Nanotechnologies in Russia最新文献

The synthesis of glycolide-lactide copolymers and the formation of nonwoven fibrous matrices based on them by electrospinning are described. The obtained materials are used as patches during pancreatic resection. It is shown in laboratory animals (rats) that the use of polyglycolide-lactide matrices reduces the incidence of pancreatic fistula formation by forming a barrier with the abdominal organs.

The one-step synthesis of nanocomposites based on MXenes and graphene oxide by initiating a pulsed discharge between metal electrodes immersed in acetonitrile is presented. The obtained structures are characterized using various methods, including transmission electron microscopy, X-ray phase analysis, and X-ray photoelectron spectroscopy. The results confirm the multilayer structure of the nanocomposites based on nitrogen-containing MXenes with an average interlayer distance of 0.2 nm. The obtained structures demonstrate high efficiency in the photothermal conversion of sunlight and, therefore, are promising materials for creating water desalination plants.

The effect of preliminary holding in the melt state on the characteristics of composite materials based on polypropylene is studied depending on the type of nanoscale carbon filler. Electrically conductive detonation nanodiamond soot and electrically conductive carbon black are used as fillers. The electrophysical, adhesive, tribological, and mechanical characteristics of the obtained composites are studied depending on the duration of their preliminary holding in the melt state. It is shown that the observed changes in the characteristics of the composites can be explained by the process of migration of carbon fillers to the surface of the composite melt during its heat treatment, and the nature of their change depends on the type of filler used.

A method for producing composite materials for cranioplasty based on polylactide and poly-ε-caprolactone, which contain chitosan threads as a reinforcing filler, is described. Chitosan threads are obtained via wet spinning by precipitating acetic acid solutions of chitosan in an alcohol-alkaline medium. The melting temperatures of polylactide and poly-ε-caprolactone are significantly lower than the degradation temperature of chitosan, which makes it possible to obtain composite materials using heat-treatment methods, e.g., calendering and pressing. The composite material based on polylactide has strength and elastic characteristics close to those of cancellous bone tissue, and the composite based on poly-ε-caprolactone has those of cortical bone. This allows us to recommend the obtained composite materials for preclinical and clinical studies as bone-tissue implants, in pediatric cranioplasty for the treatment of injuries and diseases of the skull bones.

The work presents studies of the temperature dependences of the coefficients of linear thermal expansion (CLTE) of effective thermoelectric materials Si_0.8Ge_0.2 (1.8 wt % P) and Si_0.8Ge_0.2 (0.8 wt % B), which are synthesized by induction melting, and nanostructured thermoelectric materials obtained by spark plasma sintering. The density of the nanostructured thermoelectric materials (2.94 g/cm³) is 98% of the density of the synthesized thermoelectric materials (2.99 g/cm³). The synthesized and nanostructured thermoelectric materials have similar Vickers microhardness values of ~1100 H_V. The CLTE value of the nanostructured thermoelectric materials is 2–3% higher than that of the synthesized thermoelectric materials. The temperature dependences of the CLTE are similar in nature and are within the range of 3.84 × 10^–6 up to 4.71 × 10^–6 K^–1. For n- and p-type SiGe, the values of the CLTE are almost identical.

The possibility of optimizing the design of a piezoelectric nanogenerator (PENG) based on an array of vertically oriented nitrogen-doped carbon nanotubes (N-CNTs) to increase the efficiency of external mechanical energy conversion is investigated. It is found that the optimal parameters of the top electrode of the PENG include a 0.6-μm-thick polysilicon layer, a 0.6-μm-thick aluminum coating, and a perforated membrane with holes of 2 μm² in a 24 × 24 array. It is shown that the proposed design ensures uniform deformation of the N-CNTs and allows an increase in the value of the generated voltage to 3.55 V. The obtained results confirm the prospects of using N-CNTs as a functional material for creating highly efficient PENG.

