Origin of second-harmonic generation in the incommensurate phase of K2SeO4

We show that a ferroelectric phase transition takes place in the incommensurate phase of the K2SeO4 crystal. The ferroelectric character of the IC phase explains the second-harmonic generation observed in the corresponding temperature range.Comment: 5 pages, 1 figur

Universal mechanism of discontinuity of commensurate-incommensurate transitions in three-dimensional solids: Strain dependence of soliton self-energy

We show that there exists a universal mechanism of long-range soliton attraction in three-dimensional solids and, therefore, of discontinuity of any commensurate-incommensurate (C-IC) phase transition. This mechanism is due to the strain dependence of the soliton self-energy and specific features of the solid-state elasticity. The role of this mechanism is studied in detail for a class of C-IC transitions where the IC modulation is one-dimensional, the anisotropy in the order parameter space is small, and the symmetry of the systems allows the existence of the Lifshitz invariant. Two other mechanisms of soliton attraction are operative here but the universal mechanism considered in this paper is found to be the most important one in some cases. Comparison with the most extensively studied C-IC transition in $\rm K_2SeO_4$ shows that the experimentally observed thermal anomalies can be understood as a result of the smearing of the theoretically predicted discontinuous transition.Comment: 8 pages (extended version, title changed

Chemistry for Sustainable Development 15 (2007) 465-471 Quality Enhancement of Straight-Run Petroleum Fractions from High-Wax Mongolian Oils

Abstract The effect of ozonation and dewaxing of Mongolian high-wax oils on the hydrocarbon type composition of petroleum fractions has been studied. The evolution of composition and properties of straight-run petroleum fractions (IBP 180 o C) during reforming on a zeolite catalyst has been examined. It has been demonstrated that after ozonation followed by oil thermolysis the petroleum fractions are enriched with aromatic hydrocarbons while the content of naphthenic ones diminishes. Dewaxing of high-wax oil with liquefied gas has been shown to remove predominantly normal alkanes from petroleum fractions. It has been demonstrated that on catalytic thermal refining of straight-run petroleum fractions the products obtained are depleted of normal paraffin and naphthenic hydrocarbons by 2-5 times, enriched with aromatics by 2-4 times, octane rating of gasoline is enhanced by 18-40 points

Thermal Conversion of Heavy Oil Systems and Analysis of Structural Changes of their High Components with PMR Method

Heavy oil systems are thermolyzed with different ratios of amount of resins and asphaltenes: 3.4, 3.8, 5.3, and 12.4. The change in yield and composition of gaseous, liquid and solid products of thermolysis is shown depending on the ratio of the resin: asphaltenes. In the liquid products of thermolysis, resins content decreases and s the amount of asphaltenes and oils increases. According to PMR spectroscopy, the distribution of protons is compared in the secondary resin and asphaltene molecules of the initial samples and the thermolysis products. It is shown that the relative content of hydrogen aromatic rings in the molecules of asphaltenes is higher, and for [beta]- and [gamma]- positions relative to the aromatic rings and heterofunction, it is lower than in the resin molecules

Mechanochemical conversion of acetylene in quartz – ultrafine metal powder system

We have studied the effect of nano-sized metal powders (Zn, Ni), obtained by electric explosion of wires, on mechanochemical conversions of acetylene in the presence of quartz. In the process of acetylene mechanical treatment (MT) in the presence of quartz, benzene is formed. During the mechanical grinding of quartz in planetary-centrifugal mills, active radical sites are formed on quartz surface. It is possible to suppose that due to the influence of mechanical energy acetylene triple bond breaks to form ethyl radicals, which are subjected to chemosorption on active quartz sites with subsequent formation of benzene. The addition of ultrafine Zn powder decreased, while Ni powder considerably increased benzene yield. In the process of MT, particles of ultrafine Zn powder are agglomerated which results in the decrease of its catalytic activity. The increase in benzene yield at the use of ultrafine Ni powder as the additives is associated with catalytic conversion of acetylene into benzene on the newly formed nickel surface. The injection of ultrafine Zn and Ni powders in quartz-acetylene system caused no changes in quantitative composition of acetylene conversion products but affected the amounts of one or other component formation

