Lichenized fungi as a multicomponent biological system are an interesting but difficult research object. In view of the complex interaction of the myco- and photobiont, the slow growth of natural thalli, their exceptional exactingness to environmental factors, the study of the biological characteristics of lichens is significantly difficult. This article discusses the problem of studying the anatomical and morphological structure of the myco- and photobiont of lichenized fungi using the tissue culture method on the example of rare species (Lobaria pulmonaria) and species with pharmaceutical potential (Usnea dasopoga, Cetraria islandica). The authors proposed a method for cultivating of myco- and photobionts of these species on synthetic nutrient media for the purpose of further research on the characteristics of lichenized fungi. Fragments of thalli, apothecia (for C. islandica), and soredia (for U. dasopoga and L. pulmonaria) were used as donor material. For the introduction of the photobiont under sterile conditions, a homogenate of the thallus region was prepared. Pure cultures of the myco- and photobiont of L. pulmonaria, U. dasopoga, and C. islandica were obtained on three types of hormone-free nutrient media, namely MS nutrient medium, modified MS medium with a reduced nitrogen content, Czapek medium. The verification of the research results was carried out taking into account the microscopy of the obtained cultures of myco- and photobionts. Using microscopy, the dimensional characteristics of the obtained mycobionts were determined. The diameters of the hyphae of L. pulmonaria, U. dasopoga, and C. islandica were 4.3–4.4 µm, 4.6 µm, and 4.1–4.3 µm, respectively, which corresponds to the size of the hyphae in natural samples. The use of the tissue culture method makes it possible to study and analyze the biological characteristics of lichenized fungi as a multicomponent biological system, as well as to contribute to the preservation of rare species and their components in the Red Data Book; while optimizing the method of cultivating myco- and photobiont on synthetic nutrient media, to reduce the anthropogenic load on natural populations of lichens when using them as medicinal raw materials.
The paper presents main clauses of a method for selecting main parameters of smoothing devices for railway direct current traction substation, which are intended for developing a state standard. The authors have created a list of required initial data for selecting parameters of smoothing devices. For each type of the connection line the authors have proposed optimal types of smoothing devices with the consideration for characteristics of direct current traction substations. As a result, they have determined the order of calculation of the main parameters of the smoothing device.
The article notes the tendency of introducing asynchronous engines, entailing the necessity to introduce the equipment which is intended to carry out maintenance, repair and acceptance check-outs. The general part of test circuits for asynchronous motors by the loading-back method with two controlled inverters is emphasized. The mathematical model of similar schemes’ functioning is shown. The article gives the results obtained by mathematic simulation of physical processes in the direct current link in the loading-back scheme for asynchronous machines Significant ripple voltage of constant voltage and DC in these circuits is noted. The issue of measuring power in the DC link passing through one inverter to the test engine and through another inverter from the load generator is considered. The authors carried out calculation of the capacities mentioned in the steady state modes for asynchronous machines with nominal power of 0.37 kW, 5.5 kW and 250 kW at different values of capacitor capacitance included in the DC link. Basing on the results of calculations, the authors found the dependence between the relative value of the procedural error in determining power in the DC link by the product of the current values of pulsed voltages and current. The current value from the product of instantaneous values of voltage and current at some time interval was taken as the true value of power. It is shown that at the capacitor capacity above some critical value this procedural error does not exceed 0.9% at the nominal power of the test engines 0.37 kW; 0.3% – at the power of 5.5 kW; 0.2% – at the power of 250 kW. This error increases dramatically when capacitor capacitance decreases. It is shown that the value of the capacitance corresponding to the inflection of the considered dependence approximately corresponds to the value necessary for limiting ripple voltage in the DC link of up to 600 V.
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