Effects of Moisture and Stresses on the Structure and Properties of Polyester Resin

The results of a complex study of structural changes in a cured Norpol 440 polyester resin under the action of damp environment and mechanical loading are presented. A considerable effect of absorbed moisture on the structure and some characteristics of the material is revealed by using thermophysical methods and X-ray diffractometry. The joint effect of moisture and mechanical stress is estimated by investigating the creep in stationary and nonstationary moisture conditions. The anisotropy of the material structure formed during creep is evaluated from the results of dilatometric measurements. It is found that the degree of anisotropy of the material after creep accompanied by moisture sorption is higher than that after creep in the conditions of moisture equilibrium with atmosphere. It is established that the aftercure and relaxation of the residual creep deformation come to an end at heating to 80-85°C. At a further rise in temperature and repeated heating, changes in the material structure are not observed.     

Novel trialkylsilyl(germyl)-substituted thienyl- and furylbenzimidazoles and their N-substituted derivatives – synthesis,structure and cytotoxic activity

The reaction of 1,2-phenylenediamine with a variety of silicon- or germanium-containing 2-furaldehydes or 2-thienylcarbaldehydes in DMFA gave the corresponding benzimidazole derivatives in moderate yields (36–49%) in the presence of sodium hydrogen sulfite. As a result, a new series of silyl, germyl substituted hetarylbenzimidazoles were synthesized and their in vitro cytotoxicity was studied. The quaternisation of N-substituted benzimidazoles by heating with various alkyl, allyl and propargyl chlorides and bromides leads to the formation of benzimidazolinium salts. Potential cytotoxic activity of synthesized new benzimidazoles and benzimidazolinium salts was tested in vitro on two monolayer tumour cell lines: MG-22A (mouse hepatoma), HT-1080 (human fibrosarcoma) and normal mouse fibroblasts (NIH 3T3) and compared with corresponding benzimidazoles.     

Viscoelastic properties of a silica-filled styrene-butadiene rubber under uniaxial tension

A model composite — a silica-filled styrene-butadiene rubber with a various filler volume content — was tested for creep and creep recovery at different tensile load levels to evaluate the effect of viscoelasticity on the deformational properties of filled rubbers. A constitutive equation describing the diagram of equilibrium deformation of the composite in quasi-static loading was obtained from an analysis of creep test results. The equation was common for the filled rubber at different filler content. The existence of such a curve has been confirmed by experimental unloading diagrams registered in cyclic loading-unloading tests. It is shown that the phenomenological equations obtained from an analysis of creep recovery test results can be used successfully for describing the hysteresis loops of second and subsequent cycles for cyclic tests with a constant maximum stretch ratio.     

Muography of Large Natural and Industrial Objects

Physics of Atomic Nuclei -     

Poisson's ratio and the incompressibility relation for various strain measures with the example of a silica-filled SBR rubber in uniaxial tension tests

The controversy in the definition of Poisson's ratio (PR) as a material constant is discussed in this study. PR of an isotropic material is usually defined as the ratio, taken with the opposite sign, between its lateral and longitudinal strains under the action of longitudinal stresses. However, if deformations of the material are large, the value of PR depends on the strain measure used. Five different measures of strain are considered, and a unified relation in terms of stretch ratios is obtained for calculating the PR. It is demonstrated that only for Hencky strains is the value of PR of an incompressible material constant and equal to 0.5 over its entire extension range. Other measures lead to stretch-dependent PRs. A generalized relation for the volume strain is found in terms of strain invariants. With the example of uniaxial tension of a silica-filled rubber, the Cauchy and Hencky strains are used to demonstrate different ways for checking the incompressibility of a material and the evaluation of PR. The level of incompressibility of the rubber and its practical importance are evaluated.     

Connection between weak and generalized solutions to infinite-dimensional stochastic problems

We investigate the stochastic Cauchy problem for the first order equation with singular white noise and generators of regularized (integrated, convoluted) semigroups in Hilbert spaces and abstract distribution spaces. Weak solutions for the problem in the Ito form and generalized solutions for the “differential” problemin abstract distribution spaces are constructed in dependence on properties of the generator. We show connections between these solutions.     

Synthesis and search for compounds with hemostatic activity in the series of 4-(het)aryl-4-oxobut-2-enoic acid derivatives

New 4-aryl-2-(4-arylamino)-1-(piperazin-1-yl)but-2-ene-1,4-diones and 2-{[2-(3-R-adamantan-1-yl)-2-oxoethylidene]hydrazinyl}-4-(het)aryl-4-oxobut-2-enoic acids were synthesized and used to obtain water-soluble compounds. Their influence on the blood coagulation system was studied, which revealed compounds with a high hemostatic activity and a low acute toxicity. A relationship between structure and pharmacological effect of the synthesized compounds was established.     

Synthesis ofO,O-diethylSe-alkyl selenophosphates by the reactions of diethyl phosphite with alkaneselenenyl halides

The reactions of diethyl phosphite with alkaneselenenyl halides in chloroform at 20°C afforded the correspondingO,O-diethylSe-alkyl selenophosphates. Dedicated to the memory of Academician M. I. Kabachnik on his 90th birthday. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2099–2101, October, 1998.     

Muon Radiography of Large Natural and Industrial Objects—A New Stage in the Nuclear Emulsion Technique

Journal of Experimental and Theoretical Physics - A new study of a historical object on the territory of the Russian Federation, the Holy Trinity Danilov Monastery, implemented by the muon...     

Estimation of the Fragmentation Effect in the Registration of Superheavy Nuclei of Galactic Cosmic Rays in Pallasites

Journal of Experimental and Theoretical Physics - We report on the results of model calculations for estimating the fragmentation effect in the registration of heavy and superheavy nuclei of...