Nanotechnologies in Russia最新文献

Under adverse environmental conditions bacterial cells survive by activating the “stringent response,” which is mediated by the accumulation of small signaling alarmone molecules (p)ppGpp. The synthesis of (p)ppGpp from ATP and GDP/GTP and their hydrolysis to GDP/GTP and pyrophosphate are catalyzed by enzymes of the RSH (RelA/SpoT Homologue) family. Studying the complex allosteric mechanism underlying the bifunctional activity of these enzymes and the maintenance of intracellular levels of (p)ppGpp is a topical issue in modern science. In this work we determine the conformational stability and binding efficiency of the bifunctional homologue of the RSH family Rel_Seq385 with nucleotides depending on their concentration and the ionic composition of the reaction mixture.

A genome-wide association study is conducted to identify gene polymorphisms in pigs associated with common pathologies in young animals. The genomes of 97 pigs (Landrace and Large White breeds) are sequenced, followed by genome-wide association analysis to identify possible markers of potentially heritable defects (malnutrition, gastroenteritis, scrotal hernia and cryptorchidism, tremors at birth). Polymorphisms are found in various genes, including those associated with development of the nervous system and the formation of neurological diseases, even in the case of pathologies not directly related to the functions of the nervous system.

Biomineralization is the process by which living organisms contribute to the formation of insoluble metal-ion deposits through their metabolic reactions with the environment. One of the most common biominerals on Earth is calcium carbonate, which is formed by various organisms during the process of mineralization. These biominerals have unique properties that differ from inorganic minerals, including their degree of crystallinity, isotopic and trace-element composition, and polymorphic structure. This review will explore the role of bacterial cell walls and extracellular macromolecules in the biomineralization process, as well as present the main hypotheses on how microbial cells and their components initiate this process. Additionally, we discuss the conditions for the formation of a wide range of calcium carbonate polymorphs and their stability within biological systems. Understanding the mechanisms and dynamics of biomineralization is crucial for scientific and technological innovation, as it allows us to better understand microbial ecology and biogeochemical cycles. This knowledge could open up new opportunities for the creation of innovative materials and technologies.

Nitrogen-doped carbon materials are promising supports for synthesis of electrocatalysts used in low-temperature fuel cells. Pt/C and PtCo/C catalysts with different platinum weight fractions on a nitrogen-doped Ketjenblack EC-300J support have been obtained by the liquid-phase synthesis. The transmission electron microscopy study of the catalyst microstructure has shown that both materials exhibit a narrow size distribution of metallic nanoparticles and a low degree of their agglomeration. Study of the electrochemical behavior of the catalysts on a rotating disk electrode has shown that both materials significantly outperform their commercial counterparts in both the electrochemically active surface area and activity in the oxygen reduction reaction. It has been found that the maximum efficiency of a membrane-electrode assembly with the use of the obtained catalysts on the cathode is achieved at an ionomer/carbon weight ratio of 0.9. The peak powers of the membrane-electrode assemblies achieved using this ratio have been 652 and 666 mW/cm² for mono- and bimetallic catalysts, respectively. The use of the obtained PtCo/C catalyst on the cathode of the membrane-electrode assembly allowed for an increase in its productivity by 8% as compared with its commercial counterpart.

To measure residual elastic stresses in the surface layers of recrystallized commercially pure α-Ti before and after the shock-wave action of a picosecond laser pulse, which leads to nanostructuring of a thin surface layer, a method of correlating images of rectangular cross-section depressions (slots) cut by a focused ion beam in the column of a scanning electron-ion microscope is used. It is suggested that laser treatment helps to relieve residual stresses in the surface layers of the studied sample.

Nanotubular titanium dioxide (TiO₂) films have been fabricated by chemical anodic oxidation on a titanium substrate. The initial amorphous oxide films have been subjected to heat treatment at 400, 450, and 500°C. The effect of the annealing temperature on the structural and I–V characteristics has been comprehensively studied. It has been shown that annealing at 400°C for 30 min leads to the formation of the anatase (TiO₂) phase with a fraction of up to ~98%. The sample microstructure exhibits a high degree of ordering and uniformity of the TiO₂ array vertically aligned relative to the substrate. The average nanotube inner diameter is approximately 50–60 nm and the nanotube wall thickness is 10–15 nm. Raman spectra of the samples have revealed the main vibrational modes E_g, E_g, B_1g, A_1g, and E_g corresponding to the anatase (TiO₂) phase. The calculated O–Ti–O bond lengths ranging from 1.89 to 2.85 Å are typical of a distorted TiO(_{6}^{{8 - }}) octahedron. The I–V characteristics of the films are nonlinear and typical of oxide materials with the resistance switching effect. The results obtained confirm that the heat treatment enables the targeted modification of the structure and properties of TiO₂ nanotubes.

A photoconvertible fluorescent protein based on PAGFP, named PC-mGFP, is developed using molecular evolution in a bacterial system. PC-mGFP undergoes photoconversion from the green fluorescent state with a large Stokes shift to the green fluorescent state when irradiated with 405-nm light. The properties of PC-mGFP are characterized in vitro and in the cytosol of mammalian cells. PC-mGFP can be applied in the field of cellular imaging.

The effect of gold nanoparticle functionalization based on the high-affinity binding of biotinylated antibodies to streptavidin on the surface of gold nanoparticles, which ensures oriented arrangement of the antibodies, as well as the effect of the size of the nanolabel on the sensitivity of immunochromatographic assay, is studied. The object of study is the anti-Müllerian hormone, a biomarker of the state of the female reproductive system. Two methods of antibody immobilization are considered: high-affinity streptavidin–biotin binding and physical adsorption. Oriented immobilization demonstrates the absence of nonspecific interactions and an increase in assay sensitivity. An increase in the size of nanoparticles in the immunoconjugate leads to a decrease in the limit of detection. The identified patterns make it possible to develop a test system with a hormone detection limit of 0.1 ng/mL and a working range of 1.0–42.1 ng/mL. The possibility of using the test system in fivefold diluted blood serum is demonstrated.

One promising application of nuclear-physics methods in medicine is boron neutron capture therapy (BNCT). A key aspect of the effectiveness of BNCT is the production of boron-containing materials with the required concentration and the ability to keep the drug within the tumor. This work presents the results of the initial stage of boron-10 nanoparticle synthesis, which includes the synthesis of submicron particles by milling boron-10 in a planetary ball mill. Solutions of boron-10 in isopropanol with submicron particle sizes of 150–600 nm are obtained. The optimal milling conditions are determined to ensure the required boron-10 concentration and minimize the presence of impurities.

The phase behavior of a liquid-crystal (LC) matrix incorporated by new azo-chromophore compounds that undergo conformational changes under irradiation by light with wavelengths of 365 and 450 nm has been studied. The illumination conditions optimum for controlling the transition from the isotropic to LC phase have been established together with the time required for the UV-induced LC transition to the isotropic phase and the time for which a medium retains its isotropic liquid properties after UV illumination. The feasibility of controlling the localization of CdSe/ZnS quantum dots incorporated into the matrix with azo-chromophore has been demonstrated. A dynamic experiment with displacement of the sample relative to a slit mask has shown the possibility of moving quantum dots along with the isotropic melt front; the temperature optimum for this effect has been determined.