Evaluation of the microstructure and mechanical properties of a new modified cast and laser-melted AA7075 alloy

The mechanical properties and microstructure of as-cast and homogenized AA7075 were investigated. This alloy was modified by adding transition elements 0.3%Sc + 0.5%Zr, 1%Ti + 0.2%B, and 1%Fe + 1%Ni for use in additive manufacturing applications. After adding Ti + B and Sc + Zr, the structure became uniform and finer with the formation of the Al3(Sc, Zr) and TiB2 phases. Coarse structures were obtained with the formation of an extremely unfavorable morphology, close to a needle-like structure when Fe + Ni was added. The mechanical properties of the modified alloys were increased compared to those of the standard alloy, where the best ultimate tensile strength (UTS) and yield strength (YS) were obtained in the AA7075-TiB alloy compared to the standard alloy in as-cast and homogenized conditions, and the highest hardness value was provided by Fe + Ni additives. The effect of the laser melting process on the microstructure and mechanical properties was investigated. Single laser melts were performed on these alloys using 330 V and a scanning speed of 8 mm/s. During the laser melting, the liquation of the alloying elements occurred due to non-equilibrium solidification. A change in the microstructures was observed within the melt zone and heat-affected zone (HAZ). The hardness of the laser-melted zone (LMZ) after adding the modification elements was increased in comparison with that of the standard alloy. Corrosion testing was performed using a solution of 100 mL distilled water, 3.1 g NaCl, and 1 mL HCl over 5, 10, and 30 min and 1 and 2 h. The corrosion resistance of the alloy modified with FeNi was low because of the non-uniform elemental distribution along the LMZ, but in the case of modification with ScZr and TiB, the corrosion resistance was better compared to that of the standard alloy. © 2019 by the authors.Ministry of Science and Higher Education of the Russian FederationThe author (Asmaa M. Khalil) gratefully acknowledges financial support from the Ministry of Science and Higher Education of the Russian Federation in the framework of Increase Competitiveness Program of MISiS (Support project for young research engineers)

Influence of Adding Modifying Elements and Homogenization Annealing on Laser Melting Process of the Modified Alznmgcu with 4%si Alloys

AlZnMgCu, the high-strength aluminum alloy, is unsuitable for laser melting applications due to its high hot cracking sensitivity and large solidification temperature range. Adapting this alloy for laser melting processing is a high-demand research issue for extending its use. Thus, this paper investigates the effect of adding 4%Si, 4%Si-Sc + Zr, 4%Si-Ti + B, and homogenization annealing on the laser melting process (LMP) of AlZnMgCu alloy. Homogenization annealing at 500◦ C for 6.5 h was selected to dissolve most of the low melting temperature phases into the grain matrix and perform stable alloys for the LMP. The pulsed laser melting process (PLM) was performed on the as-casted and the homogenized samples. The microstructures of the as-casted, the homogenized alloys, and after the LMP were evaluated. In addition, the hardness of the base metal (BM) and laser melted zone (LMZ) were measured. The results revealed that the microstructure was enhanced and refined in the as-cast state by adding the modifiers due to the increasing nucleation potency of solidification sites and the formation of primary Al3 (Ti, Zr, Sc) phases. The average grain size was decreased by 15.6 times when adding 4%Si + 0.4%Zr + 0.29%Sc, while it decreased by 10.2 times when adding 4%Si + 1%Ti + 0.2%B. The LMZ of the as-casted samples exhibited a non-uniform distribution of the grains and the elements after the LMP. This was attributed to the evaporation of Zn, Mg during the high laser power process besides the non-uniform distribution of elements and phases in samples during casting. After the laser treating of the homogenized samples with 4%Si-Sc + Zr, uniform columnar grains were formed in the direction of the laser. The presence of Ti and B changed the crystallization nature, resulting in the LMZ with very fine and equiaxed grains due to forming many nucleation centers during solidification. The hardness values have positively increased due to Si addition and adding a combination of Ti + B and Sc + Zr. The maximum hardness was 153.9 ± 5 HV achieved in the LMZ of the homogenized samples of 4%Si + 1%Ti + 0.2%B. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This research was partially funded by Russian Foundation for Basic Research (RFBR) with project number 19-38-60037

