Nanotechnologies in Russia最新文献

Currently, studies aimed at creating stimulus-sensitive nanostructured and microstructured drugs, in which the release of a chemotherapeutic agent occurs in a controlled manner under the effect of a certain stimulus, are widespread. This study is devoted to the creation of a polymer model of gefitinib with photoinduced release due to the inclusion of a photosensitizer in the dosage form. The obtained samples are characterized by a particle diameter of up to 150 nm with a rather narrow size distribution. A study of the cytotoxic activity of polymer particles under photoexposure reveals a combined effect of gefitinib and the photosensitizer, with the cytotoxic activity of the samples exceeding the effect of free gefitinib by 1.4–1.7 times.

Using of isotopic compounds is a fundamental methodology for conducting biological and medical research. Investigations in this area is necessary for developing new medicines, including deuterated compounds, which can be used directly as medicines. The application of liquid-phase and solid-phase methods for introducing hydrogen isotopes into organic compounds is considered. It has been shown that using of heterogeneous and homogeneous catalysts to activate isotope exchange makes it possible to obtain preparations with a high deuterium and tritium content. Nanocatalysts, in which both metals and their carriers can exist in a nanoform, have made a great contribution to the successful application of these methods. Special attention is paid to the patterns associated with the interphase transfer of activated isotope particles and their spillover effects on the label incorporation and distribution in organic molecules.

The channels of single-walled carbon nanotubes (SWCNTs) are filled with iron bromide FeBr₂. Images of the filled SWCNTs are obtained using transmission electron microscopy. The Raman spectra of the filled SWCNTs are studied. A shift of peaks towards higher frequencies is observed. The X-ray photoelectron spectra of the filled SWCNTs are studied; it is found that charge density transfer occurs between the nanotubes and the embedded FeBr₂.

A Verilog-A model of a spiking neural network is developed, and its dopamine-like learning is carried out in solving the problem of recognizing the simplest images. The necessity of using unipolar pulses from postsynaptic neurons to implement dynamic plasticity of the “bell-shaped” and “anti-bell-shaped” types, as well as the positive effect of the inhibitory layer of neurons on the operation of the system, is shown. A hardware and software complex implementing this neural network and the dynamics of changes in the conductivity window of a memristor synaptic connection obtained with its help when emulating different “dopamine levels” in a neuromorphic system are presented.

The role of conductive fillers in the physical and chemical properties of composite materials based on poly(styrene-butadiene-styrene) is studied in comparison with the neat matrix. Using a three-stage extrusion method, composite materials are produced with the addition of a filler: silver or aluminum particles at a concentration of 1, 5, and 10 wt %. The structure of the composite materials is studied using wide-angle and small-angle X-ray scattering methods. The domain organization of the materials is revealed. The sizes of the filler crystallites and the value of the typical scattering order of the block copolymer is defined. Based on scanning electron microscopy data, the sizes of the filler particles and their distribution throughout the volume of the composite materials are estimated. It is found that the introduction of up to 10 wt % filler has low effect on the mechanical behavior of the composite materials compared to a polymer matrix, but changes their electrophysical properties. The principal possibility of using the obtained composite materials for 3D printing is demonstrated.

The high-temperature treatment of nanofibrous carbon, carried out at 2600°C (in the absence of air), is investigated. The obtained samples are studied using thermal analysis, transmission electron microscopy, and Raman spectroscopy. The carbon samples are tested as active material in gas sensors for the detection of nitrogen dioxide. It is shown for the first time that heat treatment of nanofibrous carbon leads to a sharp increase in sensitivity by ~5 times at 1 ppm NO₂ relative to the initial sample. Unlike other treatment methods, heating to high temperatures in the absence of air leads to an increase in the degree of graphitization, formation of the well-ordered structure of nanofibers, the removal of catalyst residues, and an increase in the functional characteristics of the sensors.

A nanoscale material, which has a tysonite structure (space group (Pbar {3}c1)), in the form of a transparent xerogel for the ceramic solid electrolyte (La_1‒хNd_х)_0.95Sr_0.05F_2.95 is obtained by the method of coprecipitation from an aqueous solution of nitrates. The dependences of the unit-cell parameters of the tysonite solid solution (La_1–хNd_х)_0.95Sr_0.05F_2.95 a and c on the composition x are additive (they satisfy Vegard’s rule). With increasing x, the average size of crystalline grains in the coherent scattering region (CSR) of the nanopowders increases from 8–9 to 23.5–26.5 nm. The ionic conductivity of a ceramic sample prepared by cold pressing from a nanopowder of the composition (La_0.5Nd_0.5)_0.95Sr_0.05F_2.95 with a density of ~80% of the theoretical value with the parameters of the trigonal unit cell a = 7.1008 ± 0.0004 Å, c = 7.2796 ± 0.0005 Å, and CSR = 10 ± 0.5 nm is measured. The electrical conductivity of (La_0.5Nd_0.5)_0.95Sr_0.05F_2.95 nanoceramics is 2 × 10^‒3 S/cm at 500 K. The activation energies of ion transfer in the high- and low-temperature regions of electrical conductivity are 0.37 ± 0.04 eV (T > 560 K) and 0.48 ± 0.01 eV (T < 560 K), respectively. The high conductometric characteristics of the nanoceramics make it possible to consider the method of coprecipitation from aqueous solutions as a cost-effective technology in fluoride materials science.

Despite the development of metal oxide gas sensors in recent decades, the low selectivity and high operating temperatures required for their operation have continued to drive the search for new materials for gas sensors. Significant improvements in the design of highly efficient gas sensors have been achieved due to advances in microfabrication and nanofabrication technologies and the application of nanostructured materials; therefore, the review considers the main types of conductometric sensors for gas detection with an emphasis on the use of nanomaterials in this area. Achievements in fundamental and applied research that have led to the development of highly efficient chemiresistive devices are presented. Approaches to the synthesis of new materials with unique structures and gas-sensing properties are also presented, and the prospects for new technologies and future applications of chemiresistive gas sensors are highlighted.

The results of the heterophase interaction of refractory-phase nanoparticles of Al₂O₃, ZrO₂, and HfO₂ with cobalt melts containing harmful impurities of nonferrous metals (tin and antimony) are investigated and summarized. It is shown that after the introduction of nanoparticles in the Co–Sn and Co–Sb systems, the degree of impurity removal, depending on the isothermal holding time, was 13–31 and 10–26 rel. %, respectively. It is found that the redistribution of impurities with nanoparticles in the melt in the form of ensembles and their removal to the phase boundary Me–gas/slag/ceramics can be represented as a two-stage process.

At present, there is every reason to assume that ETosis by various blood cells leads to the formation of different types of extracellular traps (ETs), the biological functions and clearance of which are apparently not the same. The results of in vitro model experiments to create DNA–histone networks at different DNA : histone ratios allow us to propose a method using polymer microspheres with surface amino (PMS⁺) and carboxyl (PMS^–) groups as sorbents for the isolation from whole blood and quantification of oppositely charged ETs. Quantitative analysis of the interaction of blood ETs with PMS⁺ and PMS^– shows that the total number of ETs adsorbed on PMS⁺ and PMS^– is significantly increased in patients with type-2 diabetes mellitus and polyneuropathy compared to healthy volunteers. Moreover, a significant predominance of ETs adsorbed on PMS⁺ is associated with microalbuminuria. The obtained data suggest that the proposed approach could be promising for application in both fundamental research and clinical practice.