Features of the Structure Formation of Diffusion Boride Layers upon Preliminary Activation

The features of the structure formation of diffusion layers obtained by technology, including preliminary surface treatment of steel products made of U8 steel and subsequent boriding in powder media, have been investigated. The pretreatment consisted of dynamic alloying in the superdeep penetration (SDP) mode with a SiC-based powder composition. As a result, the thickness of the diffusion layer increases, its porosity decreases, and the proportion of the high-boron FeB phase in the layer increases.

Renewable-Resource Technologies in Mining and Metallurgical Enterprises Providing Environmental Safety

The article addresses the issue of mining and industrial waste stored in tailings and heaps in mining areas, and it explores the existing, as well as new, ways of reducing its harmful impact on the environment. On the basis of the Russian experience in mining industry in Ural, it presents a process which makes it possible to eliminate the amassed hazardous waste, retrieve the valuable material (metals) stored in it, and use the remaining waste as backfill in order to both: store it underground (and not on the surface) and prevent the disasters caused by the collapse of the abandoned shafts, thus prolonging the functioning of the mining areas. The process includes preliminary activation treatment of materials found in industrial waste in a disintegrator to protect the environment from toxic pollution. The promising results of the experiment have been discussed, taking into account the complexities of economic evaluation of the idea.

Forces of RBC interaction with single endothelial cells in stationary conditions: Measurements with laser tweezers

Red blood cells (RBCs) are able to interact and communicate with endothelial cells (ECs). Under some pathological or even normal conditions, the adhesion of RBCs to the endothelium can be observed. Presently, the mechanisms and many aspects of the interaction between RBCs and ECs are not fully understood. In this work, we considered the interaction of single RBCs with single ECs in vitro aiming to quantitatively determine the force of this interaction using laser tweezers. Measurements were performed under different concentrations of proaggregant macromolecules and in the presence or absence of tumor necrosis factor (TNF-[Formula: see text]) activating the ECs. We have shown that the strength of interaction depends on the concentration of fibrinogen or dextran proaggregant macromolecules in the environment. A nonlinear increase in the force of cells interaction (from 0.4 pN to 21 pN) was observed along with an increase in the fibrinogen concentration (from 3[Formula: see text]mg/mL to 9[Formula: see text]mg/mL) in blood plasma, as well as with the addition of dextran macromolecules (from 10[Formula: see text]mg/mL to 60[Formula: see text]mg/mL). Dextran with a higher molecular mass (500[Formula: see text]kDa) enhances the adhesion of RBCs to ECs greater compared to the dextran with a lower molecular mass (70[Formula: see text]kDa). With the preliminary activation of ECs with TNF-[Formula: see text], the force of interaction increases. Also, the adhesion of echinocytes to EC compared to discocytes is significantly higher. These results may help to better understand the process of interaction between RBCs and ECs.

Activation of diffusion during the formation of boride layers on the surface of steel parts

The features of structure formation of diffusion layers obtained by the technology, including preliminary surface treatment of steel products and subsequent thermal diffusion boriding in powder media, have been investigated. Pretreatment consisted in surface activation by superdeep penetration with a powder composition based on SiC of steel samples made of У8 steel. The features of the activation zones and their distribution over the surface are noted. The features of the activation zones and their quantitative characteristics are noted. A structural analysis of the obtained diffusion layers for the variants of low-temperature (650 °C) and high-temperature (920 °C) boration has been carried out. The chemical composition of the layer and the distribution of the main elements in it are analyzed. In both cases, a change in morphology was noted, consisting in the formation of a more compact diffusion layer and rounding of boride needles in the zone adjacent to the base metal. An increase in the layer thickness by 20–50 % and an increase in the proportion of the high-boron FeB phase relative to the variant of borating without preliminary activation were established.

Caspase 9 and Caspase 3 Immunohistochemical Pattern in Skeletal and Cardiac Muscles at Different Times after Death: An Experimental Study on PMI Estimation

(1) Background: The estimation of the post mortem interval (PMI) is a challenge for forensic pathologists because data emerging from methods commonly applied are not always conclusive, since several conditions exist that may affect the reliability of these parameters. Thus, new approaches have been proposed to overcome such a limit. In recent years, several studies have been performed on proteins analyzing their expression/degradation patterns in relation to the progressing of the post mortem interval. (2) Methods: The immunoreactivity patterns of two apoptosis mediators—Caspase 9 and Caspase 3—have been tested in order to evaluate their potential role as markers of the post mortem interval. The immunohistochemical analysis was performed on samples of skeletal and cardiac muscles obtained from rats at 0, 4, 8, 12, 24 and 72 h after death. (3) Results: The observed immunoreactivity patterns of both Caspase 9 and Caspase 3 showed a significant correlation with increasing post mortem interval either in skeletal or cardiac muscles, while the comparison of the immunoreactivity patterns of the two apoptotic mediators within each tissue appeared consistent with a preliminary activation of the “initiator” Caspase 9, which, in turn, subsequently activates the “executioner” Caspase 3. (4) Conclusion: The different expressions and decrease immunohistochemically observed on both caspases with progressing PMI support the usefulness of the combined analysis for post mortem interval estimation.