Immunogenetic characteristics of unrelated hematopoietic stem cell donors recruited in the Sverdlovsk, Saratov, Yaroslavl and Vladimir regions

Aim of the study was to investigate the distribution features of HLA alleles and multilocus haplotypes in potential donors of hematopoietic stem cells recruting in the Sverdlovsk, Saratov, Yaroslavl and Vladimir regions. Material and methods. Sequence Based Typing technology was used to identify human leukocyte antigen (HLA)-A, -B, -C, -DRB1 alleles from 2683 Russian unrelated bone marrow volunteers living in the Sverdlovsk (n = 1018), Saratov (n = 825), Yaroslavl (n = 604) and Vladimir (n = 236) regions. HLA allele and haplotype frequencies were estimated via maximum-likelihood analysis from genotypic data through an expectation-maximization (EM) algorithm for unknown gametic phase. Results and discussion. In all studied populations, 16 HLA-A, 13 HLA-C, 13 HLA-DRB1 alleles were selected. In the locus HLA-B, 28 alleles were detected in the populations of the Sverdlovsk and Yaroslavl regions, 27alleles – in the Saratov region, 25 alleles – in the Vladimir. Seventeen alleles, HLA-A*02, HLA-A*03, HLA-A*01, HLA-A*24, HLA-B*07, HLA-B*35, HLA-С*07, HLA-С*06, HLA-С*04, HLA-С*03, HLA-С*12, HLA-DRB1*15, HLA-DRB1*07, HLA-DRB1*01, HLA-DRB1*13, HLA-DRB1*04, HLA-DRB1*11 exhibit frequencies over 10 %. The highest frequency extended haplotype in the all studied populations HLA-A*01-B*08-C*07-DRB1*03, was observed frequencies of 4,4 % – in the Sverdlovsk region, 3,2 % – in the Saratov region, 4,9 % – in the Yaroslavl region and 4,2 % – in the Vladimir region. Routine HLA typing allowed us to define four new HLA alleles in the populations of the Sverdlovsk and Saratov region

The creation and characterization of the bread wheat line with a centric translocation T2DL.2RL

The development of bread wheat introgressions with alien genetic material from cultural and wild Triticeae species is an effective method for expanding the wheat gene pool necessary for breeding. To date, numerous collections of introgressions as substitutions and chromosome modifications have been obtained; however, the creation and study of wheat with new valuable traits still remain an important line of research. Rye Secale cereale L., whose chromosomes carry genes that control valuable economic and biological characteristics and properties, is widely used to produce new wheat forms. In this study, a wheat-rye translocation obtained by backcrossing the wheat-rye disomic-substitution line 2R(2D)1 with the variety Novosibirskaya 67 was characterized. The chromosomal composition of karyotypes was studied using fluorescent in situ hybridization and C-banding. Two centric translocations, derived from two long arms of chromosomes 2D and 2R, T2DL.2RL, were identified, the remaining 40 wheat chromosomes did not undergo modifications. Meiosis in the lines was stable. Chromosomes T2DL.2RL formed bivalents in all meiocytes, which confirmed their homology. The morphological characteristics of the spike in the T2DL.2RL line and Novosibirskaya 67 did not differ. A comparative analysis of productivity between the T2DL.2RL translocation line and the parental forms, Novosibirskaya 67 and the 2R(2D)1 line, was carried out. The T2DL.2RL line is inferior to Novosibirskaya 67 in all characters with different confidence levels. The productivity characters of the 2R(2D)1 line exceeded or did not differ from those of T2DL.2RL, however, the mass of 1000 grains was significantly lower. The results showed the effect of the T2DL.2RL translocation on the trait “plant height”. This character was significantly lower than that of Novosibirskaya 67 in two vegetation periods. Consequently, the T2DL.2RL translocation reduces plant height and productivity

Towards the matter of genetic consulting in various forms of congenital and hereditary eye diseases

