Controlled thermal degradation of high-molecular-weight poly-3-hydroxybutyrate (PHB) was studied in dimethylformamide (DMF), bromoform, tetrabromoethane, and trichloropropane. Samples with molecular weights of 1.6 kDa and higher were obtained. PHB degradation in pure DMF and in trichloropropane resulted in the formation of C-terminal crotonic acid residues at the sites of polymer chain scission. In the case of bromoform and tetrabromoethane, 3-bromobutyric acid residues were formed (61–68

The research of biochemical thermo- and salt-sensitive markers - long-chain alkenones in sediments of lakes of the North Minusinsk valley is an important contribution to the understanding of climatic changes in this region. We found that the total concentration of alkenones in the top layers of bottom sediments of saline lakes increases significantly at a salinity of about 20 g l-1. Also, it was found that the average chain length of alkenones in the surface sediments rises with increasing salinity and thus can be used as an indicator of salinity, and the ratio of alkenones C37/C38 varies widely, suggesting that this index can be used as a paleo-indicator of salinity. The high correlation between ,  and  indices with salinity indicates their potential for paleosalinity reconstruction. The obtained functional dependences were additionally verified in the core of bottom sediments of Lake Utichie-3 and confirmed the possibility of using alkenones as a paleo-indicator of climatically determined salinity changes in endorheic lakes. The taxonomic composition of haptophyte algae and alkenone composition in the studied lakes were comparable to lakes in prairie regions of North America.

Isothiocyanates (ITCs) are substances formed in the result of hydrolysis of glucosinolates and widely found in plants of the cruciferous and Solanaceae families. ITCs are used in agriculture, medicine and the food industry. This article describes the preparation of complexes based on 3 types of ITCs (allyl isothionate (AITC), benzyl isothionate (BITC) and 2-phenylethyl isothiocinate (PEITC)) and their effect on ecologotrophic groups (ETG) of forest soil microorganisms. It has been proved that the deposition of ITC in bentonite contributes to the prolonged release of AITC, BITC, PEITC and reduces the time of their hydrolysis in the soil. Application of free forms of ITC decreased the number of ammonifiers by 2.6 times (when AITC was added), increased the number of nitrogen fixers up by 1.2 times (when BITC was added), and decreased the number of actinomycetes by 21, 1.4 and 1.9 times when AITC, PEITC and BITC were used, respectively. The number of micromycetes increased only when PEITC and BITC were introduced into the soil. The introduction of ITC/bentonite complexes into the soil resulted in a significant decrease in the number of ammonifiers for AITC/bentonite and PEITC/bentonite samples. The introduction of AITC/bentonite complex into the soil increased the number of nitrogen fixers, actinomycetes and micromycetes. The deposition of PEITC and BITC in the bentonite also led to an increase in the number of micromycetes and nitrogen fixers, respectively, which is most likely due to their low concentrations in contrast to free ITC.

Biomarkers of the presence of animals and humans (fecal stanols) are well preserved in lake sediments. They are produced by intestinal microflora from sterols. Coprostanol and epicoprostanol are specific human stanols, since they are produced in the greatest quantities when compared to animals. These stanols are used to reconstruct the population history of water bodies. In this work, fecal stanols have been studied for the first time in the bottom sediments of Lake Zapovednoye, located in Evenkia (Siberia, Russia). The analysis is carried out using a gas chromatograph with a mass spectrometric detector. Along the entire core, there are no pronounced signals of coprostanol and epicoprostanol compared with other stanols, which indicates a negligible contribution of humans to the pool of fecal stanols. It is obvious that throughout the entire studied time interval (up to 2500 years ago) there were no permanent settlements in the lake’s drainage basin, which is generally consistent with the extremely low population density of this region and unfavorable living conditions.

