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Transformers are critical elements of electrical networks and systems. The operational reliability of oil-filled transformers largely depends on the characteristics of the insulation, which is confirmed by the failure statistics. A number of factors affecting the insulation of electrical machines are identified, including excessive moisture, with its negative consequences outlined. The complexity and shortcomings of the use of traditional technologies for drying solid insulation are indicated, which focus on the search and implementation of the latest technologies in the system of maintenance and repair of transformers — automated insulation restoration systems (AIRS).Taking into account the development of technical progress in the field of service maintenance of transformers, the negative impact of moisture on the reliability, durability and overload capacity of electrical machines, especially those beyond their normal service life, a new look at the criteria for the moisture content of cellulose insulation is proposed. A review is made of the normative requirements for the moisture content of the insulation of oil-filled transformers of a number of Russian and foreign standards. On the basis of the Oommen equilibrium curves, the shortcomings of the lack of comparability of the humidity criteria for solid and liquid insulation in STO 34.01–23.1– 001–2017 and RD 34.45–51.300–97 are presented. It is proposed to single out several areas of the operational state of transformers in terms of “moisture content of solid insulation (paper)”. The optimal period for the use of AIRS has been determined.The AIRS technology is implemented in a TRANSEC module, which enables to carry out work under load, without adversely affecting predictive diagnostics. The design features of the TRANSEC module, the principle of operation, functional and design differences from standard transformer units – thermosiphon /adsorption filters — are outlined. The results of testing the TRANSEC technology in an existing electrical installation serviced by PJSC Rosseti are presented. Six months of trial operation of the TRANSEC module demonstrated the restoration of insulation characteristics on operating equipment without additional involvement of personnel. Besides, during the testing of the TRANSEC technology, the influence of oil temperature on the information content of the assessment of solid insulation parameters was confirmed. Proposals are formulated on the revision of industry documentation in the established part.

BACKGROUND: Vaccination is currently considered the most successful strategy against the SARS-CoV-2 virus. However, cases of infection despite vaccination, so-called breakthrough infections, have been reported worldwide. AIM: To evaluate the impact of vaccination against the new coronavirus infection COVID-19 on the morbidity of university students. MATERIALS AND METHODS: The incidence of new coronavirus infection (COVID-19) among the students of North-Western State Medical University named after I.I. Mechnikov (further University) from September 1 to December 15, 2020 and 2021 was analyzed. There were 4876 and 4681 students under observation. Data on vaccination, probable site of transmission infection were collected by interviewing the ill people. Statistical processing of data was performed using EpiInfo software. RESULTS: For the analyzed period 191 cases of COVID-19 among students were detected, the incidence of COVID-19 was 4.08 per 100 students, for the same period of the academic year 2020 it was 5.50, despite the fact that the incidence among St. Petersburg residents in 2021 was 1.75 times higher than in 2020. Re-infection was detected in 35 (18.3%) cases, 18 of whom were also vaccinated against COVID-19. A probable place of transmission infection was established in 36.1% of the cases, the most frequent being contact with a patient at their place of work in a health-care facility. By December 15, 2021, a total of 62.8% of students had been vaccinated against COVID-19. The incidence among vaccinated students was 2.72 per 100 students and 4.94 per 100 among unvaccinated students. A risk factor for breakthrough infections after vaccination was close contact with the source of infection: vaccinated persons had close contact in 50% of cases, compared with 28.9% of unvaccinated persons. The most important were contact with a patient in a health care setting and having multiple sources of infection, 31.1% and 5.6%, respectively. CONCLUSIONS: Vaccination against COVID-19 was an effective preventive intervention. A risk factor for disease after vaccination is close contact with the source of infection. Establishment of collective immunity after vaccination is decisive for the vaccination-to-disease ratio, which starts to develop with 70-80% of vaccinated individuals. The use of a mask in public places and social distancing remain important preventive measures.