Purpose. To evaluate the results in genetic consulting of patients with various forms of congenital and hereditary eyes pathology.Material and methods. The study is based on an analysis of results in genetic consulting and molecular genetic investigations of DNA samples of 18 patients: congenital corneal dystrophy (n=3); congenital cataract (n=11); Norrie disease (n = 4). All patients had a comprehensive ophthalmologic clinical and functional examination according to the forms of pathology. Geneticist physician conducted a genealogical analysis. A study of exons and flanking intronic regions was performed using methods of analysis of amplified fragment length polymorphism, restriction fragments and direct sequencing.Results. The clinical diagnosis of endothelial corneal dystrophy with autosomal recessive mode of inheritance using molecular genetic methods in 2 of the 3 cases was confirmed, and a de novo mutation in the gene SLC4A11 non-described previously was found. In the group with hereditary diseases the lens pathogenic mutations were detected in the GJA3 andGJA8 genes in 2 of 11 cases (18%). Pathogenic mutations in NDP gene were detected only in 2 of 4 family members studied, and its sibling proband, directed to the genetic analysis of patients with a clinical diagnosis Norrie disease. In another of the studied probands the diseasecausing mutation was not reveled, and thus, the molecular genetic diagnosis of Norrie disease was not confirmed.Conclusion. For the first time in the Russian Federation pathogenic mutations in the gene SLC4A11 collagen, previously did not described in the literature, were revealed in patients with congenital endothelial corneal dystrophy, in a patient with congenital cataract in the gene GJA8. The success of genetic consulting depends on the complete genealogical analysis, and the correct determination of the clinical and genetic form of pathology

Clinical and functional features and quality of life in depressive disorders in patients undergoing pulmonary thromboendarterectomy

Aim. To conduct a comparative analysis of clinical and functional parameters and quality of life (QoL) in patients with chronic thromboembolic pulmonary hypertension (CTEPH), depending on the presence of a depressive disorder in long-term postoperative period.Material and methods. The study included 182 patients with CTEPH in the long term after surgery. Depending on the Patient Health Questionnaire 9 ( PHQ-9) data, all patients were divided into 2 groups: the 1st group — patients without depressive syndrome in the long-term postoperative period, the 2nd — patients with depressive syndrome. A comparative assessment of the initial clinical and functional characteristics, as well as QoL was carried out using the SF-36 questionnaire in both groups of patients. In patients who had a coronavirus disease 2019 (COVID-19), a comparative assessment using the Post-COVID-19 Functional Status (PCFS) scale was carried out.Results. Clinically relevant depressive syndrome in patients with CTEPH in the long term after surgery was registered in 25,3% of cases. In the 2nd group of patients, prior myocardial infarction (p=0,02), concomitant chronic cerebrovascular disease (p=0,01), as well as moderate and severe post-COVID-19 functional limitations according to the PCFS scale (p=0,004) were significantly more often recorded compared with the 1st group. In the 2nd group of patients, the level of QoL in almost all parameters was significantly lower in comparison with the 1st group (p<0,05). Decreased QoL (score <40) in the 2nd group concerned numerous parameters, including the physical and mental health components. In the 1st group of patients, reduced QoL was observed only in some physical parameters.Conclusion. The group of patients with CTEPH with depressive syndrome in the long-term postoperative period was characterized by a higher incidence of concomitant chronic cerebrovascular disease and a history of myocardial infarction compared with patients without depressive disorders. In the group of patients with depressive disorders, moderate and severe post-COVID-19 functional limitations according to the PCFS scale were more often observed. Depressive disorders in patients with CTEPH in the long-term postoperative period were accompanied by significantly reduced QoL parameters. Patients experienced the greatest difficulties both during normal daily activities and in professional activities

Algorithm for determining the authenticity of biomedical cell preparations containing mesenchymal stem cells

The use of mesenchymal stem cells (MSCs), which have a pronounced immunomodulatory activity, is a promising direction in the development of biomedical cell preparations (BMCPs). In oncohematology, the use of BMCPs containing MSCs is aimed at supporting hematopoiesis during cotransplantation with hematopoietic stem cells (HSCs) and suppressing immune conflicts during allogeneic unrelated transplantation and severe autoimmune processes. An obligatory stage of registration of BMCPs is confirmation of the identity of the MSC cell line (CL), which includes the establishment of morphological characteristics, evaluation of the expression of specific markers and proteins, and confirmation of the genetic stability of CL during cultivation. Determination of markers of genetic stability is possible using various methods, however, according to the recommendations of the American National Standardization Institute, the standard is the analysis of short tandem repeats (STR analysis). The purpose of the study is to develop an algorithm for determining the authenticity of BMCPs containing MSCs, including STR analysis. Material and methods. Identification of MSC cells in BMCP was performed according to the criteria of the International Society for Cell Therapy. Viable cells were counted in a Goryaev chamber. Immunophenotypic characteristics of MSCs were determined by flow cytometry. The level of production of specific proteins was assessed using enzyme immunoassay. Genetic stability markers were identified by STR analysis. Results and discussion. The methods were tested in triplicate for ten BMCP samples to confirm the reproducibility and reliability of the results. The developed algorithm for determining the authenticity of BMCP has a high accuracy, as it includes the STR analysis technique, which makes it possible to identify 19 polymorphic STR markers located on different alleles. Using the method will allow BMCP manufacturers to go through the procedure of state registration of drugs

