PREPARATION A SERIES OF ATROPISOMERIC BIPY-DIOXIDES BY OXIDATIVE COUPLING AND THEIR APPLICATION IN ASYMMETRIC CATALYSIS

The authors thank the Russian Science Foundation for Grant No. 18-73-10156

Конспект рода Anopteris (Pteridophyta, Pteridaceae)

In the article a synopsis of the genus Anopteris (Prantl) Diels is given. The synopsis of Anopteris includes three species. For each species, the Latin name, basionym, nomenclatural citation, synonyms, information on locus classicus, type, habitat, and distribution are given. An original key for identification of the species of Anopteris is also prepared. The localities of occurrence of each species are precisely given. Приведен конспект рода Anopteris (Prantl) Diels. Конспект включает три вида. Для каждого из них приводится латинское название, базионим, номенклатурная цитата, синонимы, откуда описан, информация о типе, данные о местообитании, распространение по странам с цитированием мест сбора и общее распространение. Для определения всех видов рода Anopteris составлен оригинальный ключ, указаны подробные места произрастания. Приведен конспект рода Anopteris (Prantl) Diels. Конспект включает три вида. Для каждого из них приводится латинское название, базионим, номенклатурная цитата, синонимы, откуда описан, информация о типе, данные о местообитании, распространение по странам с цитированием мест сбора и общее распространение. Для определения всех видов рода Anopteris составлен оригинальный ключ, указаны подробные места произрастания.

Морфология спор Parahemionitis arifolia (Cheilanthoideae, Pteridaceae)

A study of spores of the single species of the genus Parahemionitis Panigrahi was performed using the method of scanning electronic microscopy (SEM). Spores of Parahemionitis arifolia (Burm. f.) Panigrahi are tetrahedral trilete, roundish-triangular in polar position, with micro-wrinkled exospore and sculptured perispore. Sculpture of perispore is cristate-reticulate, cristae are quite regularly distributed and form reticulum with small mostly closed polygonal luminae of different shape. Laesura arms are often obscured by numerous cristae. Size of spores is 53–63 × 40–42 μm. Spores of P. arifolia are similar in perispore sculpture with those of species of some cheilanthoid ferns

Концепция построения и реализации высокоскоростного транспорта

The article discusses the issues of implementation and organization of high-speed transport. The objective of the article is to consider possible options for implementing highspeed (HS) motion systems using the principle of magnetic levitation, which will ensure high speeds for delivery of goods and carrying people over long distances. To achieve this objective, it is necessary to develop an engine and technical solutions for design of HS rolling stock, make decisions on energy supply infrastructure and the HS track, address safety issues and new control systems considering the state of the infrastructure and its design elements. The article discusses several options for implementation of high-speed transport systems, differing in the power supply system, current collection and track based on the magnetic levitation approach. An original approach is proposed in implementation of magnetic levitation transport using the technology of electromagnetic guns designed to implement traction forces of a magnetic levitation vehicle. The advantage of this approach is that it opens the possibility of maneuvering for the vehicle while driving. This allows to abandon switch turnouts, now significantly limiting the use of magnetic levitation transport. A mathematical model describing interaction of an electromagnetic gun and supermagnets located on the track is considered. In constructing the model, methods of the theory of electromagnetic field and interaction of magnetic bodies were used, and when constructing a model of interaction of rolling stock with a magnetic track, methods of mathematical algebra and the Cauchy theorem were used. The article discusses various principles of organization of movement using the magnetic levitation for urban, suburban, and intercity transport.В статье рассматриваются вопросы реализации и организации движения высокоскоростного транспорта. Цель статьи – рассмотреть возможные варианты реализации высокоскоростных систем (ВС) движения сиспользованием принципа магнитной левитации, что обеспечит высокие скорости доставки грузов и населения на большие расстояния. Для достижения поставленной цели требуются разработка двигателя и технических решений конструкции ВС подвижного состава, принятие решений по инфраструктуре энергообеспечения и пути ВС, по вопросам обеспечения безопасности и новых систем управления, учитывающих состояние инфраструктуры и элементов её конструкции. Рассмотрено несколько вариантов реализации систем высокоскоростного транспорта, различающихся системой питания, токосъёма и пути на основе магнитолевитационного подхода. Предложен оригинальный подход с использованием технологии электромагнитных пушек, предназначенных для реализации тяговых усилий магнитолевитационного транспортного средства. Преимущество данного подхода заключается в том, что открывается возможность маневрирования транспортного средства во время движения. Это позволяет отказаться от стрелочных переводов, существенно ограничивающих применение магнитолевитационного транспорта. Рассмотрена математическая модель, описывающая взаимодействие электромагнитой пушки и супермагнитов, расположенных на пути. При построении модели использовались методы теории электромагнитного поля и взаимодействия магнитных тел, а при построении модели взаимодействия подвижного состава с магнитным путём – методы математической алгебры и теорема Коши. Также предложены различные принципы организации движения на основе магнитолевитационного подхода для городского, пригородного и междугороднего транспорта