УПРАВЛІННЯ КРЕДИТНОЮ ДІЯЛЬНОСТІ БАНКУ ДЛЯ ЗАБЕЗПЕЧЕННЯ ЙОГО ФІНАНСОВОЇ СТАБІЛЬНОСТІ

Concept of financial stability of bank and economic essence of bank’s credit activity are considered in the article. The indexes of financial stability and indexes of efficiency, profitability, liquidity of bank establishment, and also economic indicators and norms of the banking system are analysed.Crediting activation assists the further increase of economy, development and origin of new entities, creation of workplaces, development infrastructure of country, those are basis of financial stability. In parallel, crediting is one direction of banks’ activity, that provides their profitability.The article is dedicated to the analysis of tendencies and features of credit activity of domestic banks. Efficiency of management of credit activity JSC CB "Privatbank" and JSC "Oschadbank" on the modern stage of economic development are analized. Authors analyse the structure of a loan portfolio JSC CB "Privatbank" and JSC "Oschadbank", efficiency of management of a loan portfolio by correlation of basic management parameters - profitability and risk. The analytical estimation of the credit activity state of JSC CB "Privatbank" and JSC "Oschadbank" and its influence on financial stability of the banking system, and also on return on assets of the indicated bank institutions and optimal strategy of banks’ credit activity.The modern state is analysed and practical recommendations are sunstantiated in relation to the improvement of bank institutions’ credit activity with the aim of providing their financial stability.Conclusions about the necessity of efficiency management crediting of domestic banks’ increase by optimal forming and management of a loan portfolio at a minimum level of risk are drawn.В статье рассмотрено понятие финансовой устойчивости банка и экономическая сущность кредитной деятельности банков. Осуществлено аналитическую оценку состояния кредитной деятельности банковских учреждений и ее влияние на финансовую устойчивость банковской системы. Проанализировано современное состояние и обоснованы практические рекомендации по совершенствованию кредитной деятельности банковских учреждений.У статті розглядаються поняття фінансова стабільність банку та економічна сутність кредитної діяльності банку. Аналізуються показники фінансової стабільності та показники рентабельності, прибутковості, ліквідності банківської установи, а також економічні показники та норми банківської системи.Активізація кредитування сприяє подальшому зростанню економіки, розвитку та виникненню нових суб'єктів господарювання, створенню робочих місць, розвитку інфраструктури країни, що є основою фінансової стабільності. Паралельно кредитування є одним з напрямків діяльності банків, що забезпечує їх прибутковість.Стаття присвячена аналізу тенденцій та особливостей кредитної активності вітчизняних банків. Проаналізовано ефективність управління кредитною діяльністю АТ КБ «Приватбанк» та АТ «Ощадбанк» на сучасному етапі економічного розвитку.  Авторами проаналізовано структуру кредитного портфеля АТ КБ «Приватбанк» та АТ «Ощадбанк», ефективність управління кредитним портфелем за співвідношенням основних параметрів управління - прибутковості та ризику. Визначено аналітичну оцінку стану кредитної активності АТ КБ «Приватбанк» та АТ «Ощадбанк» та її вплив на фінансову стабільність банківської системи, а також на рентабельність активів вказаних банківських установ та оптимальну стратегію кредитної діяльності банків.Проаналізовано сучасний стан та обґрунтовано практичні рекомендації щодо поліпшення кредитної діяльності банківських установ з метою забезпечення їх фінансової стабільності.Зроблено висновки про необхідність підвищення ефективності управління кредитуванням вітчизняних банків шляхом оптимального формування та управління кредитним портфелем при мінімальному рівні ризику

Composition of Initiated Cracking Products of High-sulfur Natural Bitumen

The analysis of the cracking products of bitumen Karmalskoye deposits (the content of fractions boiling up to 200 °C 6,7% wt.) has been performed. The influence of power plant coal ash microspheres on orientation of cracking bitumen components is stated. Bitumen cracking leads to significant yields of gas and coke for more than 20% wt. and destructions of all components. The initiated bitumen cracking in the presence of 10% microspheres at cracking temperature 450 °C leads to reduction of gas and coke yields and increase in fractions of ibp (initial boiling point) –360 °C at 10% wt. in comparison with products of the thermal bitumen cracking. The analysis of composition and amount of sulfur compounds in initial bitumen and the cracking products in the various conditions has shown that the thermal cracking leads to increased homologues benzothiophene contents due to partial destruction of resins, and to decrease in the content of homologues dibenzothiophene

