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

Thermal expansion of a lead sulfide nanofilm

The thermal expansion of a lead sulfide nanofilm produced by chemical bath deposition was determined by X-ray diffraction (XRD). The thickness of the synthesized film was about 100 nm, and the average size of the coherent scattering regions as determined from XRD was about 40 nm. The lattice constant of the PbS nanofilm was measured as a function of the annealing temperature from 293 to 473 K and as a function of the annealing time at a constant temperature of 423 K. The thermal expansion coefficient derived was found almost twice as large as that for coarse-grained PbS. © 2013 Elsevier B.V. All rights reserved. All rights reserved

Simulations of zns deposition on Ag2S surface and formation of Ag2S/ZnS heteronanostructure

Simulation of ZnS deposition from aqueous solution on a surface of crystalline Ag2S has been performed to determine the features of formation of Ag2S/ZnS heteronanostructures. The classical molecular dynamics and density functional theory have been used to study the features of the initial stages of ZnS growth on Ag2S [001] surface. By classical molecular dynamics it was established that sulfur atoms initially are adsorbed on the Ag2S. Zinc atoms were shown to be adsorbed after sulfur atoms. However, the final location of the first adsorbed Zn layer was closer to the Ag2S surface than location of the first adsorbed S layer. Density functional theory calculation showed that Zn atoms were indeed closer to Ag2S surface and confirmed classical molecular dynamics results. However, density functional theory results are more precise since they made possible to account for Ag2S surface reconstruction. © 2020 Institute of Physics Publishing. All rights reserved.This study was supported by the Russian Science Foundation (grant no. 19-79-10101) through the Institute of Solid State Chemistry of the Ural Branch of the RAS

Polymorphic Phase Transformations in Nanocrystalline Ag2S Silver Sulfide in a Wide Temperature Interval and Influence of Nanostructured Ag2S on the Interface Formation in Ag2S/ZnS Heteronanostructure

Phase transformations that take place in nanocrystalline Ag2S silver sulfide have been systematically studied at temperatures from 298 to 893 K. The crystal structures of the polymorphic modifications α-Ag2S, β-Ag2S, and γ-Ag2S of nanocrystalline Ag2S have been found. It is established that the interstitial spacings between ions of silver in the superionic phases β-Ag2S and γ-Ag2S are noticeably smaller than diameter of the Ag+ ion. As a result of which, the probabilities of filling the sites of the metal sublattices of these phases with Ag atoms are very small. It was found that the “α-Ag2S—β-Ag2S” and “β-Ag2S—γ-Ag2S” transitions between polymorphic modifications of silver sulfide occur as phase transformations of the first order at temperatures of ~440–442 K and ~850–860 K. The structure of interface forming by nanostructured Ag2S and ZnS is considered, taking into account the anisotropy of elastic properties of these sulfides. It is established that a large amount of cubic zinc sulfide stabilizes the cubic structure of β-Ag2S argentite at 300 K during the co-deposition of Ag2S/ZnS heteronanostructures from colloid solutions. It is found that placing Ag atoms at four crystallographic positions located in one plane of the unit cell of cubic β-Ag2S argentite is most favorable for the appearance of Ag2S/ZnS heterostructures. The smallest strain distortions at the interface are observed at the minimum difference of shear moduli of the components forming heteronanostructure. The distributions of elastic characteristics, including the shear moduli of monocrystalline particles of cubic β-Ag2S argentite and ZnS sphalerite from the [hkl] direction, are found. The formation of Ag2S/ZnS heteronanostructures, in which the interface is formed by the (hk0) ≡ (110) plane of ZnS sphalerite and the (hk 0.4123) ≡ (1 1 0.4123) plane of β-Ag2S argentite, is the most energetically favorable. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Russian Academy of Sciences, РАН; Russian Science Foundation, RSF: 19-73-20012, 19-79-10101The research of Ag2S phase transformations has been supported by the Russian Science Foundation (grant 19-73-20012), and the investigation of interface in Ag2S/ZnS heteronanostructure has been supported by the Russian Science Foundation (grant 19-79-10101), respectively, through the Institute of Solid State Chemistry of the Ural Branch of the RAS.Authors are grateful to V.S. Gaviko for the in situ high-temperature XRD measurements and to V.V. Makarov for the HRTEM investigation (Institute of Metal Physics, Ural Branch of Russian Academy of Sciences). S.I.S. is grateful to E. Yu. Gerasimov for the help in TEM investigations.Funding: The research of Ag2S phase transformations has been supported by the Russian Science Foundation (grant 19-73-20012), and the investigation of interface in Ag2S/ZnS heteronanostructure has been supported by the Russian Science Foundation (grant 19-79-10101), respectively, through the Institute of Solid State Chemistry of the Ural Branch of the RAS

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

Эффективность хирургических методов коррекции морбидного ожирения и возможности их использования у больных с терминальной стадией хронической болезни почек при подготовке к трансплантации почки

Obesity is a modern «epidemic» not only in the general population but also among patients with end-stage renal disease (ESRD) who require kidney transplantation (KTx). The objective of this literature review is to analyze global studies on surgical methods of treating morbid obesity and their potentials in ESRD patients in preparation for KTx.Ожирение – это современная «эпидемия» не только среди населения в целом, но и среди пациентов с терминальной стадией почечной недостаточности, которым требуется выполнение трансплантации почки. Целью данного обзора литературы является анализ проведенных мировых исследований по изучению хирургических методов коррекции морбидного ожирения и возможности их использования у больных с терминальной стадией хронической болезни почек при подготовке к трансплантации почки

ДИФФУЗНАЯ СКЛЕРОЗИРУЮЩАЯ ПНЕВМОЦИТОМА (СКЛЕРОЗИРУЮЩАЯ ГЕМАНГИОМА)

Sclerosing pneumocytoma is a rare tumor. Most frequently it occurs in women at the age from 30 to 50 years old. Prevalently sclerosing pneumocytoma is a tumor with a single localization at the periphery of the lung. However sometimes diffuse lesions of both lungs can develop, when indurated foci of the tumor are located in the lung tissue. The article presents the clinical case of diffuse sclerosing pneumocytoma in 57-year-old female patient. Marginal excision has been performed for diagnostics of the disease. The set of immunohistochemical stains with monoclonal antibodies was used for accurate identification.Склерозирующая пневмоцитома является редкой опухолью. Чаще всего она встречается у женщин в возрасте от 30 до 50 лет. Наиболее часто склерозирующая пневмоцитома представлена одиночным расположенным на периферии легкого образованием. Тем не менее иногда наблюдается диффузное поражение обоих легких, когда опухоль определяется в виде плотных очагов в легочной ткани. Представлено клиническое наблюдение диффузной склерозирующей пневмоцитомы у пациентки 57 лет. Для диагностики заболевания выполнена краевая резекция легкого. Для точной идентификации клеток использован комплекс иммуногистохимических окрасок с моноклональными антителами

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