The well-defined bootstrap effect in the macroinitiator-mediated pseudoliving radical copolymerization of styrene and acrylic acid

The bootstrap effect is observed in the pseudoliving radical copolymerization of styrene and acrylic acid mediated by a macroinitiator: the adduct of poly(acrylic acid) with a nitroxide radical. In this case, the macroinitiator serves as a peculiar “microreactor” with an increased local concentration of acrylic acid; as a result, the apparent activity of acrylic acid is higher than that in copolymerization mediated by low-molecular-mass initiators.     

Relaxation spectroscopy of LC main chain polymers: Experimental and theoretical investigations

A series of thermotropic main chain polymers with extended dimethylsiloxane segments was investigated. The study of dielectric properties of polymers revealed the relationship between their ability to form a mesophase and their molecular mobility. The peculiar behaviour of dielectric α-relaxation parameters during the transition from mesomorphic to isotropic members of this polymeric series was shown. The theoretical approaches were developed for understanding macrochain dynamics of liquid crystalline polymers. The theoretical and experimental results are in good agreement.     

Study of Medieval Russian Enamel Pendant Using a Complex of Nondestructive Methods

Crystallography Reports - A medieval Russian bronze pendant icon with enamel images, dated to the period from the 12th to the first half of the 13th century was studied. The investigation was...     

Synthesis of Cyclic Derivatives of Carbonyl Compounds of Furan Series

Cyclic acetals of furan aldehydes (furfural, 5-hydroxymethylfuran-2-carbaldehyde and furan-2,5-dicarbaldehyde) and alcohols (ethylene glycol and 2-sulfanylethanol) were synthesized. The effect of the ratio of the starting reagents on the yield of acetals obtained was studied.     

Interactions of uracil and its derivatives with polyfunctional acids

Russian Chemical Bulletin - The previously obtained experimental and quantum chemical data on the composition, structure, stability, and thermodynamic properties of complexes of uracil and a series...     

Production of Granulated NaP Zeolite without Binder

Possibility was examined of synthesizing zeolites granulated without a binder with the use of a preliminary ultrasonic treatment of the suspension at a frequency of 22 kHz from mixtures of sodium metasilicate and aluminum and silicon oxides with various Si: Al ratios. It was found that, after the preliminary treatment, extrusion of grains, and calcination at 650°C, crystalline phases Na₆Al₄Si₄O₁₇, Na₈Al₄Si₄O₁₈, Na₂Al₂O₄, and Na₂SiO₃ phases are formed in the sample with Si: Al = 1. These phases are precursors for synthesis of NaA and NaP zeolites and sodalite via hydrothermal crystallization in a NaOH solution with concentration of 2 M. Upon a similar treatment of a sample with Si: Al = 2, there are crystalline phases α- and β-Na₂Si₂O₅, from which only NaP zeolite is formed in the course of crystallization. The hydrothermal crystallization in a 6 M alkali solution yields sodalite, irrespective of the Si: Al ratio. It was shown that an ultrasonic treatment gives a gel-like system at Si: Al = 1 and a powdered material at Si: Al = 2, which yields by the end of synthesis samples with cactus-like or wool-like morphology, respectively.     

Nondissipative curves in Hilbert spaces having a limit of the corresponding correlation function

In this work a class of nondissipative curves in Hilbert spaces whose correlation functions have a limit ast± is presented. These curves correspond to a class of nondissipative basic operators that are a coupling of a dissipative operator and an antidissipative one. The wave operators and the scattering operator for the couple (A ^*, A) ( ) are obtained. The present work is a continuation and a generalization of the investigations of K.Kirchev and V.Zolotarev [1, 2, 3] on the model representations of curves in Hilbert spaces where the respective semigroup generator is a dissipative operator. This article includes four parts. A new form of the triangular model of M.S. Livic ([4, 5]) for the considered operators is introduced in the first part by the help of a suitable representation of the selfadjoint operatorL. This allows us to describe the studied class of nondissipative curves. The second part studies some results concerning the application of the analogue for multiplicative integrals of the well-known Privalov's theorem ([6]) about the limit values in the scalar case. This analogue is a reconstruction of measure by limit values in Stieltjes-Perron's style and it is obtained by L.A. Sakhnovich ([7]). Another problem, considered in the second part is the analogue inC ^m of the classical gamma-function and several properties for further consideration. In the third part the asymptotics of the studied curves corresponding to the nondissipative operators-couplings of a dissipative and an antidissipative operator with absolutely continuous real spectra and the limits of their correlation functions are obtained In the fourth part a scattering theory of a couple (A ^*, A) with a nondissipative operatorA from is constructed as in the selfadjoint case ([8, 9, 10]) and in the dissipative case ([7]). These results show an interesting new effect: the studied nondissipative case is near to the dissipative one.Partially supported by Grant MM-810/98 of MESC     

The structure of electron beam-modified cellulose triacetate

The structure, relaxation, and surface properties of cellulose triacetate (CTA) fibers and films modified by electron-beam irradiation in the absorbed dose range of D = 0−1000 kGy have been studied. The relation of the glass transition and melting temperatures of the irradiated CTA samples with the local density and the fractal dimensionality of the macrochain has been revealed. It has been shown that the radiation-chemical processes associated with the rupture of acetal bonds and the hydrolysis of CTA acetate groups predetermine the change in the structural and relaxation characteristics of the irradiated samples, as well as a nonmonotonic form of the dependence of the density and the surface energy of the films upon the absorbed dose near the threshold value of D = 75 kGy.