—This critical review considers the fundamental concept, methods of obtaining, stability, and properties of a new class of materials—high-entropy alloys and compounds. An analysis of factors that ...determine the structure and stability of multicomponent disordered solid solutions has been carried out. Particular attention has been given to results obtained since 2017. The concept of temperature regions within stable and metastable phases, which explains the available experimental data, has been proposed.
The low-energy electron beam dispersion (EBD) is used to prepare a double-layer film on titanium (Ti) substrates, with polycaprolactone (PCL) and ciprofloxacin hydrochloride (CIP) as the bottom ...layer, as well as the polyurethane (PU) as the upper layer (PCL: CIP/PU = 1:1/1, mass ratio). The surface of the film is uniform, and there is no obvious interface between two layers and the thickness of the single-layer and double-layer films is 2 μm and 2.6 μm respectively. It is found that CIP has been successfully carried by PCL. The amount of CIP increases from the bottom layer to the interface in the vertical direction, indicating the diffusion of CIP from the bottom to the upper layer when PU is deposited. The double-layer film gradually releases CIP through the micropores on the surface. As a comparison, in the single-layer film, CIP is quickly released leaving a PCL network structure. The double-layer film results in prolonged sustained release time of CIP to be 21 days, significantly longer than 7 days in the single-layer film. Thus, the double-layer film is expected to be applied in medical implants to reduce the risk of inflammation and infection caused by bacterial proliferation after surgeries.
•Using Low-energy electron beam deposited drug-loaded double-layer film containing undestroyed ciprofloxacin.•Underlying film: Polycaprolactone/Ciprofloxacin hydrochloride (CIP); Upper film:Polyurethane.•Antibacterial prolonged-release time of CIP increased to 21 days.•CIP released and left undegraded polycaprolactone forming a network structure.•Polyurethane was degraded to form micropores, which provided release channels for CIP.
: The main purpose of this work is to study the effectiveness of using FeCeOx nanocomposites doped with Nb2O5 for the purification of aqueous solutions from manganese. X-ray diffraction, ...energy–dispersive analysis, scanning electron microscopy, vibrational magnetic spectroscopy, and mössbauer spectroscopy were used as research methods. It is shown that an increase in the dopant concentration leads to the transformation of the shape of nanoparticles from spherical to cubic and rhombic, followed by an increase in the size of the nanoparticles. The spherical shape of the nanoparticles is characteristic of a structure consisting of a mixture of two phases of hematite (Fe2O3) and cerium oxide CeO2. The cubic shape of nanoparticles is typical for spinel-type FeNbO4 structures, the phase contribution of which increases with increasing dopant concentration. It is shown that doping leads not only to a decrease in the concentration of manganese in model solutions, but also to an increase in the efficiency of adsorption from 11% to 75%.
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•The molecular structure of Norfloxacin coating is identical to Norfloxacin’s target.•EBD of the mixture of polymer and silver nitrate is accompanied by the formation AgNPs into ...polymer matrix.•PLA-based nanocomposite coatings with Norfloxacin and AgNPs have antibacterial activity against E. coli and S. aureus.
The synthesized poly(lactic acid)-based (PLA-based) biodegradable nanocomposite coatings with antibacterial properties were prepared from active gas phase generated by low-energy electron beam dispersion of the powder mixture of PLA and antibacterial components (Norfloxacin and silver nitrate, respectively) in vacuum. The molecular structure, morphology, optical property and chemical states of PLA-based coatings were investigated by ATR-FTIR, Uv–Vis, TEM and XPS. The analyses of ATR-FTIR spectra confirm the formation of polymer and the doped antibacterial components and show the interaction between them. XPS data show that the Ag nanoparticles are of metallic nature in the case of PLA-based nanocomposite coatings containing silver. The antibacterial activity of PLA-based coatings deposited on different substrates was tested against E. coli ATCC 25922 and S. aureus ATCC 12600 using the agar diffusion method on the solid LB agar medium. The influence of substrates on their antimicrobial behavior was stated.
