Functionalized hyperbranched polymers via olefin metathesis

Hyperbranched polymers are highly branched, three-dimensional macromolecules which are closely related to dendrimers and are typically prepared via a one-pot polycondensation of AB_(n≥2) monomers.^1 Although hyperbranched macromolecules lack the uniformity of monodisperse dendrimers, they still possess many attractive dendritic features such as good solubility, low solution viscosity, globular structure, and multiple end groups.^1-3 Furthermore, the usually inexpensive, one-pot synthesis of these polymers makes them particularly desirable candidates for bulk-material and specialty applications. Toward this end, hyperbranched polymers have been investigated as both rheology-modifying additives to conventional polymers and as substrate-carrying supports or multifunctional macroinitiators, where a large number of functional sites within a compact space becomes beneficial

Ferrofluid Valve Operated By the Magnetic Field of a Straight Current-carrying Wire

Integrated valves produce increased control and make up an essential part of different devices, especially in microfluidics. The use of ferrofluid in valves is one of actuation methods. Different magnetic fields could be used to operate a ferrofluid valve. In the present paper, we propose to use the magnetic field created by a straight current-carrying wire to operate a ferrofluid valve which can open the channel formed by two coaxial cones and a cylinder. Numerical modelling of the valve behaviour for different values of ferrofluid volumes and currents in the wire is done for two cases: when the ferrofluid wets and does not wet surrounding solid boundaries. It is shown that the presence of limiting cones allows the ferrofluid to sustain the pressure drop which is much bigger in case of non-wetting than in case of wetting. In case of wetting the ferrofluid cannot sustain any pressure drop at small currents, but in case of non-wetting the ferrofluid can do it even at zero current. It is found that in case of non-wetting spasmodic and hysteresis phenomena are possible for some values of ferrofluid volumes and currents in the wire

Biostability of cotton fibers with different natural colors and selection

ArticleBiodamageability is one of the weak sides of the cotton - plant fiber. Economic loss from the cotton damage caused by microorganisms is significant. Toxic chemical compounds are used to preserve the cotton fiber. This has a negative impact on environment and cotton consumer s. The degree of the cotton biodamage depends on selection variety, types of cultivation, storage conditions and other factors. One of the directions in cotton planting is selection of the boll - stained cotton. It was established that naturally colored cott on of different varieties has high biostability. It allows to product hypoallergenic, eco - friendly textile and reduces impact on the environment. The purpose of the work is stability evaluation for microbiological damage of different cotton varieties inclu ding those naturally colored during long - term storage in different temperature and humidity conditions. The research lasted for 10 years. The species composition of the cotton microflora was determined, the impact of fiber on microorganisms and dynamics of samples biodamage was studied in the work. The results obtained show preservation of microflora viability on cotton fiber when storing it under normal conditions for a long - term period. With an increase in temperature and humidity necessary for microorgan isms’ growth, the fiber destruction processes are amplified. It was established that cotton damage degree depends on the regimes and terms of its storage as well as the color of the fiber. Nature - colored cotton is more resistant for microorganisms, some va rieties inhibit the growth of mold fungi

A quantitative analysis of the image of Russia in the Asia-Pacific region media

The study analyzes the shaping of the image of Russia through media focused on the countries of the Asia-Pacific region China, Japan and South Korea. Based on the analysis of bilateral relations between Russia and the People's Republic of China, Russia and the Republic of Korea, Russia and Japan, a model of communication between our country and the countries of the Asia-Pacific region has been built. The goal of the study is to carry out a quantitative content analysis of the image of Russia broadcast through the media focused on the countries of the Asia-Pacific region (China, Japan and South Korea). The study used the method of content analysis, the theoretical model of communication and the theory of the image. The mechanisms of forming the image of the state in political psychology are described. The main theoretical approaches are considered and the study of communicative and informative perception of the image of Russia, formed through the media of the APR countries, is carried out. Totally 4244 messages in the years 2015 - 2017 were analyzed. The results of content analysis show that most of the reports about Russia and the events connected with it are of a neutral, informative nature. The articles have no emotional tone, the bulk of the reports contain a dry statement of facts. Information agencies broadcast events through the prism of their ideology, most of them keep neutrality, the articles have an analytical, overview, commentary or narrative orientation.peer-reviewe

Developing the electronic course «Design of information systems» on the stepik educational platform

