Cherkasy, Ukraine

Cherkasy National University
Cherkasy, Ukraine
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Vasylyshyna E.,Cherkasy National University
Journal of Food, Agriculture and Environment | Year: 2017

Studies conducted over the years 2015-2016 with the fruits of cherry variety Shpanka and grapes variety Moldova. Preparation of fruit included sorting, inspection, washing, holding 30 min in solutions of 20% sugar and ascorutin 4% or 20% of the sugar with the addition of 1% chitosan, removing moisture, freezing at -24°C, packing in plastic bags of 0.5 kg and storage at -18°C and by taking control of untreated cherries and grapes packed in plastic bags. The total content of soluble dry matter in fresh cherries was 16.1% and in grapes 16.4%, content of tanning and coloring substances was 0.65% in cherries and in grapes 0.3%. After six months of storage in the frozen state dry soluble substances in processed cherries and grapes increased 2.5 and 24% compared with controls. Content of tanning and coloring substances remained unchanged to the end of storage, compared with the control and were 0.51-0.65% in cherries and 0.3-0.34% in grapes. The loss of phenolic compounds in cherries after six months of freezing was 20-50%.The smallest leakage tanning and coloring agents and ascorbic acid were for fruits, processed 20% solution of sugar with the addition of 1% chitosan. The antioxidant activity correlated with the content of tannins and coloring substances, regardless of the ascorbic acid content. © 2017, World Food Ltd. and WFL Publishers. All rights reserved.

Konogray V.A.,Cherkasy National University
Hydrobiological Journal | Year: 2017

The article deals with areas of different plants communities, their spatial distribution and total phytomass within the Kremenchuk reservoir (the Dnieper River, Ukraine). Primary production of the plant communities was calculated. Principles of sustainable use of phytoresources were proposed. © 2017 Begell House, Inc.

Minaev B.,KTH Royal Institute of Technology | Minaev B.,Cherkasy National University | Baryshnikov G.,Cherkasy National University | Agren H.,KTH Royal Institute of Technology
Physical Chemistry Chemical Physics | Year: 2014

Organic light-emitting device (OLED) technology has found numerous applications in the development of solid state lighting, flat panel displays and flexible screens. These applications are already commercialized in mobile phones and TV sets. White OLEDs are of especial importance for lighting; they now use multilayer combinations of organic and elementoorganic dyes which emit various colors in the red, green and blue parts of the visible spectrum. At the same time the stability of phosphorescent blue emitters is still a major challenge for OLED applications. In this review we highlight the basic principles and the main mechanisms behind phosphorescent light emission of various classes of photofunctional OLED materials, like organic polymers and oligomers, electron and hole transport molecules, elementoorganic complexes with heavy metal central ions, and clarify connections between the main features of electronic structure and the photo-physical properties of the phosphorescent OLED materials. This journal is © 2014 the Owner Societies.

Bondarchuk S.V.,Cherkasy National University | Minaev B.F.,KTH Royal Institute of Technology
Chemical Physics | Year: 2011

Density functional theory (DFT) calculations of several 2-X-substituted phenyl cations (X = 2-CHO, 2-CH2OH, 2-CHS, 2-CHNH, 2-OCHNH, 2-SCHNH, 2-CHCH-CHCH2, 2-CHCH2 and 2-NO2) have been carried out in the gas phase and in acetonitrile (MeCN) at the B3LYP/6-31G(d,p) level of theory. The stationary point geometry of these aryl cations have been found to be in strong dependency of the medium. In the gas phase, unexpected behavior of considered aryl cations takes place resulting in the rearrangement or ring closure reaction. Such the cyclization reaction is proceeding via the nearby atom of the substituent which appears in relative vicinity (up to ∼3 ) to the cationic center. Only in the case of 2-NO2 derivative, the geometry optimization has lead to rearranged quazi-quinoid structure of the cation that, obviously, takes place because of instability of the ring formed. Scan of the potential energy surface (PES) of 2-nitrophenyl cation has displayed no any reaction path leading toward the rearranged structure. Thus, the impossibility of existing of the singlet state of 2-nitrophenyl cation in the gas phase has been offered. The singlet-triplet transition of 2-nitrophenyl cation has been discussed in terms of the spin-orbit coupling (SOC) effects. © 2011 Elsevier B.V. All rights reserved.

