Fractionation and composition of the carbohydrates ofFicus carica

The fractional compositions of the carbohydrates of the four most promising varieties ofFicus carica L. — Smena, Kadota, Chumlakuri mtsvane, and Turetskii korichnevyi — have been investigated. The qualitative and quantitative monosaccharide compositions of the carbohydrates isolated have been determined. The bulk of the dry matter of the fruit consists of ethanol-soluble oligosaccharides — up to 74.53%. The composition of the residue obtained after the fractionation of the carbohydrates has been studied. It contains ligin bound to mineral elements.     

Stability of plane poiseuille flow of a viscous anisotropic fluid

Experimental investigations show that the presence in a fluid of fibers and rigid asymmetric particles leads to a greater stability of flow in tubes and lowers the turbulent frictional resistance in a certain range of Reynolds numbers [1]. In the present paper, the anisotropic structure of a fluid with additives is described by Ericksen's rheological model [2]. The parameters of the model are particularized in accordance with the paper [3] of Pilipenko, Kalinichenko, and Lemak, and in the limiting case of weak Brownian motion allowance is made for the effect of the predominant orientation of the particles and the influence of additives on the longitudinal and shear viscosity. The stability of the Poiseuille flow is considered in the linear formulation. In an anisotropic viscous fluid, an equation of Orr-Sommerfeld type has a singular point. A rule for choosing the path of integration avoiding the singular point is obtained on the basis of a generalization of the method of Dikii [4] proposed in an investigation of the stability of the flow of an ideal fluid. The results of numerical calculations of the neutral stability curve for two-dimensional perturbations are given.     

Sobolev functions on infinite-dimensional domains

We study extensions of Sobolev and BV functions on infinite-dimensional domains. Along with some positive results we present a negative solution of the long-standing problem of existence of Sobolev extensions of functions in Gaussian Sobolev spaces from a convex domain to the whole space.     

Fractionation and composition of the carbohydrates of leaf vegetables

The qualitative and quantitative compositions of the carbohydrates of the leaf vegetables Lactuca sativa L., Spinacea oleracea L., and Rumex acetosa L. have been studied.     

1-Phenacylmethyl-2-(acylaminothiocarbonylamino)pyridinium bromides as protectors of steel acid corrosion

Inhibiting effect of 1-phenacylmethylpyridinium bromides containing acylthiourea substituents in the pyridine ring on corrosion of mild steel in sulfuric acid (3 M) was studied.     

On local operators diagonal with respect to the system of Hermitian polynomials

We present necessary conditions for operators diagonal with respect to the system of Hermitian polynomials to be local.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 47, No. 4, pp. 555–561, April, 1995.     

Drag of a plane plate in a stream of a polymer solution having variable concentration

One of the methods of reducing the frictional resistance of bodies moving in water is the discharge of a water-soluble polymer admixture into the turbulent boundary layer on the surface of the body. For dilute polymer solutions having constant concentration, existing semiempirical methods of calculation which use information on the effect of long molecules on the rearrangement of the flow in the boundary layer enable one to calculate the resistance of smooth and rough tubes [1] with sufficient accuracy and to analyze effects of the redistribution of local tangential stresses on the surface of plane plates [2]. Methods of calculating the drag of plates that have been developed up to the present time are also suitable for predicting the reduction of turbulent friction of elongated bodies by polymer admixtures. It is of interest to generalize these methods to the case of variable concentration. Below we consider the problem of calculating the turbulent boundary layer on a plane plate when a polymer solution is injected near its leading edge. For its solution we use the simplifying assumption that it is possible to replace the actual distribution of the concentration of polymer admixtures along a normal to the surface of the plate with an effective uniform distribution. This assumption enables us to estimate the discharge rate of the polymer that is required to obtain a given reduction in the frictional resistance.     

Photoinitiated grafting polymerization of acrylic acid onto the surface of polyethylene under pulsed laser radiation

Photoinduced grafting polymerization on the surface of PE films induced by nanosecond pulsed laser radiation is studied. The grafting is performed from the liquid phase composed of acrylic acid and a photoinitiator (benzophenone) dissolved in it. Pulsed laser radiation with a wavelength of 355 nm, a pulse duration of 11 ns, and a repetition rate of 10 Hz is used. Formation of the surface-graft polymer is followed by IR-ATR spectroscopy and contact-angle measurements. It is found that the time of laser treatment sufficient for the efficient modification of the PE surface with the grafted poly(acrylic acid) is in the range from 0.5 to 1.0 s at a laser-pulse energy density of 200–500 mJ/cm². At energy densities beyond this range, the efficiency of the reaction decreases rapidly. The results on laser grafting are compared with the results of grafting during UV irradiation with a lamp at a wavelength of 365 nm.