AbstractLong-term field studies of the effect of presowing seed treatment of spring wheat (Triticum aestivum L.) with XeCl-excilamp UVB radiation on sowing qualities of seeds and plant productivity have been carried out. The features of morphogenesis at various stages of growth and development of wheat plants have been determined. A subdose of exposure has been identified that increases the crop yield. The studies prove the prospects of introducing UVB treatment into the pool of modern agricultural technologies.

AbstractData on microporosity (micropore size distribution) in the range from several angstroms to several nanometers, obtained by measuring the positron annihilation lifetime (PALS method) and by measuring CO2 sorption (low-temperature gas sorption, LTGS) are collated for a number of polymers with amorphous (polyetherimides, PEI) and semicrystalline (polyphenylene oxides, PPO) structures. The microporosity estimates based on the positron annihilation and CO2 sorption data are compared with published data obtained both experimentally and by the group contribution method for the permeability of these materials. The discrepancies found and their possible causes are discussed.

AbstractThe influence of the dose of presowing γ-irradiation of tubers on the anatomical and morphological structure, yield, and tasting properties of potatoes of the Meteor variety has been studied. Morphological disorders—beak-shaped and heart-shaped tubers of a large fraction and small tubers in the form of embryos—were found in potatoes grown from tubers irradiated with doses of 500–600 Gy, although no external anatomical and morphological differences were noted in the stems and leaves of potato plants in the course of the vegetative development regardless of the presowing irradiation dose of tubers. Irradiation of seed tubers with doses of 200–300 Gy led to the highest yield and profitability and the best tasting qualities of grown potatoes. Experiments on the toxicity of potato tubers irradiated with doses of 100–1500 kGy and juice released during their radiolysis with doses of 1200–5000 kGy showed no negative effect on the animals that consumed them. At the same time, the physiological processes of digestion, excretion, and metabolism in experimental animals were not inhibited and the level of glucose in their blood remained within physiological reference values. The experimentally established highest doses of γ-irradiation of potatoes and the doses of introducing aqueous dispersions of the irradiated products into mice (gram of substance per 1 kg of live weight of the animal) that did not cause clinical manifestations were 10 g/kg for powdered potato tubers irradiated with a dose of 1500 kGy and 20 g/kg for dried juice powder released in the course of irradiation of potato tubers with a dose of 2000 kGy.

AbstractThe nitration of phenol with plasma-activated water (PAW) generated by pulsed radiation of an electric spark discharge has been studied. Long-lived nitrogen-containing active species that accumulate in water during treatment are nitrous acid and the …ONOOH/ONOO− complex, which decomposes into peroxynitrite and peroxynitrous acid. Their concentration in PAW after 10 min of treatment was ~10−3 mol/L. When PAW is mixed with phenol in a 1 : 1 ratio, the identified reaction product is 4-nitrophenol. The yield of nitration through PAW is equal to the nitration yield by the direct action of hot plasma radiation on a phenol solution.

AbstractThe plasma-induced conversion of small ethanol impurities in argon in a nonequilibrium atmospheric-pressure glow discharge has been studied. Simulation results show that the dominant species resulting from ethanol conversion are CO, H2, H, CH4, C3H3, C2H2, C2H4, and C2H5. In addition, the formation of molecular carbon particles and significant concentrations of CH3 and CH2 radicals, which are precursors of aminodiamonds, has been revealed.

AbstractThe applicability of laser ablation of metal targets for obtaining triply charged ions of metal atoms, including low-melting metals, has been experimentally demonstrated. By analyzing the luminescence spectra of a plasma plume during laser ablation of a metal target immersed in superfluid helium, the main channel for the formation of helium ions in plasma at a laser beam power density below the breakdown threshold of the helium medium has been determined. It has been shown that the ionization of helium atoms occurs in two steps, the formation of the HeM3+ ionic complex and the dissociation of the complex via its interaction with a metal atom.

AbstractThe aim of this study is to examine methane (CH4)/nitrogen (N2) gas mixture plasma surface modification for various polymers including in polytetrafluoroethylene (PTFE), polystyrene (PS), polycarbonate (PC), and high-density polyethylene (HDPE). The static wetting properties of methane (CH4)/nitrogen(N2) plasma deposited films on conventional polymers were investigated using the sessile droplet method. The change of hydrophilicity and surface free energy was monitored by static contact angle measurement. The static contact angle is an excellent indication of the change in surface state properties from plasma surface modification. A new quick image-capturing device enables static contact angle measurement 2 to 4 seconds after contact with the polymeric surface. Significant increases in the surface energies of PTFE, PS, PC, and HDPE by CH4/N2 mixture gas plasma treatments were observed. The experimental results show the critical position of chemical species in the interaction between CH4/N2 mixture gas plasma and the polymeric substrate, which can be controlled by surface modification to tailor the hydrophilicity of the polymers.

