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Bulk nanomaterials with an open porosity offer exciting prospects for creating new functional materials for various applications in photonics, IR-THz optics, metamaterials, heterogeneous photocatalysis, monitoring and cleaning toxic impurities in the environment. However, their availability is limited by the complexity of controlling the process of synthesis of bulk 3D nanostructures with desired physicochemical and functional properties. In this paper, we performed a detailed analysis of influence of a silica monolayer chemically deposited on the surface of a monolithic ultraporous nanostructure, consisting of a 3D nanofibril network of aluminum oxyhydroxide, on the evolution of structure and morphology, chemical composition and phase transformations after heat treatment in the temperature range of 20−1700 °C. The experimental results are interpreted in the framework of a physical model taking into account surface and volume mass transport and sintering kinetics of nanofibrils, which made it possible to estimate activation energies of the surface diffusion and sintering processes. It is shown that the presence of a surface silica monolayer on the surface affects the kinetics of aluminum oxyhydroxide dehydration and inhibits diffusion mass transfer and structural phase transformations. As a result, the overall evolution of the 3D nanostructure significantly differs from that of nanomaterials without surface chemical modification.

Helicopters are widely used for air transportation and aerial work with cargo on external cables, one of the most challenging and dangerous uses. The main reason for the flight complication is the change in the controllability characteristics of the helicopter because of the presence of cargo. As of today, flight tests are mainly conducted to determine the feasibility of aerial transportation and aerial work involving external cargo. In addition, they are conducted to determine safe flight regimes when performing such operations. From a flight safety perspective, it is always desirable to know the changes in the control parameters before flight tests are performed. A proposal was made to use theoretical methods, including numerical simulations, to solve these problems. At present, work is progressing to isolate the effects of different cargoes on the external cable suspension and its direct effects on the static and dynamic characteristics of the helicopter’s control and stability. The effect of cargo mass and sail weight on the control efficiency is expressed by the helicopter’s angular acceleration, which is gained by deviating the cyclic pitch handle—a static control and stability indicator. When considering dynamic control and stability, the influence of the length of the external suspension cable on the transition time was investigated. The results obtained were refined for inclusion in all flight manuals for Mi-8 helicopters concerning flights with cargoes attached to the external suspension cables, the size and weight of the suspension cables as well as the methods of instruction and for preparing the crew for flights with upgraded cargo, including instruction via flight simulators.

In this study, high-pressure torsion (HPT) was used to process austenitic 316LVM stainless steel at 20 °C and 400 °C. The effects of HPT on the microstructure, mechanical, and functional properties of the steel were investigated. By applying both HPT modes on the 316LVM steel, a nanocrystalline state with an average size of the structural elements of ~46–50 nm was achieved. The density of the dislocations and twins present in the austenite phase varied depending on the specific HPT conditions. Despite achieving a similar structural state after HPT, the deformation temperatures used has different effects on the mechanical and functional properties of the steel. After HPT at 20 °C, the yield strength of the 316L steel increased by more than nine times up to 1890 MPa, and the fatigue limit by more than two times up to 550 MPa, when compared to its coarse-grained counter-parts. After HPT at 20 °C, the 316LVM steel exhibited better ductility, higher low-cycle fatigue resistance, greater resistance to corrosion, and improved in vitro biocompatibility compared to processing at 400 °C. The reasons for the deterioration of the properties after HPT at 400 °C are discussed in the article.

The potential medical Zn-1.7%Mg and Zn-1.7%Mg-0.2%Zr alloys strengthened using high-pressure torsion (HPT) were investigated in this work. HPT led to a significant refinement of the microstructure of both alloys with the formation of an ultrafine-grained structure (UFG). The average grain size after HPT was ~700–800 nm for both alloys. The formation of the UFG structure led to an increase in the ultimate tensile strength of up to 401 ± 16 and 482 ± 12 MPa for the Zn-1.7%Mg and Zn-1.7%Mg-0.2%Zr alloys, respectively. Additionally, a variation in ductility of the Zn-1.7%Mg and Zn-1.7%Mg-0.2%Zr alloys of up to 56.3 ± 16.9% and 4.4 ± 0.6%, respectively, was also observed, apparently due to textural changes. HPT led to a small increase in the degradation rate of the alloys after 1 day of incubation in the medium. However, an increase in the incubation period of up to 30 days slowed down the degradation process and leveled the difference between the initial and HPT-treated state of the alloys. HPT did not affect the cytotoxicity of the Zn-1.7%Mg-0.2%Zr alloy and contributed to the reduction of hemolysis. Thus, the processing of the Zn-1.7%Mg and Zn-1.7%Mg-0.2%Zr alloys using HPT accelerated their biodegradation without compromising their biocompatibility.

