Nanoindustry

In this work, samples of selenium nanoparticles stabilized with cocamidopropylamine oxide were obtained by chemical reduction in an aqueous medium. Quantum chemical modeling of the process of stabilization of selenium nanoparticles by cocamidopropylamine oxide molecules was carried out, as a result of which it was found that this interaction is energetically favorable (∆E ≥ 2399.568 kcal/mol) and chemically stable (0.035 ≤ n ≤ 0.067 eV), and the interaction of the selenium atom with cocamidopropylamine oxide through a secondary amino group (∆E = 2400,099, n = 0.067 eV). As a result of optimization of the synthesis method, optimal concentrations of selenic acid, ascorbic acid and cocamidopropylamine oxide were determined – 0.004, 2.118 and 0.180 mol/dm³. The stability of selenium nanoparticles was also studied depending on the active acidity of the medium and the ionic strength of the solution. It has been established that selenium particles have high stability in the pH range of the medium from 1.81 to 4.56 (from 12 ± 2 nm to 24 ± 5 nm). Based on the analysis of the dependences of the average hydrodynamic radius on the ionic strength, it was found that Na⁺ and Cl^- ions do not significantly affect the stability of the particles (R varies from 12 ± 2 to 15 ± 2 nm), and selenium nanoparticles are stable when SO₄^2– ions with concentrations up to 0.5 mol/dm³ are added to the sol.

The effect of water subjected to cavitation and kept after cavitation for 8 months on the enzyme horseradish peroxidase (HRP) was studied using atomic force microscopy (AFM) and spectrophotometry (SP). No significant changes in the adsorption of HRP on freshly cleaved mica were detected compared to the control enzyme sample. On the contrary, the enzymatic activity of HRP after incubation in water subjected to cavitation 8 months ago decreased twofold. After keeping the enzyme solution in water subjected to cavitation, compared to the control enzyme sample. The detected effect should be considered in the development of biotechnological processes that involve the use of liquid media cavitation.

In this paper we study the effect of multiple martensitic transformations (thermal cycling) on an equiatomic TiNi alloy in the coarse-grained and ultrafine-grained states, considers the thermodynamic aspect of the occurrence of martensitic transformations, changes in the entropy and energy of the process. The change in the dissipative energy determines the change in the hysteresis of transformations in the CG and UFG states. It should be noted that the UFG state is characterized by a larger increase in the elastic energy of martensite plates ∆E_el^M→A. The change in ∆E_el^d energy is compared with the structure data obtained by the X-ray method and TEM. A greater increase in the density of dislocations in the CG state is also subject to an increase in the energy of defects. A slightly lower value of the dissipative energy E_dis in the UFG state and a decrease in its values in the CG state after TC confirms the data on the transformation hysteresis. The paper also presents mechanical properties and calculation of contributions to hardening in the investigated states. The calculated and experimental values of yield strength in TiNi alloy are compared.