In the article, the regularities of the influence of structural transformations that occur when modifying current-conducting electrodes of elements from piezoelectric ceramics by the low-energy ...ribbon-shaped electron stream on the performance characteristics (wear resistance and corrosion resistance) of these electrodes. The technological experiment of obtaining modified electrodes on piezoceramic elements is based on a combined process of thermal deposition of a thin silver coating on piezoelectric ceramics in a vacuum. For two groups of samples (formed by the technology proposed by the authors, silver coatings on piezoelectric elements and coatings obtained in an industrial way), the surface state (microrelief, element composition) and the wear rate were studied.
The structural features, hardness, elastic modulus, and wear resistance of Fe–Cu–Ni–Sn composites with different CrB
2
contents, produced by cold pressing and subsequent sintering with additional hot ...pressing, were studied by X-ray diffraction, scanning electron microscopy, microindentation, and tribological testing. The micromechanical and tribological tests were performed on composite samples 10 mm in diameter and 5 mm thick in dry friction conditions. The test results showed that the mechanical and tribological properties of the composites depended on the CrB
2
content. The microhardness and elastic modulus of the samples varied from 1.2 to 9.2 GPa and from 110 to 245 GPa, respectively, depending on their composition, resulting from the uneven distribution of α-Fe, Cu, Cu
9
NiSn
3
, NiSn
3
, and CrB
2
phases. The addition of 2 wt.% CrB
2
to the 51Fe–32Cu–9Ni– 8Sn composite increased its hardness from 1.2–2.8 GPa to 2.0–4.5 GPa and the elastic modulus from 110–190 GPa to 130–200 GPa and decreased the wear rate from 22.93 ∙ 10
–3
to 10.19 × 10
–3
mm
3
∙ N
–1
∙ m
–1
. The mechanism of increasing the wear resistance of the composite sample containing 2 wt.% CrB
2
in comparison with the starting composite was associated with the refinement of iron and copper grains from 5–40 μm to 2–10 μm and the presence of discrete areas of greater hardness and higher elastic modulus. A further increase in the CrB
2
content from 2 to 8 wt.% in the composite was accompanied by a simultaneous increase in hardness from 2.0–4.5 GPa to 4.8–9.2 GPa, elastic modulus from 130–200 GPa to 150–245 GPa, and wear rate from 10.19 ×10
–3
to 16.68 ∙10
–3
mm
3
∙ N
–1
∙ m
–1
. The higher wear rate of these composites was due to excessive brittleness caused by excessive CrB
2
content.
Lake Baikal is facing several environmental stressors, including climate change and nearshore eutrophication. To assess recent ecological changes in Lake Baikal and provide a baseline for future ...comparisons, we sampled spring plankton communities from the pelagic zone of the lake in 2016 and compared these data with unpublished and published historical information going back to 1990. In 2016, one pelagic long-term monitoring station was sampled in early spring (March) during ice cover and 21 long-term monitoring stations located throughout the lake were sampled in late spring (May-June). We measured water chemistry parameters at most stations and the abundance, taxonomic composition and biomass of bacteria, ciliates and phytoplankton at several locations in different areas of the lake. Biotic parameters from 2016 were compared with historical data, showing significant changes in the spring pelagic microbial community since the 1990s. We show increased quantities of small species, mixotrophic ciliates, and the appearance (or increasing number) of small coloured and colourless flagellates. We also show substantially decreased densities of formerly dominant heavily silicified diatoms such as Aulacoseira spp. Since 2007, Synedra acus subsp. radians, a smaller and weakly silicified diatom, has dominated the spring plankton of the lake. These results suggest that Lake Baikal’s pelagic plankton community may be changing, with climate likely playing a dominant role in these changes.
In the context of global changes in the world socio-economic system, the formation of an international educational research space, in the technological platform of the education system, the ...widespread use of distance learning technologies it is extremely relevant to conduct a comparative analysis of the involvement of Russian and foreign students in the educational process in Russian universities. The article provides the results of an electronic questionnaire survey of 760 foreign and 2,280 Russian students at universities located in 38 regions of the Russian Federation in all federal districts. Russian and foreign students assessed their level of involvement in the educational process in distance and face-to-face learning according to the parameters of four types of involvement: emotional (affective), behavioral, cognitive and academic. Involvement in the educational process during the distance learning decreases among all students, while for foreign students it is to a greater extent than for Russian students, which is due to the linguistic, cultural, mental characteristics of this category of students. Organizational, technical, psychological and emotional barriers were identified as problems that reduce the involvement in the educational process in the distance learning format of Russian and foreign students.
