Erratum to: Several Articles in JETP Letters Published Online First

JETP Letters - An Erratum to this paper has been published: https://doi.org/10.1134/S0021364022330013     

Self-assembly and gel formation processes in an aqueous solution of L-cysteine and silver nitrate

The experimental and theoretical study of self-assembly and gel formation processes in an aqueous solution of L-cysteine and silver nitrate (CSS) is performed. A method to obtain CSS-based hydrogel is described. Its characteristic feature is the formation of a spatial gel network at a low concentration of the dispersed phase (～0.01%) and the thixotropic behavior. The experimental examination of this system provides the formulation of a phenomenological model of the gel formation. Based on it, an atomistic computer model is made to verify our assumptions. It is shown that due to the formation of donor-acceptor sulfur-silver bonds there form clusters from silver mercaptide (SM) zwitterions, from which in turn filamentous aggregates form. An analysis of the molecular configurations formed shows that the filamentous aggregates are stabilized by the interaction of 3 ?NH ₃ ⁺ and ?C(O)O^? groups belonging to SM zwitterions in the composition of the neighboring clusters. The obtained conclusions underlie the mesoscopic model based on which we managed to illustrate the processes of generation and growth of filamentous aggregates in large spatial scales.     

Reversible and Irreversible Deactivation of Supported Bimetallic Catalysts for the Dehydrogenation of Lower Paraffins

The reasons and nature of the deactivation of spinel-supported bimetallic Pt–Sn, Pt–In, and Pt–Cu catalysts in the steam dehydrogenation of C₄–C₅paraffins are analyzed. The deactivation can be reversible and irreversible. Reversible deactivation is associated with the effects of the composition of reaction medium and gaseous medium for preliminary treatment on the surface composition of supported bimetallic alloys and with the coking of catalysts. Irreversible deactivation can result from the irreproducibility of the phase composition and dispersion of supported alloys in dehydrogenation–regeneration cycles and from the carbon erosion of catalysts. This erosion consists in the removal of active metal particles to the bulk of carbon deposits. The formation of carbon deposits on the surfaces of spinel supports and bimetallic catalysts is considered. Recommendations for optimizing the composition and the operating conditions of catalysts are given in order to reduce the effects of factors that result in reversible and irreversible deactivation.     

On Some New Possibilities for Controlling Quantum Systems Using Unipolar Extremely Short Pulses

Optics and Spectroscopy - Based on an approximate solution of the Schrödinger equation, the effect that a pair of extremely short small-amplitude subcycle pulses has on a quantum system is...     

Effect of peripheral substitution of copper phthalocyanine molecules on the electroconductivity in thin films during interaction with ammonia

A decrease in the ability for oxygen bonding of PcCu molecules in peripheral substitution has been studied by measurements of conductivity in the presence of ammonia.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1491–1493, August, 1995.The work was financially supported by the International Scientific and Technical Center (Project No. 015-94). The authors are grateful to Associate Professor G. P. Shaposhnikov (Ivanovo Institute of Chemical Technology) for the phthalocyanine samples he kindly supplied.     

Solid-phase synthesis of oxytocin and its analysis by high performance liquid chromatography

A mixture of peptides containing 30.4% of oxytocin has been obtained by the solid-phase method on the benzhydrylamine resin UR-95. A procedure is given for the quantitative determination of oxytocin in a mixture of peptides.All-Union Scientific-Research Institute of the Technology of Blood Substitutes and Hormone Preparations, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 892–897, November–December, 1987.     

Crystallisation process on the stage of the gel-to-solid transformation in thermo-reversible polyethylene gels

The crystalline phase in gels and solid (gel derived) samples of ultra-high molecular weight polyethylene was studied using the low-frequency Raman spectroscopy and the differential scanning calorimetry methods. The Raman data evidence the presence in gels of tiny crystallites whose thickness (3-5 nm) depends on the sort of solvent used. After removal of the solvent by drying or squeezing the original gels, there appear some extra ordered regions (6-12 nm in size) coexisting in solid material with the primary crystallites which remain unchanged. It is concluded that the gel-to-solid transformation is accompanied by a secondary crystallisation process which is weakly (if ever) dependent on the incipient crystalline entities in gels.