Khmelnytskyi, Ukraine

Khmelnitsky National University
Khmelnytskyi, Ukraine
Time filter
Source Type

Bregnhoj M.,University of Aarhus | Westberg M.,University of Aarhus | Minaev B.F.,Khmelnitsky National University | Ogilby P.R.,University of Aarhus
Accounts of Chemical Research | Year: 2017

ConspectusSinglet oxygen, O2(a1Δg), the lowest excited electronic state of molecular oxygen, is an omnipresent part of life on earth. It is readily formed through a variety of chemical and photochemical processes, and its unique reactions are important not just as a tool in chemical syntheses but also in processes that range from polymer degradation to signaling in biological cells. For these reasons, O2(a1Δg) has been the subject of intense activity in a broad distribution of scientific fields for the past ∼50 years.The characteristic reactions of O2(a1Δg) kinetically compete with processes that deactivate this excited state to the ground state of oxygen, O2(X3ςg-). Moreover, O2(a1Δg) is ideally monitored using one of these deactivation channels: O2(a1Δg) → O2(X3ςg-) phosphorescence at 1270 nm. Thus, there is ample justification to study and control these competing processes, including those mediated by solvents, and the chemistry community has likewise actively tackled this issue.In themselves, the solvent-mediated radiative and nonradiative transitions between the three lowest-lying electronic states of oxygen [O2(X3ςg-), O2(a1Δg), and O2(b1ςg+)] are relevant to issues at the core of modern chemistry. In the isolated oxygen molecule, these transitions are forbidden by quantum-mechanical selection rules. However, solvent molecules perturb oxygen in such a way as to make these transitions more probable. Most interestingly, the effect of a series of solvents on the O2(X3ςg-)-O2(b1ςg+) transition, for example, can be totally different from the effect of the same series of solvents on the O2(X3ςg-)-O2(a1Δg) transition. Moreover, a given solvent that appreciably increases the probability of a radiative transition generally does not provide a correspondingly viable pathway for nonradiative energy loss, and vice versa.The ∼50 years of experimental work leading to these conclusions were not easy; spectroscopically monitoring such weak and low-energy transitions in time-resolved experiments is challenging. Consequently, results obtained from different laboratories often were not consistent. In turn, attempts to interpret molecular events were often simplistic and/or misguided. However, over the recent past, increasingly accurate experiments have converged on a base of credible data, finally forming a consistent picture of this system that is resonant with theoretical models. The concepts involved encompass a large fraction of chemistry's fundamental lexicon, e.g., spin-orbit coupling, state mixing, quantum tunneling, electronic-to-vibrational energy transfer, activation barriers, collision complexes, and charge-transfer interactions.In this Account, we provide an explanatory overview of the ways in which a given solvent will perturb the radiative and nonradiative transitions between the O2(X3ςg-), O2(a1Δg), and O2(b1ςg+) states. © 2017 American Chemical Society.

Goldengorin B.,Khmelnitsky National University | Krushinsky D.,University of Groningen | Slomp J.,University of Groningen
Operations Research | Year: 2012

Lately, the problem of cell formation (CF) has gained a lot of attention in the industrial engineering literature. Since it was formulated (more than 50 years ago), the problem has incorporated additional industrial factors and constraints while its solution methods have been constantly improving in terms of the solution quality and CPU times. However, despite all the efforts made, the available solution methods (including those for a popular model based on the p-median problem, PMP) are prone to two major types of errors. The first error (the modeling one) occurs when the intended objective function of the CF (as a rule, verbally formulated) is substituted by the objective function of the PMP. The second error (the algorithmic one) occurs as a direct result of applying a heuristic for solving the PMP. In this paper we show that for instances that make sense in practice, the modeling error induced by the PMP is negligible. We exclude the algorithmic error completely by solving the adjusted pseudo-Boolean formulation of the PMP exactly, which takes less than one second on a general-purpose PC and software. Our experimental study shows that the PMP-based model produces high-quality cells and in most cases outperforms several contemporary approaches. © 2012 INFORMS.

Agency: European Commission | Branch: FP7 | Program: CSA | Phase: ICT-2011.5.6 | Award Amount: 752.51K | Year: 2011

eGovPoliNet sets up an international community in ICT solutions for governance and policy modelling. The international community of researchers and practitioners will share and advance research and insights from practical cases around the world. To achieve this, eGovPoliNet will build on experiences accumulated by leading actors bringing together the innovative knowledge of the field. Capabilities, tools and methods brought forward by academia, ICT industry, highly specialised policy consulting firms, and policy operators and governance experts from governments will be investigated and collected in an international knowledge base. Comparative analyses and descriptions of cases, tools and scientific approaches will complement this knowledge base. Therewith, the currently existing fragmentation across disciplines will be overcome.Functions of eGovPoliNet towards community building, RTD monitoring and comparative analysis will mainly be conducted in an internet-based participatory manner, complemented with regular physical meetings attached to conferences. Community building of experts from academia, industry and public organizations, and other interested stakeholders will be supported by a community portal for knowledge sharing, collaboration, dissemination, and multidisciplinary constituency building in an open environment. eGovPoliNet expertise covers a wide range of aspects for social and professional networking and multidisciplinary constituency building along the axes of technology, participative processes, governance, policy modelling, social simulation and visualisation. Regular physical and virtual meetings with off- and online discussions and comparative studies will contribute to capacity building of the community.Through sharing of approaches and exposing them to the communitys discussions, eGovPoliNet will advance the way research, development and practice is performed worldwide in using ICT solutions for governance and policy modelling.

