Antimicrobial Activity and Degradation of Superhydrophobic Magnesium Substrates in Bacterial Media

The interest in magnesium-based materials is promoted by their biocompatibility, their bioresorbability, and their recently discovered antibacterial potential. Until now, the widespread use of magnesium alloys in different corrosive environments was inhibited by their weakly controllable degradation rate and poorly understood microbiologically induced corrosion behavior. To better understand the degradation and usability of magnesium-based alloys, in this study we have fabricated superhydrophobic coatings on a magnesium-based alloy, and analyzed the behavior of this alloy in bacterial dispersions of Pseudomonas aeruginosa and Klebsiella pneumoniae cells in phosphate-buffered saline. It was shown that the immersion of such coatings in bacterial dispersions causes notable changes in the morphology of the samples, dependent on the bacterial dispersion composition and the type of bacterial strain. The interaction of the superhydrophobic coatings with the bacterial dispersion caused the formation of biofilms and sodium polyphosphate films, which provided enhanced barrier properties in magnesium dissolution and hence in dispersion medium alkalization, eventually leading to the inhibition of magnesium substrate degradation. The electrochemical data obtained for superhydrophobic samples in continuous contact with corrosive bacterial dispersions for 48 h indicated a high level of anticorrosion protection.

Antimicrobial activity and degradation of superhydrophobic magnesium substrates in bacterial media

The interest in magnesium-based materials is promoted by their biocompatibility, bioresorbability, and by their recently found antibacterial potential. Until now the widespread use of magnesium alloys in different corrosive environments was inhibited by their weakly controllable degradation rate and poorly understood microbiologically induced corrosion behavior. To better understand the degradation and usability of magnesium-based alloys, in this study we have fabricated the superhydrophobic coatings on top of magnesium-based alloy and analyzed the behavior of this alloy in bacterial dispersions of Pseudomonas aeruginosa and Klebsiella pneumoniae cells in phosphate buffered saline. It was shown that immersion of such coatings into bacterial dispersions causes notable changes in the morphology of the samples, dependent on the bacterial dispersion composition and the type of bacterial strain. The interaction of superhydrophobic coatings with the bacterial dispersion caused the formation of biofilms and sodium polyphosphate films, which provided enhanced barrier properties for magnesium dissolution and hence for dispersion medium alkalization, eventually leading to inhibition of magnesium substrate degradation. Electrochemical data obtained for superhydrophobic samples continuously contacted with the corrosive bacterial dispersions during 48 h indicated a high level of anti-corrosion protection.

Oxidative Destruction of Vulcanized by Changing the Dispersion Composition of Oxidized Vulcanized

The aim of the present work is to study the processes of oxidative destruction of waste vulcanizates (flakes) with nitric acid. The composition of the particles of the main reaction product was determined (oxidized vulcanized). The IR spectra of hexane and acetone extracts of the oxidized vulcanizates are also presented. It was found that the rubber component of the vulcanizates undergoes deep structural changes leading to the formation of products characterized by chemical heterogeneity

Modification of dispersion systems and its motion in cylindrical pipes

This paper analyzes the dependence of properties of turbid flow on the dispersion composition and concentration of solid particles. The article presents the features of the transfer of river suspended solids and water in the pressure stations, that is, the effect on the distribution of kinematic and dynamic parameters of the flow of suspended particles of hydraulic transport.

Environmental safety of residential and public areas in the context of PM2.5, PM10 monitoring on the leaves of apricot trees (Prunus armeniaca)

Introduction. Fine dust puts human health at risk in populated areas. The research is focused on dust particles on the leaves of apricot trees (Prúnus armeníaca) in the residential area of the Central Akhtuba district of the Volgograd region (the area of single family houses and low rise townhouses) and in the public area (the area of public amenities) located in close proximity to construction and development enterprises, machine builders, etc. as compared to the dispersion composition of dust on the leaves of apricot trees (Prúnus armeníaca) in the territory occupied by rural housing communities in the conditionally clean zone (the benchmark zone) in absence of any man-induced loadings coming from industrial facilities (Oroshenets gardeners’ non-commercial partnership, Volgograd, Soviet district). The goal of the research is to study the dispersion composition of dust and to identify fine dust PM2.5 and PM10 using plant monitoring systems in the residential area. The objectives include the sampling of dust particles from plant leaves, dust analysis, and identification of areas exposed to ecological risks. Materials and methods. The leaves of apricot trees (Prúnus armeníaca), growing in residential and public areas of the Central Akhtuba district of the Volgograd region and in the territory of Oroshenets gardeners’ non-commercial partnership, Volgograd, Soviet district (the conditionally clean benchmark zone) represent the study material. Methods of research include leaf wash into the beaker full of distilled water, suspension filtration using AFA-VP analytical filter, filtrate production and natural drying at the temperature not exceeding 30–40 °C, and placement of the dried filtrate on the slide of an optical microscope. The distribution of dust particles was performed pursuant to State Standard of Russia 56929-2016. Results. The co-authors have identified the zones exposed to ecological risks in residential and public areas of the Central Akhtuba district of the Volgograd region (Bolnichnaya st., residential houses in Nechayeva, Omskaya streets, a kindergarten in Kavkazskaya st.: PM2.5, PM10) and safe residential areas (a boarding school in Vorovskogo st.: PM10 — 20 μm and 20–40 μm). Conclusions. Further studies of residential and public areas of the Central Akhtuba district of the Volgograd region are to be performed to identify the chemical composition of dust particles and the source of fine dust polluting the air and to develop a roadmap of environmental actions.

Research on impact of manufacturing dust on the environment

Glass production, like any other production, is directly related to its environmental impact. Therefore, one of the important measures is to study the environmental impact of the rapidly growing glass industry. Determining the amount of dust emitted by the SAF glass factory in the city of Taraz, include the main sources of dust formation in the glass factory, the amount of dust and their dispersion composition. The studies showed the concentration of dust is slightly higher than the normal values established in the loading and unloading workshop, in the dosing device and in the soda loading area and in the working area of the glass melting furnace. This directly affects the environment and health of longtime workers.

The Dispersion Composition of Polymethylmethacrylate Suspensions and Molecular Weights of Polymers Obtained by Suspension Polymerization in the Presence of Acrylic Copolymers as Surfactants

The dispersion composition of polymer suspensions and molecular weights of polymers obtained by suspension polymerization of MMA in the presence of polymer surfactants – methylmethacrylate and methacrylic acid copolymers – were studied. It is shown that a highly dispersed fraction of particles with diameters of 0.02–2.0 µm and a fraction of particles with large diameters (up to 1000 µm) are always present in the polymer suspension. After fractionation of polymer suspensions 3 fractions of particles with different diameters were obtained. For each particle fraction the molecular masses of polymers were determined by viscometry. A significant difference in the values of the molecular masses of polymers obtained as particles of small and large diameters – 105 and 106 Da, respectively – is shown. The presence of a highly dispersed fraction of particles in which a polymer of high molecular weight is formed has a noticeable effect on the average molecular weight of the polymer. In particles of small diameter polymerization takes place according to a mechanism close to the emulsion, due to the fact that the volume of such particles contains a small amount of radicals. The high rate of polymerization leads to the formation of a polymer of high molecular weight, the appearance of a gel effect and a decrease in the termination constant. In most particles, polymerization proceeds by a mechanism close to the solution polymerization, and polymers of low molecular weight are formed. This makes it possible to synthesize polymers of a given molecular weight in drops of certain dispersity.