The concepts of the mechanisms of the antiseptic action of silver preparations, which are widely known in the world scientific community, can be boiled down to the suppression and destruction of harmful bacteria, viruses, and fungi. For example, this is the death of pathogens (bacteria, fungi) due to oxidative stress, which is caused by the increased generation of reactive oxygen species when silver ions affect the cell respiration pathway. However, this mechanism could equally lead to the death of beneficial bacteria and healthy cells in the body, which contradicts the centuries-old history of using silver compounds for medical purposes. The review puts forward the idea of a fundamentally different mechanism of the therapeutic antiseptic action of silver ions: the induction of stress, which, in turn, has a stimulating effect on the body, activating its own resources (similar to transformational psychological running, cold exposure, and sauna use). The occurrence of stress during exposure to silver ions is explained by the fact that silver is not an essential (vital) element for mammals, is not constantly present in the body, and thus the body is forced to adapt to it as to the novel perturbance during such exposure. In order to ensure a therapeutic effect, it is necessary that the duration and intensity of the stressful impact not be too great to avoid chronic stress and distress, which, as is known, lead to suppression of the body’s vital resources.

Pazopanib is a multitargeted tyrosine kinase inhibitor that suppresses angiogenesis and proliferation of tumor cells. To increase its bioavailability, a model of a liposomal dosage form of pazopanib is developed and its main pharmaceutical and technological characteristics are determined. It is found that a composition including the active substance, egg phosphatidylcholine, cholesterol, and poly(ethylene glycol) lipid in a mass ratio of 1 : 75 : 7.5 : 0.75 possesses the best properties (size, polydispersity index, and surface charge). To determine the pazopanib concentration in model mixtures, ultraviolet (UV) spectrophotometry is used, which demonstrates the specificity of the method and its linearity (the ability to obtain results within a specified range that are directly proportional to the concentration of the analyte in the sample). The liposomal dispersion is stabilized by lyophilization, and a 10%-aqueous sucrose solution is selected as a cryoprotectant. Pazopanib in the final product is determined by high-performance liquid chromatography. The stability of the lyophilized liposomal dosage form for six months at a storage temperature of no higher than –18°C is shown.

It has been previously shown that on a three-dimensional microgel matrix based on recombinant spidroin rS1/9, induced pluripotent stem cells effectively differentiate into a heterogeneous cell population enriched with dopaminergic neurons. An analysis of the functional maturity and activity of the obtained neuronal cultures is carried out, for which they are stereotaxically in vivo administered to mice with a toxin-induced model of Parkinson’s disease. It is shown that the introduction of all analyzed cell-culture variants leads to an increase in the number of dopaminergic neurons and an increase in the proportion of this type of cells in the total cell pool in substantia nigra compacta. This increase is already observed upon the introduction of a microgel based on a mixture of recombinant spidroin proteins rS1/9 and rS2/12 in a ratio of 1 : 1 with 10% heparin-binding peptide and RGDS peptide.

Single-phase hollow spheres based on calcium manganite CaMnO₃ and gadolinium-doped Ca_0.96Gd_0.04MnO₃ with the perovskite structure Pnma are synthesized via the method of spray solution combustion synthesis. Spark plasma sintering leads to the production of a secondary phase of marokite CaMn₂O₄ with the Pbcm structure, while doping promotes to decrease the marokite content. A change in the parameters of the perovskite crystal lattice is established, which indirectly indicates the substitution of Ca²⁺ with Gd³⁺ and the formation of oxygen vacancies: both factors lead to a change in the Mn³⁺/Mn⁴⁺ ratio in the structure and, as a consequence, an increase in the electrical conductivity in the doped material due to a decrease in the activation energy of polaron hopping between localized states of Mn³⁺ and Mn⁴⁺. The resulting morphology enhances phonon scattering processes, which leads to a decrease in the thermal conductivity. The combination of the above factors leads to a significant increase in the thermoelectric efficiency: for Ca_0.96Gd_0.04MnO₃ the value zT reaches 0.26 at T = 975 K, which is 117% higher than that of the undoped sample (zT = 0.12). This confirms the promise of the chosen approaches for creating highly efficient thermoelectric ceramics.