Litvin V.A.,Khmelnitsky National University | Minaev B.F.,Khmelnitsky National University | Minaev B.F.,KTH Royal Institute of Technology
Materials Chemistry and Physics | Year: 2014

In this paper we demonstrate the use of synthetic humic substances (HSs) in the synthesis of gold nanoparticles in which the unprecedented control of particle size and shape is achieved by varying the experimental conditions. In this reaction, the synthetic HSs are used as a reductive and protective reagent. A number synthetic HSs from different fenol precursors are tested. The nanoparticles formation processes were monitored by UV-visible spectroscopy, and the results were analyzed by transmission electron microscopy and X-ray diffraction. The preference of synthetic HSs over natural HSs is determined by a standardization problem resolution due to the strict control of the HSs formation conditions that expand the areas of application of the gold nanoparticles fabricated with such technique. These nanodispersions are aggregately stable for more than one year. The possible formation mechanism of primary gold nanoclusters is proposed. © 2014 Elsevier B.V. All rights reserved.

Litvin V.A.,Khmelnitsky National University | Minaev B.F.,Khmelnitsky National University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

In this present study, silver nanoparticles were synthesized using synthetic humic substances (HSs) as reducing and stabilizing agents. Preference of synthetic HSs over natural humic matter is determined by a standardization problem resolution of the product due to the strict control of conditions of the synthetic HSs formation. It allows to receive the silver nanoparticles with the standardized biologically-active protective shell that is very important for their use, mainly in medicine. The concentration of sodium hydroxide, synthetic HSs, silver nitrate and temperature employed in the synthesis process are optimized to attain better yield, controlled size and stability by means of UV-visible technique. In the optimal reaction conditions the concentrated silver colloids (55 mM) with 99.99% yield are obtained which were stable for more than 1 year under ambient conditions. The received silver nanoparticles are characterized by UV-visible spectroscopy, X-ray diffraction (XRD), FT-IR spectroscopy and transmission electron microscopy (TEM). The antimicrobial activity of silver nanoparticles against fungal and bacterial strains is also shown. © 2013 Elsevier B.V. All rights reserved.

Zaspa Y.P.,Khmelnitsky National University
Journal of Friction and Wear | Year: 2012

The transition to the condition of autowave motion is illustrated on the example of a dynamic system consisting of weights linked to a pulley moving with friction in the pulley axis under the force of gravity. The coherent interaction between the external modes of nonstationary directed motion and the internal wave modes under the studied conditions induces the effects of negative dynamic friction. The tangential intensification of the counterbody friction in the intervals of positive feedback actuates both the tangential and normal component of the full contact response that has no counterparts in the equilibrium tribodynamics. This effect is explained by the resonance automodulation of contact friction by elastic waves of stresses. The qualitative parameters controlling the changes in external friction conditions are introduced, similar to the Reynolds number in hydroaeromechanics. The general problems of contact tribodynamics and hydroaerodymics of the boundary layer are analyzed in respect to the coherent interaction in the friction system and the wave impulse transfer. © 2012 Allerton Press, Inc.

Horiashchenko S.,Khmelnitsky National University
20th International Scientific Conference: Mechanika 2015 - Proceedings | Year: 2015

The paper presents an device for polymer coating. Technologies for the coating and duplicating of the surface of leather and textile materials by the polymeric films have been developed on the basis of experimental device. Research has shown that the formation of the polymer layer is accompanied by the occurrence of such phenomena: the wetting of the surface of the upper parts of the details of clothing; capillary penetration of substances into the structure of porous material and adhesion. Received examples of polymeric coating on the fabric.

Litvin V.A.,Khmelnitsky National University | Galagan R.L.,Khmelnitsky National University | Minaev B.F.,Khmelnitsky National University
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2012

In this work, we demonstrate efficiency of the usage of synthetic humic substances (HSs) as reducing and stabilizing agent in preparation of silver nanoparticles for the first time. Preference of synthetic HSs over natural HSs is determined by a standardization problem resolution due to the strict control of conditions of the HS formation that expands the areas of application of the silver nanoparticles made on their basis. The formation of silver nanoparticles is confirmed by the UV-vis spectroscopy, X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The potentiometric and spectrophotometric data of kinetic study of the silver nanoparticles formation are reported. On the basis of various observations, a three-stage of silver nanoparticles formation is proposed: a fast formation of the Ag 2O microphase in system after mixing of reagents; reduction of silver ions on the surface of Ag 2O particles according to the zero-order kinetics; growth of silver nanoparticles due to reduction of silver ions from a solution on a surface of already generated nucleus of silver nanoparticles according to the first order kinetics after the Ag 2O microphase dissolution. © 2012 Elsevier B.V.

Hovorushchenko T.,Khmelnitsky National University
Proceedings of the International Conference on Computer Sciences and Information Technologies, CSIT 2015 | Year: 2015

In this paper the analysis of the known approaches to detection of emergent properties of software system in the context of involvement for this of the software quality models was done. The attempt of evaluation of share of the non-functional requirements in the software quality models was done. © 2015 Lviv Polytechnic National University.

Pastukh I.M.,Khmelnitsky National University
Technical Physics | Year: 2016

A new model of nitriding is proposed on the basis of the energy initial conditions. © 2016, Pleiades Publishing, Ltd.

Loading Khmelnitsky National University collaborators
Loading Khmelnitsky National University collaborators