The article describes the process of creating an electronic course on the Stepik platform. A comparative analysis among educational platforms has been carried out. The advantages and disadvantages are shown. Reflects the main features of the service StepikВ статье рассмотрен процесс создания электронного курса на платформе Stepik. Проведен сравнительный анализ среди платформ образовательного назначения. Показаны преимущества и недостатк

Hybridogenic Activity of Invasive Species of Asteraceae

We studied taxa from genus Bidens, Solidago, and Erigeron, sect. Conyza (Asteraceae). By analyzing the nucleotide sequences of the internal transcribed spacer (ITS1)-ITS2 site, the hybrid origin of the Bidens × decipiens, previously attributed to the North American alien species B. connata, was confirmed. The analysis of trnL-trnF sequences showed that the native B. cernua is the maternal species and the invasive B. frondosa is the paternal species in all probabilities. Diagnostic morphological features of the three Solidago taxa growing together in the vicinity of Pskov have been studied: a native S. virgaurea, an invasive species of North American origin S. canadensis, and their hybrid S. × niederederi. S. × niederederi has an intermediate position between S. virgaurea and S. canadensis. The hybrid origin of S. × niederederi is proven by molecular analysis of nuclear DNA nucleotide sequences (ITS1-ITS2 site). It is not yet possible to unambiguously answer the question which parent species is maternal and which is paternal. We also studied invasive species of the genus Erigeron sect. Conyza in the Mediterranean. Occasionally occurring in Southern Europe, individuals of E. canadensis × E. sumatrensis with intermediate morphological features, described as “Conyza × rouyana,” are likely unstable and soon “absorbed” by the parent species E. sumatrensis. Contrary to the hypothesis by C. Elton explaining the success of plant invasion in a new homeland by strengthening hybridization processes in the secondary distribution range

Research and simulation of images classification algorithm for distributed objects obtained by remote sensing of the Earth's surface

Application of ultra-wideband signals and large apertures makes it possible to obtain a sufficiently detailed radar image of a spatially distributed object at the processing unit output. But the problem of optimal classification of synthetic aperture radar (SAR) data remains relevant due to specific features of radar images. The paper describes solution of the synthesis problem for optimal SAR image classification algorithm. The optimal set of very informative and small dimension features is found and features based on the moments of SAR images are proposed. A comparative analysis of classification algorithms using various features is made, and the ratio is proposed, which can be used as the classification sign that is invariant to object shift and to specific distortions caused by the object rotation. © 2016 Academic Publications, Ltd

Effective slip over superhydrophobic surfaces in thin channels

Superhydrophobic surfaces reduce drag by combining hydrophobicity and roughness to trap gas bubbles in a micro- and nanoscopic texture. Recent work has focused on specific cases, such as striped grooves or arrays of pillars, with limited theoretical guidance. Here, we consider the experimentally relevant limit of thin channels and obtain rigorous bounds on the effective slip length for any two-component (e.g. low-slip and high-slip) texture with given area fractions. Among all anisotropic textures, parallel stripes attain the largest (or smallest) possible slip in a straight, thin channel for parallel (or perpendicular) orientation with respect to the mean flow. For isotropic (e.g. chessboard or random) textures, the Hashin-Strikman conditions further constrain the effective slip. These results provide a framework for the rational design of superhydrophobic surfaces.Comment: 4+ page

Quantitative Estimation of the Ratio of GABA-Immunoreactive Cells in Neocortical Grafts

Somatosensory anlage from 17-18 day old rat embryos were transplanted in place of the removed barrel cortex in adult rats. Six to eight months after transplantation, the grafts were either completely separated by glial scar or partly separated and partly confluent with the host neocortex. Each was studied histologically and immunostained for GABA. It was found that in partly confluent grafts the neuronal density was similar or even higher than in the host cortex, while the cell number in the separate grafts was much lower than in the nearby host cortex. The number of GABA-positive cells, however, was in all grafts significantly lower (2.9% on average) than in the normal cortex (11.8% on average).The decline in GABA-stained nerve cells was highest in separated grafts, but was somewhat less marked in transplants partly confluent with the host tissue. The possible role of partial or total deafferentation as well as the relative vulnerability of the transplanted tissue by temporary hypoxia and other metabolic disturbances are discussed as the probable factors in selective decline of GABA-ergic cells in the transplanted somatosensory cortex