THEORETICAL BASIS OF THE STRUCTURE OF BITUMENS AND OTHER ORGANIC BINDERS

Abstract

For the development of a general theory, organic binders (OB) are considered as two-phase disperse systems. The particle of the dispersed phase (Ph) is a nucleus (asphaltene, polymer, other filler) which immobilizes a part of the dispersing medium (M). Ph is a whole in heat motion and deformation.

The type of the disperse structure (DS) in OB and the properties of OB depend on the Ph volume (C_v ) equal to the product of the weight content of Ph, voluminosity coefficient λ (a relationship of volumes of Ph and their nuclei), the relationship of Ph densities and their nuclei.

C_v is a criterion of the general classification of OB on types of DS. At C_v = 0.487 and C_v = 0.613 we supposed and observed structural transitions. This is the basis of the method of designing OB with the required DS.

In theory the C_v -reduced highest Newtonian viscosity curve has been desdribed, the rheological method for determining basic parameters of DS of binders has been developed. Parameters of DS of 18 model bitumens containing various asphaltenes have been calculated. An adhesive ability of OB is conditioned by Van der Waals forces between particles of the dispersed phase and determined by the interaction constant we proposed.     

Relationship of structure and thixotropic properties in bitumens and complex organic binders

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 8, pp. 31–34, August, 1991.     

Relation between the space flight-induced frequency of dominant lethal mutations and the level of allozyme heterozygosity in Drosophila melanogaster populations

Currently, the treatment of falciparum malaria is seriously compromised by spreading drug resistance. We studied the effects of camptothecin, a potent and specific topoisomerase I inhibitor, on erythrocytic malaria parasites in vitro. In Plasmodium falciparum, camptothecin trapped protein-DNA complexes, inhibited nucleic acid biosynthesis, and was cytotoxic. These results provide proof for the concept that topoisomerase I is a vulnerable target for new antimalarial drug development.     

IMPROVEMENT OF WORKING CHARACTERISTICS OF ROAD BITUMENS

This article deals with those characteristics of road asphalts/bitumens and methods for improving performance.     

Resistance of frozen soils to disintegration under high-pressure hydraulic jets

Conclusions 1. The frozen soil volume disintegrated by a high-pressure hydraulic jet is proportional to its initial specific kinetic energy.2. As the water content of frozen soils increases, and also as their temperature decreases, the depth of the slit cut in them by the hydraulic jet decreases also.3. The relations between the depth of cut in frozen clays and their temperature are practically similar to the curves of content of non-freezing water in these soils in the temperature interval from –1°C to –5°C.Scientific-Research Institute of Bases and Underground Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 21–23, May–June, 1984.