Astrakhan State University

About: Astrakhan State University is a education organization based out in Astrakhan, Russia. It is known for research contribution in the topics: Percolation & Carbamate. The organization has 547 authors who have published 565 publications receiving 2367 citations.

Synthesis and Antimycobacterial Activity of 5-(Arylmethylene)Hexahydropyrimidine-2,4,6-Triones

Abstract: A series of 5-(arylmethylene)hexahydropyrimidine-2,4,6-triones were synthesized. Their antimycobacterial activity and acute daily toxicity with respect to M. lufu were investigated.

Synthesis of New Functionally Substituted Aryl- and Hetarylcarbamates Based on Ninhydrin

Abstract: The condensation of methyl (ethyl) phenylcarbamates with ninhydrin in concentrated sulfuric acid gave dialkyl [1,3-dioxoindan-2,2-diyldi(4,1-phenylene)]biscarbamates. Treatment of the latter with hydrazine hydrate resulted in the transformation of the indandione fragment into phthalazinone. Ninhydrin reacted with methyl (hydroxyphenyl)carbamates in glacial acetic acid to produce dihydroxy derivative of oxotrihydroindeno[ 1,2-b][1]benzofuran possessing a carbamate group. Tandem reaction of ninhydrin with methyl (acetylphenyl) carbamates on heating in boiling glacial acetic acid, followed by addition of hydrazine hydrate in acetonitrile, afforded methyl (5-oxo-5H-indeno[1,2-c]pyridazin-3-yl)phenylcarbamates.

The Use of Raman Spectroscopy and Methods of Quantum Chemistry for Assessing the Relative Concentration of Triglycerides of Oleic and Linoleic Acids in a Mixture of Olive Oil and Sunflower Seed Oil

Abstract: The Raman spectra of five samples of sunflower seed oil and five samples of cold-pressed olive oil of various brands are recorded in the range of 500–2000 cm–1. Within the framework of the B3LYP/6-31G(d)/6-31G(d,p)/6-31+G(d,p)/6-311G(d)/6-311G(d, p)/6-311+G(d,p) methods, the structural models of eight fatty acids (oleic, linoleic, palmitic, stearic, α-linolenic, arachidonic, eicosapentaenoic, and docosahexaenoic) are constructed, and also within the framework of the B3LYP/6-31G(d) method, the structural models of triglycerides of the first four of the above acids are obtained. The vibrational wavenumbers and intensities in the IR and Raman spectra are calculated. The Raman spectra of olive oil and sunflower seed oil were simulated by using the supermolecular approach. We investigated the dependence of the relative intensity of the vibrational bands νexp = 1660 and 1445 cm–1 on the concentration of triglycerides in oils of oleic and linoleic acids and the dependence of the intensity of these bands on the degree of saturation of fatty acids. Experimental and empirical dependences are constructed to estimate the relative concentration of triglycerides of oleic and linoleic acids in a mixture of olive oil and sunflower seed oil. The applicability of the density functional theory together with the vibrational spectroscopy for the identification of mixtures of vegetable oils is discussed.

Experimental Simulation of the Generation of a Vortex Flow on a Water Surface by a Wave Cascade

Abstract: The generation of a vortex flow by waves on a water surface, which simulate an energy cascade in a system of gravity waves at frequencies of 3, 4, 5, and 6 Hz, has been studied experimentally. It has been found that pumping is accompanied by the propagation of waves on the surface at different angles to the fundamental mode and by a nonlinear interaction between waves resulting in the generation of new harmonics. It has been shown that large-scale flows are formed by modes of the lowest frequency of 3 Hz intersecting at acute angles. The energy distribution of the vortex motion can be described by a power-law function of the wavenumber and is independent of the energy distribution in a system of surface waves. The energy coming to large-scale vortex flows directly from the wave system is transferred to small scales. A direct rather than inverse energy flux is established in the system of vortices.

The Websites of International Association Organizations in the Science and Engineering Area: Analysis of Their Functionality, Webometric Ranks, and Role in the Scientific Information Space

Abstract: The position of international scientific associations (commonwealths, unions, and alliances) in the general structure of scientific organizations, as well as the role of such associations in the formation of the scientific information space, both national and international, are shown. For the associations, we analyzed the basic methodological issues of the construction of their websites, the information content of web pages, provision of the necessary functionality and user experience, and compliance to the rules of information security. This paper discusses the sources and composition of the information published on the websites of international associations working in the science and engineering area and defines the particular features of the structure of certain websites and their functional capabilities. The design and software solutions used on these websites are characterized. A detailed comparative study of webometric ranks is carried out and the main areas of their application in decision making by Russian researchers and research teams, as well as content managers of the websites of Russian research and development establishments, universities, institutes, and scientific communities are defined.