Complex alloying, combining in a certain sequence the saturation of surface layer of material with atoms of metals and gases, is now widely used in most industrialized countries of the world. The present work is devoted to the revelation and analysis of dependences of element and phase composition, defect substructure, mechanical (microhardness) and tribological (wear resistance and friction coefficient) properties changes of alloying carbon steel subjected to combined treatment including the saturation of the sample surface layer by aluminum and subsequent nitriding. The material used for the study was AISI 5135 steel, which in the initial state has a structure represented by ferrite grains and pearlite grains of lamellar morphology. The combined modification was carried out in a single vacuum space on the TRIO setup with the chamber dimensions of 600×600×600 mm3 equipped by switching unit for realization of elion (electron and ion) mode of treatment. Aluminizing was carried out at the temperature of 963 К during 4 h. The cathode of electroarc evaporator was made of A7 grade aluminum alloy (98.8 % Al). Subsequent nitriding of aluminized layer was carried out at the temperature of 803 К during 2 h. It was established that the modified layer with the thickness of 70 μm is formed as a result of the combined treatment. It is demonstrated that the combined steel modification is accompanied by the formation of multiphase submicro- and nanostructure state including aluminum nitrides, iron and chromium nitrides and aluminides. It is revealed that the steel hardness is maximal on the modification surface and it exceeds by 3 times that of the initial steel. Wear resistance under the dry conditions decreases after the combined modification.

The current lack of literature on the safe use of low-voltage measuring circuits in coal mines leads to the fact that they are trying to make unreasonable demands or simply prohibit their use under any far-fetched pretext. At the same time, measuring low-voltage circuits are an important integral component of diagnostics and information content of mining equipment control systems. This is due to the fact that the theory and models of the ignition of a methane-air mine atmosphere (MMA) solve problems in a narrow setting and cannot be used in the general mine case. The article identifies the conditions and parameters for the ignition of the MMA from the low-voltage measuring circuit (NVC),developed criteria for the ignition of the form the NVC, the existing model of the possible ignition process of the MMA from the NVTs is finalized. Currently, there are two theories of ignition of the HCV: thermal and ionic. From the author's point of view, the thermal model of VSH ignition from the electric discharge of the NSC is based on the analysis of the propagation of the temperature wave from some heat source in an inert environment. The thermal ignition model of VHS does not take into account many details of the physics of the combustion mechanism, such as the chain nature of individual acts of chemical interaction, the activation energy of molecules in the formation of active centers, and it is based on postulating some electric discharge. An assessment of the intrinsic safety and the possibility of self-expansion of the NVC flame core has been carried out. The approbation of research at three foreign conferences and the interest of foreign colleagues in them are shown. The article contains links to the state budget topics of the National Academy of Sciences of Ukraine and the numbers of state registration of Ukraine.

Melanotic neuroectodermal tumor of infancy is a rare neoplasm that predominantly involves cranial bones and tends to occur during the first year of life. About 500 cases have been described in the literature to date; 6% of them have been reported to be malignant. Treatment for these malignant tumors was not documented and often turned out to be ineffective.Here we report a case of a child aged 2 years and 4 months who presented with a rapidly growing mass in the maxillary region spreading through the orbit into the anterior cranial fossa. The patient’s parents gave consent to the use of their child’s data, including photographs, for research purposes and in publications. He was treated at the Russian Children’s Clinical Hospital from July 2018 to November 2019. The child underwent chemoradiation and staged surgical removal of the tumor. Treatment with ICE and radiation therapy led to a significant reduction of the tumor volume and enabled us to perform cytoreductive surgery with the removal of the mass in the maxilla. Further treatment according to the CWS 2009 guidance for high-risk patients with NRSTS (NonRhabdomyosarcoma Soft Tissue Sarcoma) and radiation therapy resulted in further regression of intraorbital and intracranial components of the tumor and we performed a radical resection of the residual tumor conglomerate. Investigations during the course of treatment revealed no signs of metastatic involvement. The behavior of malignant melanotic neuroectodermal tumors of infancy is unpredictable, that is why in case of the massive involvement of the facial bones when surgery is associated with a high risk of functional impairment or cosmetic deformity, one should consider preoperative chemotherapy to reduce tumor size and intraoperative blood loss. Moreover, chemotherapy in combination with resection makes it possible to minimize the risk of local relapse or metastasis.

