44 research outputs found

    Variability of the structure of winter microbial communities in Chelyabinsk lakes

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    Microorganisms form complex and dynamic communities that play a key role in the biogeochemical cycles of lakes. A high level of urbanization is currently a serious threat to bacterial communities and the ecosystem of freshwater bodies. To assess the contribution of anthropogenic load to variations in the structure of winter microbial communities in lakes, microorganisms of four water bodies of Chelyabinsk region were studied for the first time. We used cultural, chromatography-mass spectrometric, and modern methods of statistical data processing (particularly, multivariate exploratory analysis and canonical analysis of correspondences). The research showed that the composition of winter microbial communities in lakes Chebarkul’, Smolino, Pervoye, and Shershenevskoye Reservoir did not differ significantly between the main phyla of microorganisms. The dominant microorganisms were found to be of the Firmicutes phylum and Actinobacteria phylum. The structure of bacterial communities had special features depending on the characteristics of the water body and the sampling depths. Thus, in the lakes Smolino, Pervoye, and Shershenevskoye Reservoir, an important role was played by associations between microorganisms – indicators of fecal contamination: coliform bacteria and Enterococcus. On the contrary, in Chebarkul’ Lake, members of the genus Bacillus, which are natural bioremediators, formed stable winter associations. However, the differences between water bodies and sampling depths reflected 28.1% and 9.8% of the variability of the winter microbial communities, respectively. The largest contribution (about 60%) to the variability of the structure was made by intra-water processes, which determined the high heterogeneity of samples from different water areas. We assume that an important role in this variability was played by the high anthropogenic impact in a large industrial metropolis. In our opinion, this line of research is very promising for addressing key environmental issues

    PROBLEM ISSUES OF SCHOOL MATHEMATICS EDUCATION

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    В статье рассматриваются проблемы подготовки школьников к Государственной Итоговой Аттестации по математике. Представлен анализ возникающих проблем и пути их преодоленияThe article deals with the problems of teaching schoolchildren to the State Final Certification in Mathematics. There is the analysis of emerging problems and ways to overcome the

    Tungstate Based Ceramics Obtained By Spark Plasma Sintering Method – Possible Material for Consolidation of Radioactive Wastes’ Components

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    The Spark Plasma Sintering method was used to produce high-density ceramics from tungstates SrWO4 and NaNd(WO4)2 with scheelite structure. These compounds are proposed as possible matrices for the consolidation of radwaste components. Powder samples were obtained by coprecipitation method and studied by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). After sintering, the samples retained their phase identity (scheelite structure). The total duration of sintering was ∼ 13-15 min, the relative density was reached ∼ 92, 99%. Keywords: Tungstates, RW, Spark Plasma Sintering, high density, microstructur

    Electrical Properties of Li+-Substituted Solid Solutions Based on Gd2Zr2O7

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    Abstract: Solid solution (Formula presented.) with a pyrochlore structure is synthesized for the first time. The cationic composition is confirmed via chemical analysis and nuclear reactions. It is found that the stoichiometry with respect to lithium is retained up to 1100°C. The lattice parameter diminishes in the homogeneity range 0 ≤ x ≤ 0.30, while the free volume of migration grows. Introducing lithium into the Gd sublattice raises oxygen–ion conductivity, due to the emergence of oxygen vacancies and enhancement of their mobility. Maximum conductivity is reached for composition with х = 0.10 (~1 × 10−3 Ω−1 cm−1, 650°C). An assumption is made about the formation of associates of the type (Formula presented.) at high contents of the dopant (x = 0.30), accompanied by an increase in the activation energy of conductivity. © 2021, The Author(s).This work was performed with a grant from the Russian Foundation for Basic Research, project no. 20-43-660033, and financial support from the State Atomic Energy Corporation ROSATOM (State Contract no. Н.4о.241.19.21.1070 of April 16, 2021; electronic identifier 07731000003210000330001)

    Investigation of the microstructure of the fine-grained YPO4_4:Gd ceramics with xenotime structure after Xe irradiation

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    The paper reports on the preparation of xenotime-structured ceramics by the Spark Plasma Sintering (SPS) method. Phosphates Y0.95_{0.95}Gd0.05_{0.05}PO4_4 (YPO4_4:Gd) were obtained by the sol-gel method. The synthesized nanopowders are collected in large agglomerates 10-50 mkm in size. Ceramics has a fine-grained microstructure and a high relative density (98.67%). The total time of the SPS process was approximately 18 min. High-density sintered ceramics YPO4_4:Gd with a xenotime structure were irradiated with Xe+26^{+26} ions (E = 167 MeV) to fluences of 1×10121\times10^{12}-3×10133\times 10^{13} cm2^{-2}. Complete amorphization at maximum fluence was not achieved. As the fluence increases, an insignificant increase in the depth of the amorphous layer is observed. According to the results of grazing incidence XRD (GIXRD), with an increase in fluence from 1×10121\times10^{12}-3×10133\times 10^{13} cm2^{-2}, an increase in the volume fraction of the amorphous structure from 20 to 70% is observed. The intensity of XRD peak 200 YPO4_4:Gd after recovery annealing (700^\circC, 18 h) reached a value of ~80% of the initial intensity I0.Comment: 16 pages, 10 figure