Potato cyst nematode (PCN) poses a great challenge for potato cultivation throughout the world. Being a rather difficult parasite due to a number of its physiological features, specifically a long-term viability of the eggs, PCN causes drastic damage to worldwide agriculture. Development of long-acting preparations deposited with nematicidal ingredients could be a novel prospective approach for PCN management. In this work, composite granules based on polycaprolactone and montmorillonite (PCL/MMT) (100:0; 90:10; 75:25; 50:50) were studied as carriers for oxamyl nematicide (~ 10 wt.% of granules). It was shown that the obtained granules are able to maintain the activity of oxamyl for 20 days and facilitate its gradual release. The maximum release of oxamyl was noted for PCL/MMT 50% granules and amounted to 82.6 µg/ml. The nematicidal effect of PCL/MMT 50% granules with oxamyl against G. rostochiensis has been demonstrated on potato variety "Krasnoyarskiy ranniy".

Oligomers of poly-3-hydroxybutyrate (PHB) were prepared by aminolysis of high molecular weight PHB with ethylenediamine and 1,4-diaminobutane. Polymer-oligomer blends (10, 30, and 50% content of the oligomers) were prepared as films by solution casting. As the content of oligomers increased, a gradual increase in the hydrophilicity of the polymer surface was observed, resulting reflected in the water contact angle decrease from 84° to 72–76°. In addition, a moderate decrease in elongation at break, Young's modulus, and tensile strength for the blends were observed as more oligomer was added to the film. Finally, the viability of NIH-3T3 mouse fibroblasts was higher compared to intact PHB when growing in non-prepared polymer/oligomer mixtures. These findings confirm the benefits of the introduction of a hydrophilic functionalized oligomer into the PHB matrix in terms of improving the biocompatibility of the resulting polymer/oligomer blends.

In this study, the characteristics of extruded granules based on biodegradable poly-ε-caprolactone and montmorillonite deposited with allylisothiocyanate and their effect on Globodera rostochiensis RoI were investigated. The prepared granules were characterized using Fourier-transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. It was shown that encapsulation efficiency of allylisothiocyanate in montmorillonite depends on the conditions of complex preparation and ranges from 0.76 to 29.83%, and in poly-ε-caprolactone/montmorillonite/allylisothiocyanate granules after thermal processing it decreases down to 1.06 %. According to the results of Fourier-transform infrared spectroscopy it was found that allylisothiocyanate inclusion did not result in formation of new chemical bonds, but significantly affected the temperature of poly-ε-caprolactone degradation that decreased from 537 to 472 °С. In comparison with the thermogram of montmorillonite, the weight loss corresponding to dehydration at 100 °С decreased by 2.9 %, which probably means that part of the intramolecular water was replaced by allylisothiocyanate molecules encapsulated in montmorillonite. In the experiment with two potato varieties infested with nematode cysts it was shown that soil treatment with allylisothiocyanate solutions allows to decrease number of cysts of Globodera rostochiensis RoI compared to positive control (non-treated infested potato) in 1.5–3.0 times depending on the variety. Moreover, in contrast to allylisothiocyanate solutions, poly-ε-caprolactone/montmorillonite/allylisothiocyanate granules are more effective that makes them promising for applications in Globodera rostochiensis RoI control.

The results of the study of hydrodynamic and mass transfer parameters of a stirred bioreactor during gas dispersion from the cavity of an open vortex to the area with reduced pressure in the liquid behind the impeller paddles are presented. New data were obtained on gas content, dispersed composition of gas bubbles, stirring power, and intensity of mass transfer in the air-water system, aqueous solutions of sucrose and glycerol of various concentrations and with different content of surfactants. The dependence of the stirring power on the gas content and Reynolds number, as well as the mass transfer coefficient on the boundary surface and energy dissipation, have been established. It is assumed that when calculating the dissipation of energy spent on developing a boundary surface, it is necessary to take into account the influence of viscous friction forces in the liquid. Dispersion of gas into liquid through an open vortex cavity in a stirred bioreactor allowed to increase the gas content, the boundary surface and to intensify mass transfer compared to conventional aeration systems.

