Nanotechnologies in Russia最新文献

Preparations based on silybin are used as hepatoprotectors in the treatment of liver lesions of various etiologies. The main disadvantage limiting their use is low bioavailability associated with the low solubility of silybin in water. To solve this problem, numerous delivery systems are created that increase its solubility, including those based on biodegradable polymers. This study presents a method for producing a polymer composition containing silybin (PCS) based on copolymers of lactic and glycolic acids. The content of the active ingredient in the product is 5%, its entrapment efficiency in particles is more than 90%; the Z-average particle size in an aqueous suspension is about 200 nm, the polydispersity index is less than 0.2, and the zeta potential is from ‒1 to ‒5 mV. The high antioxidant activity of silybin in the polymer composition by galvanostatic coulometry, as well as in the reaction of the nonenzymatic autoxidation of adrenaline, is shown. In an in vivo study on a model of acute toxic hepatitis induced by carbon tetrachloride, the more pronounced hepatoprotective effect of PCS is found compared with free silybin.

Remagnetization processes of amorphous glass-coated microwires have been studied using First Order Reversal Curve (FORC) analysis. This method allows us to study the magnetostatic interactions in these samples. The number, shape, size, and location of the peaks in the FORC diagram can provide information about the different remagnetization processes of the microwires and their system. The sign of magnetostriction of the sample strongly influences the type of FORC diagram. The remagnetization process also depends on the mechanical stresses at the ends of the Fe-based microwire. This dependence tends to zero with increasing wire length. For Co-based samples, the effect of the demagnetization factor on the FORC diagram has been described. In addition, the magnetostatic interactions for a system of densely packed microwires with positive magnetostriction are visualized in this work.

The large-scale commercialization of polymer electrolyte membrane (PEM) water electrolyzers is still constrained by their high capital cost, which is largely associated with the use of noble metal-based electrocatalysts. There is an urgent need to reduce their loading in the composition of electrocatalytic layers. In the present work, an approach of the microporous sublayer made of titanium nitride (TiN_x) and formed over the anode surface by magnetron sputtering is proposed. It contributes to an increase in the anode electrocatalyst utilization, opening up wide possibilities to reduce its loading.

In this work, a three-component system is obtained based on gellan, a graft copolymer of pullulan with side chains of poly(2-methyl-2-oxazoline), and CaCl₂, which is capable of forming gels upon contact with an aqueous solution of NaCl. Such a composition can be used for medical purposes, in particular for the treatment of ophthalmological diseases. In this work, the molecular characteristics of the initial components of the gel are obtained and its viscoelastic properties are studied. It was established that graft copolymers of pullulan with poly(2-methyl-2-oxazoline) are integrated into the gel composition, while an increase in their proportion reduces its elastic properties. The obtained gel retain elastic properties upon heating up to 70°C.

The data obtained for the first time on the influence of the sequence of metal deposition and the conditions of formation of the Re-containing component on the properties of a series of catalysts 1.9 wt % Pt–1.8 wt % Re/Ce_0.75Zr_0.25O₂ in the water gas shift reaction are presented. It is shown that catalysts in which platinum is deposited first have a content of both metals close to the expected level and make it possible to achieve the maximum CO conversion at a lower temperature compared to a monometallic platinum catalyst. Based on the data on CO chemisorption and calculations of the reaction rate per platinum surface area, it is assumed that the role of the Re-containing phase is to a greater degree related to the stabilization of a highly dispersed platinum state, rather than to participation in the catalysis of the reaction.

Proton exchange membrane (PEM) water electrolysis allows the production of green hydrogen using renewable but unstable energy sources such as wind or solar power. The lifetime assessment of a PEM water electrolyzer and its components require lengthy and costly testing, so there is a need for the development and application of accelerated stress-testing methods, which allow the accelerated investigation of degradation processes occurring under realistic operating conditions. In this study, the dynamic cycling and constant operation of the membrane electrode assembly of a PEM water electrolyzer at elevated voltages are considered as two methods of accelerated stress testing. The degradation depth, its distribution, and mechanisms are studied using electrochemical impedance spectroscopy, polarization curve breakdown into voltage losses components, and scanning electron microscopy. The greatest depth of degradation (up to 133 mV) is achieved during continuous operation of the membrane electrode assembly at elevated voltage, due to the anode porous transport layer (PTL) surface passivation and slow oxygen transport in its porous structure. The degradation depth of the membrane electrode assembly after dynamic cycling is found to be significantly lower (7–20 mV), and is related to degradation of the catalyst layer, with the decrease of mass transport losses being significantly responsible for the decrease in the overall degradation rate observed at high current densities. The influence of the anode catalyst loading reducing and the Ti-hydride protective coating on the surface of the anode PTL on the degradation of the PEM water electrolyzer is also considered. The use of a protective coating on the surface of the PTL provides the formation of a compact anode catalyst layer with a developed interface between the catalyst layer and PTL even at the reduced anode catalyst loading.