Kovalchuk A.O.,Cherkasy National University | Gusak A.M.,Cherkasy National University | Tu K.N.,University of California at Los Angeles
Nano Letters | Year: 2010

Modification of the classical Zeldovich nucleation theory for nonstationary conditions is presented. It is applied to the recently discovered repeating nucleation events in point contact reactions between metal and silicon nanowires to form epitaxial silicides; the nucleation provides the reproducible quasi-stationary conditions satisfying the fundamental suppositions of the modified theory. The modified theory enables us to predict the rate of repeating nucleation at nanoscale level by developing a theory of the incubation time. The understanding is extremely important for the design and applications of nanoheterostructures. © 2010 American Chemical Society.

Tang W.,University of California at Los Angeles | Tang W.,Los Alamos National Laboratory | Picraux S.T.,Los Alamos National Laboratory | Huang J.Y.,Sandia National Laboratories | And 4 more authors.
Nano Letters | Year: 2013

At the nanoscale, defects can significantly impact phase transformation processes and change materials properties. The material nickel silicide has been the industry standard electrical contact of silicon microelectronics for decades and is a rich platform for scientific innovation at the conjunction of materials and electronics. Its formation in nanoscale silicon devices that employ high levels of strain, intentional, and unintentional twins or grain boundaries can be dramatically different from the commonly conceived bulk processes. Here, using in situ high-resolution transmission electron microscopy (HRTEM), we capture single events during heterogeneous nucleation and atomic layer reaction of nickel silicide at various crystalline boundaries in Si nanochannels for the first time. We show through systematic experiments and analytical modeling that unlike other typical face-centered cubic materials such as copper or silicon the twin defects in NiSi2 have high interfacial energies. We observe that these twin defects dramatically change the behavior of new phase nucleation and can have direct implications for ultrascaled devices that are prone to defects or may utilize them to improve device performance. © 2013 American Chemical Society.

Vasylyshyna E.,Cherkasy National University
Acta Scientiarum Polonorum, Technologia Alimentaria | Year: 2016

Background: Cherries are a valuable dietary raw material and possess medicinal properties. Considering the nutritional, medical and vitamin value of cherry fruits, the purpose of this research was to produce a scientific justification for preserving the quality of cherry fruits using different freezing methods. Material and methods: To do this, cherr y fruits from the Lotovka (Cerasus vulgaris) variety were frozen in various ways: packed in polyethylene bags (control); previously suspended in a 20% sugar solution and packing frozen cherry in polyethylene bags; suspended in a 20% sugar solution with the addition of 4% ascorutin and frozen followed by pre-packaging in polyethylene bags; cherry fruits were frozen in a 20% sugar solution in plastic cups of 0.25 cm3; they were also frozen in a 20% sugar solution with the addition of 4% ascorutin in plastic cups. The frozen products were stored at a temperature not higher than -18°C for up to 6 months. Result: Studies have shown the appropriateness of freezing cherry fruits, particularly in a 20% sugar solution with the addition of 4% ascorutin. The advantages of these fruits are in ascorbic acid preservation in 1.5 times and reduction of tanning and coloring substances only by 27%, soluble solids to 7%, sugars - 4%, acids - 12%, in tasting evaluation of 5 points. Conclusions: Frozen cherry fruits in a 20% sugar solution with the addition of 4% ascorutin can be used in dietary nutrition for patients with cardiovascular diseases. © Wydawnictwo Uniwersytetu Przyrodniczego w Poznaniu.