AbstractPhotoprocesses in aqueous solutions of the styryl dye 1-ethyl-4-{(E)-2-[4(methylthio)phenyl]vinyl}pyridinium perchlorate (1) and its complexes with cucurbit[n]urils (CB[n], n = 6–8) have been studied using the methods of stationary and time-resolved optical spectroscopy. The fluorescence intensity increases by approximately 3 times in 1 : 1 complexes of 1 and CB[6], whereas CB[7] has almost no effect on the fluorescence intensity. In 2 : 1 complexes with CB[8], the photocycloaddition reaction does not occur, with strong fluorescence quenching being associated with the formation of nonreactive dimers. The fluorescence decay kinetics of 1 has two characteristic times, 1.4 and ~130 ps, and changes little in the complexes. The photoinduced intramolecular charge transfer in 1 is an order of magnitude smaller than in the well-known dye DASPI.

AbstractThe kinetic features of change in the strength of oriented polypropylene (PP) as a result of radiation oxidation have been established. The relationship between the change in the strength of oriented PP (slit-film yarns) after irradiation in air and the structural characteristics of the polymer is shown. A kinetic model is presented that takes into account the supramolecular (fibrillar) structure of the oriented polymer and the kinetic features of radiation-induced oxidation.

AbstractIn poly-N-epoxypropylcarbazole films containing 10 wt % CHI3 as an additive, diffraction gratings with a period of about 1 μm have been recorded by electron-beam irradiation at various radiation doses. The influence of the duration of storage in the dark of diffraction gratings on their diffraction efficiency has been examined. A postradiation increase in the diffraction efficiency of gratings recorded at relatively low electron radiation doses was observed. The diffraction efficiency values stabilized approximately on the sixth day after recording the diffraction gratings.

AbstractNanocomposites based on aqueous polyurethane latex and graphene oxide have been synthesized and characterized. The structure and composition of the nanocomposites were studied using elemental analysis, optical microscopy, IR spectroscopy, DSC, and thermogravimetry. The nanocomposites showed higher thermal stability and increased mechanical strength compared to those of the original polymer. It has been established that the Young’s modulus of latex films after the introduction of 2 wt % graphene oxide increased by a factor of almost 6. In this case, the fracture stress decreased only slightly by 10–15%. The influence of the particle size of graphene oxide on the mechanical properties of the composites was found, namely: composites with larger particles of graphene oxide had a higher Young’s modulus, and their relative elongation at break decreased.

AbstractThe γ-radiolysis of 2-fluoroethanol-1, 2,2,2-trifluoroethanol-1, 3-fluoropropanol-1, and 4,4,4-trifluorobutanol-1 in aqueous solutions in an inert atmosphere or in the presence of oxygen has been studied. It has been found that the dehalogenation of hydroxyl-containing organic compounds is induced by •ОН and Н• radicals rather than hydrated electrons. The carbon-centered α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH are defluorinated much more efficiently than α-fluoroalkyl radicals, both vicinal (F–•CHCH2OH) and nonvicinal (F–•CHCH2CH2OH). In the absence of oxygen, α-fluoroalkyl radicals eliminate fluoride ions by the mechanism of nucleophilic substitution, and this process is enhanced in the presence of alkali. In an oxygenated medium, the dehalogenation of α-fluoroalkyl radicals occurs via the addition of oxygen molecules to them and the subsequent disproportionation of resulting peroxyl radicals. The dehalogenation of the α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH is inhibited by oxygen through their oxidation.

AbstractThe effect of γ-radiation doses from 100 to 3000 kGy on the toxic properties and germination of oat seeds has been + studied. A tendency has been noted for a 15–25% decrease in the germination of oat seeds under laboratory conditions in the range of presowing irradiation doses of 10–700 Gy. After irradiation with a dose higher than 1 kGy, the seeds lost their ability to germinate. Curves reflecting the dependences of the length of oat stalk on the dose of presowing irradiation of seeds exhibited two areas with a characteristic separation point at doses of 70 Gy, below which the degree of influence of the irradiation dose on the height of seedlings and their growth ability increased noticeably. The toxicity of radiolyzed oat grains depended on the dose of γ-irradiation of grains and the mode of additional feeding of experimental mice. It was established that a γ-radiation dose lower than 100 kGy did not affect the toxicity of fodder oat grain, and radiation doses of 400 kGy or higher made irradiated grains unsuitable for feeding mice without additional feeding with compound feed. The higher the dose of γ-irradiation of oat grain, the earlier experimental mice died en masse: after 14–15, 9, 8, and 6 days of feeding at radiation doses of 580, 1000, 1700, and 3170 kGy, respectively. The reason for the toxic manifestation of irradiated oat grains and the death of mice treated with irradiated grain, apparently, can be the formation of toxic substances in oat grains irradiated with high doses due to the occurrence of physicochemical reactions in the course and after irradiation and a decrease in the nutritional value of products associated with the destruction of vitamins and other food components. Intoxication after consumption of oat grains irradiated with a dose of 400–3170 kGy was clinically manifested by depression, lethargy of animals, and signs of dehydration and diarrhea against the background of a strong decrease in the body weight of experimental animals. It is expedient to use radiolyzed oat grains for technical purposes, especially, if they were treated with high doses of radiation.