Studies on the producers of L-lactic acid are highly relevant at the moment due to the broad scope of its applications. This study was aimed at selecting culture parameters for a milk-derived thermophilic strain of Weizmannia coagulans that is capable of producing L-lactic acid. It was found that the strain productivity depends on the culture temperature, stirring rate, medium pH, used neutralizing agent, and glucose concentration. The culture in flasks and a fermenter revealed that in 56 hours, the strain is capable of producing up to 80.4 g/L of lactic acid at a corresponding average productivity of 1.44 g/(L×h) with a conversion of about 99%. The most optimal parameters to achieve the highest indicators were a temperature of 50 °С, medium pH of 6.5, and a stirring rate of 150 rpm. This strain was shown to be uninhibited by high glucose concentrations; conversely, it exhibited higher productivity at glucose concentrations of 100–120 g/L in the medium. Among the neutralizing agents used for pH adjustment, the Ca(OH)2 agent was selected, which has the least effect on the size of producer cells during fermentation and whose by-products are the least toxic. The obtained results indicate that further studies on the metabolic properties and genetic modification of this strain are required in order to increase productivity, reduce the inhibitory effect of the target product on the metabolism of the producer, and obtain elevated lactic acid titers in a short fermentation time.

The ability of esters of primary and secondary alcohols butyl acetate and L-menthyl acetate (2-isopropyl-5-methylcyclohexyl acetate) to interact with thionyl chloride in the presence of zinc halides (chloride or bromide) was studied. 1-chlorobutane with a minor admixture of 2-chlorobutane (less than 3.6 %) was the main product of the reactions of butyl acetate. For L-menthyl acetate, the main product was 2-chloro-1-isopropyl-4-methylcyclohexane with minor impurities mainly represented by 1-isopropyl-4-methylcyclohexene and other six- membered unsaturated hydrocarbons. When ZnBr2 2 used as a catalyst, impurities of bromo- substituted hydrocarbons were found in the reaction products, which demonstrates the possibility of halogen atoms exchange between zinc halide and the resulting organic products of the reaction.

The bottom sediments of the lakes contain biochemical markers of fecal intake, which have been renewed interest in the last few years. This analysis is one of the newest trends in paleolimnology. Fecal markers include sterols recovered by the intestinal microflora – stanols, which are indicators of fecal intake into reservoirs. Relative to other mammals, humans produce the largest amount of coprostanol. Therefore, based on its presence in bottom sediments, the dynamics of human presence in early times can be reconstructed, as well as the fecal anthropogenic load on reservoirs. Using the gas chromatography method with mass spectrometric detection, for the first time we estimated the contents of coprostanol, epicoprostanol, 5α-cholestanol and cholesterol in the bottom sediments of Lakes Peyungda and Zapovednoye (Evenkia, Krasnoyarsk Krai), and also estimated the indices R1 and R2, reflecting the human contribution to fecal intake. The absence of an increase in the proportion of coprostanol in both lakes may indicate a slight anthropogenic impact. Both in the modern period and in earlier times (about 5000 years for Peyungda and 2500 years for Zapovednoye), there were probably no settlements near the lakes.

The study of fecal compounds in lake sediments is one of the newest trends in paleolimnology. Some stanols are produced by the intestinal microflora of animals from sterols found in food. Once in water bodies, these substances remain in bottom sediments for millennia; therefore, they are biochemical indicators of fecal intake. In humans and animals, similar 5β-stanols are synthesized, but their percentages differ. The human intestinal microflora produces more coprostanol and epicoprostanol than that of other animals, so these 5β-stanols are used to reconstruct the history of the population of water bodies, as well as to assess the anthropogenic load. In the present work, using gas chromatography with mass spectrometric detection, the vertical distribution of fecal stanols and their precursor cholesterol in dated bottom sediments of Lake Shira (southern Siberia, Republic of Khakassia) for a period of about 1000 years was studied for the first time. It is shown that the relative share of coprostanol and epicoprostanol was higher in sediments corresponding to the periods when the anthropogenic load in the lake’s drainage basin was supposedly increased: during the heyday of the medieval state of the Yenisei Kyrgyz (9th–11th centuries); during the period of mass colonization by the Russian population (17th–18th centuries); and in the 19th–20th centuries, during the development of resort activities. The absolute content of all fecal stanols during the last hundred years is higher, which can be explained both by an increase in fecal inflows and by the degradation of stanols, leading to a decrease in the content of fecal stanols in the underlying core layers. The results can be useful for monitoring the efficiency of treatment facilities, as well as for identifying the historical dynamics of human presence in the lake’s catchment area.