Evaluation of the effi ciency of the activity of the register of potential donors of hematopoietic stem cells

Introduction. One of the problems in providing Russian transplant clinics with unrelated hematopoietic steam cells (HSCs) is the lack of an interaction scheme “Registry — HSC collection center — Transplant center”. In order to ensure effective operation at the donor activation stage, registries need regulated and stable cooperation with the Collection center with a clear distribution of duties and responsibilities for both parties. Aim: to evaluate the effectiveness of the Kirov Registry.Materials and methods. Since 2009, the Kirov Registry has been systematically working with HSC donors (as of 25/11/2019, the total number of donors was 46,922, of which 43 % male, 57 % female; 49 % regular blood donors, 51 % volunteers from donor actions) since 2013. The Registry has its own Collection Center. The effectiveness of the Registry was evaluated by indicators: the number of donations, donor activation time, the number of refusals at the stages of preliminary activation and donation of cellular material. Results. As of 25/11/2019, more than 1,000 preliminary activations of potential HSC donors were performed, of which 175 were completed by collection of HSCs. The use of the created and validated activation model with the employment of the Registry and the Collection Center currently provides the following activation times: the period for sending a sample for confi rming HLA typing does not exceed 14 days; the total time to satisfy the transplant center request for cellular material does not exceed 2 months. A detailed analysis of the causes of refusals at the stages of preliminary activation and after receiving a request for the collection of cell material was carried out. Conclusion. Between 2009 and 2019 the Kirov registry has developed a model of effective work with the donors of the HSCs at all stages of the chain “Registry — HSC collection center — Transplant center”. The effectiveness of the work is confi rmed by the demand for donors, observance of the donor activation time, and a relatively low percentage of refusals from donations.

Ensuring Strength of Fine Grained Concrete with Mixed Cement Binders

The article presents the results of the evaluation of the strength of fine-grained concrete of ordinary grades on mixed cement binders with ash and slag waste of thermal power plants. To ensure the required strength, the preliminary activation of the mixed binder was envisaged, which is one of the main techniques for reducing cement consumption. Experimental-statistical models of the strength properties of fine-grained concrete was obtained, which make it possible to predict the required strength with a minimum consumption of cement and the optimal concentration of ash in the binder.

The method of processing technogenic tailings of chromium

Taking into account the existing demand for chromium concentrates, the extraction of chromium from technogenic formations of sludge storages of the tailings of chromium ore beneficiation is an important practical task. The comprehensive utilization of beneficiation sludge will increase the profitability of production and solve the environmental problems of the region. The importance of solving the problem of involving in processing tailings is connected not only with the environment but also with the need to increase the production of chromium. Modern gravity enrichment technologies make it possible to efficiently produce chromium concentrates from large and medium fractions of chromite-containing ores, while finely divided sludge is practically not extracted due to the difficulty of separating complex minerals into concentrates and waste rock. This paper presents the results of studies on the gravity processing of tailings. The technology includes the enrichment of the fine fraction-0.2+0 mm of tailings of the dressing plant of chromite-containing ores by gravity methods using a KNELSON centrifugal separator. In technology, the efficiency of the operation of gravity enrichment is provided by the preliminary activation of the fine fraction in a solution of sodium bicarbonate (NaHCO3). With gravitational enrichment, the total chromite concentrate was obtained containing 51.3% Cr2O3. The output of concentrate was 41.7%. The extraction of Cr2O3 in the concentrate was 68.1%.

Obtaining of heat-insulating materials based on silica-containing waste with the addition of dolomite

The paper presents the results of the study of feasibility of obtaining high-quality foamed thermal insulation materials based on a silicate matrix with addition of dolomite. It has been found out that the preliminary activation of a suspension based on a silica-containing component at a temperature of 90°C for 5-7 minutes allows accelerating the coagulation of silica fume and the synthesis of sodium silicates. Optimal foaming conditions for the charge frothing are 650-700°C for 25 minutes. There have been obtained foam silicates with a relatively uniform finely porous structure and stable physical and technical properties with density 0.38-0.48 g/cm³, strength up to 3 MPa, thermal conductivity 0.048-0.054 W/(m·K).