Abstract
In the national security system of the Russian Federation, food security (FS) is also one of the important tasks, since without a reliable food supply, it is impossible to avoid dependence ...on other States. Decree of the President of the Russian Federation No. 20 of January 21, 2020 “On the Approval of the Food Security Doctrine of the Russian Federation” approved a new FS Doctrine. The doctrine considers the FS as a multi-component system that includes, as components, the availability of food, its economic, social and physical availability, stability over a long period of time, as well as food issues. To provide cognitive modeling, we can represent the FS support system as a weighted directed graph, whose points correspond to the elements of the set, and whose arcs correspond to the non-zero elements of the W relation. The ratio W can be represented as a matrix of dimension n*n, where n is the number of factors, which can be considered as the adjacency matrix of the graph. The dynamics of the evolution of the simulated socio-economic system and the forecast of its development were obtained by summing increments. The components of the vector of predicted increments of the FCM calculated using the adjacency matrix are calculated at consecutive points in time. It is shown that the following concepts should be taken as key concepts in cognitive modeling of the level of FS: production, consumption, stocks and imports of food, as well as a number of additional ones that characterize the ecological and economic infrastructure for ensuring PB. Modeling has shown that the fluctuating nature of changes in the indicators of all concepts during the transition period forms 3 groups: increasing (FS level, Production, Crop production), stagnating (Consumption) and falling indicators (Import, Irrigation reclamation, Economy, Ecology). The identified trends in the evolution of the main concepts of the level of food security in the context of import substitution should be taken into account when developing programs to ensure FS by subjects of various levels.
Abstract
The article considers the specifics of constructing an artificial neural network (ANN) for predicting the dynamics of time series levels (TS) of grain yield in arid conditions on the example ...of the Volgograd region. In order to justify the choice of the architecture and hyperparameters of ANN, a preliminary statistical analysis of the simulated TS was performed. The autocorrelation functions of the retrospective yield series constructed in this case can be taken into account when choosing ANN hyperparameters for predicting grain yield. A number of ANN architectures based on recurrent layers, including LSTM, were analyzed. The best results of neural network modeling are obtained for cascading groups of layers of a seriesparallel architecture. The proposed neural network technology for predicting TS yield levels using a pre-forecast autocorrelation analysis of retrospective levels reduces the error of short-term forecasting of grain yield in the arid natural and climatic conditions of the Lower Volga region. Taking into account the results of autocorrelation analysis allows you to choose the values of ANN hyperparameters more reasonably. The achieved accuracy of the regression problem was 82..87%, which can be considered acceptable for planning agricultural production for 1-2 years. The ways of improving the accuracy of the neural network solution of the problem of predicting productivity in the arid conditions of the Lower Volga region using retrospective TS of productivity are formulated.
The composition of a multilayer coating on the basis of Mg + Ca + P2O5, applied to the surface of an intramedullary implant to initiate the growth of bone tissue, has been proposed and justified. The ...possibility of etidronate and polymethylsilsesquioxane deposition (PMSQ) by an electron beam is first established during the research process. The efficiency of using the PMSQ coating system as a separate layer has been evaluated. It is shown that the exchange processes between the multilayer system and the buffer solution are responsible for the destruction of the cross-linked organosilicone layer. For this reason, using PMSQ as a layer, which initiates HA nucleation, is ineffective. The formation of calcium and zinc phosphates has been established in etidronate and phosphorus (V) oxide interaction with the corresponding metals. The multilayer system Mg + Ca + etidronate + P2O5 + Zn + P2O5, heat-treated at 200°С, is shown to be highly resistant to abrasion. The layer system transforms into HA in the SBF buffer solution. The effect of heat treatment is manifested in an increase in the structural ordering of individual layers.