In this study the effect of processing methods on physical and chemical properties of polylactide (PLA) (Mn 130 kDa, L-93/ D-7) was investigated. PLA-films were obtained by solution casting and melt extrusion using Bestfiilament extruder equipped with flat-slot die. SEM, AFM, FTIR-spectroscopy and DSC were used for characterization of the films. The films obtained by flat-slot die melt extrusion had a relief surface with prominent strands and inclusions, while the cast films had a smooth surface with pores or gaps ranging in size from 20 to 60 μm. The average roughness (Ra) and root-mean-square roughness (Rq) of the surface of cast films were at the level of 45-48 and 37-39 nm, respectively. Meanwhile, for the melt films these values increased and corresponded to 122 and 65 nm, respectively. According to FTIR, both types of films were characterized by an increase in the absorption peaks at 1800-1700, 1450-1470 and 1350-1320 cm-1, which correspond to stretch vibrations of ester bond and bending vibrations of the C-H bond, respectively. DSC data showed decrease in crystallinity of PLA and change in its internal structure from amorphous-crystalline to amorphous after the processing.

In this work, the biodegradation of polylactide films, granules and tapes at temperatures of 23 °C and 8 °C in humus and chernozem soils was investigated. It was found that under the conditions studied, polylactide products are poorly biodegradable – for 84 days of exposure in the soil, the weight loss of all products did not exceed 10%. According to the results of microbiological assessment of the microflora of soils in which destruction occurred, no destructors of this type of biodegradable polymer were identified by inoculation in nutrient media containing polymer as the only carbon source.

Eco-friendly polymer composites in the form of granules based on biodegradable polycaprolactone (PCL) with the inclusion of montmorillonite (MMT) from 5 to 50 wt% were prepared by solution-casting and melt extrusion. The physicochemical properties of the composite granules were studied using FTIR spectroscopy, XRDA, DSC, and TGA methods. The paper presents comparative values of crystallinity of composite granules which depend on the method of measuring (XRDA, DSC). It was shown that the crystallinity of PCL/MMT granules was affected by the preparation method and by the MMT content, and that with increase in MMT content, crystallinity increased by up to 61–67%. The change in crystallinity of the granules also affected its biodegradation in soil. At the end of exposure in soil, the mass loss for the granules prepared by solution-casting was more than 90%, whereas for the composite granules prepared by extrusion it was less than 60%. Applying melt extrusion enabled obtaining intercalated composites with predictable features, whereas only mixed-structure microcomposites could be prepared by solution-casting.

Abstract. The core-top calibration study of 22 lakes indicates that in salt lakes the total alkenones increase sharply at a salinity of about 20 g/L, while alkenones are absent in the sediments of freshwater lakes. For the first time, this study shows that the Uk40 and Uk40 unsaturation indices are positively correlated with salinity and thus can be used to reconstruct salinity. The C37/C38 ratio is negatively correlated with salinity, and therefore this parameter can be used as an indicator of salinity. Also, the %C37:4 indicator is not correlated with salinity. It was found that the average chain length of alkenones increases with salinity, but the correlation was weak. Analysis of the alkenone composition and 18S rRNA suggests that all lakes are inhabited by Group II haptophytes, except for one freshwater lake, where the Group I of LCA-producing haptophytes was found. The taxonomic composition of haptophyte algae and the alkenone composition in the lakes were comparable to those in the lakes of the Canadian Prairies, apparently due to the similarity of climatic factors and the ionic composition of lake water in the two regions.

