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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.

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.

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.

Using 1H NMR spectroscopy, we studied the relative mobility of the NO2 group in 1-alkyl-5-nitro-1,2,4-triazoles in the reaction of nucleophilic heterocyclic substitution by aliphatic oligoethers. The main pathways of the SNipso substitution process and the composition of resultant products from competitive reactions were examined, and the key factors influencing the relative mobility of the nitro group, such as the nitrotriazole substrate constitution, the carbon skeleton length of the O-nucleophilic agent and the process conditions, were discussed. Several independent competitive reactions directed towards the substitution of the nitro group at position C(5) in the alkyltriazole substrate by different types of nucleophiles such as alkoxide-, hydroxide- and triazolonate anions were observed to take place under conditions used. The major reaction yielded oligoethers containing terminal alkyltriazole heterocycles. Secondary reactions occurred to form the corresponding triazolone and N–C triazolyl triazolone structures in the reaction system. Additionally, in excess of the alkaline agent, alkaline hydrolysis was observed to proceed at the final stages of the process involving the O-nucleophile having a longer oligoether backbone in the series studied, leading to the formation of new O-nucleophilic sites. The obtained findings can provide a foundation for devising a method for the modification of a wide range of commercially available aliphatic oligo- or polyethers to prepare functional macromolecules whose terminals carry bioactive 1,2,4-triazole heterocycles located at a desired distance from each other. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this study was to evaluate costs associated with the primary intervention of the Mediterranean Lifestyle Program (MLP), which targeted postmenopausal women with type 2 diabetes at [...]

The wide use of pesticides in agriculture has caused uncontrolled distribution of these chemicals in the environment, calling for the development and investigation of new environmentally friendly formulations, which would reduce human impact on nature. In the present study, the metribuzin (MET), tribenuron‐methyl (TBM), and fenoxaprop‐P‐ethyl (FPE) herbicides were encapsulated in microparticles of degradable microbial polymers – polyhydroxyalkanoates (PHAs) – of two types – poly‐3‐hydroxybutyrate [P(3HB)] and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate [P(3HB/3HV)]. The use of P(3HB) resulted in higher yields of microparticles (63% to 79%) and larger sizes of the particles, whose average diameter was 0.60 ± 0.06–0.75 ± 0.11 μm, while the average diameter of copolymer particles varied between 0.43 ± 0.12 and 0.55 ± 0.05 μm. Encapsulation efficiency was rather determined by the type of herbicide and its solubility, varying from 24.7% to 48.2%. In vitro herbicide release from microparticles to water was affected by herbicide solubility and PHA chemical composition. The readily soluble MET showed the highest release rate, and over 30 days, 64% and 78% of the encapsulated amounts were released from P(3HB) and P(3HB/3HV) microparticles, respectively. High herbicidal activity of microparticles loaded with metribuzin and tribenuron‐methyl was demonstrated in the laboratory stands of the Elsholtzia ciliata weed plant. [ABSTRACT FROM AUTHOR]