Theory of dilute polymer solutions in viscoelastic fluid with a single relaxation time

Rheological equations of state of dilute polymer solutions in viscoelastic fluid with one relaxation time are derived by applying a structural approach. The system under consideration is simulated by the superposition of two interpenetrating interacting conitua. The hydrodynamic behaviour of single polymer chains is simulated using the subchain model representing a linear sequence of frictional centres, spherical Brownian particles chain-bonded by means of elastic forces. The oscillatory shearing flow of the solution is studied on the basis of the equations derived. The expressions for the complex viscosity and relaxation times are determined. It is shown that the availability of polymer additions brings about a strong smearing of the relaxation spectrum of the carrying medium.     

Elements de la théorie de catégories polyadiques

Sans résumé Presented by J. D. Monk.     

Photoisomerization of symmetrical carbocyanine dyes from higher excited states

Conclusions The photoisomerizatioa of symmetrical carbocyanine dyes proceeds only from the first singlet excited electronic state and does not proceed from the higher excited states.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2613–2614, November, 1977.     

On wide-band mirrors for soft X-ray range

The properties of smooth curved surfaces which can deflect the soft X-ray beams to large angles and reflect them effectively are considered. The wave sliding along the curved cylindrical surface has been analysed and the structure of the electromagnetic field has been found both in the medium and in vacuum. Large reflectivity has been predicted in wavelength regions 50 Å < λ < 150 Å and λ < 20 Å for several elements with known optical constants. In contrast to the multilayer structures which are widely used now, the curved mirrors provide a large reflectivity in a broad X-ray wavelength region.     

Flow of elasticoviscoplastic thixotropic polymer systems

The necessity and possibility of taking into account the strain-rate dependence of the plastic strength in deriving mathematical models of the flow of heavily filled polymer systems is demonstrated.