Nanotechnologies in Russia最新文献

The aim of the study was to increase the sensitivity of immunochromatographic assay (ICA), achieved using gold nanorods modified with 5,5'-dithiobis-(2-nitrobenzoic acid). The resulting nanomarker makes it possible to quantify the target analyte using colorimetry and surface-enhanced Raman spectroscopy (SERS). One of the widespread mycotoxins, ochratoxin A (OTA), was chosen as the object of study. After functionalization of gold nanorods with antispecies antibodies, the SERS-active tag was used to detect immune complexes formed in the analytical zone as a result of the competitive interaction between free OTA and the hapten-protein conjugate for the binding sites of specific antibodies. After immunochromatographic assay, SERS intensity of 5,5'-dithiobis-(2-nitrobenzoic acid) was measured. Under optimized conditions, the detection limit of OTA in the colorimetric detection mode was 1.7 ng/mL, and when recording ICA results using SERS, it decreased to 33 pg/mL.

The results of studying the structural features of samples of zinc-oxide films obtained by magnetron deposition on chips of lanthanum-magnesium hexaaluminate and the surface of sapphire substrates with a gold buffer layer are presented. Analysis of the structure and morphology of the films is carried out using a set of methods, including high-resolution X-ray diffractometry, the method of constructing pole figures, and transmission electron microscopy. It is shown that when using cleavages of lanthanum-magnesium hexaaluminate, an epitaxial ZnO film is formed without signs of growth rotating domains. The use of a gold buffer layer during growth on sapphire substrates improves the crystalline quality of ZnO films, but does not completely suppress domain growth.

The diffusion tensor of nitrogen vacancies in crystalline aluminum nitride with a wurtzite structure is calculated, and the nature of its dependence on the concentration of vacancies and the temperature of the system is studied. The results obtained are necessary for the development of a closed hydrodynamic description of the processes of formation and evolution of vacancy filaments in nitride memristive structures with resistive switching.

The types of metal-composite particles produced as a result of the chemical silvering of DEALTOM multiwalled carbon nanotubes (MWCNTs) dispersed in a solution are studied. A silver polycrystalline coating of the surface of MWCNTs is obtained by the adsorption method. A new property is discovered, namely the fusion of silver-plated nanotubes obtained in this way into crown particles and the ability to agglomerate into various macrostructures. Studying the Dealtom metallized MWCNT structure by means of the scanning electron microscope reveals the following types of metallization in the samples: lamellar silver crystals (0.1–3 μm) on few and single active centers of the MWCNT surface; a silver polycrystalline layer on the surface of the MWCNTs; a polycrystalline coating of each MWCNT in a coil of nanotubes with subsequent fusion into a single silver crown particle (1–10 μm); hybrid particles, which are lamellar crystals of silver on the polycrystalline silver surface of the crown particle; the fusion of two or more crown particles into a 1D chain and 2D carpet macrostructures. The synthesized hybrid particles with nanobranched pointed morphology are promising for use in surface-enhanced Raman scattering (SERS) spectroscopy for determining ultra-low concentrations of substances as well as for analyzing biological objects.

Changes in the fine structure of natural graphite ground in a planetary mill in an atmosphere of air and Ar + 10% CH₄ are studied by X-ray diffraction. The profiles of the experimentally observed asymmetric maxima of 002 graphite are decomposed into the minimum number of symmetric components described by the Pearson VII function using the Origin program (determination coefficient R² is 0.985–0.999). The asymmetric peaks 002 can be represented as a superposition of the minimum number of components of symmetrical expansion. In this case, the calculated values of the interplanar spacings (d₀₀₂) of the decomposition components are quite close to the values of d₀₀₂ of the metastable states (phases) given earlier in publications. It is shown that the process of dispersion and structural transformations develops along the path of the successive formation of components with an increased interplanar spacing d₀₀₂ in the range from ∼3.36 to ∼3.55/3.68 Å. Dispersion is not limited to a reduction in the particle size of graphite. Replacing the air atmosphere with Ar + 10%CH₄ has the most significant effect on graphite dispersion in the first ~40 min.