This work investigates the growth and productivity characteristics of such lactic-acid producing strains, as Lactobacillus delbrueckii subsp. bulgaricus 19-11 (VKPM B-2368), Lactobacillus acidophilus 5 Ds (VKPM B-2846) and Lactococcus lactis subsp. lactis (VKM B-1662) on standard MRS medium using glucose syrup as a carbon substrate. According to the results of batch cultivation of the selected strains in 5L fermenters for 72 h, the productivity was established to decrease in the Lactobacillus delbrueckii subsp. bulgaricus 19-11 > Lactobacillus acidophilus 5 Ds > Lactococcus lactis subsp. lactis series. L. delbrueckii subsp. bulgaricus 19-11 showed the maximum lactic-acid productivity of 1.94 g/(l×h) with a glucose conversion degree of 87%. After cultivation, a slight decrease in the content of nitrogen, potassium and sodium in the culture liquid of the studied strains was observed. In all strains, the content of other macronutrients (phosphorus, calcium, sulphur, magnesium, barium and iron) increased in proportion to the addition of glucose syrup during cultivation, which is directly related to their significant content in its composition. The Lactobacillus delbrueckii subsp. bulgaricus 19-11 and Lactobacillus acidophilus 5 Ds strains produced racemic (DL) lactic acid, whereas Lactococcus lactis subsp. lactis produced lactic acid with a 73% L-isomer content. The use of glucose syrup in biotechnological processes can contribute to the implementation of waste-free production in the respective enterprises.

The degradation patterns of bacterial poly-3-hydroxybutyrate (PHB) in chloroform solution under the action of thionyl chloride in the presence of zinc chloride were studied. When 2.5.mol of zinc chloride and 100 mmol of thionyl chloride were introduced into the solution of 25 mmol PHB, a decrease in the molecular weight of the polymer was observed. During the reaction, a relatively rapid decrease in the molecular weight of the polymer was noted in the first hour of the experiment; thus, the values of the weight-average molecular weight decreased from 840 kDa to 483, 167, 58.6, and 16.7 kDa after 1, 5, 24, and 96 h of the experiment, respectively. The polydispersity also gradually decreased from 2.69 at the beginning to 1.92 at the end of the experiment. Oligomers of PHB containing 3-chlorobutyric acid and 3-hydroxybutyryl chloride residues at the O and C ends of the polymer chain, respectively, were obtained. The results confirm the ability of thionyl chloride to interact with aliphatic esters in the presence of zinc compounds, and demonstrate the possibility of using this reaction to produce oligomeric derivatives of polyesters bearing chloralkyl and acid chloride functional groups.

Abstract. The analysis of biochemical markers of fecal intake is one of the newest trend in paleo-limnology. Stanols (cholestanol, stigmastanol, etc.) produced by the intestinal microflora from sterols are indicators of fecal influx into a water body. Coprostanol is synthesized in the human intestine, therefore, the presence of coprostanolin bottom sediments can be used to reconstruct the dynamics of the population in the lake watershed and to evaluate the dynamics of fecal pollution. Using the gas chromatography method, we were the first to estimate the content of cholestanol and coprostanol in the dated core layers of the bottom sediments of Lake Shira. The raised proportion of coprostanol indicates an increase in fecal anthropogenic inflows into the lake in the modern period, as well as in earlier periods of the history of Khakassia, in particularly during the existence of the Yenisei Kyrgyz state (VIII - XIII centuries CE).

To find out whether Al2O3 nanofiller is effective in improving the characteristics of polymer composites, composite polymer films based on biodegradable polylactide and epoxidized aluminum oxide nanofibers were obtained by solution casting. Surface morphology, mechanical and thermal properties of composites were studied by SEM, IR-Fourier spectroscopy, DSC and DMA. It was shown that, below and above the percolation threshold, the properties of the films differ significantly. The inclusion of alumina nanoparticles up to 0.2% leads to a plasticizing effect, a decrease in the crystallization temperature and the melting enthalpy and an increase in the tensile stress. An increase in the content of alumina nanoparticles in films above the percolation threshold (0.5%) leads to a decrease in the crystallinity of the films, an increase in stiffness and a drop in elasticity. Finding the percolation threshold of alumina nanoparticles in PLA films makes it possible to control their properties and create materials for various applications. The results of this study may have major significance for the commercial use of aluminum oxide nanofibers and can broaden the research field of composites.