Nanotechnologies in Russia最新文献

Nanosized powders (Ce_1–xPr_x)_0.95Sr_0.05F_2.95 (x = 0, 0.5, 1) with a tysonite structure (sp. gr. (Pbar {3}c1)) are synthesized by the thermal decomposition of trifluoroacetate precursors in an inert environment. The ceramics are cold pressed, and their X-ray and conductometric properties are studied. It is found that the mixed composition nanoceramics (Ce_0.5Pr_0.5)_0.95Sr_0.05F_2.95 (x = 0.5) demonstrate a higher electrolytic characteristics compared to the compositions with x = 0 and 1. The value of its ionic conductivity is σ_dc = 6.5 × 10^‒3 S/cm at 500 K. The cation composition of the studied solid electrolyte (Ce_0.5Pr_0.5)_0.95Sr_0.05F_2.95 is promising for further optimization of the ceramic synthesis process and application in various electrochemical devices.

The problem of providing high-quality medical care to patients with skin injuries remains relevant. One of the promising directions in the treatment of wound is the use of coaxial nanofibers as a drug-delivery system. Thus, this work summarizes current scientific developments in the field of creating wound dressings based on coaxial nanofibers. The polymers most often met in publications and their combinations used to produce coaxial nanofibers are presented, as well as examples of the introduction of various bioactive molecules into their composition.

A combination of materials such as a PVDF-based composite with 10 wt % CoFe₂O₄ nanoparticles and a method of ME stimulation of stem cells using a perpendicularly shifting low-frequency (0.3 Hz) magnetic field with a given amplitude are proposed. Optimal stimulation parameters—magnetic field strength, number of stimulations per day and duration—are systematically established to maximize the proliferation of multipotent mesenchymal stem cells up to 30% confirmed by WST-1 analysis.

A number of systems capable of forming gels upon contact with an aqueous solution of NaCl, two components of which are represented by gellan and CaCl₂, are studied. The third component is pullulan with different molar masses. Systems such as these could be used for medical purposes, particularly for the delivery and controlled release of drugs. The influence of the molar mass of pullulan on the rheology of the resulting gel is analyzed to optimize its viscoelastic properties. It is that reducing the molar mass of pullulan integrated into the gel composition improves the viscoelastic properties of the system. It is established that the gels obtained at room temperature during interaction with an aqueous solution of NaCl did not deteriorate when heated up to temperatures of ~60–70°C.

The properties of Cu/NC/D/Ni memristive structures with a (CoFeB)_x(LiNbO₃)_100–x nanocomposite layer and a LiNbO₃ dielectric layer with a thicknesses of 230 and 20 nm, respectively, are studied. It is found that the resistive switching (RS) voltage of the structures decreases greatly from 2.4 to 0.5 V with increasing temperature from 270 to 380 K. The negative magnetoresistance (MR) and its noticeable influence on the voltage and current of RS, which reaches ~5% with a MR value of 1.8%, is revealed. The peculiarity of the RS structure effect is associated with the fairly efficient injection of spin-polarized electrons from the Ni electrode into the conduction band of the LiNbO₃ layer at positive bias voltages of the upper Cu electrode. In this case, the filling of deep energy-distributed traps in the LiNbO₃ layer, which is observed above a certain voltage applied to the structure, leads to a sharp increase in current and manifestation of the RS effect, depending on both temperature and magnetic field. Under these conditions the structures demonstrate spike-timing-dependent plasticity (STDP), which confirms the possibility of their use as synapses in the development of neuromorphic systems.

The biological activity of exosomes secreted by neural (NSC) and mesenchymal stem cells (MSC) isolated from a SC conditioned medium using differential ultracentrifugation, depth filtration, and sedimentation with polyethylene glycol is characterized and compared. The obtained preparations are characterized by size, presence of specific exosomal markers, and protein concentration. The biological activity of exosomes is assessed by their ability to increase the survival and clonogenic activity of irradiated NSCs. The ability of mouse SC exosomes isolated with all these methods to increase the survival and clonogenic activity of irradiated NSCs is shown, but NSC exosomes obtained by ultracentrifugation exhibited the highest efficiency. Any of these methods can be used to obtain biologically active exosomes.

The anomalous solubility of an interpolyelectrolyte complex (IPEC) of chitosan (CN) and sodium chondroitin sulfate (SCS) in a monosodium glutamate (MSG) solution associated with its dissociation into the initial components is discovered and studied using viscometry, turbidimetry, dynamic light scattering, static light scattering, and gravimetry. It is shown that complete dissociation of the stoichiometric interpolyelectrolyte complex of the said polyelectrolytes can be achieved in a monosodium glutamate solution with an order of magnitude lower ionic strength than in solutions of other salts. The possibility of the reverse formation of the interpolyelectrolyte complex of chitosan and sodium chondroitin sulfate from its decay products as the concentration of monosodium glutamate decreases is revealed. The possible areas of application of this phenomenon are identified, in particular, in medicine.

The growing interest in graft copolymers based on natural polysaccharides is associated with the wide range of their applications in medicine, particularly in ophthalmology. Samples of comb-shaped pullulan copolymer with side groups of poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline) are studied using molecular hydrodynamics methods. The influence of the molar mass of the initial pullulan on the properties of the resulting graft copolymers is studied. The conformational characteristics of graft copolymers, the grafting number of the side chains of poly(2-oxazoline) were obtained from the analysis of molecular hydrodynamic data.

Biogenic nanoparticles of silver (AgNPs) and cadmium sulfide (CdSNPs), which were obtained by microbial synthesis using the bacteria Shewanella oneidensis MR-1 and Bacillus subtilis 168 respectively in the presence of ions of the corresponding metals and sulfur, are used for inclusion in the composition of polymer materials of various types. Nonwoven materials based on polyamide and polylactide are obtained and characterized: the average fiber diameter in materials made from polyamide is 1.1 µm, and in materials made from polylactide, it is 3.7 and 7.2 µm. The surface properties of the nonwoven fabrics when in contact with water are assessed as hydrophobic for polylactide and hydrophilic for polyamide. Due to the different surface properties of the nonwoven materials, AgNPs and NPsCdS are effectively included into the composition of polyamide, where a coating of biogenic NPs is present in all fiber layers, and in the polylactide matrix, only in the surface layers. The antimicrobial activity of AgNPs and CdSNPs is retained in the polyamide-based material and is demonstrated for a wide range of microorganisms from various systematic groups.

Co_xFe_3–xO₄ (x = 0.0, 0.5, and 1.0) single-phase microcrystalline samples are obtained by mechanochemical synthesis. They are studied comprehensively by X-ray structural analysis, vibration magnetometry, Mössbauer spectroscopy, and neutron diffraction. The crystal-chemical formulas are established, and the magnetic properties of the compounds are characterized. The Co_xFe_3–xO₄ (x = 0.0, 0.5, and 1.0) nanoparticles are obtained by wet high-energy milling of the single-phase microcrystalline samples. It is shown that the average size of the synthesized nanoparticles is from 11 to 13 nm. There is a decrease in the coercive force for all Co_xFe_3–xO₄ nanocrystalline samples compared to their microcrystalline analogs, which is due to there being a large proportion of nanoparticles in the superparamagnetic state. The specific power loss values calculated from hyperthermia effect measurements appear to be maximum (3.5 W g^–1) for the Fe₃O₄ sample (x = 0.0), which is explained primarily by the ratio of its coercive force and the amplitude of the applied alternating field strength.