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  • Author: O. M. Kovalchuk x
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O. M. Kovalchuk

Abstract

A new fossil species Perca neopleistocenica Kovalchuk, sp. n. from Southern Ukraine is described. It differs from other species of the genus by width and configuration of praeoperculum, and also by quantity of cogs on the posterior edge of os praeoperculare

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O. M. Kovalchuk

Abstract

A new species of pikeperch from the Upper Miocene strata of Ukraine (Egorovka 2 locality, MN 12) is described in the paper. Extinct species Sander svetovidovi sp. n. differs from the Miocene and recent taxa of the genus Sander by the configuration of the quadrate bone, form and sizes of the lateral condyle and also presence of additional double crista on the anterior inferior edge of quadratum.

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A. Šoster and O. M. Kovalchuk

Abstract

The present paper deals with results of the study of porgy fish (Sparidae) remains from the upper Miocene, lower and upper Pliocene, and the lower Pleistocene of Ukraine. Isolated molariform teeth were assigned to Pagrus cinctus, Pagrus sp., as well as to Sparidae? gen. et sp. indet. These findings expand our knowledge of the species composition of the Late Cenozoic fish assemblages of Southeastern Europe and force partially reconsider conclusions formulated earlier about their environment.

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L. I. Rekovets and O. M. Kovalchuk

Abstract

This paper presents analytical results of the study of adaptatiogenesis within the family Arvicolidae (Mammalia, Rodentia) based of morphological changes of the most functional characters of their masticatory apparatus — dental system — through time. The main directions of the morphological differentiation in parallel evolution of the arvicolid tooth type within the Cricetidae and Arvicolidae during late Miocene and Pliocene were identified and substantiated. It is shown that such unique morphological structure as the arvicolid tooth type has provided a relatively high rate of evolution of voles and a wide range of their adaptive radiation, as well as has determined their taxonomic and ecological diversity. The optimality of the current state of this group and evaluation of evolutionary prospects of Arvicolidae were presented and substantiated here as a phenomenon in their evolution.

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T. V. Krakhmalnaya and O. M. Kovalchuk

Abstract

The skull fragment of muskox Ovibos moschatus (Artiodactyla, Bovidae) obtained from Chasha River bed alluvium near the Buryn (Sumy Region, North-Eastern Ukraine) is described here in detail. It belongs to a young male, and presumably dates back to Late Pleistocene. This new find slightly extends the known Ukrainian range of the species to the east. Taxonomic attribution of extinct muskox and dispersal of Ovibos moschatus within the territory of Ukraine during the Late Pleistocene are also discussed in the paper.

Open access

Oleksandr Kvartenko, Larysa Sabliy, Nataliya Kovalchuk and Andriy Lysytsya

Abstract

The use of the biological method is promising for treating underground waters from iron compounds. Iron bacteria used in the process are widely spread in weak acidic and neutral underground waters containing iron ions (II), dissolved carbon dioxide and minimum concentrations of oxygen. The relevant direction of present-day biotechnology is the use of iron bacteria for treating underground waters. The goal of this research is to compare the efficiency of using the biological method for treating underground iron containing weak acidic and neutral waters under different conditions. As the test-objects, Gallionella and Lepthotrix iron bacteria were used. The sedimentation of bio-minerals was obtained from the washout waters of the biological deironing station. Calcium soda was used as an additional source of inorganic carbon for bacteria. As a result of the studies it is established that the use of the non-reagent method gives the possibility to achieve only 80% efficiency in removing iron compounds while the use of sodium carbonate results in increasing efficiency up to 93%. To determine the contribution of biological purification of ground water from iron compounds, the bacteria were inhibited with the preparation of polyhexamethylene guanidine (PHMG) chloride. It was found that inhibition of Gallionella and Lepthotrix led to the reduction of 50% of the iron removal effect. The mechanism was developed of inhibiting the process of iron bacteria metabolism by PHMG (polyhexamethylene guanidine). The new technology of arranging a block-module station for treating underground waters is proposed.