Vol 51, No 2 (2017)

With the use of thermomechanical spectrometry in two modes, coaxial, when the load application vector is coplanar with the compacting pressure vector (semicrystalline copolymer) during the measurement of the deformation of a copolymer of tetrafluoroethylene with perfluoro(propyl vinyl ether), and mutually perpendicular (completely amorphous copolymer), it has been established that the axial compression of the copolymer brought its topological structure to an absolutely anisotropic state. After γ-irradiation, the semicrystalline structure of the copolymer was retained regardless of the radiation dose. The minimum values of the glass transition temperature of the amorphous block and the degree of crystallinity were observed in the copolymer irradiated to a dose of 150 kGy. The molecular weight distribution functions of interjunction chains in the networks of the amorphous blocks of the initial copolymer and its γ-irradiated analogs are bimodal.

The kinetics of hydrogen generation by heterogeneous hydroreactive compositions with aluminum, which was preliminarily γ-irradiated in air, held in aqueous solutions at room temperature, and annealed at a high temperature, was studied. Changes in the hydrogen generation kinetics depending on the γ-radiation dose, the composition of aqueous solution, and the temperature are caused by the conversion of aluminum oxide coatings, which should be taken into account in the prediction of the corrosion resistance of structural materials under the conditions of exposures at nuclear power plants.

The molecular–topological structure of a copolymer of tetrafluoroethylene and perfluoro(propyl vinyl ether) subjected to γ-irradiation and thermal annealing has been studied for the first time with the use of thermomechanical spectrometry. The pseudonetwork structure of the copolymer contains an amorphous block (interjunction chains) and crystalline segments (branching points). The diblock amorphous and crystalline structure with a crystal structure fraction of 0.21 transformed into an almost completely amorphous structure with a crystallite fraction of 0.06 after the irradiation of the copolymer at a dose of 600 kGy. Thermal annealing at 483 K formed a new structure: a high-temperature amorphous block.

A spectral-luminescence study of neutral (pH 7) and alkaline (pH 11 and 14) aqueous solutions of the anticancer drugs 5-fluorouracil (FU) and tegafur has been performed. The fluorescence spectra of the N3- and N1-centered anions of 5-fluorouracil, its dianion, and the tegafur monoanion with emission maxima at wavelengths (λ_em) of 358, 372, 366, and 358 nm and photoluminescence quantum yields (φ) of 11.2 × 10^–4, 35.1 × 10^–4, 26.5 × 10^–4, and 8.6 × 10^–4, respectively, have been recorded for the first time. The fluorescence characteristics of the FU anionic forms have been related to the magnetic shielding constant as one of the criteria of aromaticity.

Luminescence decay curves have been measured for InP@ZnS colloidal quantum dots (CQDs) synthesized at different ratios between 1-octanethiol and 1-dodecanethiol. The luminescence lifetime distributions reflecting the ratios between the on, off, and grey states of CQDs have been calculated. With an increase in the portion of 1-octanethiol, the distribution is shifted toward the on states, which almost completely suppresses fluorescence blinking at all detection wavelengths.

The effect of pressure in a plasma reactor on the synthesis of mixtures of H₂O₂ and ClO₂^- has been studied. The yield of oxidants, selectivity for chlorites, the rate of the process, and its energy consumption have been treated as optimization parameters. Functional dependences of the optimal time of the plasma treatment of NaCl solutions on the reactor pressure with respect to parameters, such as the process selectivity and chlorite yield, have been determined.

Processes occurring in a metal melt during plasma-assisted melt gasification of carbonaceous feedstock have been studied in the mode of alternating feeding the reactor with the carbonaceous feedstock and oxidant. Vacuum residue was used as an oxygen-free carbonaceous material, and air and steam were used as an oxidant. The results of the study show that by alternating the carbonaceous-feedstock pyrolysis step and the step of carbon oxidation in the metal melt, it is possible to produce synthesis gas with any desired H₂/CO ratio.

It has been found that ultrasonic irradiation of graphite in N-methylpyrrolidone is accompanied by the formation of polymer nanoparticles. These particles form aggregates with n-layered graphene particles, the formation of which prevents graphene particles from precipitation during centrifugation.