Bondarchuk S.V.,Cherkasy National University | Minaev B.F.,Cherkasy National University | Minaev B.F.,Tomsk State University
Chemical Physics Letters | Year: 2014

The recently introduced nucleophilicity index (N) of unsaturated compounds, which are typical π-nucleophiles, correlates (R = 0.9229) with their singlet-triplet energy splitting (ΔS-T) between the ground singlet and the excited 3(ππ*) state. The latter quantity is proposed for the activation barrier (Ea) determination of the nucleophile-electrophile addition reactions. A new approach for calculation of the Ea value is developed for reactions between alkenes and the p-methoxybenzhydryl cation. This scheme involves some simple DFT parameters, namely, the ΔS-T of the reactants and products. The experimentally available Ea values for the above reaction correlate well (R = 0.9944) with the calculated data. © 2014 Elsevier B.V. All rights reserved.

Bondarchuk S.V.,Cherkasy National University | Minaev B.F.,Cherkasy National University
Journal of Molecular Structure: THEOCHEM | Year: 2010

Calculations of 25 unsaturated compounds in the ground singlet and excited triplet states have been carried out using density functional theory (DFT) method at B3LYP/6-31G(d, p) level of theory. Their oxidized radical cation forms have also been calculated. Correlations between the yields of the Meerwein reaction products and the corresponding lowest unoccupied molecular orbital (LUMO) energies as well as the triplet excitation energies have been established. Activation of the unsaturated compounds via the triplet excited state formation has been shown as induced by exchange interaction either with paramagnetic aryl radical or with paramagnetic aryl triplet cation. Two competing routes of the Meerwein reaction have been offered depending on the presence of the catalyst. In the absence of redox (catalytic) systems the reaction is considered to be a direct ion addition. Spin-orbit coupling effects enabling the singlet-triplet transition in the aryl cations are also discussed. © 2010 Elsevier B.V.

Mudrak R.,Cherkasy National University
Economic Annals-XXI | Year: 2014

The presence of food security at the macro level does not guarantee food security at the micro level. This creates a serious management problem - how to ensure food safety at all levels of the national economy. The aim of the paper is to investigate the influence factors of consumer behaviour in his household's food security and to develop proposals to neutralize the individual factors of food insecurity. Pressing social and economic problem in Ukraine is non-rational consumer behaviour of households. The most telling example is expenditure on food items that do not represent the nutritional value and are harmful to health - alcohol and tobacco. The share of cash expenditures on alcohol in the poorest I, II and III decile groups no less than the share of cash expenditures in V decile group. The share of cash expenditures on tobacco increases over the reduction of average income. One of the main causes of the food insecurity is excessive income differentiation, diverse popularization and promotion of prestigious consumption patterns in the media. Low levels of gastronomic culture and lack of basic knowledge of many Ukrainian domestic households also are destructive factors of safe and quality nutrition. This study leads to the following conclusions and suggestions: 1) the national food security and food security of individual households differ in their object of research methods and influence factors evaluation; 2) the household food security depends on the model of consumer behaviour; 3) the spending pattern of the households is formed under the influence of the surrounding social environment; 4) consumer behaviour of the domestic households is non-rational because of: a) in the Ukrainian social environment wealthy households formed costly, prestigious model of consumer behaviour, being actively propagated by the media. The poor households fall into the psychological trap of inferiority complex and looking out from it by copying consumer behaviour of the wealthy households; b) low level of gastronomic culture; c) the lack of full information to consumers. In order to partially neutralize the effect of the negative factors that cause irrational consumer behaviour of the households, it is necessary to apply a set of measures. In particular: 1) solving behavioural problems should be connected with the approval of the ruling middle class; 2) using of educational and outreach activities designed to promote public awareness of rejection and condemnation of arrogance material possessions is essential; 3) creation of educational awareness campaign should be worked out aimed at gastronomic culture raising and consumer education of the households. Management measures development to implement such proposals is a promising direction for further research. © 2014 Institute of Society Transformation.

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