Exact solution for the simplest binary system of Kerr black holes

The full metric describing two counter-rotating identical Kerr black holes separated by a massless strut is derived in the explicit analytical form. It contains three arbitrary parameters which are the Komar mass M, Komar angular momentum per unit mass a of one of the black holes (the other has the same mass and equal but opposite angular momentum) and the coordinate distance R between the centers of the horizons. In the limit of extreme black holes, the metric becomes a special member of the Kinnersly-Chitre five-parameter family of vacuum solutions generalizing the Tomimatsu-Sato delta=2 spacetime, and we present the complete set of metrical fields defining this limit.Comment: 9 pages, 1 figure, typos corrected, a footnote on p.6 extende

Informative wavelengths for trace atmospheric gas sounding with an OPO-lidar in the 3–4 μm spectral region

In this work, a search for information-bearing mid-IR wavelengths for HCl and HBr sounding with a differential absorption lidar based on an optical parametric oscillator has been carried out. Lidar echo signals have been calculated at the wavelengths chosen during sounding of gas components along vertical paths 0–5 km long. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

OPO-laser system for atmospheric sounding in the MID-IR range

A laser system is designed that provides for tunable generation of nanosecond radiation pulses in the 3–4 μm range. Optical block-diagram and specifications of the system are presented. The laser system as a part of a differential absorption lidar designed can be used for remote control of pollutant concentrations along surface atmospheric path

INCREASING THE WEAR RESISTANCE OF ADAPTERS AND DRILL PIPES BY ELECRTROMECHANICAL PROCESSING

The directions of the research on increasing the wear resistance of drill pipe locks, threaded joints and casing drill string have been defined: application of drill pipes from the nose-resistant surfacing to the lock with Russian and foreign materials (hardbanding); hardening of the surface layer of drill pipe locks by electromechanical processing; hardaning of the external and internal locking thread of drill pipes by electromechanical processing. Comparative tests of the wear resistance of various hardening materials (hardbanding) of Russian and foreign production and the drill pipe lock without surfacing have been made. The recommendations for increasing the wear resistance of threaded joints by the method of electromechanical processing are developed, which determine the ways of increasing the resource and reliability of drill pipes and sub-assemblies, the formation of unique properties of parts, reducing the labor-capacity of manufacturing and restoring parts, increasing the efficiency of enterprises and organizations, protecting the environment and creation of competitive products. The materials of the article are of practical value for specialists of various fields engaged in the issues of increasing the reliability of technological equipment. The production success of using wear resistant surfacing technology on the body of a drill pipe joint is due to the possibility of using relatively simple and mobile welding equipment, carrying out work in the places of use of a drilling tool or temporary (permanent) production bases with a small transport arm from the field, re-depositing surfacing materials restoration of drill pipe locks; a wide and growing list of companies that receive accreditation for the production of these works

Low-Temperature Predicted Structures of Ag2S (Silver Sulfide)

Silver sulfide phases, such as body-centered cubic argentite and monoclinic acanthite, are widely known. Traditionally, acanthite is regarded as the only low-temperature phase of silver sulfide. However, the possible existence of other low-temperature phases of silver sulfide cannot be ruled out. Until now, there have been only a few suggestions about low-temperature Ag2S phases that differ from monoclinic acanthite. The lack of a uniform approach has hampered the prediction of such phases. In this work, the use of such an effective tool as an evolutionary algorithm for the first time made it possible to perform a broad search for the model Ag2S phases of silver sulfide, which are low-temperature with respect to cubic argentite. The possibility of forming Ag2S phases with cubic, tetragonal, orthorhombic, trigonal, monoclinic, and triclinic symmetry is considered. The calculation of the cohesion energy and the formation enthalpy show, for the first time, that the formation of low-symmetry Ag2S phases is energetically most favorable. The elastic stiffness constants cij of all predicted Ag2S phases are computed, and their mechanical stability is determined. The densities of the electronic states of the predicted Ag2S phases are calculated. The prediction of low-temperature Ag2S structures indicates the possibility of synthesizing new silver sulfide phases with improved properties. © 2023 by the authors.Russian Science Foundation, RSF: 19-79-10101-ПThis research was supported by the Russian Science Foundation (grant no. 19-79-10101-П) through the Institute of Solid State Chemistry of the Ural Branch of the RAS. The computations were performed on the Uran supercomputer at IMM UB RAS. Crystal structures were visualized using the VESTA software

Родственная трансплантация почки - первый опыт в клинической больнице Святителя Луки

Kidney transplantation (KT) is regarded as the most effective therapeutic approach for people with end-stage renal disease. However, for a number of reasons - constant increase in the incidence of diseases contributing to formation and development of chronic kidney disease, as well as continuing shortage of donor organs - 78-95% of patients in need of a kidney transplant do not receive the necessary treatment, and the waiting list stretches for several years. This paper presents the first outcomes of KT for chronic glomerulonephritis performed at St. Luke’s Clinical Hospital in St. Petersburg, in collaboration with the staff of Shumakov National Medical Research Center of Transplantology and Artificial Organs. Трансплантация почки является наиболее эффективным видом медицинской помощи пациентам с терминальной почечной недостаточностью. Однако по ряду причин (постоянное увеличение частоты встречаемости заболеваний, способствующих формированию и развитию хронической болезни почек, а также сохраняющийся дефицит донорских органов) 78-95% пациентов, нуждающихся в пересадке почки, не получают необходимого лечения, а очередь в листах ожидания растягивается на несколько лет. В статье в виде клинического случая представлены первые результаты родственной трансплантации почки при хроническом гломерулонефрите, проведенной в СПб ГБУЗ «Клиническая больница Святителя Луки» совместно с сотрудниками ФГБУ «НМИЦ ТИО им. ак. В.И. Шумакова» Минздрава России