Search

ABSTRACT: Introduction. In the article the use of powder elastomeric modifier capable of rapid breakdown into micro- and nanofragments upon contact with hot bitumen to improve the low-temperature properties of bitumen is presented. The indicators of resistance to cracking are determined by various methods and their dependence on the thermal history of the samples. Methods and Materials. At temperatures up to –36о C the oscillatory rheological tests (4-mm DSR test) of RTFO-aged samples of bitumen BND 60/90 and modified binder (MB) which contain the active powder of discretely devulcanized rubber (APDDR) produced by high-temperature shear-induced grinding from the crumb rubber of worn tires have been conducted. MB was prepared by mixing bitumen (3 min; 160оC and 600 rpm) with 12.5 wt.% APDDR. Results and Discussion. The effect of the test parameters on the rheological parameters has been studied. Structural transitions in bitumen and MB by methods of differential scanning calorimetry (DSC) and the cracking temperature of the same samples in static conditions in the ABCD test were detected. It is revealed: a decrease in the temperature of actual cracking of the MB sample compared to bitumen. Conclusion. It is shown that APDDR as a modifier affects the structure of bitumen and reduces the temperature sensitivity of bitumen to external influences.

For the first time, by atomic force microscopy (AFM) methods, micro- and nanofragments of micronized powder elastomeric modifier (PEM) formed at the short-term (3 min at 160 °C) interaction of PEM with hot bitumen have been demonstrated. It is the technology of high-temperature shear-induced grinding of a worn-out tire’s crumb rubber or its co-grinding with styrene–butadiene–styrene (SBS) block copolymer which provides the creation of the PEM structure inclined to rapid degradation in hot bitumen. The formation just after the preparation process of a new structure of a modified binder, more resistant to external effects, is supported by the data of rheological tests. Performance tests for a modified binder using Superpave standard adopted by the road industry for bituminous binders showed an extended temperature range, resistance to rutting, and low-temperature and fatigue cracking. The better resistance to low-temperature and fatigue cracking is certainly related to energy absorption and crack growth stopping in the presence of micron and submicron resilient PEM fragments in accordance with the mechanism of increasing impact toughness in plastics.

Structural features of crumb rubber (CR) particles obtained by grinding on rollers and ultra-disperse powder elastomeric modifiers (PEM) obtained by high-temperature shear-induced grinding (HTSG) of CR or co-grinding with butadiene styrene thermoplastic elastomer (SBS) have been studied by electron and optical microscopy methods. Samples of modified bitumen were obtained at different mixing times (1–40 min) in a wide temperature range (120–180 °C). The products of interaction of PEM with hot bitumen precipitated on filters when washed with solvent from modified bitumen (MB) were studied by scanning electron microscopy (SEM). The self-similarity PEM particles and PEM breakdown fragments in bitumen up to the size of 100–200 nm were noted. The rapid (for 1 min) decomposition of PEM particles into fragments is shown, which is due to the specific structure formed as a result of HTSG. It has been suggested that this fragmentation may be caused by bitumen penetrating deep into the porous particle and breaking it, due to differently directed swelling pressure and precede the classical swelling associated with the penetration of solvent between rubber macromolecules, or occur concurrently with it.

The role of hybridization as one of the factors of speciation in mammals has been underestimated for a long time, but now there is a lot of data on its impact in mammalian evolution. Hybridization of species often occurs in their secondary contact zones, which is a natural model for testing factors that ensure species integrity. Studies of hybrid zones are increasingly revealing the essential role of ecological and behavioral features both in initiating crossbreeding and in maintaining interspecific barriers. We studied the hybridization of two species of marmots Marmota baibacina and M. sibirica in the zone of sympatry in Mongolian Altai Mountains. We used a bioacoustic approach to determine the localization of individuals of different species and their cohabitation sites. Genetic typing with two diploid nuclear markers and one marker each of paternal and maternal lines was used to identify hybrids. Habitat preferences of marmots were studied to understand the conditions for the formation of heterospecific pairs. We found a high proportion of hybrid individuals in boulder screes where conditions for the formation of heterospecific pairs probably exist. Our data indicate the viability and fertility of F1 hybrids and their descendants. We hypothesize that the environmental preferences and behavioral features of both species of marmots are important factors that both create conditions for hybridization and limit hybrid dispersal.

The drawing of Netherlandish painter Pieter Bruegel the Elder The Big Fish Eat the Little Fish reflects perhaps not political allusions, as it is interpreted in the history of art, but a graphic food-chains scheme. It is possible that the picture engraving, stored in the British Museum, has influenced the creation of the food-chains concept by British ecologists Johnstone [1], Hardy [2] and Elton [3]. The taxonomic attachment of organisms depicted in the drawing has been determined.

All the diversity of sound signals by mammals is subordinated two basic functions: function implementation of the populations of genotype and function realization of the ecological niche of species populations. The basic functions have resulted from some relatively independent trends in the evolution of sound signals as those developing the genetically determined structure and the ecologically determined functions. A relative independence of the above trends in the sound signal evolution supports variation.

In the study we have first described the chemical composition of the volatile substances from the top soil layer by the example of the steppe marmot colony. Volatile components that could be stable elements of the biological signal field are contained in the greatest quantity (mkg/g) in the samples from the burrows. Their least content is in the samples from the background. The intermediate position is occupied by the sample collected from the pathways. We have identified the following classes of compounds: fatty acids, aldehydes, hydrocarbons, alcohols and nitriles.

It is described an alarm call of Marmota himalayana and M. baibacina from China. In the signalM. himalayana from the Northwest Plateau were not found differences from the signal marmots, this species inhabiting other parts of the range in China, India and Nepal. Signal M. baibacina inhabiting in East Tian-Shan, markedly different from the signal marmots, this species inhabiting other parts of the area in Russia and Kazakhstan. There are discussed some situational variants of the signal and signal propagation in burrows.

China is inhabited by 4 species of Marmots. The northwest of China are Marmota caudata, M. baibacina; the northeast is M. sibirica; in the Qinghai-Tibet Plateau — M. himalayana. There are the deserts between areas of M. caudata, M. baibacina, M. sibirica and an area of M. himalayana. They form an insuperable ecological barrier, interfering with expansion of an area of Marmots.

Charles Darwin was not only the author of the theory of the evolution which basis is made by the concept of natural selection, but also the outstanding evolutionary ecologist. The contribution of Darwin to ecology is underestimated because in its works there is no conceptual framework of modern ecology. Natural selection and struggle for life in «Origin of species» of Ch. Darwin correspond the Volterra - Gause competitive exclusion principle. Darvinian «a place in the nature» to identically modern concept «ecological niche».