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•The coffee-ring effect vanishes if concentration of laponite exceeds 5%.•Three-stage process is observed at low laponite concentrations.•The droplet mass and height are decreasing ...almost linearly.
Formation of the ring-like pattern by nano-particles of the desiccated droplet of a laponite-based aqueous nanofluid (the well known ‘coffee-ring effect’) is studied. The temperature was controlled and fixed (T=300K). The laponite concentration was controlled and varied in order to investigate its effect on the pattern formation. It was observed that the coffee-ring effect vanishes if concentration of laponite exceeds 5%. A simple model for analysis of colloidal sessile droplet desiccation is proposed. The model describes correctly dynamics of the drying droplet profile and the final shape of the dried film (deposit). The model is based on the mass conservation law and reasonable assumption that deposit (gel phase) prevents the flows.
Modified extractants, carbamoylmethylphosphine oxides Ph
2
P(O)CH
2
CON(R)CH
2
P(O)Ph
2
(R = Et,
i
-Pr, Bu, Oct), containing a phosphoryl group in the amide part of the molecule, have been ...synthesized. The extraction of microquantities of REE(III), U(VI), and Th(IV) with solutions of the obtained extractants in organic solvents from nitric acid solutions has been studied. The stoichiometry of the extractable complexes was determined, and the influence of the extractant structure, the organic diluent nature, and the aqueous phase composition on the efficiency and selectivity of the U(VI), Th(IV), and REE(III) extraction into the organic phase was considered. It has been shown that the modification of diphenyl(
N
,
N
-dialkylcarbamoylmethyl)phosphine oxide by introducing an additional coordinating group CH
2
P(O)Ph
2
into the amide part of the molecule leads to an increase in the efficiency of heavy REE(III) extraction and a decrease in the efficiency of light REE(III), and also Th(IV) and U(VI) extraction from nitric acid solutions. The degree of REE(III), U(VI), and Th(IV) extraction into the organic phase by the carbamoylmethylphosphine oxides increases significantly in the presence of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonylimide.
The article presents the result of our own observation of the patient with a poor control of type 2 diabetes mellitus (DM) for a long period, complicated by obliterating atherosclerosis of the ...arteries of the lower extremities, Menckeberg’s sclerosis and chronic ischemia threatening loss of the lower extremity (CLLI). A feature of the clinical manifestation are complications associated with potentially regional (angiosomal) ischemia of the foot, as well as variant anatomy, represented by hypoplasia of the vascular lower leg in the patient. The clinical consequences of vascular calcification due to long-term decompensation of carbohydrate metabolism and the development of diabetic distal polyneuropathy (DDP) led to falsely high values of the cuff test in the patient. Disadvantages of non-invasive methods for diagnosing limb ischemia and advantages of the complex application of tests for diseases of the arteries of the lower extremities are discussed. Using WIFI classification according to the degree of ulceration, the degree of ischemia, and the degree of infection on the foot (Wound, Ischemia and Foot Infection), the tactics of managing the patient are presented. The important role of ultrasonic duplex scanning (USDS) in the visualization of the arteries of the legs and feet in patients with DM is substantiated. The importance of a multidisciplinary approach in the management of a comorbid patient with type 2 diabetes and CLTI is emphasized.
Aim. To assess the rate of promoter methylation of putative TSGs for PCa in tumor tissue and in urine of PCa patients for better understanding of regulation of gene expression upon the PCa ...development and to evaluate the possibility to use the data on TSGs’ methylation for the development of noninvasive PCa markers. Methods. A quantitative methyl-specific PCR (qMSP) was used for the analysis of a methylation rate in prostate tissues and cell lines, and an ordinary MSP was performed for the study of urine samples. Results. We found that the RASSF1A promoter demonstrated a higher methylation rate in the TMPRSS2:ERG fusion positive PCa. The methylation of NKX3.1, PTEN and RASSF1A in DNA from urine was more common for cancer patients than for healthy donors. The promoters of CDH1 and GDF15 were methylated more frequently in PCa patients, than in patients with inflammatory disease. Conclusions. The abovementioned five genes can form a panel for early non-invasive detection of PCa. This set can be combined with the detection of the TMPRSS2:ERG fusion transcript. More work should be done to understand the molecular mechanisms explaining the functional role of promoter methylation of the selected genes.