    Effect of dexamethasone therapy on factors of adhesiveness and coagulation in acute lower limb ischemia

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    Leukocyte-platelet adhesion during hypoxia, tissue damage, activation of inflammation and coagulation is associated with the expression of ICAM-1 membrane molecules and integrins by blood and tissue cells. At the same time, platelet adhesion receptors determine their adhesion to the endothelium and recruited lymphocytes. The role of platelets in the pathogenesis of ischemic cardiovascular diseases also consists in their ability to modulate both hemostasis and inflammatory reactions, which is accompanied by the secretion of inflammatory mediators and factors that promote the recruitment of leukocytes to tissue damage sites. Purpose of the study: to study the effect of the synthetic glucocorticoid dexamethasone on the expression of adhesion receptors CD18+ and CD54+ on leukocytes, the content of platelets and fibrinogen in the blood of patients with ALLI, the relationship of these indicators with the severity and outcome of the disease.To study the effect of anti-inflammatory therapy, a group of 32 patients treated with dexamethasone was formed; the comparison group was represented by 71 patients with basic therapy, the control group consisted of 15 volunteers. After revascularization, all patients received antiplatelet and anticoagulant therapy. Dexamethasone infusions were carried out in a course of 4 to 6 days after reconstructive surgery. In all patients, the content of C-reactive protein in the blood, the content of platelets and fibrinogen were determined. The number of lymphocytes expressing adhesion molecules ICAM-1 (CD54+) and integrins (CD18+) was counted using the immunocytochemical method. Studies were performed before surgery and on days 1, 3, 7, and 10 after surgery.With exacerbation of ischemia and damage to the endothelium, the accumulation of cytolysis products, the expression of adhesion molecules increases both on endotheliocytes and on inflammatory effector cells – leukocytes and platelets. Adhesion molecules conduct an activation signal inside the cell, which promotes adhesion of leukocytes and platelets to the endothelium, lymphocytic-platelet adhesion, the formation of a parietal thrombus, and possible occlusion of damaged vessels. Increased expression of adhesion molecules is associated with the activation of metabolism, inflammation, coagulation and oxidative stress, stimulates all hematopoietic lineages, including platelets. The level of involvement of cellular reactions in the pathogenesis of the disease affects the effectiveness and duration of treatment, the risk of recurrent thrombosis and death. Anti-inflammatory therapy with dexamethasone contributed to earlier remission, a decrease in the proportion of infectious complications, such as wound suppuration from 10% to 6%, the number of necessary amputations from 32% to 16%, the frequency of deaths from 31% to 6%, and a reduction in hospital stay from 13 days to 10.Inflammation, adhesiveness of effector cells and thrombosis are important factors in the pathogenesis of acute lower limb ischemia. Therapy with dexamethasone helps to reduce the level of systemic inflammatory response, the number of necessary amputations, the number of complications and adverse outcomes in the treatment of ALLI, and reduce the length of stay in the hospital

    Preparation of NZP-type Ca0.75+0.5xZr1.5Fe0.5(PO4)3-x(SiO4)x powders and ceramic, thermal expansion behavior

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    Ca0.75+0.5xZr1.5Fe0.5(PO4)3–x(SiO4)x (x = 0–0.5) solid solutions have been synthesized by a sol–gel process and characterized by X-ray diffraction, IR spectroscopy, and differential scanning calorimetry. As expected, the synthesized phosphatosilicates crystallize in a NaZr2(PO4)3-type structure (trigonal symmetry, sp. gr. R3c). The thermal expansion of the solid solutions has been studied by high-temperature Xray diffraction in the temperature range from 25 to 800°C. Their thermal expansion parameters have been calculated and analyzed as functions of composition. Highdensity ceramics based on the Ca0.875Zr1.5Fe0.5(PO4)2.75(SiO4)0.25 phosphatosilicate have been produced by spark plasma sintering and their structure and properties have been studied in detail.This work was supported by the Russian Science Foundation, project no. 16-13-10464: Advanced ceramic like mineral materials with improved and adjustable service characteristics: design, synthesis, study.Peer reviewe

    Опыт успешного хирургического лечения пациентки с глубоким и обширным гнойно-некротическим поражением нижней конечности при нейроишемической форме синдрома диабетической стопы

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    The article presents the successful surgical treatment experience in a patient with deep and extensive purulent-necrotic lesion of the lower limb with a neuroischemic form of the diabetic foot syndrome. The possibilities of modern methods by revascularization, surgical treatment of purulent focus and extensive postoperative complex configuration wounds local treatment are demonstrated.В статье приведен опыт успешного хирургического лечения пациентки с глубоким и обширным гнойно-некротическим поражением нижней конечности при нейроишемической форме синдрома диабетической стопы. Продемонстрированы возможности современных способов реваскуляризации, хирургической обработки гнойного очага и местного лечения обширных послеоперационных ран сложной конфигурации

