Volume 58, Nº 5 (2024)

The degradation of albumin and its constituent amino acids tryptophan, tyrosine, and phenylalanine under the influence of corona discharge cold plasma, pulsed radiation of hot plasma, and 253.7-nm UV light from a mercury lamp has been studied. The concentration of products before and after treatment was determined by measuring the fluorescence yield. The reaction mechanisms leading to protein degradation are oxidation, nitration, and reduction of disulfide bonds. The degree of protein and amino acid degradation is compared with the effect of hydrogen peroxide. The possibility of assessing the bactericidal effectiveness based on fluorescence yield is discussed.

In this paper, a series of Ag_xCu_1–xGaSe₂ (0 ≤ x ≤ 1) solid solution powders were prepared by solid-phase synthesis. The single-phase tetragonal structure of the samples (space group I-42d) was determined by a combination of X-ray phase analysis and Raman spectroscopy. It is shown that their lattice parameters do not conform to the Vegard's law up to x ≈ 0.4. It is found that the width of the forbidden band of the samples also changes nonlinearly: first decreases and then increases. The study of the spectra of low-temperature luminescence and microwave photoconductivity decay has shown that for a series of samples with x from 0 to ≈0.4, and then at the section with x > 0.4, an increase in the lifetime of photogenerated current carriers in Ag_xCu_1–xGaSe₂ powders is characteristic. The observed phenomenon seems to be due to the replacement of deep traps for charge carriers, such as selenium vacancies, by smaller cationic vacancies.

A photoinitiating system based on a charge transfer complex (CTC) between a cationic sulfonium salt derivative synthesised on the basis of thioxanthene-9_–one and heterocyclic nitrogen- and sulphur-containing donor compounds of thiazole derivatives has been developed. It was found that the absorption bands of the formed CTCs lie in the blue region of the visible spectrum, and the presence of the phenolic ring in conjugation with the thiazole fragment leads to a hyperchromic effect in the absorption spectrum of the complexes. The molecular composition 1: 1 of CTC was confirmed by using the isomolar series method. The modified Benesi–Hildebrand equation was used to calculate the complexation constant (Kas (278 K) = 48.1 l / mol). Using the Vant Hoff equation, thermodynamic parameters were calculated: enthalpy (ΔH = –11.5kJ / mol), entropy (ΔS° = –9.3 J / mol∙K) and Gibbs energy (ΔG° = –8.95 kJ / mol). According to the negative enthalpy change, the reaction of CTC formation is an exothermic process. The formed complexes possess photosensitivity in the spectral region of the charge transfer band (400-500nm), which allows to use them as sensitizers of holographic photopolymer materials for recording holograms by laser radiation λ = 457nm with high diffraction efficiency ≈75 %.

The radiation-induced telomerization of tetrafluoroethylene in pentafluorochlorobenzene, pentafluorobromobenzene, and hexafluorobenzene has been studied. It has been shown that the process efficiency and the chain length of the resulting telomers depends on the binding energy of the substituent in the fluorinated benzene rings. An analysis of the IR spectra showed that changes in the molecular structure of telomers occurred under the influence of gamma radiation; these changes were expressed in the detachment of terminal benzene rings and the formation of terminal carboxyl groups. In addition, polymer chain degradation leading to the formation of telomers with a shorter chain length was observed. The hydrophobic properties of the samples of all irradiated telomers were preserved.

In papain macromolecules irradiated with γ-rays, fragments with terminal primary amino groups are formed, which appear in FTIR spectra as a broad peak with a maximum at 3440 cm^–1, as well as an intense absorption band centred at 1706 cm^–1 as a result of valence vibrations of carbonyl groups. The intensity of the absorption bands of the radiolysis products increases linearly with the irradiation dose of papain. At the same time, with increasing irradiation dose, a marked weakening of the intensity of the maxima of the absorption peaks of the peptide bond is observed, which indicates radiation destruction of the main chain of papain.

In this paper, parametric studies of kinetic processes of electrodeless high-frequency induction (HFI) and superhigh-frequency (SHF) discharges in plasma in iodine have been carried out within the framework of a global model. The dynamics of the formation of the component composition of the plasma has been obtained for different modes. It is shown that at small times an ion-ion plasma is formed, and at times from a few fractions to units of milliseconds the transition from ion-ion to electron-ion plasma occurs. The model made it possible to determine the most optimal modes of iodine plasma generation in modern electric rocket engines.