Effects of B vitamins on the radiation-induced transformations of hydroxyl-containing organic compounds

In this work, the interaction of B vitamins with α-hydroxyl-containing carbon-centered radicals formed upon the irradiation of deaerated aqueous solutions of ethanol, ethylene glycol, α-methylglycoside, maltose, and α-glycerophosphate at pH 7 was studied by means of continuous radiolysis. Within the framework of the density functional theory, the homolytic bond dissociation enthalpies (BDEs) of -C-H, -O-H, and -N-H bonds and H-atom addition enthalpies (HAEs) at the -C=O and -C=N groups of the test compounds were calculated. The set of the experimental and theoretically calculated data suggests that vitamin B₂, nicotinamide and pyridoxal phosphate effectively oxidize α-hydroxyl-containing carbon-centered radicals, whereas vitamins B₁ and B₆ reduce these radicals to prevent their recombination and fragmentation reactions.     

Activation Radionuclides in the Process of Irradiation of a Niobium Target at the Cyclone 18/9 HC Cyclotrone

Physics of Atomic Nuclei - The accumulation of long-lived radionuclides (LRNs) produced in water [18O]H2O under irradiation at the Cyclone 18/9 HC cyclotron with a niobium target and an input...     

Reactions of cyclopentanone, γ-butyrolactone,and their derivatives with α-hydroxyethyl radicals

The interaction of cyclopentanone, 2-cyclopentenone, 1,3-cyclopentanedione, 3-methyl-1,2-cyclopentanedione, γ-butyrolactone, 2(5H)-furanone, ascorbic acid, and 5,6-O-isopropylidenyl-2,3-O-dimethylascorbic acid with α-hydroxyethyl radicals (α-HER) generated during the radiolysis of deaerated ethanol has been studied in the continuous irradiation mode. The test compounds, except γ-butyrolactone, oxidize α-HER. 2(5H)-Furanone and 2-cyclopentenone give hydroxyethylation products via the free-radical chain mechanism. In contrast to 2(5H)-furanone and 2-cyclopentenone, ascorbic and 5,6-O-isopropylidenyl-2,3-O-dimethyl-L-ascorbic acids are weaker oxidants for α-HER and attach these radicals at the multiple carbon-carbon bonds.     

Spectroscopic and proton-acceptor properties of biologically active molecules of benzoic acid and its derivatives

We have measured the absorption, fluorescence, fluorescence excitation spectra, fluorescence quantum yields, and IR Fourier-transform spectra of aromatic acids in solutions. We have considered spectroscopic particular features of benzoic acid, its hydroxylated and methoxylated derivatives. Using quantumchemistry methods, we have calculated and interpreted electronic spectra. Data of calculations have been compared with experimental results. We have ascertained the main channels and mechanisms of photophysical relaxation processes in the molecules under study. Proton-acceptor properties of molecules of aromatic acids have been evaluated. We have analyzed in detail mechanisms by which hydrogen bonds are formed, intramolecular charge redistribution is realized, and the electron density of oxygen atoms changes. Spectroscopic indications of participation of oxygen-containing groups in intramolecular interactions and in intermolecular interactions with the formation of cyclic dimers have been revealed.     

Adhesion of Irradiated Diazoquinone–Novolac Photoresist Films to Single-Crystal Silicon

High Energy Chemistry - In this work, the effect of γ-irradiation on the adhesion properties of FP9120 diazoquinone–novolac photoresist films deposited on single-crystal silicon wafers...     

Radiation-induced modification of reflection spectra beyond the ion path region in polyimide films

Modification of the surface layers of polyimide films under γ-radiation and implantation with 30–100 keV Ni, Mn, Ag, Co, Fe and B ions in the dose range of 10¹⁵–1.5 × 10¹⁷ cm^–2 are investigated by reflection spectra measurements. Ion implantation is shown to lead to the modification of reflection from the rear (unimplanted) polymer side. Depending on the kind of ion and implantation mode a strong increase in the integrated reflection coefficient in the polymer opacity range is observed, as well as growth of the reflection intensity of optical bands λ₁ = 254 and λ₂ = 311 nm and their shifts to the short-wavelength region. The change in the reflection coefficient far beyond the implanted region is caused by the radiation-induced transformation of the polymer supermolecular structure near the surface and the relaxation of mechanical stress formed during film production.     

Comparative Dehalogenation of 1-Chloro-2-Hydroxyethane and 1-Chloro-2-Methoxyethane by γ-Irradiation

High Energy Chemistry -     

Ion Implantation in Diazoquinone–Novolac Photoresist

High Energy Chemistry - The processes of modifying the structural and optical properties of FP9120 and S1813 diazoquinone–novolac photoresist films on single-crystal silicon wafers beyond the...