OPTIMIZATION OF CATALYST STRUCTURE FOR ASYMMETRIC ALLYLATION-TYPE REACTIONS OF FUNCTIONALIZED TRICHLOROSILANES WITH AROMATIC ALDEHYDES

The authors thank the Russian Science Foundation for Grant 18-73-10156-П

Modeled Tracheidograms Disclose Drought Influence on Pinus sylvestris Tree-Rings Structure From Siberian Forest-Steppe

Wood formation allows trees to adjust in a changing climate. Understanding what determine its adjustment is crucial to evaluate impacts of climatic changes on trees and forests growth. Despite efforts to characterize wood formation, little is known on its impact on the xylem cellular structure. In this study we apply the Vaganov-Shashkin model to generate synthetic tracheidograms and verify its use to investigate the formation of intra-annual density fluctuations (IADF), one of the most frequent climate tree-ring markers in drought-exposed sites. Results indicate that the model can produce realistic tracheidograms, except for narrow rings (<1 mm), when cambial activity stops due to an excess of drought or a lack of growth vigor. These observations suggest that IADFs are caused by a release of drought limitation to cells formation in the first half of the growing season, but that narrow rings are indicators of an even more extreme and persistent water stress. Taking the example of IADFs formation, this study demonstrated that the Vaganov-Shashkin model is a useful tool to study the climatic impact on tree-ring structures. The ability to produce synthetic tracheidogram represents an unavoidable step to link climate to tree growth and xylem functioning under future scenarios

Asymmetric Propargylation of Aldehydes Catalyzed by New Chiral Lewis Bases

The authors thank the Russian Science Foundation for Grant № 18-73-10156

Electronic energy band parameters of CuInSe2 : Landau levels in magnetotransmission spectra

Magnetotransmission (MT) at magnetic fields up to 29 T was used to study the electronic structure of CuInSe2 in thin polycrystalline films. The zero field absorption spectra exhibited resolved A, B, and C free excitons. Quantum oscillations, due to diamagnetic excitons comprising electrons and holes from Landau levels quantized in the conduction and valence band, respectively, appeared in the MT spectra at fields over 5 T. Spectral energies of Landau levels and binding energies of the corresponding diamagnetic excitons, theoretically calculated assuming a quasicubic approximation of the CuInSe2 tetragonal lattice structure, helped to identify the character of the experimentally observed diamagnetic excitons. Spectral energies of diamagnetic excitons in the MT spectra with different circular polarizations were used to determine the electron and light hole effective masses, whereas heavy hole masses as well as the γ and γ1 Luttinger parameters, Ep Kane energy, and F parameter of the influence of remote bands, as well as their polaron values, were calculated using the Luttinger theory

Stereoselective Synthesis of Atropisomeric Bipyridine N,N′-Dioxides by Oxidative Coupling

Bipyridine N,N′-dioxide is a structural fragment found in many bioactive compounds. Furthermore, chiral analogues secured their place as powerful Lewis base catalysts. The scope of the existing methods for the synthesis of atropisomeric bipyridine N,N′-dioxides is limited. Herein, we present a practical, highly chemo- and stereoselective method for oxidative dimerization of chiral pyridine N-oxides using O2 as a terminal oxidant. A series of 13 axially chiral bipyridine N,N′-dioxides were synthesized in up to 75% yield. © 2019 American Chemical Society