Enantioselective "organocatalysis in disguise" by the ligand sphere of chiral metal-templated complexes

Asymmetric catalysis holds a prominent position among the important developments in chemistry during the 20th century. This was acknowledged by the 2001 Nobel Prize in chemistry awarded to Knowles, Noyori, and Sharpless for their development of chiral metal catalysts for organic transformations. The key feature of the catalysts was the crucial role of the chiral ligand and the nature of the metal ions, which promoted the catalytic conversions of the substrates via direct coordination. Subsequently the development of asymmetric organic catalysis opened new avenues to the synthesis of enantiopure compounds, avoiding any use of metal ions. Recently, an alternative approach to asymmetric catalysis emerged that relied on the catalytic functions of the ligands themselves boosted by coordination to metal ions. In other words, in these hybrid chiral catalysts the substrates are activated not by the metal ions but by the ligands. The activation and enantioselective control occurred via well-orchestrated and custom-tailored non-covalent interactions of the substrates with the ligand sphere of chiral metal complexes. In these metal-templated catalysts, the metal served either as a template (a purely structural role), or it constituted the exclusive source of chirality (metal-centred chirality due to the spatial arrangement of achiral or chiral bi-/tridentate ligands around an octahedral metal centre), and/or it increased the Brønsted acidity of the ligands. Although the field is still in its infancy, it represents an inspiring combination of both metal and organic catalysis and holds major unexplored potential to push the frontiers of asymmetric catalysis. Here we present an overview of this emerging field discussing the principles, applications and perspectives on the catalytic use of chiral metal complexes that operate as "organocatalysts in disguise". It has been demonstrated that these chiral metal complexes are efficient and provide high stereoselective control in asymmetric hydrogen bonding catalysis, phase-transfer catalysis, Brønsted acid/base catalysis, enamine catalysis, nucleophilic catalysis, and photocatalysis as well as bifunctional catalysis. Also, many of the catalysts have been identified as highly effective catalysts at remarkably low catalyst loadings. These hybrid systems offer many opportunities in the synthesis of chiral compounds and represent promising alternatives to metal-based and organocatalytic asymmetric transformations

Entanglement entropy in de Sitter: no pure states for conformal matter

In this paper, we consider the entanglement entropy of conformal matter for finite and semi-infinite entangling regions, as well as the formation of entanglement islands in four-dimensional de Sitter spacetime partially reduced to two dimensions. We analyze complementarity and pure state condition of the entanglement entropy of pure states and show that they never hold in the given setup. We consider two different types of Cauchy surfaces in the extended static patch and flat coordinates, correspondingly. For former, we found that entanglement entropy of a pure state is always bounded from below by a constant and never becomes zero, as required by quantum mechanics. In turn, the difference between the entropies for some region and its complement, which should be zero for a pure state, in direct calculations essentially depends on how the boundaries of these regions evolve with time. Regarding the flat coordinates, it is impossible to regularize spacelike infinity in a way that would be compatible with complementarity and pure state condition, as opposed, for instance, to two-sided Schwarzschild black hole. Finally, we discuss the information paradox in de Sitter and show that the island formula does not resolve it. Namely, we give examples of a region with a time-limited growth of entanglement entropy, for which there is no island solution, and the region, for which entanglement entropy does not grow, but the island solution exists.Comment: v1: 25 pages, 10 figures; v2: 25 pages, 10 figures, references added, notation clarifie

Entanglement Islands and Infrared Anomalies in Schwarzschild Black Hole

In this paper, island formation for entangling regions of finite size in the asymptotically flat eternal Schwarzschild black hole is considered. We check the complementarity property of entanglement entropy which was implicitly assumed in previous studies for semi-infinite regions. This check reveals the emergence of infrared anomalies after regularization of a Cauchy surface. A naive infrared regularization based on ``mirror symmetry'' is considered and its failure is shown. We introduce an improved regularization that gives a correct limit agreed with the semi-infinite results from previous studies. As the time evolution goes, the endpoints of a finite region compatible with the improved regularization become separated by a timelike interval. We call this phenomenon the ``Cauchy surface breaking''. Shortly before the Cauchy surface breaking, finite size configurations generate asymmetric entanglement islands in contrast to the semi-infinite case. Depending on the size of the finite regions, qualitatively new behaviour arises, such as discontinuous evolution of the entanglement entropy and the absence of island formation. Finally, we show that the island prescription does not help us to solve the information paradox for certain finite size regions.Comment: v1: 55 pages, 19 figures; v2: 57 pages, 19 figures, references added, Sec. 5 presentation improve