The structure, phase composition, corrosion and mechanical properties, as well as aspects of biocompatibility in vitro and in vivo, of a Zn-1%Mg-0.1%Dy alloy after equal-channel angular pressing (ECAP) were studied. The structure refinement after ECAP leads to the formation of elongated α-Zn grains with a width of ~10 µm and of Mg- and Dy-containing phases. In addition, X-ray diffraction analysis demonstrated that ECAP resulted in the formation of the basal texture in the alloy. These changes in the microstructure and texture lead to an increase in ultimate tensile strength up to 262 ± 7 MPa and ductility up to 5.7 ± 0.2%. ECAP slows down the degradation process, apparently due to the formation of a more homogeneous microstructure. It was found that the alloy degradation rate in vivo after subcutaneous implantation in mice is significantly lower than in vitro ones. ECAP does not impair biocompatibility in vitro and in vivo of the Zn-1%Mg-0.1%Dy alloy. No signs of suppuration, allergic reactions, the formation of visible seals or skin ulcerations were observed after implantation of the alloy. This may indicate the absence of an acute reaction of the animal body to the Zn-1%Mg-0.1%Dy alloy in both states.

A study of microstructure, phase composition, mechanical properties, corrosion processes, and biocompatibility in vitro of the Zn–1%Mg and Zn–1%Mg–0.1%Ca alloys in an annealed state and after rotary swaging (RS) is presented. Partially recrystallized microstructure is formed in the studied alloys after RS at 200 °C. RS reduces the mass fraction of intermetallic phases in comparison with annealed states of the alloys. RS at 200 °C increases the strength of the Zn–1%Mg and Zn–1%Mg–0.1%Ca alloys up to 248 ± 9 and 249 ± 9 with the growth of ductility up to 10.3 ± 3% and 14.2 ± 0.9%, respectively. The structure after RS at 200 °C does not lead to a change in the corrosion resistance of the studied alloys. However, an increase in the incubation period of the alloys in a growth medium slows down the degradation process due to the formation of a film consisting of degradation products. Rotary swaging does not impair the biocompatibility of the Zn–1%Mg and Zn–1%Mg alloys, maintaining the viability and integrity of blood cells, preventing hemolysis, and ensuring the adhesion and proliferation of osteogenic cells on the surface of samples.

An attempt to improve the functional characteristics of a degradable Fe-Mn-5Si shape memory alloy by means of structure refinement by equal-channel angular pressing (ECAP) was made. In the course of ECAP, an austenitic ultrafine-grained structure was obtained. In shear bands with a thickness of 301 ± 31 nm, twins 11 ± 1 nm in size were formed. Due to the resulting structure, the tensile strength was doubled up to 1419 MPa, and the yield strength was increased up to 1352 MPa, four times higher compared with the annealed state. Dynamic indentation tests revealed a decrease in Young’s modulus by more than 2.5 times after ECAP compared to values measured in the annealed state. The results of the study of hemolytic and cytotoxic activity in vitro, as well as the local and systemic reactivity of the body of laboratory animals after implantation of the test samples indicate the biocompatibility of the alloy after ECAP. Biocompatibility, high specific strength and low modulus of elasticity open prospects for Fe-Mn-5Si alloy after ECAP to be used for the production of degradable implants that can effectively provide the fastening function in osteoreconstruction.

A study of the effect of high-pressure torsion (HPT) on the structure, phase composition, corrosion resistance, mechanical properties and bioactivity in vitro of Zn-1%Mg-0.1%Ca alloy was performed. It was shown that HPT leads to refinement of the alloy microstructure with the formation of recrystallized α-Zn grains with an average size of 750 ± 30 nm, and grains of a mixture of different phases with a size of 38 ± 7 nm. In addition, precipitation of Ca-enriched particles ~20 nm in size was observed. X-ray phase analysis showed that the Zn-1%Mg-0.1%Ca alloy consists of five phases (Zn, Mg2Zn11, MgZn2, CaZn11 and CaZn13), whose volume fraction does not change after HPT. It was found that HPT does not lead to a deterioration in the corrosion resistance of the alloy. At the same time, HPT leads to an increase in the yield stress of the alloy from 135 ± 13 to 356 ± 15 MPa, the ultimate tensile strength from 154 ± 5 to 416 ± 31 MPa, and the ductility from 0.4 ± 0.1 to 5.5 ± 2.8%. No significant increase in hemolytic activity, bactericidal activity, and the ability to colonize the surface of the alloy by cells was revealed during the conducted studies. Additionally, there was no significant difference in these parameters in comparison with the control. However, HPT contributes to a decrease in the cytotoxicity of the alloy by an average of 10% compared to the annealed alloy. The conducted studies allow us to conclude that the Zn-1%Mg-0.1%Ca alloy is promising material for the development of biodegradable orthopedic medical implants.

Despite the achievements that have increased viability after the transplantation of allogeneic hematopoietic stem cells (aHSCT), chronic graft-versus-host disease (cGVHD) remains the main cause of late complications and post-transplant deaths. At the moment, therapy alternatives demonstrate limited effectiveness in steroid-refractory illness; in addition, we have no reliable data on the mechanism of this condition. The lack of drugs of choice for the treatment of GVHD underscores the significance of the design of new therapies. Improved understanding of the mechanism of chronic GVHD has secured new therapy goals, and organized diagnostic recommendations and the development of medical tests have ensured a general language and routes for studies in this field. These factors, combined with the rapid development of pharmacology, have helped speed up the search of medicines and medical studies regarding chronic GVHD. At present, we can hope for success in curing this formidable complication. This review summarizes the latest clinical developments in new treatments for chronic GVHD.

