The coating formation technique for artificial knee ligaments was proposed, which provided tight fixation of ligaments of polyethylene terephthalate (PET) fibers as a result of the healing of the bone channel in the short-term period after implantation. The coating is a frame structure of single-walled carbon nanotubes (SWCNT) in a collagen matrix, which is formed by layer-by-layer solidification of an aqueous dispersion of SWCNT with collagen during spin coating and controlled irradiation with IR radiation. Quantum mechanical method SCC DFTB, with a self-consistent charge, was used. It is based on the density functional theory and the tight-binding approximation. The method established the optimal temperature and time for the formation of the equilibrium configurations of the SWCNT/collagen type II complexes to ensure maximum binding energies between the nanotube and the collagen. The highest binding energies were observed in complexes with SWCNT nanometer diameter in comparison with subnanometer SWCNT. The coating had a porous structure—pore size was 0.5—6 μm. The process of reducing the mass and volume of the coating with the initial biodegradation of collagen after contact with blood plasma was demonstrated. This is proved by exceeding the intensity of the SWCNT peaks G and D after contact with the blood serum in the Raman spectrum and by decreasing the intensity of the main collagen bands in the SWCNT/collagen complex frame coating. The number of pores and their size increased to 20 μm. The modification of the PET tape with the SWCNT/collagen coating allowed to increase its hydrophilicity by 1.7 times compared to the original PET fibers and by 1.3 times compared to the collagen coating. A reduced hemolysis level of the PET tape coated with SWCNT/collagen was achieved. The SWCNT/collagen coating provided 2.2 times less hemolysis than an uncoated PET implant. MicroCT showed the effective formation of new bone and dense connective tissue around the implant. A decrease in channel diameter from 2.5 to 1.7 mm was detected at three and, especially, six months after implantation of a PET tape with SWCNT/collagen coating. MicroCT allowed us to identify areas for histological sections, which demonstrated the favorable interaction of the PET tape with the surrounding tissues. In the case of using the PET tape coated with SWCNT/collagen, more active growth of connective tissue with mature collagen fibers in the area of implantation was observed than in the case of only collagen coating. The stimulating effect of SWCNT/collagen on the formation of bone trabeculae around and inside the PET tape was evident in three and six months after implantation. Thus, a PET tape with SWCNT/collagen coating has osteoconductivity as well as a high level of hydrophilicity and hemocompatibility.
The authors have studied the influence of a probiotic and a gastrointestinal adsorbent on the histostructure of the digestive tract of broilers. Day-old broilers were divided into groups of 50 heads each by the method of analog pairs in terms of live weight. Control broilers received a basic diet. Broilers of the 1st experimental group during the first three days of the experiment received probiotic Vetom-1.1 (0.006%) containing spores of Bacillus subtilis with the basic diet, and broilers of the 2nd experimental group received gastrointestinal adsorbent Enterosgel (0.008%). For histological studies, three heads of broilers were selected at day 1 of age, day 4 of age, and at the end of the experiment (after the end of feeding the preparation and before the transition to the basic diet) from the average weight of each group. Samples were excised from the middle of the crop, the glandular part of the stomach, the duodenum, the jejunum, and the proximal part of the cecum of birds. At the end of the experiment, the positive aftereffect of the preparation persisted in the crop and duodenum. At the same time, in the experimental group, the thickness of the submucous membrane of the stomach decreased, and in the cecum, the layer of villi increased.
The article deals with the development of approaches to the integrated use of multitrophic aquaculture resources in the recreational business. It is revealed that multitrophic aquaculture allows successfully combining several areas in nature management. This includes obtaining high-quality food products (both of animal and plant origin), protecting and growing valuable medicinal plants, expanding the area of melliferous plants, and cultivating various industrial crops. It is proved that fish farming, often being extensive, can be considered as a kind of organic farming in the framework of recreational projects using multipurpose reservoirs. It is revealed that reservoirs used in recreational business, as well as the territories directly adjacent to them, are often characterized by an increased level of biodiversity that allows considering such territorial complexes as important stabilizing ecological zones.
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