Электронная база вариативных явлений

The paper is an overview of the Repository of Variationist Research (https://vastry.ru/), an online storage and interactive plotting tool for quantitative sociolinguistic data. The paper describes a number of sociolinguistic experiments from which the data come and outlines the Repository and the toolkit it provides to its users.В статье предлагается обзор электронной системы “Репозиторий исследований вариативности” (https://vastry.ru/). Репозиторий предназначен для хранения количественных результатов вариационных социолингвистических исследований и создания интерактивных графиков на основе количественных данных. В статье описаны некоторые экспериментальные исследования, охарактеризован репозиторий и возможности, которые он предоставляет исследователям

Local quenches in fracton field theory: non-causal dynamics and fractal excitation patterns

We study the out-of-equilibrium dynamics induced by a local perturbation in fracton field theory. For the ${\mathbb Z}_4$ and ${\mathbb Z}_8$-symmetric free fractonic theories, we compute the time dynamics of several observables such as the two-point Green function, $\langle \phi^2\rangle$ condensate, energy density, and the dipole momentum. The time-dependent considerations highlight that the free fractonic theory breaks causality and exhibits instantaneous signal propagation, even if an additional relativistic term is included to enforce a speed limit in the system. For the theory in finite volume, we show that the fracton wave front acquires fractal shape with non-trivial Hausdorff dimension, and argue that this phenomenon cannot be explained by a simple self-interference effect.Comment: v1: 25 pages, 7 figures; v2: 25 pages, 7 figures, references added, minor correction

A study of some key problems of hall accelerator operation over the expended range of discharge voltage

Hall accelerators (HA) (thruster) are effectively applied in space propulsion and as a source of ions for controlled fusion and another programs. For HA modernization (by expansion of a discharge voltage range) some key problems have been studied: the determination of potential drop in various zones of discharge interval; the calculation of HA integrated characteristics; the determination of influence of low-frequency azimuthally plasma heterogeneity on electron movement.На часі прискорювач Хола (ПХ) (рушій) успішно застосовується у складі космічних рушійних установок, як джерело іонів для проведення реакцій ядерного синтезу та ін. Для удосконалення ПХ (шляхом розширення діапазону розрядної напруги) деякі ключові проблеми було виділено й досліджено: розраховано перепади потенціалу на окремих зонах розрядного прошарку; розраховано інтегральні характеристики; досліджено вплив низькочастотних коливань плазми на рух електронів.В настоящее время ускоритель Холла (УХ) (двигатель) успешно применяется в составе космических двигательных установок, как источник ионов для проведения реакций ядерного синтеза и др. Для усовершенствования УХ (путём расширения диапазона разрядного напряжения) некоторые ключевые проблемы были выделены и изучены: рассчитаны перепады потенциала на различных участках разрядного промежутка; рассчитаны интегральные характеристики; исследовано влияние низкочастотных колебаний плазмы на движение электронов

Treatment of ischemic stroke caused by dissection and occlusion of internal carotid artery in a young patient

The type and etiology of stroke in young patients are known to differ from those in elderly patients, that influences the diagnosis and treatment. Dissection of cerebral arteries holds the top position in the structure of the causes of ischemic stroke in children and young people below 45 years. Currently no clear guideline on the proper treatment of this pathology exists. The article presents the case of acute ischemic stroke in a young patient (the stroke was caused by the occlusion due to dissection of the internal carotid artery) successfully treated with radiosurgical method - stenting of the cervical part of the artery with the transition to petrous segment of the left carotid artery using combined proximal and distal protection of cerebral vessels. The control of patient's state and results of angiography and ultrasound demonstrate the favourable immediate and medium-term prognosis for the patient

INSTITUTIONAL MECHANISMS OF UNIVERSITY TEACHER PROFESSIONAL DEVELOPMENT

Purpose of the study: Conditions of qualifications’ dynamic development, rapid obsolescence of existing competencies actualize the need to create a system of continuous professional growth of teachers on staff training. The purpose of the article is to develop organizational mechanisms that contribute to the professional growth of the teacher inflexible response conditions of education to socio-economic changes. Methodology: The research methodology relies on the lifelong education concept, defining the design principles of a teacher professional growth system: consistency, continuity, self-development, participative nature, pedagogical reflexing Results: The system of the teacher’s professional growth in the educational institution possessing properties of hierarchy, flexibility, and dynamism is developed. The principles and organizational mechanisms for this system’s implementation are revealed: corporatism as a way to create targeted educational platform based on digital technology; tutoring as the insurance of the teacher’s and the educational organization’s interests  through the accompany of career advancement; branding as a result of the teacher’s and the educational organization’s competitiveness in the market of educational services; road maps for planning, monitoring and support of the teacher’s career development. Applications of this study: The article is intended for teachers, managers, employees of personnel services of educational organizations. Novelty/Originality of this study: For the first time the self - learning system of the teacher professional growth is offered which is capable to exist and productively function in modern dynamic conditions at the expense of adaptive organizational mechanisms of reaction to social and economic changes