Khulsanurus magnificus gen. et sp. nov., is described based on a partial skeleton, including cervical and caudal vertebrae, scapulocoracoids, humerus, and pubis from the Late Cretaceous (Campanian)...

Asiapator onchin gen. et sp. nov. is based on a dentary fragment from the middle Eocene (Irdinmanhan) Khaychin Formation at Khaychin Ula 3 locality, Mongolia. The preserved dentition includes di1 being replaced by i1, dp2 or p2, roots of dp4, and erupting p4. This is the first record of the Apatemyidae in Central Asia. The holotype of A. onchin provides the first direct evidence for dental replacement in the Apatemyidae, showing diphyodont first lower incisor and fourth lower premolar. Asiapator has only one lower incisor as in all apatemyids except Unuchinia from the Paleocene of North America. Asiapator is similar to Unuchinia and differs from more derived apatemyids in having a simple unmodified anterior premolar (dp2 or p2). Asiapator likely evolved from a North American immigrant.

Five partially preserved mammaliaform petrosals recovered from Middle Jurassic sediments of the Berezovsk coal mine (Krasnoyarsk Krai, Russia) show similarities to other early mammaliaforms like the morganucodontan Morganucodon and the docodontan Haldanodon in having an inflated promontorium and a curved and apically inflated cochlear canal, but they are distinct from dryolestoid and derived mammalian petrosals by the weak coiling of the cochlear duct and the presence of a perilymphatic foramen with an open perilymphatic sulcus. The two larger and robust specimens exhibit striking similarities to docodontan petrosals. Inside the bone an intricate circumpromontorial venous plexus was discovered, as recently described for the docodontan Borealestes, confirming that this structure is consistently present in basal non-mammalian mammaliaforms. The three smaller and slender petrosals probably belong to haramiyidans and are unique in showing a septum-like structure medially along the cochlear nerve entrance. The protruding perforated bony bar, which is preserved in two of the three, is interpreted here to be a remnant of a bony septum with multiple foramina for cochlear nerve fibres, representing an autapomorphic feature of Haramiyida. This newly described passageway for nerve fibres shows that the formation of the osteological structure surrounding the nervous pathways of the cochlea is more plastic among the non-mammalian mammaliaforms than previously thought.

A mandible fragment and four isolated teeth of the fossil foxes, Vulpes alopecoides (Del Campana, 1913), Vulpes cf. vulpes (Linnaeus, 1758) and Vulpes sp., are described from the Early Pleistocene locality of Taurida cave (Crimea, Late Villafranchian, 1.8–1.5 Ma). Based on the size and morphological features, a mandible fragment and two M1 are attributed to V. alopecoides. The structure of m1 of Vulpes cf. vulpes is similar to that of V. vulpes and V. alopecoides, but the size greatly exceeds the size limits for the latter species. Although m1 of Vulpes sp. fits the size of the lower carnassials of V. alopecoides, its morphology is definitely unique among the Early Pleistocene representatives of the genus Vulpes.

The remains of large porcupines (an incomplete skull, cranial and mandibular fragments, isolated teeth and postcranial bones) from the Early Pleistocene Taurida cave locality in central Crimea (Belogorsk district, Zuya village) are referred to the species Hystrix (Hystrix) refossa Gervais, 1852, which has not been reported from Crimea previously. Based on the stages of eruption, replacement and attrition of the lower dentition, the presence of individuals of six age categories, from juvenile to senile, was established. One dentary shows an intravital loss of cheek teeth, presumably caused by abnormal development of their roots and sockets.