Enantioselective Total Synthesis of (+)-Cassiol

An enantioselective total synthesis of (+)-cassiol is reported. The complex derived from Pd-2(pmdba)(3) and enantiopure t-BuPHOX ligand catalyzes enantioconvergent decarboxylative alkylation to generate the quaternary carbon stereocenter at an early stage. The overall synthetic strategy involves a convergent late-stage coupling of two fragments. The synthesis features a longest linear sequence of eight steps

A Pulsational Model for the Orthogonal Polarization Modes in Radio Pulsars

In an earlier paper, we introduced a model for pulsars in which non-radial oscillations of high spherical degree (\el) aligned to the magnetic axis of a spinning neutron star were able to reproduce subpulses like those observed in single-pulse measurements of pulsar intensity. The model did not address polarization, which is an integral part of pulsar emission. Observations show that many pulsars emit radio waves that appear to be the superposition of two linearly polarized emission modes with orthogonal polarization angles. In this paper, we extend our model to incorporate linear polarization. As before, we propose that pulsational displacements of stellar material modulate the pulsar emission, but now we apply this modulation to a linearly-polarized mode of emission, as might be produced by curvature radiation. We further introduce a second polarization mode, orthogonal to the first, that is modulated by pulsational velocities. We combine these modes in superposition to model the observed Stokes parameters in radio pulsars.Comment: 19 pages, 4 figures accepted Ap

Photoelectric characteristics of metal-Ga2O3-GaAs structures

We investigate the effect of thermal annealing in argon and of oxygen plasma processing on the photoelectric properties of GaAs-Ga2O3-Me structures. Gallium-oxide films are fabricated by photostimulated electrochemical oxidation of epitaxial gallium-arsenide layers with n-type conductivity. The as-deposited films were amorphous, but their processing in oxygen plasma led to the nucleation of β-Ga2O3 crystallites. The unannealed films are nontransparent in the visible and ultraviolet (UV) ranges and there is no photocurrent in structures based on them. After annealing at 900°C for 30 min, the gallium-oxide films contain only β-Ga2O3 crystallites and become transparent. Under illumination of the Ga2O3-GaAs structures with visible light, the photocurrent appears. This effect can be attributed to radiation absorption in GaAs. The photocurrent and its voltage dependence are determined by the time of exposure to the oxygen plasma. In the UV range, the sensitivity of the structures increases with decreasing radiation wavelength, starting at λ ≤ 230 nm. This is due to absorption in the Ga2O3 film. Reduction in the structure sensitivity with an increase in the time of exposure to oxygen plasma can be caused by the incorporation of defects both at the Ga2O3-GaAs interface and in the Ga2O3 film

Shock-Wave Experiment with the Chelyabinsk LL5 Meteorite : Experimental Parameters and the Texture of the Shock-Affected Material

A spherical geometry shock experiment with the light-colored lithology material of the Chelyabinsk LL5 ordinary chondrite was carried out. The material was affected by shock and thermal metamorphism whose grade ranged from initial stage S3-4 to complete melting. The temperature and pressure were estimated at >2000 degrees C and >90 GPa. The textural shock effects were studied by optical and electron microscopy. A single experimental impact has produced the whole the range of shock pressures and temperatures and, correspondingly, four zones identified by petrographic analysis: (1) a melt zone, (2) a zone of melting silicates, (3) a black ring zone, and (4) a zone of weakly shocked initial material. The following textural features of the material were identified: displacement of the metal and troilite phases from the central melt zone; the development of a zone of mixed lithology (light-colored fragments in silicate melt); the origin of a dark-colored lithology ring; and the generation of radiating shock veinlets. The experimental sample shows four textural zones that correspond to the different lithology types of the Chelyabinsk LL5 meteorite found in fragments of the meteoritic shower in the collection at the Ural Federal University. Our results prove that shock wave loading experiment can be successfully applied in modeling of space shocks and can be used to experimentally model processes at the small bodies of the solar system.Peer reviewe

Study readiness of teachers in rural schools to educate children with disabilities and children with HIA in terms of inclusive education

This article discusses the problem of readiness of teachers to educate children with disabilities in an inclusive environment. We analyzed the characteristics necessary for the implementation of the education of disabled children and persons with HIA. Considerable attention is paid to the competencies that a teacher should possess. Provided the results of the pilot studyВ данной статье рассмотрены проблемы готовности учителей к обучению детей с ограниченными возможностями здоровья в инклюзивной среде. Проанализированы характерные особенности, необходимые для реализации обучения детей-инвалидов и лиц с ОВЗ. Значительное внимание уделяется компетенциям, которыми должен обладать педагог. Предоставлены результаты пилотажного исследовани

Modelling of biomorphic objects on the basis of the massives from the wooden blocks

Современные технологии позволяют спроектировать объекты, которые способны подражать исходным природным формам, а также использовать экологически чистые материалы, такие как дерево. Технологическая гибкость дизайнеров и архитекторов выведет нас на уровень передовой экологичной, комфортной антропогенной среды.Modern technologies allow to design objects which are capable to imitate original natural forms and also to use eco-friendly materials, such as wood. The technological flexibility of designers and architects will bring us to the level of a front line of the eco-friendly, comfortable anthropogenic environment

Study of the regulatory measures in energy market

The article examines the problems of Russia’s cooperation in the gas sector within the Eurasian Economic Union, and on the world stage. With the advent of the new millennium, many states began to face more and more questions of their energy security and energy supply. Russia, as one of the world leaders in reserves, production and export of hydrocarbons, constantly faces increased competition at the regional and international levels. As the result, our state has to respond to such a volatile situation in foreign markets by establishing close mutually beneficial cooperation with both producers and consumers of energy resources. Therefore, the incessant changes in the international arena and the emergence of new circumstances leading to problems in the energy sector, makes this study very relevant

Conditions for the formation of a non-autonomous phase at the structural deformation of complex vanadium oxides

Received: 02.03.2018. Accepted: 10.04.2018. Published: 10.05.2018.A new previously unknown effect of a reversible transition from a singlephase system to a heterophase system containing a non-autonomous phase was observed during thermal and chemical deformations of the Zn2–2xCd2xV2O7 structure.The role of local symmetry in the formation of the non-autonomous phase is shown on the basis of X-ray diffraction studies in situ and a comparative crystal-chemical analysis of the structural deformations of isoform monoclinic solid solutions of zinc and copper pyrovanadates with zero volumetric thermal expansion.The work was supported by UB RAS (project 18-10-3-32)