    Оценка влияния полиморфизмов генов-транспортеров (RFC1, MDR1) и GGH на эффективность метотрексата при ревматоидном артрите

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    The efficacy of methotrexate (MT) in patients with rheumatoid arthritis (RA) may be determined by genetic factors.Objective: to evaluate the isolated and combined effects of single nucleotide polymorphisms (SNPs) of membrane transporter proteins (RFC1 80G>A and MDR1 3435C>T) and the GGH -401C>T gamma-glutamyl hydrolase enzyme genes on the efficacy of MT in patients with RA.Material and methods. The study group consisted of 85 patients with a confirmed diagnosis of RA, who received therapy with MT starting at 10 mg/week and increasing in dose to a maximum of 25 mg/week. Efficacy was assessed after six months of treatment using the dynamics of the DAS28 index, identifying patients who responded and those who did not respond to MT therapy.Genotyping of RFC1, MDR1 and GGH gene polymorphisms was performed by real-time polymerase chain reaction. Three different approaches were used to analyze the results: 1) analysis for each of the genes; 2) logistic regression; and 3) multifactor dimensionality reduction (MDR).Results and discussion. Single gene analysis was used to determine the most likely predictors of non-response to therapy: 1) for GGH-401C>T, TT genotype (odds ratio, OR 5.09; 95% confidence interval, C11.11—23.3); 2) forMDR13435C>T, the TT genotype (OR 2.38; 95% CI0.89-6.37); 3) for RFC180G>A, not - AA genotype (OR 1.87; 95% CI 0.93-3.76).The logistic regression model showed a significant effect of homozygous genotype GGH -401TT on the efficacy of MT with low sensitivity of the method. The multifactorial dimensionality reduction results show a significant synergistic effect of the MT transport genes (MDR1, RFC1) and the GGH enzyme encoding the conversion of MT to the elimination form.Conclusion. Using various statistical methods, the following results were obtained: Single gene analysis revealed the most likely predictors of nonresponse to MT therapy: GGH -401C>T - TT genotype, MDR1 3435C>T - TT genotype, RFC1 80G>A - not-AA genotype; the method of multiple logistic regression allowed to determine the significant effect of GGH -401ТТ genotype on the effect of the drug with a low sensitivity of the method; the isolated effect of polymorphisms is probably less pronounced than their combined effect on the effectiveness of MT. SNP synergism is a major contributor to the development of treatment resistance. MDR is a promising method that can be used in the future to assess the impact of SNPs.Эффективность метотрексата (МТ) у больных ревматоидным артритом (РА) может определяться генетическими факторами.Цель исследования — оценить изолированное и совместное влияние однонуклеотидных полиморфизмов (SNP) генов мембранных белков-транспортеров (RFC1 80G>A и MDR1 3435C>T) и гена фермента гамма-глутамилгидролазы GGH -401C>T на эффективность МТ у больных РА.Материал и методы. Исследуемую группу составили 85 больных с достоверным диагнозом РА, которым проводилась терапия МТ начиная с 10 мг/нед с повышением дозы максимально до 25 мг/нед. Эффективность оценивалась после 6 мес лечения по динамике индекса DAS28, были определены пациенты, отвечающие и не отвечающие на терапию МТ.Генотипирование полиморфизмов генов RFC1, MDR1 и GGH выполнено методом полимеразной цепной реакции в режиме реального времени. Для анализа результатов использовались три различных подхода: 1) анализ по каждому из генов; 2) логистическая регрессия и 3) многофакторное снижение размерности (Multifactor Dimensionality Reduction, MDR).Результаты и обсуждение. С помощью анализа по отдельным генам идентифицированы наиболее вероятные предикторы отсутствия ответа на терапию: 1) для GGH-401C>T — генотип TT(отношение шансов, ОШ5,09; 95% Доверительный интервал, ДИ 1,11—23,3); 2) для MDR13435C>T-генотип TT(ОШ2,38; 95% ДИ0,89-6,37); 3) Для RFC180G>A - генотип не АА (ОШ 1,87; 95% ДИ 0,93-3,76).Модель логистической регрессии свидетельствует о значимом влиянии на эффективность МТ носительства гомозиготного генотипа GGH -401TT при низкой чувствительности метода. Результаты многофакторного снижения размерности демонстрируют значимое синергичное влияние генов транспорта МТ (MDR1, RFC1) и фермента GGH, кодирующего конверсию МТ в форму Для элиминации.Заключение. С помощью разных статистических методов получены следующие результаты: анализ по отдельным генам выявил наиболее вероятные предикторы отсутствия ответа на терапию МТ: GGH - 401C>T - генотип TT, MDR1 3435C>T - генотип TT, RFC1 80G>A - генотип не AA; метод множественной логистической регрессии позволил определить значимое влияние генотипа GGH - 401ТТ на эффект препарата при низкой чувствительности метода; изолированное влияние полиморфизмов, вероятно, менее выражено, чем их совместное воздействие на эффективность МТ. Синергизм SNP вносит большой вклад в формирование резистентности к терапии. MDR - перспективный метод, который может быть использован в дальнейшем для оценки влияния SNP
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