AbstractThe spectral fluorescence characteristics of 5-aminouracil (5AU) and 6-aminouracil (6AU) in neutral and alkaline aqueous solutions have been studied. With the use of the density functional theory, it has been shown that uracils preferentially dissociate at the N1–H bond. The acid–base equilibrium constants pKa1(5AU) = 9.4 and pKa1(6AU) = 8.95 were determined by a fluorescence method. It was concluded that the ultrashort lifetime of the excited singlets of 5AU and 6AU prevents the measurement of the acid–base equilibrium constant of uracils in an electronically excited state.

AbstractThe possibility of using semiconductor nanocrystals in photodetectors for optical detection of open flame has been explored. The spectral range boundaries of response of flame detectors have been concretized. In accordance with this, colloidal lead sulfide nanocrystals absorbing in the range of 1–1.5 µm have been synthesized. Photoresistors with different ligand compositions have been made from these particles. For the obtained samples, the current–voltage characteristics were measured and the photosensitivity and specific detectivity parameters were calculated. A theoretical estimate of the flame detection range has been made for the samples. It has been shown that a photosignal can be reliably detected at a distance of more than 80 m.

AbstractLong-lived delayed fluorescence of dispersions of microcrystals of naphthalene–β-cyclodextrin–cyclohexane ternary complexes has been studied. It has been established that the delayed fluorescence is due to the T–T annihilation process. The kinetics of delayed fluorescence has a nonexponential character; the average lifetime is 0.68 s. The shape of the decay rate curves of delayed fluorescence does not depend on the intensity of excitation light. The nonexponential nature of the delayed fluorescence is presumably associated with the presence in the crystals of paired naphthalene molecules with different mutual positions and pair formation energies.

AbstractIt has been shown that for obtaining hydrophobic coatings, it is reasonable to use fluoroalkylalkoxysilanes (FASs) with a longer fluoroalkyl chain than FAS-19, so that the F/Si molar ratio exceeds 5–6. It is proposed to purposefully change not only the chain length of oligomers, but also the structure of solutions from dilute colloidal solutions to structured gels, with the F/Si ratio being controlled. In the case of polycondensation of investigated fluoroalkylalkoxysilanes on a hydroxylated surface, a strong silicone framework is formed, which is chemically bonded to the surface and to fluoroalkyl chains oriented perpendicular to it.

AbstractThis paper reports on the study that gamma-ray irradiation-induced polymerization of N-isopropyl acrylamide (NIPA) to form Poly(N-isopropyl acrylamide) (PNIPA), which was then grafted on the surface of polyvinylidene fluoride (PVDF) membrane to prepare modified PVDF-g-PNIPA membrane. We analyzed the influence of different irradiation doses and dose rates on the grafting rate of modified membranes, and the grafting rate increased with the irradiation dose under a certain irradiation dose. Through analysis of Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA), the efficient progress of the grafting reaction was confirmed. With the increase of the grafting rate, the pore size of the membrane surface decreased gradually, but the surface roughness of the membrane tended to increase through the analyse of scanning electron microscopy (SEM) and atomic force microscopy (AFM). Finally, a mechanistic explanation for the grafting of PNIPA on the surface of PVDF membranes based on these experimental results was proposed.

AbstractThe influence of the mixture composition on the electrophysical parameters and plasma emission spectra of mixtures of tetrafluoromethane and trifluoromethane with nitrogen under dc glow discharge conditions has been analyzed. It has been established that the reduced electric field strength changes nonlinearly with an increase in the proportion of the second gas in both mixtures. The reduced intensity of atomic fluorine emission in the CF4/N2 mixture is shown to pass through a maximum at a nitrogen volume fraction of 0.2, whereas a monotonic change in this dependence is observed for the CHF3/N2 mixture. The reduced emission intensities of CF2 radicals decrease monotonically with an increase in the nitrogen fraction in both mixtures.

AbstractThe mechanism of oxygen atom transfer between triplet molecules of a nitro compound and dimethyl sulfide is considered. This reaction pathway can be one of the possible routes in the reaction of photochemical oxidation of the sulfur compound. Quantum-chemical modeling has shown the feasibility of such a reaction as having a fairly low activation energy. The transition states of the reaction have almost the same structure in various solvents. The calculation of spin densities and charges on atoms in transition states has shown no significant charge separation. This finding is also confirmed by calculation of the activation parameters of the oxygen transfer reaction involving various solvents. The activation energies remain almost unchanged with an increase in the solvent permittivity. All the data obtained suggest the radical mechanism of oxygen atom transfer with the participation of the triplet nitro compound.