Formation of SnS,SnS<Subscript>2</Subscript>, and PbS films from thiourea coordination compounds

Deposition of semiconductor tin and lead sulfide films from thiourea coordination compounds was examined. The nature of the ligands in the intermediate complexes formed was determined, and the influence of these precursors on the formation and phase composition of SnS, SnS₂, and PbS thin layers was examined.     

Uncomplemented subspaces of Lorentz spaces

In the paper we construct a system of bounded functions which generates an uncomplemented subspace in the Lorentz space Λ(α) for all α∈(0,1). Lower bounds of the norms of the projector onto such subspaces are obtained. Translated fromMatematicheskie Zametki, Vol. 68, No. 1, pp. 57–65, July, 2000.     

Ring contraction of 1,3-bis(5-bromopentyl)alloxazine

The reaction of 1,3-bis(5-bromopentyl)alloxazine with ethylamine in propan-2-ol resulted in replacement of the terminal bromine atoms by ethylamino groups and was accompanied by contraction of the pyrimidine ring so that the products were 1,3-bis[5-(ethylamino)pentyl]alloxazine and 1,3-bis[5-(ethylamino)-pentyl]imidazo[4,5-b]quinoxalin-2-one.     

Fibril stability in solutions of twisted -sheet peptides: a new kind of micellization in chiral systems

The problem of fibril (fibre) formation in chiral systems is explored theoretically being supported by experiments on synthetic de novo 11-mer peptide forming self-assembled -sheet tapes. Experimental data unambiguously indicate that the tapes form fibrils of nearly monodisperse thickness ca . 8-10 nm. Fibril formation and stabilisation are attributed to inter-tape face-to-face attraction and their intrinsic twist, correspondingly. The proposed theory is capable of predicting the fibril aggregation number and its equilibrium twist in terms of molecular parameters of the primary tapes. The suggested novel mechanism of twist stabilisation of finite aggregates (fibrils) is different to the well-known stabilisation of micelles in amphiphilic systems, and it is likely to explain the formation and stability of fibrils in a wide variety of systems including proteinaceous amyloid fibres, sickle-cell hemoglobin fibres responsible for HbS anemia, corkscrew threads found in chromonics in the presence of chiral additives and native cellulose microfibrillar crystallites. The theory also makes it possible to extract the basic molecular parameters of primary tapes (inter-tape attraction energy, helical twist step, elastic moduli) from the experimental data. Received 7 May 1999 and Received in final form 15 February 2000     

Structures of products of the reaction of dimethylsulfonium phenacylide with benzylidenecyanoacetamide

Benzylidenecyanoacetamide reacted with dimethylsulfonium phenacylide to form 2-benzoyl-1-cyano-3-phenylcyclopropanecarboxamide and a product of its intramolecular cyclization,viz., a derivative of 3-azabicyclo[3.2.1]hexan-2-one. The structures of the products were established by X-ray diffraction analysis.     

Thermochemical Study of Gaseous Salts of Oxygen-containing Acids: VII. Alkaline-Earth Metal Niobates

The existence of gaseous alkaline-earth metal niobates was established by high-temperature mass spectrometry. The constants of equilibria involving the niobates and the corresponding oxides were calculated, and the standard enthalpies of formation and atomization of gaseous BeNbO₃, CaNbO₃, SrNbO₃, BaNbO₂, BaNbO₃ and BaNb₂O₅ were determined.     

Effect of local molecular ordering on the temperature behavior of the relaxation time of order-parameter fluctuations in the isotropic phase of PAA nematic liquid crystal

The behavior of the relaxation time of order-parameter fluctuations in the isotropic phase of PAA nematic liquid crystal was investigated on the basis of the spectra of depolarized (inelastic) light scattering in a wide temperature range including the immediate vicinity to the temperature of the nematic phase transition. The experimental data were analyzed within the Landau—de Gennes theory. The temperature limits of applicability of the Landau—de Gennes theory to the isotropic-phase dynamic properties are obtained. The minimum correlation length is determined, at which the effect of local ordering on the dynamics of slow orientational motion of isotropic-phase molecules is dominant.