COVID-19 is a real challenge for the protective immunity. Some people do not respond to vaccination by acquiring an appropriate immunological memory. The risk groups for this particular infection such as the elderly and people with compromised immunity (cancer patients, pregnant women, etc.) have the most serious problems in developing an adequate immune response. Therefore, dendritic cell (DC) vaccines that are loaded ex vivo with SARS-CoV-2 antigens in the optimal conditions are promising for immunization. Lymphocyte effector cells with chimeric antigen receptor (CAR lymphocytes) are currently used mainly as anti-tumor treatment. Before 2020, few studies on the antiviral CAR lymphocytes were reported, but since the outbreak of SARS-CoV-2 the number of such studies has increased. The basis for CARs against SARS-CoV-2 were several virus-specific neutralizing monoclonal antibodies. We propose a similar, but basically novel and more universal approach. The extracellular domain of the immunoglobulin G receptors will be used as the CAR receptor domain. The specificity of the CAR will be determined by the antibodies, which it has bound. Therefore, such CAR lymphocytes are highly universal and have functional activity against any infectious agents that have protective antibodies binding to a foreign surface antigen on the infected cells.

The study shows that multiaxial deformation (MAD) treatment leads to grain refinement in magnesium alloy WE43. Compared to the initial state, the MAD-processed alloy exhibited smoother biocorrosion dynamics in a fetal bovine serum and in a complete cell growth medium. Examination by microCT demonstrated retardation of the decline in the alloy volume and the Hounsfield unit values. An attendant reduction in the rate of accumulation of the biodegradation products in the immersion medium, a less pronounced alkalization, and inhibited sedimentation of biodegradation products on the surface of the alloy were observed after MAD. These effects were accompanied with an increase in the osteogenic mesenchymal stromal cell viability on the alloy surface and in a medium containing their extracts. It is expected that the more orderly dynamics of biodegradation of the WE43 alloy after MAD and the stimulation of cell colonization will effectively promote stable osteosynthesis, making repeat implant extraction surgeries unnecessary.

The effect of equal channel angular pressing (ECAP) on the microstructure, texture, mechanical properties, and corrosion resistance of the alloys Mg-6.0%Ag and Mg-10.0%Gd was studied. It was shown that ECAP leads to grain refinement of the alloys down to the average grain size of 2–3 μm and 1–2 μm, respectively. In addition, in both alloys the precipitation of fine particles of phases Mg54Ag17 and Mg5Gd with sizes of ~500–600 and ~400–500 nm and a volume fraction of ~9% and ~8.6%, respectively, was observed. In the case of the alloy Mg-6.0%Ag, despite a significant grain refinement, a drop in the strength characteristics and a nearly twofold increase in ductility (up to ~30%) was found. This behavior is associated with the formation of a sharp inclined basal texture. For alloy Mg-10.0%Gd, both ductility and strength were enhanced, which can be associated with the combined effect of significant grain refinement and an increased probability of prismatic and basal glide. ECAP was also shown to cause a substantial rise of the biodegradation rate of both alloys and an increase in pitting corrosion. The latter effect is attributed to an increase in the dislocation density induced by ECAP and the occurrence of micro-galvanic corrosion at the matrix/particle interfaces.

Dysregulation of the immune system undoubtedly plays an important and, perhaps, determining role in the COVID-19 pathogenesis. While the main treatment of the COVID-19 intoxication is focused on neutralizing the excessive inflammatory response, it is worth considering an equally significant problem of the immunosuppressive conditions including immuno-paralysis, which lead to the secondary infection. Therefore, choosing a treatment strategy for the immune-mediated complications of coronavirus infection, one has to pass between Scylla and Charybdis, so that, in the fight against the “cytokine storm,” it is vital not to miss the point of the immune silence that turns into immuno-paralysis.

Application of cytostatics in cancer patients’ chemotherapy results in a number of side effects, including the inhibition of various parts of hematopoiesis. Two sulfated polysaccharides, fucoidan from the seaweed Chordaria flagelliformis (PS-Fuc) and fucosylated chondroitin sulfate from the sea cucumber Massinium magnum (PS-FCS), were studied as stimulators of hematopoiesis after cyclophosphamide immunosuppression in mice. Recombinant granulocyte colony-stimulating factor (r G-CSF) was applied as a reference. Both tested polysaccharides PS-Fuc and PS-FCS have a similar activity to r G-CSF, causing pronounced neutropoiesis stimulation in animals with myelosuppression induced by cyclophosphamide (CPh). Moreover, these compounds are also capable to enhance thrombopoiesis and erythropoiesis. It should be noted that PS-FCS demonstrated a greater activity than r G-CSF. The results indicate the perspective of further studies of PS-Fuc and PS-FCS, since these compounds can be considered as potentially promising stimulators of hematopoiesis. Such drugs are in demand for the accompanying treatment of cancer patients who suffer from hematological toxicity during chemo and/or radiation therapy.