Composition of Pre-ozonated High-Sulfur Natural Bitumen Cracking Products

The results analysis of fractional and material composition of the cracking products of Ashalchinskoye and Karmalskoye bitumen deposits was presented in this work. The effect of bitumen ozone-oxygen mixture pretreatment followed by cracking on thermolysis processes was investigated. It was shown that molecules of resins and asphaltenes containing large amounts of aliphatic fragments in its structure readily undergo thermal decomposition to form additional distillate fractions. Low content of aliphatic fragments leads to aromatization of the naphthenic cycles in the molecule of resins and asphaltenes, the thermal degradation reactions proceed in high yields of gas and coke

Evaluation of saturated and aromatic hydrocarbons oil-oil maturity correlation parameters (SE Pannonian Basin, Serbia)

Twenty three crude oils from the Serbian part of the Pannonian Basin (14 from the Vojvodina Province and 9 from the Drmno Depression) were investigated, aimed at an evaluation of oil-oil maturity correlation parameters based on the distribution and abundance of saturated biomarkers and alkylarene constituents. Factor and cluster analyses were used for this purpose. Factor analyses using varimax rotation were first run separately, i.e., of maturity parameters based on the abundance of (a) n-alkanes and isoprenoids, (b) steranes and triterpanes, (c) alkylnaphthalenes, and (d) alkylphenanthrenes. These analyses yielded 9 important "maturity factors". Eight of them, showing higher than 30 % of variance, were further involved in another factor analysis, as well as in cluster analysis using the Ward method. In this way, all maturity parameters based on saturated biomarkers and alkylarenes were evaluated and ranged, considering the fact that the observed factors represented their linear combinations. The results showed that in the correlation of crude oils from the Serbian part of the Pannonian Basin, the most important were maturity parameters based on isomerization reactions involving one methyl group in thermodynamically less stable alpha-methylnaphthalenes, ethylnaphthalenes, dimethylnaphthalenes and methylphenanthrenes, and their change into more stable isomers with the methyl group in the beta-position in the aromatic ring. Processes constituting high loadings factor 2 and factor 3 parameters were also defined. Hierarchy between the "factors" and parameters were controlled, and approved, by cluster analysis using the Ward method. Finally, the investigated crude oils were correlated by factor and cluster analyses, using all the important "maturity factors". Differences in maturity were observed between the Vojvodina and Drmno Depression crude oils, as well as between oils originating from South Banat, North Banat and the Velebit oil field (Vojvodina locality)

The Novelties Producing by Ozonolysis of Petroleum High-Molecular Components

Specific properties of ozonolysis products of high-molecular heteroatomic compounds (resins and asphaltenes) from crude petroleums and natural bitumens are described. It is shown that polyfunctional carboxylic acids or their salts obtaining by alkaline hydrolysis of ozonization products of heavy petroleum stocks permits to produce manifold useful novelties such as high-effective demulsifiers for petroleum dehydration process instead of expensive synthetic demulsifying reagents; water-soluble organic astringents suitable for chemical land-reclamation or to prepare moulding mixtures at the foundries; oily or emulsion lubricating coolants for metal-working tools; stimulators of soil microorganisms activity and plant growth. The new chemical products of petroleum origin are not inferior to the best synthetic reagents for the same destinations but differ from the lasts advantageously on account of the simplicity of their production technology and low cost. The optimal expenses and other principal technological parameters were established both for raw material ozonization, following alkaline treatment and final product isolation stages of the production process for each new reagent described. By means of numerous laboratory experiments and field tests performed with seeds, bulbs and grafts of different agricultural plants and with ozonolysis products produced from the resinous components of different crude petroleums it was proved that high biological activity is characteristic only of the substances obtained from high-molecular compounds from low-sulfur naphthenic crude petroleums and natural bitumens occurring, as a rule, at small burial depths. These ozonolysis products are very effective stimulants for the different plants growth, suitable for a treatment of different forms of planting materials and providing significant acceleration of early growth stages, the reduction of vegetation and ripening periods, and the increase of total productivity of agricultural plants