Abstract: The paper presents the results of studying properties of magnetic lubricating oils synthesized based on fluoroorganic fluids and triethanol. The lubricating properties of oils were determined in the boundary friction mode under medium and high contact pressures. It is shown that magnetic oils based on perfluoropolyether have higher lubricating properties than oils based on other fluids, especially in the medium load range. The anti-wear properties and aggregative stability of oil begin to deteriorate sharply at temperatures exceeding 150°С. The use of perfluoropolyether liquid as an additive to oil made it possible to improve the antiwear properties of magnetic oil at medium and high contact pressures. The lubricating properties of magnetic oils based on triethanolamine are approximately the same as those of magnetic oils based on siloxanes, but worse than those of traditional non-magnetic oils. In terms of tribological properties, the studied magnetic oils are comparable to traditional plastic and liquid lubricants. The fact that magnetic oils have magnetic properties that are anomalous for liquids expands the area of their effective application significantly.
Abstract: In this paper, we studied the changes in the topography of the surface of a part made of magnetostrictive magnetoplast under the influence of a magnetic field. Theoretical analysis has shown that in composite materials when using magnetostrictive particles with a dispersion of 10-4÷10-6 m, a change in the surface roughness parameters is possible in the range of 10-7÷10-9 m, depending on the magnetostrictive constants of the filler. Local changes in the topography of the magnetoplast surface in a magnetic field with a strength of about 560 kA/m are experimentally determined, and an assessment is made of the integral changes characterizing the surface as a whole. For the experiment, a composite material containing a powder of TeFe2 material with a uniquely high linear magnetostriction (λs = 2∙103) was chosen. It has been established that the effect of the nanoroughness surface changing is especially pronounced for relatively smooth surfaces and depends on the composition, concentration, size, and orientation of the microfine magnetic filler. For the studied surfaces of magnetoplasts, the change in the height parameters of roughness exceeds 5%. In absolute terms, the change in the topography of the surface is tens of nanometers. In precision engineering, the detected effect can be used to control frictional characteristics, in particular, to change the friction force without contact, control the flow of small doses of various reactive gases, and change the dynamics of wetting processes of solid surfaces.
Abstract: Medications using liposomes are of great interest in pharmaceuticals. They increase the therapeutic index of the drug by enclosing the medicinal substance inside a biocompatible lipid envelope, which releases the solution only in the required area. Such drugs have already shown their effectiveness in the treatment of diseases related to oncology, dermatology, neurology, surgery, etc. To use liposomes for these purposes, it is necessary that their size be in the range from 50 to 200 nm. There are several ways to create vesicles of this size, but mostly they use either ultrasound exposure to a liposome solution or extrusion. The extrusion method is a method that allows to obtain the most homogeneous solution from liposomal particles. For extrusion, a special device – an extruder is required. It is a system that passes a liposomal solution under pressure through a filter with a certain pore size. In this paper, the process of liposome extrusion, types of liposomal extruders are considered and their pros and cons are evaluated, a model of a manual extruder capable of homogenizing up to 20 ml of solution was also developed. Different materials were considered and used for the construction of this device. The inspection of the extruder showed its operability and showed the advantages of using extrusion compared to the ultrasound exposure method.
Abstract: Calcium oxalates, represented by wavellite CaC2O4·H2O and weddellite CaC2O4·2H2O (the most stable forms), are the main components of stones in the genitourinary system, and are also part of dental, gallstones, and other mineral deposits. It is known that modern approaches to the study and modeling of crystallization processes make it possible to analyze the influence of a number of factors (exogenous and endogenous) arising at various levels of organization: from atoms and molecules to macroscopic processes occurring in industrial devices. The process of crystallization, taking into account the variety of acting factors and forms of crystal structures, consists of two main stages: formation of a solid phase nucleus and its growth (formation of a solute crystal). In this work, using modern approaches, the physicochemical and kinetic patterns of crystallization of calcium oxalates under conditions close to physiological are determined. The effect of physiological solution components (organic and inorganic) was studied, the staged mechanism of the solid phase formation was established, and the kinetic parameters of the growth stage were calculated (lgk = 33.1). The inhibitory effect of inorganic additives (Mg2+, Cl–), amino acids (glycine, glutamine, aspartic) and the accelerating effect of hydroxyapatite crystals, seed in the form of calcium oxalate and urea crystals on the crystallization process were revealed.