Vol 74, No 5 (2019)

The influence of the concentration of an external solution, the nature of the polar groups, and the amount of cross-linking in the resins on the degree of swelling of the ionites synthesized based on the polystyrene cross-linked by divinylbenzene is investigated. It is shown that the share of the volume of the external solution in an ionite depends only on the amount of cross-linking and is independent of the nature of the polar groups and the composition of the external solution. The dependence of the share of the volume occupied by the external solution in the swollen ionite on the percentage of divinylbenzene is determined. The model of the polymer matrix in which the concentration of the external solution affects the degree of polymer swelling but does not affect the volume of the external solution in the granule is proposed. It is shown that the “sandwich” model of the polymer matrix is most convenient for describing the properties of polymer gels in which the concentration of the external solution affects the degree of swelling of the polymer but does not affect the volume of the phase of the external solution in the granule.

A chimeric form of Penicillium verruculosum endo-1,4-β-glucanase II (EGII), the C-terminus of which contains a cellulose-binding module (CBM) of P. verruculosum cellobiohydrolase I, is produced by the genetic engineering method. In the native form, the eglI gene does not have a region encoding CBM. The resulting chimeric enzyme is isolated in a homogeneous form and its properties are studied. The addition of CBM to EGII led to a significant increase in the activity of the chimeric enzyme relative to microcrystalline cellulose (MCC) and the appearance of its adsorption capacity in relation to cellulose. However, the addition of CBM to EGII led to a decrease in activity towards soluble polysaccharide substrates (carboxymethylcellulose and β-glucan). The chimeric form of the enzyme in the composition of the cellulase complex allowed us to hydrolyze cellulose-containing substrates more effectively. The yield of reducing sugars (RS) in the case of MCC hydrolysis after 24 h with a cellulose complex containing cellobiohydrolase I, β-glucosidase, and EGII-CBM in comparison with a complex containing EGII without CBM increased by 22%, while for chopped aspen wood the RS increased by 42%.

Numerical simulation of localized plasmon resonances for an elliptical gold nanodisk 300 × 400 nm in size and 20 nm in thickness with two cylindrical holes 140 nm in diameter is carried out. Plasmon modes excited by light with longitudinal and transverse polarization are studied. The sensitivity of the dipole mode wavelength to changes in the dielectric constant of the medium is higher with longitudinal polarization and reaches values of the order of 1800 nm/RIU.

The transformation routes of allyl phenyl sulfide are calculated within the density functional theory (B3PW91/6-31G** quantum chemical approximation). We found that the chair conformation is a transition state of the first stage (the conversion of allyl phenyl sulfide into 6-(prop-2-en-1-yl)cyclohex-2,4-dien-1-thione). The second stage involves the interaction between thione and either allyl phenyl sulfide and allyl thiophenol molecule or with a second thione molecule. The cyclization of allyl thiophenol implies the formation of methyl thiocumaran. The thermal isomerization of allyl phenyl sulfide to propenyl phenyl sulfide is improbable.

Sorption of phenol, 4-nitrophenol, pentachlorophenol, and nonylphenol is studied using a magnetic sorbent based on Fe₃O₄ nanoparticles modified with humic acids (HAs) isolated from various natural sources (brown coal, peat, chernozem, and sapropel). The properties of the resulting sorbents, namely, specific surface area, saturation magnetization, and content of hydroxyl and carboxyl groups, as well as nitrogen, are studied. The best conditions for the extraction of all phenols are achieved at pH 3–6, except for pentachlorophenol, for which the highest degree of extraction is achieved at pH 3–4. The maximum recoveries of phenol, 4-nitrophenol, pentachlorophenol, and nonylphenol are 61, 68, 89, and 94%, respectively.