Changes in the composition of the surface layer of Nevaflon polyvinylidene fluoride film after treatment in gas discharges of various types (glow, dielectric barrier, corona) have been studied. The influence of the discharge type on the kinetics of etching and surface modification of polyvinylidene fluoride is shown. It has been found that the plasma treatment of polyvinylidene fluoride leads to a change in the modified surface layer of the polymer.
The effect of gamma radiation dose on the structure of an ethylene–tetrafluoroethylene copolymer has been studied. The copolymer powder has a triclinic crystal structure with space group P-1 and unit cell parameters of a = 8.84 Å, b = 5.34 Å, c = 4.90 Å, α = 99.11°, β = 85.84°, and γ = 90.89°. The coherent scattering region of the copolymer linearly increases from 4.3 to 6.8 nm with an increase in the absorbed gamma radiation dose to 2000 kGy. The degree of crystallinity of the copolymer decreases by 2.1% after irradiation with a dose of up to 100 kGy; after that, with an increase in the dose to 2000 kGy, the degree of crystallinity increases. The absence of significant changes in the crystal structure parameters of the copolymer after irradiation with a dose of up to 2000 kGy suggests that the copolymer crystal structure is resistant to radiation.
Chitosan (CS) was selected as the carbon source, and the Chitosan/dicyandiamide (CS/DCDA) precursors with hydrogen bonding interactions were prepared by freeze-drying and normal drying, and the carbon-Chitosan/graphite carbon nitride (C-CS/g-C3N4) composites were obtained after calcination. The results show that the freeze-drying process can produce more hydrogen bonding interaction between chitosan and dicyandiamide (DCDA) and more pores through recrystallization. More composite carbon is formed in the C-CS/g-C3N4-2 composite obtained after calcination. More hydrogen bonds are broken, releasing more N lone pairs of electrons, which not only facilitates the n−π* electron leap, but also facilitates the separation and photogenerated electron-hole, and provides a large number of reactive sites for photocatalytic degradation of pollutants. This results in better photocatalytic performance of C-CS/g-C3N4-2.
The radiolysis of malondialdehyde (MDA) in acidic (pH 3) and alkaline (pH 11) aqueous solutions has been studied using UV spectrometry, HPLC, and chemical analysis. It has been found that in an acidic medium, the radiation-chemical yield of degradation of MDA at concentrations greater than 3 × 10–4 mol/L exceeds 10 molecule/100 eV, indicating the occurrence of chain processes. It has been established that dissolved oxygen plays an important role in the chain process of MDA decomposition. A system of reactions was proposed to explain the results of the experiments.
The paper is dedicated to the numerical study of the dependence of plasma antenna resonance wavelengths on pressure. The study was carried out by simulating a RF capacitively coupled plasma with the Comsol Multiphysics software in one- dimensional formulation. Based on the calculated electric current in the plasma, the directional pattern and axial distribution of the electromagnetic field were found by solving Maxwell’s equations in a 2D formulation. The results showed that one of the advantages of plasma antennas is the transmission of waves at significantly longer wavelengths compared to metal antennas of similar geometry.
In this paper, the PVDF-g-PAMA membrane was prepared through gamma-ray irradiation in a monomer aqueous solution. The irradiation products’ chemical composition was examined by Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS), and the spectra confirmed that poly (allyl methacrylate) (PAMA) was successfully grafted onto polyvinylidene fluoride (PVDF) molecular chain to form the PVDF-g-PAMA membrane. The CA of the PVDF-g-PAMA modified membrane was reduced compared with the traditional PVDF membrane, indicating that the hydrophilicity and anti-fouling performance of the membrane had been improved. The output water of domestic sewage treated by the integrated MBR equipment with PVDF-g-PAMA membranes as the core component was stable, and the effluent quality was also improved. After examining the overall costs associated with using PVDF and PVDF-g-PAMA membranes, it was discovered that even though the complicated preparation process for modified PVDF-g-PAMA by gamma-ray irradiation increased the initial cost, its potent anti-fouling capabilities effectively reduced the cost of subsequent operation and maintenance, leading to a significant decrease in overall cost of project.
Calculations of electron–nuclear alignment (CIDEP multiplet effect) in radicals formed as a result of the photochemical decomposition of molecules have been performed. There is a mutual ordering of spins in the radicals: the electron and nuclear spins in the radical are oriented parallel or antiparallel. The populations of stationary states of radicals in weak magnetic fields have been calculated in the framework of the kinematic approach.
A quadratic dependence of the charge diffusion coefficient on the diameter of colloidal quantum dots (CQDs) has been established. The charge diffusion coefficient is shown to depend weakly on the polydispersity of a sample. It has been determined that a decrease in the root-mean-square displacement of a charge carrier is an exponential function of the thickness of a ligand shell and the relative fraction of particles that can become charge traps. An explanation has been proposed for the exponential dependence of the conductivity of PbS CQD layers on the CQD size, which consists in a decrease in the fraction of CQDs acting as charge carrier traps.
The hydrogenation of 2-amino-4-methyl-6-nitrophenol, 2-chloro-4-nitrophenylformamide, 4рnitro-m-xylene, 2-nitro-m-xylene, o-bromonitrobenzene, o-nitroethylbenzene, p-nitroaniline, 1-(3-nitrophenyl)-3-(4-nitrophenyl)urea, 1-(2-methoxy-4-nitrophenyl)-3-(2-methoxy-5-nitrophenyl)urea, pрnitrophenol, o-nitrophenol, 5-(3-nitrophenyl)-2,3,7,8,12,18-hexamethyl-13,17-di-n-butylporphine, 5р(4-nitrophenyl)-2,3,7,8,12,18-hexamethyl-13,17-di-n-butylporphine, 5,15-bis(4-nitrophenyl)-3,7,13,17-tetramethyl-2,8,12,18-tetra-n-butylporphine and 5,10,15,20-tetrakis(3-nitrophenyl)porphine in the presence of palladium-containing aminated activated carbon has been studied under mild conditions (solvent, ethanol; T = 25–45°C; and ({{P}_{{{{{text{H}}}_{2}}}}}) = 1 atm). It has been found that strong substituents of the first kind in aromatic nitro compounds accelerate the hydrogenation of the nitro group and the hydrogenation of porphyrins containing nitro groups on the periphery of a macrocyclic ring afford the corresponding amino derivatives.
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