Nanotechnologies in Russia最新文献

Тhe results of the heterophase interaction of nanoparticles of refractory phases with iron melts containing harmful impurities (sulfur, antimony, tin, and copper) are studied and generalized. It is shown that the degree of the removal of impurities (~0.05 wt %) in the Fe–S, Fe–Sn, Fe–Sb, and Fe–Cu systems after the introduction of nanoparticles ranges from 10 to 37 rel %. As a result of the interaction of nanoparticles with impurities of the metal melt, the formation of ensembles with new surface properties is proposed. It is shown that the redistribution of ensembles in the melt and their removal to the phase interface can be represented as a two-stage process.

Нafnium oxide is currently considered one of the most promising metal-oxide materials for creating memristive structures. Memristive structures find their application in many areas of science and technology; for example, with their help, the biosimilar emulation of synapses in neuromorphic computing systems is possible. One of the important obstacles  to the industrial use of memristors is the variability of resistive switching. Nonstoichiometry in memristor structure can be an important tool for controlling resistive switching. Therefore, in this work, memristors based on hafnium oxide in a metal–insulator–metal sandwich structure are synthesized by electron-beam deposition, which makes it possible to create nonstoichiometric films. The effect of resistive switching is studied depending on the material of the upper electrode and the thickness of the hafnium-oxide layer. The synthesis parameters are determined to achieve a balance between the main memristive characteristics.

Lithium and transition-metal phosphates are promising cathode materials for lithium-ion batteries. Lithium manganese phosphate LiMnPO₄ has a higher specific energy density than LiFePO₄ used in practice: theoretical values of 700 and 580 W h/kg, respectively. However, its use is hampered by a number of disadvantages: reduced electronic and ionic conductivity, inferior stability of the structure in the charged form, and large changes in the volume during (de)lithiation. LiMnPO₄ and LiMn_0.95Ni_0.05PO₄ samples are synthesized by the solvothermal method and studied using X-ray powder diffraction, low-temperature nitrogen adsorption, scanning electron microscopy, and electrochemical methods. It is shown that a small degree of substitution of Mn for Ni (5 at %) leads to an increase in the capacity and Coulombic efficiency of LiMnPO₄, a decrease in charge-transfer resistance, and an increase in Li⁺ diffusion coefficients.

Liposomes containing a natural antioxidant, astaxanthin esters, are prepared by dispersing the lipid film and evaporating from chloroform with further ultrasonic treatment. To increase the stability of the astaxanthin esters, liposomes based on Lipoid S75 (2 mg/mL) are modified with pluronic F68 or PEGylated distearylphosphatidylethanolamine (DSPE-PEG 2000). As a result of optimization, the ratio of phospholipid and modifiers is selected for stable liposomes with 0.5 mg/mL astaxanthin esters. Liposomes with 0.5% pluronic F68 consists of two fractions with sizes of 110 ± 15 and 440 ± 15 nm, and liposomes with DSPE-PEG 2000 (2.5 mg/mL) have one fraction with an average hydrodynamic diameter of 255 ± 40 nm. The ζ potentials of the liposomes are –35 ± 15 and –60 ± 10 mV, respectively. When mononuclear blood cells are incubated with the developed liposomes for 24 h, the survival rate is found to be 84 ± 4%. It is shown that liposomes with astaxanthin esters of different compositions inactivate the ABTS cation radical 17–50% more effectively than liposomes without astaxanthin esters.

Тhe search for new materials with high conductivity and biocompatibility for use in biosensors is an important task. One promising material is bacterial cellulose (BC) due to its high surface area, high porosity, and biocompatibility. In this study, bacterial cellulose is modified with the PEDOT:PSS conductive gel and carbon nanomaterials to increase conductivity. Thermally expanded graphite/BC/PEDOT:PSS/graphene composition is used to immobilize Gluconobacter oxydans acetic-acid bacteria on the surface of a screen-printed carbon electrode. The effect of individual components of the composite on the catalytic activity of bacteria in the presence of 2,6-dichlorophenolindophenol redox mediator is studied. The addition of BC to the composition provides a higher stability of the electrode: the drop in signal within 35 days is 9%. A microbial biosensor based on TEG/PEDOT:PSS/Graphene/BC/G. oxydans composite show better sensitivity (36.4 µA mM^–1 cm^–2) and lower detection limit (0.005 mM) as well as the widest linear detection range (0.005–2 mM) compared to the other compositions. Thus, bacterial cellulose modified with conductive additives can be applied as a matrix for the immobilization of bacteria in microbial biosensors and microbial fuel cells.

Тhis work suggests ways to improve the bioavailability of low-solubility drugs by precipitation from solutions in universal solvents on nanostructured surfaces including nanoparticles (NPs) such as SiO₂ and Fe₃O₄. The same effect is found on metal-polymer composites containing Co, Ni, and Fe obtained from unsaturated dicarboxylates. In both cases, this is achieved by increasing the total desorption surface. The examples of resveratrol and of the preparation of the sum of furocoumarins Ammifurin show an increase of the relative desorption ratio of drugs by two orders of magnitude from the surface of nanostructured CaCO₃ particles into aqueous solutions. The results of MTT tests show the comparable effects of Ammifurin and of the used metal-polymer nanocomposites on HeLa cervical cancer cells and human HepG2 liver carcinoma, thereby making their combined use potentially possible. Thus, we propose a way to improve the bioavailability of a wide class of drugs, potentially applicable for all cases when the toxicity of the carrier NPs does not exceed the independent toxicity of the target substance. The possibility of the mutual enhancement of toxicity requires a separate study and is not considered here.