Plasmon Resonance of Silver Nanoparticles as a Method of Increasing Their Antibacterial Action

In this article, a series of silver-containing dressings are prepared by metal-vapor synthesis (MVS), and their antibacterial properties are investigated. The antibacterial activity of the dressings containing silver nanoparticles (AgNPs) against some Gram-positive, and Gram-negative microorganisms (Staphylococcus aureus, Staphylococcus haemolyticus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Moraxella spp.) has been determined. Based on the plasmon resonance frequency of these nanoparticles, the frequency of laser irradiation of the dressing was chosen. The gauze bandage examined showed pronounced antibacterial properties, especially to Staphylococcus aureus strain. When 470 nm laser radiation, with a power of 5 mW, was applied for 5 min, 4 h after inoculating the Petri dish, and placing a bandage containing silver nanoparticles on it, the antibacterial effect of the latter significantly increased—both against Gram-positive and Gram-negative microorganisms. The structure and chemical composition of the silver-containing nanocomposite were studied by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS). The synthesized AgNPs demonstrate narrow and monomodal particle size distribution with an average size of 1.75 nm. Atoms of metal in Ag/bandage system are mainly in Ag0 state, and the oxidized atoms are in the form of Ag-Ag-O groups

HYDROBONDED NONWOVEN SILVER-CONTAINING MATERIAL IN TREATMENT OF ASEPTIC WOUNDS

Background. The urgent problem of surgery is the search for new and promising bandaging materials for the treatment of wounds. One of the variants may be a hydrobonded nonwoven material with silver nanoparticles, obtained by the laser ablation method. Aim of the research. To study the effect of a hydrobonded nonwoven material, containing silver nanoparticles of various sizes, on the healing of an experimental aseptic cutaneous wound and the parameters of complete and biochemical blood tests as well as to determine the possible toxicity of silver nanoparticles on the liver, kidneys and myocardium. Material and methods. Silver nanoparticles were obtained by the laser ablation method in a liquid. The wound healing effect was evaluated on a model of an aseptic skin wound in laboratory white rats. After the healing of the wound blood was taken for complete and biochemical tests. The toxic effect of a hydrobonded bandaging material on the liver, kidneys and myocardium was assessed pathomorphologically and by changes in the biochemical blood test. Results. The obtained data demonstrated acceleration of the healing of the experimental aseptic skin wound with the use of silver nanoparticles by 9.2-15.6 % and the absence of toxic effects of silver nanoparticles on the liver, kidneys and myocardium, as well as significant changes in the indices of complete and biochemical blood tests. Conclusions. Hydrobonded nonwoven material with silver nanoparticles accelerates the healing of an aseptic skin wound without causing toxic effects on the liver, kidneys and myocardium. It can be used in clinical practice after further studyin

ALL-SKY CAMERAS FOR OBSERVATION AND INVESTIGATION OF VARIABLE STARS AND METEOR SHOWERS

This paper studies the capabilities of the all-sky weather (meteorological) cameras in investigation of bright variable stars and determination of apparent radiants of meteor showers. This paper studies the capabilities of the all-sky weather (meteorological) cameras in investigation of bright variable stars and determination of apparent radiants of meteor showers.

Salicaceae-Feeding Leaf-Mining Insects in Siberia: Distribution, Trophic Specialization, and Pest Status

International audienceThis paper provides an overview of the leaf-mining insect community feeding on willows (Salix spp.) and poplars (Populus spp.) in Siberia. According to published data and our own observations, 50 leaf-mining insect species (i.e., 24 species of Lepidoptera, 15 Coleoptera, 6 Diptera, and 5 Hymenoptera) feed on those two plant genera in Siberia. Using an integrative approach combining field work, morphological and DNA barcoding analyses, we identified 32 leaf-mining insect species from 14 regions across Siberia (i.e. 64% of all leaf-mining species known on Salicaceae in this part of Russia). Among them, 26 species most often found in parks and botanical gardens, represented new faunistic records for several poorly explored regions of Siberia. We have more than doubled the list of Salicaceae-feeding leaf-mining insects in Tomsk oblast, Altai krai, and the Republic of Tuva, and for the first time provided data on leaf-miners for the Khanty-Mansi Autonomous Okrug. The micromoth Phyllocnistis gracilistylella (Gracillariidae), recently described from Japan, was found on a new host plant (Salix caprea) in the south of Krasnoyarsk krai, is new for Russia. Eight leafmining insect species (i.e., five gracillariids: Phyllocnistis labyrinthella, Ph. unipunctella, Phyllonorycter apparella, Ph. sagitella, and Ph. populifoliella; two beetles: Zeugophora scutellaris and Isochnus sequensi; and one sawfly: Heterarthrus ochropoda) can outbreak on poplars, most often in urban plantations, botanical gardens, and plant nurseries in Siberia, and can also affect natural stands. Forty-five species of 50 leaf-mining insects known to feed on willow and poplar in Siberia also occur in Central and Eastern Europe. The remaining five species (Phyllocnistis gracilistylella, Phyllonorycter sibirica, Heterarthrus fasciatus, Tachyerges dauricus, and Isochnus arcticus) are recorded in Asia only. Species richness of the family Gracillariidae, the most diverse on Salicaceae in Siberia, displays 80% similarity to that in the European part of Russia and 71% to the Russian Far East. We discuss the faunal similarity of these regions and highlight the importance of applying an integrative approach combining ecological, morphological analyses, and DNA barcoding to explore and characterize the insect fauna of poorly studied regions of Asian part of Russia