Background. The effectiveness of therapy for acute T-lymphoblastic leukemia (T-ALL) and T-lymphoblastic lymphoma (T-LBL) has significantly improved over the past decades, including through the ...implementation of hematopoietic stem cell transplantation (HSCT). The Russian multicenter ALL-2009 study (ClinicalTrials.gov NCT01193933) showed that performing autologous HSCT (auto-HSCT) in patients with T-ALL/LBL improves long-term results. However, the study was non-randomized and the need for auto-HSCT in clinical practice requires careful study.Aim. To assess the significance of auto-HSCT in patients with T-ALL/LBL in the framework of ALL-2016 multicenter, prospective, randomized study (ClinicalTrials.gov NCT03462095).Materials and methods. The study included 109 adult patients with T-ALL/LBL (m:f 82:27). Median age was 31 (18– 52) years. T-ALL was diagnosed in 88 (81 %) patients, T-LBL in 21 (19 %) patients. All patients are treated according to the ALL-2016 protocol. Using the web platform, upon completion of induction therapy (+70 days), all T-ALL/LBL patients who achieved clinical and hematological remission were randomized to the auto-HSCT arm or chemotherapy alone (CT). Centralized monitoring of minimal residual disease (MRD) in bone marrow samples was performed by multicolor flow cytometry at the control points according to the ALL-2016 protocol. Statistical analysis was performed using SAS 9.4.Results. 87 patients with T-ALL/LBL were randomized: 44 to the auto-HSCT arm and 43 to the CT arm. Further analysis included 25 patients who underwent auto-HSCT and 36 patients receiving only CT. Three-year relapse-free survival in T-ALL is estimated at 62 % (auto-HSCT) vs. 81 % (CT) (p = 0.3422), and in T-LBL – 67 % (auto-HSCT) vs. 79 % (CT) (p = 0.59). MRD persistence on the +70th day of therapy according to the ALL-2016 protocol was determined in 40 % of patients (autoHSCT) and in 67 % (CT) (p = 0.057). In a multivariate analysis, it was determined that T-ALL from early T-cell precursor (ETP-variant) and MRD persistence after the end of II phase induction are the main risk factors for relapse in the treatment according to the ALL-2016 protocol.Conclusion. Performing auto-HSCT both in patients with T-ALL and T-LBL, and with MRD persistence on day +70 according to the ALL-2016 protocol did not improve long-term results. The development of new programs for the treatment of patients with MRD persistence, as well as the ETP variant of T-ALL, is of current interest.
Modeling of thermal conductivity of reed products Tsapko, Yu V; Tsapko, A Yu; Bondarenko, O P
IOP conference series. Materials Science and Engineering,
08/2020, Volume:
907, Issue:
1
Journal Article
Peer reviewed
Open access
The present work researches processes of heat transfer by samples of mats manufactured from reed. Due to the unique properties of the reed, such as medium density, low thermal conductivity, ...relatively high weather resistance, high chemical resistance, possibility to produce parts on-site, cost-effectiveness and others, reed products are widely used in building construction despite the high rate of development of new technologies. The mechanisms of heat insulation in the result of energy transfer through the material are established, which makes it possible to influence this process. It is proven, that the mechanisms are conditioned upon the increased porosity of the material. Thus, decreasing volume weight results in decreasing thermal conductivity, and vice versa. The simulation of the heat transfer process with the flameproof coating is carried out, the dependencies of the thermophysical coefficients on the temperature are determined. Based on the obtained dependencies, the coefficient of thermal conductivity for the products made of dry pine wood is calculated and makes 0.056 W / (m · K). Features of slowing down the process of heat transfer to material made of wood wool and glue binding agent with the formation of pores were studied. This is explained by the fact that there is no movement of air in large pores, accompanied by heat transfer. Thus, there are grounds to argue for the possibility of directed regulation of the processes of the formation of thermal insulation products using the reeds characterized by voids in the stems.
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