (S)-3, respectively, as the chiral probes. The selective adsorption was measured by fluorescence analysis, and the chiral selectivity factors were found to be 1.6 for 2 and 2.25 for 3. In both cases, (R)-enantiomer was adsorbed preferably. The resulting material was characterized by transmission electron microscopy, by diffraction, and by surface area measurements, and was found to be semicrystalline with short-range ordered domains (50 A) of hexagonal symmetry.