Influence of the Ultrasonic Treatment on the Properties of Polybutylene Adipate Terephthalate, Modified by Antimicrobial Additive.

Particular attention is paid to biodegradable materials from the environmental point of view and antimicrobial materials that ensure the microbiological safety of packaged products. The aim of the work was to study the properties of the composition, based on biodegradable polybutylene adipate terephthalate (PBAT) and the antimicrobial additive-birch bark extract (BBE). Test samples of materials were obtained on the laboratory extruder by extrusion with ultrasonic treatment of the melt. The concentration of the antimicrobial additive in the polymer matrix was 1 wt %. A complex research was carried out to study the structural, physico-mechanical characteristics, antimicrobial properties and biodegradability of the modified PBAT. Comparative assessment of the physico-mechanical characteristics of samples based on PBAT showed that the strength and elongation at break indices slightly decrease when the ultrasonic treatment of the melt is introduced. It was found out, that the antimicrobial additive in the composition of the polymer matrix at the concentration of 1 wt % has a static effect on the development of microorganisms on the surface of the studied modified films. Studies of the biodegradability of modified PBAT by composting for 4 months have shown that the decomposition period of modified materials increased, compared to pure PBAT. The developed modified polymer material can be recommended as an alternative replacement for materials based on polyethylene for food packaging.

Research of the Influence of the Ultrasonic Treatment on the Melts of the Polymeric Compositions for the Creation of Packaging Materials with Antimicrobial Properties and Biodegrability.

Ensuring the microbiological safety of food products is a problem of current interest. The use of antimicrobial packaging materials is a way of solving the problem. When developing packaging materials, it is advisable to use a modern approach based on the creation of biodegradable materials. The difficulty in the selection of the polymer compositions' components lies in solving the dilemma of the joint introduction and processing of antimicrobial and biodegradable agents. The studies of the ultrasound treatment on the melts of polymer mixtures showed an increase in the dispersion process of the components of the mixture. In this regard, this work aimed to study the effect of the ultrasonic treatment on the melts of polymer compositions containing thermoplastic starch and birch bark extract (BBE). In the work, the properties of PE-based packaging materials with various BBE concentrations obtained with ultrasonic treatment of melts on a laboratory extruder were studied. Biodegradable polymer compositions containing thermoplastic starch and BBE, obtained with the use of the ultrasonic treatment during extrusion, were investigated. The methods for studying rheological, physic-mechanical, antimicrobial properties and sanitary chemical indicators of materials were used in the article. It was found that ultrasonic treatment increases the melt flow and contributes to the production of materials with the uniform distribution of additives. The BBE content from 1.0% and higher in the contents of the material provides antimicrobial properties. When studying the permeability of oxygen and water vapor of the polymer compositions based on PE and BBE, it was found that the introduction of a filler increases vapor permeability by about 8-12% compared with control samples. The optimal concentration of BBE in polyethylene compositions containing thermoplastic starch was determined. The extension of the shelf life of the food product during storage in the developed material was established.

Identification of RNA targets for the nuclear multidomain cyclophilin atCyp59 and their effect on PPIase activity.

AtCyp59 is a multidomain cyclophilin containing a peptidyl-prolyl cis/trans isomerase (PPIase) domain and an evolutionarily highly conserved RRM domain. Deregulation of this class of cyclophilins has been shown to affect transcription and to influence phosphorylation of the C-terminal repeat domain of the largest subunit of the RNA polymerase II. We used a genomic SELEX method for identifying RNA targets of AtCyp59. Analysis of the selected RNAs revealed an RNA-binding motif (G[U/C]N[G/A]CC[A/G]) and we show that it is evolutionarily conserved. Binding to this motif was verified by gel shift assays in vitro and by RNA immunopreciptation assays of AtCyp59 in vivo. Most importantly, we show that binding also occurs on unprocessed transcripts in vivo and that binding of specific RNAs inhibits the PPIase activity of AtCyp59 in vitro. Surprisingly, genome-wide analysis showed that the RNA motif is present in about 70% of the annotated transcripts preferentially in exons. Taken together, the available data suggest that these cyclophilins might have an important function in transcription regulation.