ДИСТАНЦІЙНЕ НАВЧАННЯ ЯК ІНФОРМАЦІЙНО-КОМУНІКАТИВНА ТЕХНОЛОГІЯ ДОДИПЛОМНОЇ ПІДГОТОВКИ ЛІКАРІВ З ПЕДІАТРІЇ В УМОВАХ СУЧАСНИХ ВИКЛИКІВ

For the implementation and adequate virtual provision of distance education at O. Bohomolets National Medical University, the NMU Neuron distance educational platform is used, which in the current situation can become an effective component of the educational process, while having a number of advantages. It not only provides the student with the most convenient place and time, access to electronic knowledge bases, but also significantly enhances his/her active role in the self-study process, including during the quarantined process, and requires the teacher to improve the teaching in terms of content, and in its form. The main types of distance learning courses are traditional forms of educational training: lectures, practical classes, seminars, labs, consultations and other relevant legislation. In general, distance learning technologies as a complex of modern educational technologies in the higher medical education system should be constantly improved, in particular through the use of modern educational platforms, qualitative methodological filling of web resources, introduction of the system of quality control of distance learning in order to meet the challenges of time.Для реалізації та адекватного віртуального забезпечення дистанційної освіти у Національному медичному університеті імені О. О. Богомольця використовується  дистанційна освітня платформа NMU Neuron, що  в нинішній ситуації може стати дієвою складовою освітнього процесу, маючи при цьому низку переваг. Воно не лише забезпечує навчання студента у найбільш зручному місці та часі, доступ до електронних баз знань, але й суттєво підвищує його активну роль у самому процесі самостійного навчання, зокрема й під час вимушеного внаслідок карантину, а від викладача вимагає вдосконалення викладання як за змістом, так і за його формою. Основними видами занять за дистанційною формою навчання є традиційні форми освітньої підготовки: лекція, практичні заняття, семінар, лабораторні заняття, консультації та інші, що відповідають чинному законодавству. У цілому, технології дистанційного навчання як комплекс сучасних освітніх технологій у системі вищої медичної освіти має постійно вдосконалюватися, зокрема шляхом використання сучасних освітніх платформ, якісного методичного наповнення веб-ресурсів, запровадження системи контролю якості дистанційного навчання, аби відповідати викликам часу

Эндоваскулярное лечение абдоминальной ишемии

Chronic mesenteric ischaemia constitutes a condition characterised by a decreased abdominal blood flow, which is caused by the obstruction of visceral arteries. This short communication paper presents a clinical case of endovascular treatment in a patient with the obstruction of the celiac trunk, superior and inferior mesenteric arteries. Intestinal blood supply was provided through collaterals from the system of internal iliac veins via the inferior mesenteric artery, the arc of Riolan. This clinical case confirmed that percutaneous transluminal angioplasty and stenting of the visceral arteries is the method of choice in the surgical treatment of abdominal angina.Синдром хронической абдоминальной ишемии — это заболевание, для которого характерны ишемические расстройства кровообращения органов брюшной полости, вызванные нарушениями проходимости висцеральных артерий. В данном кратком сообщении представлен клинический случай эндоваскулярного лечения пациента с окклюзией чревного ствола, верхней и нижней брыжеечной артерий. Кровоснабжение кишечника осуществлялось через коллатерали из бассейнов внутренних подвздошных вен через нижнюю брыжеечную артерию, дугу Риолана. Данный клинический случай доказывает, что методом выбора хирургического лечения является чрескожная транслюминальная ангиопластика и стентирование висцеральных артерий