Pyrylocyanines. 20. Symmetrical methoxy-substituted tetraphenyl-pyrylocyanines and their heteroanalogs

Symmetrical tetraphenyl-substituted -pyrylo-, -thiopyrylo-, and -pyridotrimethylcyanines, containing electron donor methoxy groups in two or four phenyl rings, were synthesized. Using the methods of quantum chemistry, the characteristics of the long-wave absorption bands of the dyes obtained are discussed. The independence of the theoretical conclusions from the selection of the quantum chemical parameters was demonstrated. The hypothesis of greater participation of the carbon-carbon bonds of the oxygen- and especially the sulfur-containing heteroresidues in comparison with the nitrogen-containing residues in the general system of conjugation is confirmed.For communication 19, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1486–1491, November, 1984.     

Micromagnetic Description of the ΔE-Effect in Amorphous Ferromagnets

Dependences of the magnitude of the E-effect in Fe_81.5B_13.5Si₃C₂ amorphous metal alloys on the external magnetic field and the temperature of thermomagnetic treatment are investigated. Four characteristic regions are distinguished in the dependence of the E-effect on the magnetic field strength. The experimental results are explained in the context of micromagnetism theory.     

Hydrogen photochromism in V<Subscript>2</Subscript>O<Subscript>5</Subscript> layers prepared by sol–gel technology with the use of dimethylformamide as a hydrogen donor

Here we report on the hydrogen photochromism carried out in the V₂O₅ xerogels with the use of dimethylformamide (DMF) as a hydrogen donor. The adsorption of DMF was carried out by an original method: DMF was adsorbed on the V₂O₅ surface along the formation of the xerogel from the sol containing the hydrogen donor. The mechanism of the DMF adsorption on the V₂O₅ xerogel surface has been discovered by Fourier transform infrared spectroscopy. DMF molecules have been bonded to the oxide surface by donor–acceptor and hydrogen bonds, which pre-determines easy detachment of hydrogen atoms under the action of light. It has been demonstrated that the pronounced hydrogen photocromism can be carried out in the V₂O₅ xerogels with the use of DMF. The peculiarities of the photochromism have been discussed. The spirit of the research is to provide charging of the V₂O₅ surface with the hydrogen donor along the formation of the oxide xerogel catalyst.

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Cameron–Liebler line classes in PG(n,4)

We derive a new existence condition for Cameron–Liebler line classes in \(PG(3,q)\) . As an application, we obtain the characterization of Cameron–Liebler line classes in \(PG(n,4),\,n\ge 3\) .     

Hyperbolicity study of the modulation equations for the Benjamin–Bona–Mahony equation

A complete study of the modulation equations for the Benjamin–Bona–Mahony equation is performed. In particular, the boundary between the hyperbolic and elliptic regions of the modulation equations is found. When the wave amplitude is small, this boundary is approximately defined by $k=\sqrt{3}$, where k is the wave number. This particular value corresponds to the inflection point of the linear dispersion relation for the BBM equation. Numerical results are presented showing the appearance of the Benjamin–Feir instability when the periodic solutions are inside the ellipticity region.