Adsorption of Ethylene on Neutral, Anionic and Cationic Gold Clusters

The adsorption of ethylene molecule on neutral, anionic and cationic gold clusters consisting of up to 10 atoms has been investigated using density-functional theory. It is demonstrated that C2H4 can be adsorbed on small gold clusters in two different configurations, corresponding to the pi- and di-sigma-bonded species. Adsorption in the pi-bonded mode dominates over the di-sigma mode over all considered cluster sizes n, with the exception of the neutral C2H4-Au5 system. A striking difference is found in the size-dependence of the adsorption energy of C2H4 bonded to the neutral gold clusters in the pi and di-sigma configurations. The important role of the electronic shell effects in the di-sigma mode of ethylene adsorption on neutral gold clusters is demonstrated. It is shown that the interaction of C2H4 with small gold clusters strongly depends on their charge. The typical shift in the vibrational frequencies of C2H4 adsorbed in the pi- and the di-sigma configurations gives a guidance to experimentally distinguish between the two modes of adsorption.Comment: 30 pages, 10 figure

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Rearrangement of cluster structure during fission processes

Results of molecular dynamics simulations of fission reactions $Na_{10}^{2+} \to Na_7^+ + Na_3^+$ and $Na_{18}^{2+} \to 2 Na_9^+$ are presented. Dependence of the fission barriers on isomer structure of the parent cluster is analyzed. It is demonstrated that the energy necessary for removing homothetic groups of atoms from the parent cluster is largely independent of the isomer form of the parent cluster. Importance of rearrangement of the cluster structure during the fission process is elucidated. This rearrangement may include transition to another isomer state of the parent cluster before actual separation of the daughter fragments begins and/or forming a "neck" between the separating fragments

Modernization staging brake stand for testing internal combustion engines

The issues of investigation of the parameters of the internal combustion engineare considered. It’s underlined that application of modern technologies allows to upgrade the equipment with low functional and consumer properties available now at most enterprises of automotive industryРассматриваются вопросы исследования параметров двигателей внутреннего сгорания. Подчеркивается, что применение современных технологий позволяет модернизировать имеющееся в настоящее время на большинстве предприятий автомобильной отрасли оборудование с низкими функционально-потребительскими свойcтвам

Modeling of flow two-phase mixture in curved channel pipeline

The article describes a three-dimensional simulation of the stationary motion of the gas and condensed phase particles of varying severity in a curvilinear orthogonal coordinate system of channels of gas pipelines. A numerical method for solving the equations that describe the motion of the particles, based on obtaining difference schemes and the use of a two-level iterative process. Built a multi-dimensional mathematical model of the steady flow of viscous gas hydrate particles in equilibrium axisymmetric taking into account transport and energy dissipation. Numerical calculations of the velocity field and the dispersed gas phase trajectory of mass flow of particles deposited on the walls of various sizes in a wet gas flow in a curved pipe

Modeling of flow of two-phase mixture in curved channel pipeline

This article describes the three-dimensional modeling of steady motion of gas and condensed phase particles of varying severity in a curvilinear orthogonal coordinate system gas channels. A numerical method for solving the equations that describe the motion of the particles, based on the difference scheme and the application of the two-level iterative process. Built multivariate mathematical model of viscous steady flow of gas and the equilibrium of hydrate particles in axisymmetric taking into account transport and energy dissipation. Obtained pressure field in the pipe by solving the model equations using SIMPLE method. Numerical calculations of the velocity field of the gas and the dispersed phase, the trajectory of the mass flow deposited on particles of different sizes with the wall during the wet gas in the curved pipe. The calculation of particle trajectories in different kinds of process equipment show at the option of either abrasive wear parts located in a stream, or an intense build-up and accumulation of hydrates. The results can be applied in the analysis of impact of solid particles of various sizes on the elements of gas pipelines

The Role of O-mannosyl Glycans in Drosophila Development

O-mannosylation is a specific form of glycosylation, a post-translational protein modification with O-linked mannose attached to serine or threonine residues. O-mannosylation is implicated in crucial biological processes such as neuronal and muscle development, cell adhesion and cell migration. Two O-mannosyltransferase genes have been described in mammalian genomes so far, POMT1 and POMT2. Disruptions of O-mannosylation result in congenital muscular disorders in humans. The most severe, the Walker-Warburg Syndrome is associated with mutations in POMT1 and POMT2. Just like vertebrates, Drosophila has two O-mannosyltrasferase genes, DmPOMT1 (rt) and DmPOMT2 (tw), which share significant similarities with their mammalian counterparts. Mutations in both DmPOMT1 and DmPOMT2 cause the "rotated abdomen" phenotype, a clockwise rotation of abdominal segments in adult flies. In my dissertation, I analyzed the expression patterns of rt and tw during development. Both genes have similar essentially overlapping expression patterns. Immunostaining revealed that RT and TW proteins are co-localized in the ER compartment. The analysis of double mutants revealed a mutual epistatic relationship between rt and tw, which could be evidence for RT and TW functioning in the same molecular complex. Also, I studied temporal and spatial requirements of tw during development. I found a broad "developmental window competent to fully rescue the abdomen rotation in adult flies." The spatial studies of tw requirements demonstrated that tw expression is pattern-dependent and the function of tw is cell-autonomous or it has a very short-range effect. The analysis of rescue results with different drivers suggested that the tw requirement is not strictly limited to larval epidermis or muscles alone, but required a contribution from epidermal and muscle cells with a possible involvement of CNS. I have shown that Drosophila Dystroglycan is modified with mannose in the presence of RT-TW enzymatic complex in vivo and in vitro. The co-expression of RT and TW is required to generate high-molecular-mass bands of DG. The lectin staining revealed differences in glycan compositions of DG purified from different genetic backgrounds. Overall, this research work established Drosophila as a model system to study mannosylation, which may shed light on mechanisms of muscular dystrophies in humans

Generalized mathematical model of a linear single-axis accelerometer as an integral part of the inclinometer

The article deals with the creation of a generalized mathematical model of inclinometer that allows more fully than any known prior mathematical model to study its properties under actual operating conditions. The mathematical model of inclinometer considered non-identical electrical parameters of the primary sensors. Mathematical model of a linear single-axis accelerometer is also built, which is part of the inclinometer

Building surrogate models for two-phase flow of fluids in porous media based on spatial radial basis approximation

The paper proposes a method for constructing the surrogate models for two-phase flow based on a combination of finite-difference solutions and fine-grid spatial approximation. The method provides the approximate models for solving optimal control the operating parameters of field development