At temperatures T < T_c(H) (where T_c(H) is the critical temperature and H is the characteristic pore size), in all mesoporous systems sorbed adsorbate molecules are separated into two coexisting phases “vapor in a pore” and “liquid in a pore”. The conditions for such adsorbate separation depend on the pore width and adsorbent–adsorbate interaction energies. The distribution of an adsorbate over the pore volume in different materials plays an important role in the processes of substance transfer and the establishment of an equilibrium state in them. The separation of molecules is accompanied by the formation of menisci at the vapor–liquid interface. They largely determine the overall resistance to the process of mass transfer through porous materials. The most advanced results on the description of vapor–liquid interfaces are obtained on the basis of the so-called molecular lattice-gas model, which makes it possible to calculate the molecular distributions in heterogeneously distributed models of transition regions with equal accuracy. Nondeformable pore walls create an external field that affects the molecular distribution and forms adsorption films due to the adsorbate-adsorbent interaction potential. The surface tension of the discussed menisci, as well as at the boundaries between the vapor or liquid adsorbate and solid walls, is calculated from the excess free energy of the interface (according to Gibbs). The state of the coexisting phases “vapor in a pore” and “liquid in a pore” must satisfy the equality of chemical potentials, excluding the appearance of metastable states. Methods for calculating three types of two-phase surface tensions in a three-aggregate system and a method for localizing areas of three-phase contact, as well as a microscopic description of the molecular distributions and properties of these areas are outlined. The approach is demonstrated using the example of slit-like pores with smooth and rough walls, as well as cylindrical pores and their junctions between pores of different radii. The size effects of the contact angle are studied as a function of the geometry of the pore cross section and the potential of the pore walls. The results obtained are ahead of the level of existing published works.

For the first time, a comparative analysis of 8 strains of the genus Shewanella isolated from various natural sources is carried out according to the level of the reducing activity of Ag⁺ to silver-containing nanoparticles (NPs). The characteristics of biogenic NPs in terms of shape, size, crystal-lattice parameters, hydrodynamic diameter, ζ potential, and optical characteristics are obtained using scanning transmission electron microscopy, dynamic light scattering, spectrophotometry, atomic emission spectroscopy, and assessment of the biocidal activity against various types of microorganisms, including the studied strains of the genus Shewanella. It is found that the shape of the NPs is close to spherical, the sizes vary from 2 to 30 nm, the samples are polydisperse colloidal systems. Analysis of crystal lattices of the NPs confirms the presence of AgNPs, as well as Ag₂O₂NPs and Ag₃O₄NPs in some samples. The results of atomic emission spectroscopy on the quantitative analysis of the content of Ag in the nanomaterial samples are obtained, on the basis of which strains with a high ability to form a Ag-containing nanomaterial are identified. The high sensitivity of gram-positive bacteria to AgNPs is established. Different levels of resistance of 8 strains of the genus Shewanella to the action of biogenic AgNPs are demonstrated. The results indicate the metabolic diversity of strains of the genus Shewanella isolated from various natural sources. The analysis of strains of the genus Shewanella according to the level of the reducing activity is relevant for the development of an effective technology for the “green” synthesis of biogenic NPs.

In this work, a series of samples of a homopolymer of polyferrocenoylethylmethacrylate containing ferrocene groups in side chains is synthesized for the first time using the RAFT polymerization method and comprehensively studied. A homologous series of polymers differing in molar mass is obtained in a range sufficient for conformational analysis. The main hydrodynamic characteristics of polymers (intrinsic viscosity, sedimentation, and translational diffusion coefficients) are studied, and the most probable conformation of polymers in a solution as well as the main conformational parameters (thermodynamic rigidity and polymer-chain diameter) are determined. Also, suspensions of nanoparticles are prepared on the basis of the studied polymers by the method of nanoprecipitation. The sizes of the obtained particles are analyzed both on substrates and in suspensions.