Microscopic mechanisms of thermal and driven diffusion of non rigid molecules on surfaces

The motion of molecules on solid surfaces is of interest for technological applications such as catalysis and lubrication, but it is also a theoretical challenge at a more fundamental level. The concept of activation barriers is very convenient for the interpretation of experiments and as input for Monte Carlo simulations but may become inadequate when mismatch with the substrate and molecular vibrations are considered. We study the simplest objects diffusing on a substrate at finite temperature $T$, namely an adatom and a diatomic molecule (dimer), using the Langevin approach. In the driven case, we analyse the characteristic curves, comparing the motion for different values of the intramolecular spacing, both for T=0 and $T\ne 0$. The mobility of the dimer is higher than that of the monomer when the drift velocity is less than the natural stretching frequency. The role of intramolecular excitations is crucial in this respect. In the undriven case, the diffusive dynamics is considered as a function of temperature. Contrary to atomic diffusion, for the dimer it is not possible to define a single, temperature independent, activation barrier. Our results suggest that vibrations can account for drastic variations of the activation barrier. This reveals a complex behaviour determined by the interplay between vibrations and a temperature dependent intramolecular equilibrium length.Comment: 6 pages, 5 figures, Proceeding of the EMRS 2002 Conference, to be published in Thin Solid Film

A hierarchy of models related to nanoflows and surface diffusion

In last years a great interest was brought to molecular transport problems at nanoscales, such as surface diffusion or molecular flows in nano or sub-nano-channels. In a series of papers V. D. Borman, S. Y. Krylov, A. V. Prosyanov and J. J. M. Beenakker proposed to use kinetic theory in order to analyze the mechanisms that determine mobility of molecules in nanoscale channels. This approach proved to be remarkably useful to give new insight on these issues, such as density dependence of the diffusion coefficient. In this paper we revisit these works to derive the kinetic and diffusion models introduced by V. D. Borman, S. Y. Krylov, A. V. Prosyanov and J. J. M. Beenakker by using classical tools of kinetic theory such as scaling and systematic asymptotic analysis. Some results are extended to less restrictive hypothesis

Materials based on BIFEVOX and bismuth or iron simple oxides nanopowders

Received: 22.09.2017; accepted: 17.10.2017; published: 20.10.2017.Compositions of composite materials based on BIFEVOX and nanopowders of bismuth and iron oxides have been obtained. The absence of chemical interaction between the components has been proved, the total electrical conductivity of materials in the average temperature region has been determined. It has been shown that under the selected formation conditions, it has not yet been possible to achieve significant improvement of the functional characteristics of heterogeneous compositions in comparison with individual phases. However positive results on chemical and structural stability give way to further investigations.The work was partially supported by the Scholarship of the President (SP-3376.2016.1) and Russian Foundation for Basic Research (project No 17-53-04098)

Molecular random walks and invariance group of the Bogolyubov equation

Statistics of molecular random walks in a fluid is considered with the help of the Bogolyubov equation for generating functional of distribution functions. An invariance group of solutions to this equation as functions of the fluid density is discovered. It results in many exact relations between probability distribution of the path of a test particle and its irreducible correlations with the fluid. As the consequence, significant restrictions do arise on possible shapes of the path distribution. In particular, the hypothetical Gaussian form of its long-range asymptotic proves to be forbidden (even in the Boltzmann-Grad limit). Instead, a diffusive asymptotic is allowed which possesses power-law long tail (cut off by ballistic flight length).Comment: 23 pages, no figures, LaTeX AMSART, author's translation from Russian of the paper accepted to the TMPh (``Theoretical and mathematical physics''

Формування матеріально-технічних умов проведення місцевих виборів в Україні

Крилов Ю. В. Формування матеріально-технічних умов проведення місцевих виборів в Україні / Ю. В. Крилов // Правові та інституційні механізми забезпечення розвитку держави та права в умовах євроінтеграції : матеріали Міжнародної науково-практичної конференції (20 травня 2016 р., м. Одеса) : у 2 т. Т. 1 / відп. ред. М. В. Афанасьєва. - Одеса : Юридична література, 2016. - С. 267-269

Association of the rs2167270 polymorphism of the leptin gene (LEP) with the intensity of pain in patients with osteoarthritis of the knee

Background: Osteoarthritis (OA) is a significant social problem as it is the most common disease of the joints. OA is a multifactorial disease in which great attention is paid to hereditary factors. Recently, a number of studies have demonstrated the contribution of a number of genes to the subjective assessment of pain in OA, which is the main symptom of this disease. The association of P2X7, TRPV1 and TACR1 genes and some others with pain sensitivity has been shown. One of the risk factors of pain among many others, is the increased weight. Abdominal adipose tissue is a source of release of pro-inflammatory adipokines that cause systemic inflammation associated with damage to many tissues, including subchondral bone, synovial membrane. Leptin is an endogenous hormone from the adipokine family encoded by the obesity gene leptin (LEP) and which is synthesized primarily in adipocytes.Aims: To investigate the possible association of rs2167270 (A19G) polymorphism of the LEP gene with pain intensity in ­patients with knee OA.Materials and methods: The study was conducted among women diagnosed with OA. Using the VAS scale (Visual analog scale), patients with mild knee pain — group 1 (VAS ≤ 40 mm) and patients with moderate or severe pain — group 2 (VAS>40 mm) were selected for pain assessment. Genetic variants of A19G leptin gene polymorphism were studied by polymerase chain reaction followed by restriction fragment length analysis (PCR-RFLP) method.Results: In the group of patients with moderate or severe pain intensity (group 2, n=61), a statistically significant association was shown with a higher body mass index (p=0.006) and an increased frequency of carriers of the 19GG genotype (p=0,051) compared to group 1 (n=36). Carriers of the 19GG genotype statistically significantly had a higher rate of knee pain and an early age of OA debut compared to carriers of the 19AA genotype (p=0,035 and p=0,015, respectively).Conclusions: The findings open up new possibilities for predicting pain symptoms in patients with knee OA by genetic testing of A19G polymorphic variants of the leptin gene

Generalized probabilities taking values in non-Archimedean fields and topological groups

We develop an analogue of probability theory for probabilities taking values in topological groups. We generalize Kolmogorov's method of axiomatization of probability theory: main distinguishing features of frequency probabilities are taken as axioms in the measure-theoretic approach. We also present a review of non-Kolmogorovian probabilistic models including models with negative, complex, and $p$-adic valued probabilities. The latter model is discussed in details. The introduction of $p$-adic (as well as more general non-Archimedean) probabilities is one of the main motivations for consideration of generalized probabilities taking values in topological groups which are distinct from the field of real numbers. We discuss applications of non-Kolmogorovian models in physics and cognitive sciences. An important part of this paper is devoted to statistical interpretation of probabilities taking values in topological groups (and in particular in non-Archimedean fields)