The use of low-viscosity neutral components for increasing the diffraction efficiency of photopolymer holograms

The hologram recording in low-viscosity liquid photopolymerizing compositions with a neutral component is studied theoretically and experimentally. A diffusion model of redistribution of the composition components that takes into account the polymer mobility at the initial stage of photopolymerization is proposed. It is shown that the use of methanol as a neutral component significantly increases the diffraction efficiency.     

Group contributions and hydrophobic hydration

The group contribution concept proposed by Savage and Wood is used for characterization of hydrophobic hydration. A parameter is proposed to measure hydrophobic hydration that has additive properties and can be applied to both nonelectrolytes and electrolytes. Theoretical and practical arguments are given for its use. The given results are in agreement with the published experimental data and theoretical results concerning hydrophobic hydration and interaction.     

Capture of electrons for acceleration in a betatron with time and spatial variation of the magnetic field

It is shown that an additional pulsed magnetic field superimposed on the primary magnetic field of a betatron leads to time and spatial variation of the resulting magnetic field in the working gap of the accelerator. A mathematical model is developed for the capture of electrons for betatron acceleration with the additional pulsed magnetic field. It is shown that the time and spatial variation of the magnetic field in the working gap of the accelerator during electron injection leads to an increase in the efficiency of their capture for acceleration. The method of calculation permits a direct modeling of the capture of electrons for acceleration to obtain the highest efficiency.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 40–44, May, 1988.     

Mesoionic compounds with bridging nitrogen atoms. 14. Polymethine dyes containing a thiozolo[3,4-bl[1,2,4]triazinium oxide nucleus

Monomethinecyanine and zeromethinemerocyanine dyes have been synthesized on the basis of mesoionic 6-methylthiothiazolo[3,4-b][1,2,4]triazinium-2-oxides. It was found that these newly synthesized compounds can exist both in mesoionic form and in salt form.For Communication No. 13, see Ref. [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 848–851, June, 1988.     

An inverse problem for an equation of parabolic type

In this paper we consider an inverse problem for the differential equationu _t =u _xx +q(x, t) u; the problem amounts to finding the coefficient q(x, t) from the solution of a series of Cauchy problems for this equation, the solution being specified on some manifold. Our main result is a proof of a uniqueness theorem.Translated from Matematicheskie Zametki, Vol. 19, No. 4, pp. 595–600, April, 1976.