Dielectric properties of nematic liquid crystals with Fe₃O₄ nanoparticles in direct magnetic field

Researched within the frequency range 10⁻¹–10⁶ Hz were dielectric properties of pure 6CHBT liquid crystals and 6CHBT ones with the impurity of Fe₃O₄ nanoparticles that have the mean diameter 5 nm and weight concentration 10⁻⁴ %. The study was performed without and under the influence of direct magnetic field with the induction 0.45 and 0.60 T. It has been shown that the magnetic field influences on the parameters of the near-electrode area of liquid crystal. In the case of liquid crystal with magnetic nanoparticles, the parameter changes caused by the magnetic field depend on the induction value

Disinfection of Surfaces Contaminated with SARS-CoV-2 Coronavirus by UV Radiation of Low-Pressure Mercury-Vapour Lamp

The aim of the work was to determine the effective ultraviolet (UV) doses required for the disinfection of surfaces contaminated with the SARS-CoV-2 coronavirus using a low-pressure mercury lamp. Materials and methods. To carry out prompt disinfection of surfaces, a specially designed source of UV radiation with a power of 7.5 W at a wavelength of 254 nm in the form of a portable flashlight was employed, which has a high efficiency of UV radiation output and the possibility of long-term autonomous operation from a compact battery. In the studies, a suspension culture of the SARS-CoV-2 coronavirus with biological activity of 5.3∙106 PFU/ml was used. The objects of testing were plastic Petri dishes (disposable) and office paper (grade C, density 80 g/m2 ). Results and discussion. Doses of UV radiation that provide disinfection of surfaces contaminated with the COVID-19 pathogen with an efficiency of 99.0 % (paper) to 99.95 % (plastic) have been determined. The results obtained make it possible to recommend a portable UV irradiator for use in the practice of preventive measures to combat the spread of the disease caused by the SARS-CoV-2 coronavirus

Infection Rate of Fish of the <i>Cypriniidae</i> Family by Helminth Larvae of the <i>Opisthorchiidae</i> Family in the Seym and Psel rivers Basins in Kursk Region

The purpose of the research is to study of the infection rate of freshwater mollusks and carp fish by trematodes transmitted by fish in the Psel and Seym basins in the Kursk region.Materials and methods. Helminthological material was collected from caught mollusks and fish. Mollusks were explored by the methods of life-time diagnostics and compression, and the fish by the method of compressing the spinal muscles and microscopic examination according to the method commonly used in helminthology. It was examined 200 specimens of mollusks and 1030 specimens of 6 fish species from the Cyprinidae family, from underyearling to two years of age. The species composition of trematodes was determined by identification guide.Results and discussion. Totally 4 species of helminths belonging to the Opisthorchidae: Opisthorchis felineus, Pseudamphistomum truncatum, Metorchis bilis and M. xanthosomus were identified. The extensiveness of infection by the larvae of O. felineus varied from 6.0 to 14.3 % in bleak, and 9.1% in red-eye. P. truncatum cysts were found only in bleak (8.0–11.1 %). The larvae M. bilis were found in 4 species of fish with extensiveness of infection from 5.6 to 50.0 %. 5 species of fish were infected by metacercaria M. xanthosomus (11.8–64.7 %). Epidemiological significance for humans have the first three species of the identified trematodes. The rate of fish infection indicates that the main source of opisthorchid eggs entering the examined river basins are wild and domestic birds, as well as semiaquatic mammals