Nanotechnologies in Russia最新文献

Abstract

The effect of the simulation box size on the stability of lysozyme dimers and hexamers formed in its solution before crystallization is studied by molecular dynamics. The behavior of these oligomers in boxes of different sizes is simulated, and their stability is assessed. It is shown that increasing the simulation box does not lead to refinement of the simulation results. The dimer stability weakly depends on the box sizes, while hexamers dissociated in all boxes considered, which is consistent with small-angle scattering data. The minimum distance between the protein and the box edge, at which the results of modeling oligomer behavior in crystallization solutions are reliable, is determined (1 nm).

The results of studying the electronic structure of transition-metal oxides TiO₂ and MoO₂ with a rutile-type crystal structure are presented. The electronic structure is studied theoretically within the framework of the linearized augmented-plane-wave method using the Wien2k software package. The band structure, and the total and partial densities of electronic states are calculated. Based on the filling of energy bands with electrons, an explanation is given for the different types of electrical conductivity of TiO₂ and MoO₂. The valence band and subvalent states of commercial TiO₂ and MoO₂ samples in the form of powders at two different excitation energies of 120 and 1486.6 eV are studied using X-ray photoelectron spectroscopy. Based on calculations, the observed features of the structure of the experimentally recorded spectra are interpreted.

Abstract

The need to develop a surgical instrument that can most effectively and minimally invasively remove a malignant tumor, and distinguish and destroy only tumor cells without damaging the normal cells of healthy tissue surrounding the tumor is being considered. To achieve this goal, it is proposed to use nanodiscs with special magnetic, electronic and optical properties. Nanodiscs modified with recognition ligands (aptamers) are able to bind to tumor cells and destroy them under the influence of a weak, nonheating alternating magnetic field. This allows for effective tumor destruction while minimizing the impact on surrounding healthy tissue.

Abstract

For the first time in Russia, we present a technology for temporary wafer bonding, which is used to form through holes in silicon (through-silica via (TSV) structures) with a high aspect ratio of depth to diameter (more than 10 to 1), as well as a method for transferring alignment marks from the front to the back side of a thin Si wafer, consisting in the use of a glass carrier plate, which allows for a sufficient amount of deflection of the assembly for lithography. The modernized operating parameters of Si-glass bonding, which consist in controlling the cooling rate of the plates and applying pressure to the plates during their cooling phase, ensure a reduction in the deflection of the resulting assembly by 75% before thinning and by 65% after thinning to a residual thickness of 125 μm while maintaining the mechanical integrity of the plates.

Prototypes of gas sensors with sensitive elements are made based on ZIF-8 and ZIF-67 films obtained directly on a substrate by immersion. The sensitivity of the prototypes to NO₂ and CO is assessed by simultaneously analyzing the capacitive and resistive response. It is shown that the functionalization of ZIF-8 films with layers of ZIF-67/ZIF-8 leads to an increase in the sensitivity of the sensor to NO₂ by more than 2 times compared to ZIF-8 films, and also allows CO detection. A sensor prototype based on ZIF-67/ZIF-8 films shows a resistive and capacitive sensitivity to NO₂ of 3 and 6% (for 45 ppm), 14 and 15% (for 85 ppm), and to CO of 9 and 7% (for 6 ppm), 15 and 10% (for 10 ppm). It is shown that parallel analysis of the capacitive and resistive response makes it possible to increase the accuracy of the analysis of the sensor response when exposed to various gases and can be used as the basis for a software interface for training sensor operation using artificial intelligence.

The catalytic activity in the oxygen-reduction reaction and stability in various stress-testing modes are studied for bimetallic PtCu/C catalysts with platinum contents of 20 and 30 wt %, obtained by liquid-phase synthesis methods, is studied by cyclic-voltammetry methods on a rotating disk electrode in a three-electrode cell and as part of a membrane-electrode assembly in comparison with a commercial Pt/C catalyst. Significant differences in the degree of degradation of the studied PtCu/C and Pt/C catalysts for low-temperature fuel cells are shown, namely from 33 to 67% depending on the stress-testing method and catalyst composition.

The process of the formation of gas-sensitive nanofilms ZIF-8 and ZIF-67 on substrates, which are glass chips with contact tracks formed on them, is studied. Multilayer ZIF-8/ZIF-67 nanofilms are grown on a substrate by cyclic layer-by-layer coating in solution. The film growth process is monitored after each cycle using X-ray diffraction, elemental analysis, and scanning electron microscopy. It is shown that at least three 30-minute growth cycles are required to form a strong, uniform ZIF-8 film. Additionally, the sensory properties of the obtained samples for the detection of carbon monoxide CO are studied.

The biomimetic synthesis of nanoparticles has many advantages over classical methods due to the possibility of combining special reaction conditions and a ready-made matrix to form a given particle morphology. The possibility of synthesizing zinc-sulfide nanoparticles in sprouts of Vigna radiata (L.) R. Wilczek and Lentilla lens (L.) W. Wight is investigated. It is established that the optimal biological matrix for synthesis is Vigna radiata (L.) R. Wilczek. The method used opens up a new way to producing other inorganic materials.

Abstract

The mechanical behavior of porous chitosan particles with various diameters obtained by freeze drying is investigated. The morphology of the particles is visualized by scanning electron microscopy. It is shown that the particles have a predominantly spherical shape and a honeycomb-like structure with interpenetrating pores. The mechanical characteristics of the particle material are modeled using the neo-Hookean, second-order Yeoh, Blatz-Ko, and third-order Ogden foam hyperelastic models, based on the results of mechanical compression tests between parallel plates and numerical solution of the reverse-engineering problem using the finite-element method. Force-displacement curves are plotted for the proposed models and then verified in a similar full-scale experiment with particles of another diameter.

Abstract

GaAs/AlAs(001) (2 × 4) is one of the most optimal substrates for optoelectronic and nanophotonic applications. Droplet epitaxy allows high-quality quantum dot (QD) arrays with the desired properties to be obtained, but the detailed mechanism of deposition and subsequent epitaxial growth is still questionable. In this paper, the growth mechanism of indium QDs on various GaAs/AlAs(001) surfaces is studied within calculations of density functional theory. Full geometry optimization, in which the coordinates of substrate atoms can be altered under adatom impact, is shown to be a straightforward technique for the simulation of adsorption processes. The obtained results are in good agreement with conventional methods and well-known findings. The proposed approach could become standard practice and extend the understanding of droplet epitaxy.