Features of the corrosion of coatings based on zinc alloys: oxidation products and the selective dissolution of zinc. Review

The literature review analyses and systematizes the results of corrosion studies of widely used anti-corrosion zinc coatings based on various binary systems Zn-Al, Zn-Mg, Zn-Fe, Zn-Ni, Zn-Co. The patterns of corrosion, the role of selective dissolution and corrosion products in increasing the corrosion resistance of coatings in neutral chloride-containing environments have been studied. The analysis shows that the corrosion rate depends on the chemical and phase composition of zinc coatings, which is due to differences in the corrosion behavior of the phase components of the alloys. Selective dissolution has an ambiguous effect on the corrosion resistance of coatings. On the one hand, the process of selective dissolution of zinc can be accompanied by the formation of corrosion cracks, which reduces the corrosion resistance of the coating. On the other hand, a rough surface enriched with an electropositive alloying component is formed. As a result, roughness stimulates the deposition of a denser and more compact layer of corrosion products, which reduces the access of oxygen and other electrolyte components to the coating’s surface. Under certain conditions, a film of corrosion products can provide additional resistance to the corrosion process due to low electrical conductivity. With the uniform dissolution of coatings, both the co-precipitation of complex compounds of zinc and alloying metals and the doping of the product layer with oxides or hydroxides of alloying metals occur. This also results in increased compactness and reduced electrical conductivity, which increases the corrosion resistance of the coatings. The purpose of the article: an overview of the results of studies of corrosion of zinc coatings, physical and chemical features of the formation and composition of the layer of corrosion products, the influence of corrosion products and selective dissolution on the corrosion resistance of coatings. A review of the results of studies relating to the corrosion of zinc coatings was carried out, taking into account the formation of a protective layer of corrosion products and the selective dissolution of zinc. The corrosion of zinc coatings is influenced by the structure and phase composition of the coatings, the selective dissolution of zinc, as well as the nature of the layer of corrosion products. The corrosion resistance of zinc coatings increases if a compact layer of corrosion products with low electrical conductivity is formed. The selective dissolution of zinc can have a positive effect on its protective ability due to the formation of a rough surface, which promotes the deposition of a denser layer of corrosion products. In the case of the uniform dissolution of zinc alloy coatings, alloying metals are able to integrate into the structure of zinc corrosion products, which makes the layer more compact and leads to a decrease in its electrical conductivity, significantly increasing the corrosion resistance of the coating

Corrosion of diffusion zinc coatings in sodium chloride solutions

Diffusion galvanizing is widely used in the pipe industry for coating the threaded surface of pipe couplings, protecting water and gas pipelines, and other metal products. Diffusion coatings have a number of advantages over other types of zinc coatings. In this work, electrochemical and gravimetric methods are used to study the corrosion behavior of diffusion zinc coatings in sodium chloride solutions. The corrosion rate depends non-linearly on the thickness of the coating. At the initial stages, the corrosion rate of coatings depends on the structure of the phases on the surface, and with an increase in the holding time, the corrosion rate depends to a greater extent on the properties of the products formed during the corrosion process. Films of corrosion products of diffusion zinc coatings consist of zinc oxide/hydroxide and basic zinc salts, while the composition of the film changes with increasing coating thickness

Use of big data analytics for small and medium sized businesses

Small and medium sized business has an important place in the economy of all countries. In modern conditions of Industry 4.0 development, the introduction of big data analytics into the performance of small and medium-sized businesses can become the basis for sustainability growth of their functioning and their competitive advantages’ development. However, the use of Big Data technology is not typical for small and medium enterprises. At the same time, the issues of big data analytics use by small and medium-sized businesses in the context of their resource and infrastructure constraints are poorly studied. The purpose of this article is to develop a conceptual model for the implementation of big data analytics in the activities of small and medium-sized businesses, taking into account their digitalization problems. The study was made on the basis of the Russian economy data. The analysis of the issues of big data analytics’ use for small and medium-sized businesses was based on the methodology of system analysis with the identification of object, environment and project-process development subsystems. The novelty of research consists in the fact that the development model of the structure of big data use was carried out in accordance with the content of the main tasks that must be solved within data management life cycle. The results of the study showed that the main issues of the introduction of big data analytics in the activities of small and medium-sized businesses are associated with a lack of understanding of its benefits by entrepreneurs. Also significant problems are the lack of financial resources and the lack of qualified employees capable of strategic administration of these processes. Given these problems, the authors conclude that the model for use of big data analytics by small and medium-sized businesses should be based on the use of cloud software and analysis of projects with open source big data. The article suggests the structure of the model for big data use by small and medium-sized businesses. This paper contributes to the development of ideas about the directions of digitalization of small and medium-sized businesses in order to increase the sustainability of this economic sector in the context of Industry 4.0. Further research by the authors is connected with effectiveness evaluation of mechanisms and tools of government support made for digital business transformations

Bortezomib Combination Therapy of Relapsed and Refractory Acute Lymphoblastic Leukemia in Children

Background & Aims. Despite significant success in the treatment of acute lymphoblastic leukemia (ALL) in children, relapses and drug resistance to the standard therapy remain the main cause of treatment failure. The addition of bortezomib to the combination therapy of relapsed ALL to change the sensitivity of blast cells may be a perspective approach to cure patients. The aim was to evaluate the efficacy and toxicity of the anti-relapse ALL treatment protocols REZ BFM 95/96 without bortezomib and COG AALL07P1 with bortezomib in relapsed and refractory ALL in children. Materials & Methods. The study included 54 children with a confirmed ALL of various localizations. From 1995 to 2011, ALL REZ BFM 95/96 treatment without bortezomib was administered to 26 patients. From 2011 to 2016, 28 children received COG AALL07P1 combination treatment with bortezomib. Results. The immediate treatment efficacy significantly higher in patients treated with bortezomib (85.7 % vs 57.6 %) after induction chemotherapy with the ALL REZ BFM 95/96. The analysis of the long-term outcomes (disease-free, event-free, overall survival) showed no significant differences between the groups. The event-free survival of patients with isolated bone marrow relapses for a period of 2 years was 20.3 ± 17.5 %. The tolerability of the program was acceptable, complications developing during myelosuppression were not associated with the administration of bortezomib. Conclusion. The intensification of induction chemotherapy in recurrent remission according to COG AALL07P1 protocol with the addition of bortezomib allowed to increase the number of complete remissions including MRD negative ones

Aureobasidium pullulans-Associated Invasive Mycosis in a Child with Acute Myeloblastic Leukemia: A Case Report

Severe mycotic infection occurring mainly in immunocompromised patients often exacerbates the progression of the primary oncohematological disease. It is the first attempt in Russian literature to present clinical and microbiological characteristics of invasive mycosis caused by Aureobasidium pullulans in a child with acute myeloblastic leukemia after receiving cytoreductive and antifungal treatment with favourable outcome