•The multi-layer system Mg + Ca + etidronate + P2O5 + Zn + P2O5 in SBF solution transforms into hydroxyapatite.•There is no noticeable etidronate destruction by the low energy electron beam.•The interaction of Ca and Zn with etidronate leads to the formation of metal phosphates.•Low energy electron beam allows to precipitate coatings on the basis of polymethylsilcessaceauxane.•The multi-layer system Mg + Ca + etidronate + P2O5 + Zn + P2O5 has high resistance to abrasion.
Artificial joint replacement represents the most effective approach for addressing joint pathologies. However, friction and wear, the production of debris and the release of metal ions reduce the ...durability of artificial joints and negatively impact human health.
This study focuses on a CoCrMo alloy joint femoral head and an ultra-high molecular-weight polyethylene cup, which are commonly used as standard artificial joint friction couples. Two different types of films have been deposited on the surface of the joint femoral head. Multilayer TiN/(Ti/DLC) × 3 films were deposited on the surface of the alloy ball via pulsed cathode-arc discharge, and a friction experiment was carried out by a hip friction simulation tester. As an alternative film for use in medicine, TiN films were deposited by direct current arc evaporation of the titanium cathode in a nitrogen atmosphere at a partial pressure of 1.2 × 10−1 Pa. Prior to conducting the wear test, the film structure was studied through Raman and XPS spectroscopy. The surface morphology and adhesion of the films to the joint femoral head were studied.
A change in the mass of the prosthesis has been seen when comparing the presence and absence of deposited films. Inductively coupled plasma mass spectroscopy has shown the effectiveness of protecting the surface of the prosthesis with the deposited TiN/(Ti/DLC) × 3 film. This method successfully reduces the concentration of Co and Cr released during friction. The findings indicate that the TiN/(Ti/DLC) × 3 film deposited on the joint femoral head reduces the wear of the UHMWPE cup and did not degrade over five million cycles, thus significantly exceeding the operating life of the TiN film. The results show that TiN/(Ti/DLC) × 3 film demonstrates a 55 % reduction in the generation of abrasive debris in the UHMUPE cup. Furthermore, it effectively prevents the release of metal ions from the alloy femoral head.
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•TiN/(Ti/DLC) × 3 and TiN films were deposited via a vacuum arc method.•TiN/(Ti/DLC) × 3 film enhances the wear resistance of an artificial joint ball.•TiN/(Ti/DLC) × 3 and TiN films decrease the release of Co and Cr ions from a CoCrMo alloy head.•TiN/(Ti/DLC) × 3 film reduces UHMWPE friction debris production more effectively than TiN film.
The characteristics of a machine-tractor unit are determined by the indicators of the traction resistance of an agricultural machine, which require an experimental determination. The disadvantages of ...the known devices that provide measurements during volumetric dynamometry of the working enforcers of tillage machines are the complexity of the design and high measurement error. To improve the accuracy of experimental measurements of the dynamic loading of the working bodies of tillage machines, it is necessary to improve the technical means of measurement. Experimental determination of the loading of working bodies requires the use of a system of force sensors that affect the working bodies in different planes. Force sensors are manufactured mainly using strain gauges that are glued directly to the loaded parts. To determine the forces in the traction of the hydraulic suspension system of tractors, strain gauge fingers are used. It is shown that for the same distances of the sensors, the resulting signal does not depend on the distance of the force applied on the finger axis. Usually, force sensors are calibrated one at a time on special stands. The best calibration results will be achieved when all tenzometric fingers are installed in their proper places and all sensors are calibrated simultaneously. To do this, the intermediate plate is fixed using strain fingers on the levers of the tractor hydraulic suspension. Rymbolts are installed on the plate, to which a known force is applied three times and the readings of each of the strain fingers are taken. Solving the resulting system of equations, simultaneously find all the calibration coefficients. Additionally, a device is proposed, the kinematic scheme of which allows using a single measuring device, which simplifies the technology of measuring the force on the working body and increases its accuracy.
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