Umbelliferone-6-carbonyl chloride reacted with amines and α-, β-, and ω-amino acid methyl esters to afford the corresponding
N
-substituted 7-hydroxy-2-oxo-2
H
-chromene-6-carboxamides. The reaction ...of umbelliferone-6-carbonyl chloride with glycine gave 2-(7-hydroxy-2-oxo-2
H
-chromene-6-carboxamido)acetic acid which was converted into acid chloride, and the latter reacted with benzylamines and α-amino acid methyl esters to produce compounds containing a dipeptide fragment.
This is a brief review of five-year studies of features of nontrivial three-dimensional topological structures of the electromagnetic field—optical strips—formed by vectors characterizing the sizes ...and orientation of the polarization ellipse of the light field with tracing of change in the orientations of these vectors along closed contours of various shapes, which are linked to lines of polarization singularity or are located immediately near them. The characteristics of polarization strips formed on arbitrarily oriented small circular contours around a single circular polarization singularity line of the electromagnetic field are described. The topology of polarization strips of light scattered by a dielectric sphere and a metallic spheroid with subwavelength sizes when elliptically polarized harmonic plane waves are incident on them is discussed. Optical polarization strips existing in the focal region of a parabolic mirror that tightly focus various laser beams incident on it is described. The topology of polarization ellipse strips in the electromagnetic field of laser radiation propagating in a planar metamaterial is discussed.
In this paper, an approach to the construction of nonlinear output tracking control on a finite time interval for a class of weakly nonlinear systems with state-dependent coefficients is considered. ...The proposed method of control synthesis consists of two main stages. At the first stage, a nonlinear state feedback regulator is constructed by using a previously proposed control algorithm based on the State Dependent Riccati Equation (SDRE). At the second stage, the problem of fullorder observer construction is formulated and then it is reduced to the differential game problem. The form of its solution is obtained with the help of the guaranteed (minimax) control principle, which allows to find the best observer coefficients with respect to a given functional considering the worstcase uncertainty realization. The form of the obtained equations made it possible to use the algorithm from the first stage to determine the observer matrix. The proposed approach is characterized by the nonapplicability of the estimation and control separation principle used for linear systems, since the matrix of observer coefficients turned out to be dependent on the feedback coefficients matrix. The use of numerical-analytical procedures for determination of observer and feedback coefficients matrices significantly reduces the computational complexity of the control algorithm.
Technological aspects of the formation of wear- and corrosion-resistant coatings on aluminum alloys and steel via an integrated use of methods of the low-temperature heterophase transfer, microarc ...oxidation, and magnetron sputtering. The tribological and anticorrosion properties of the coatings developed were estimated.
A method for mathematical processing of the results of measurements of the capacitance–voltage characteristics for an AlGaN/GaN HEMT (high electron mobility transistor) before and after γ-neutron ...irradiation with a fluence of 0.4 × 10
14
cm
–2
is suggested. The results of physical–topological simulation of an AlGaN/GaN HEMT on a SiC substrate are described. The error in calculating the GaN HEMT parameters due to inaccuracy in determining the electron distribution profile is determined.
It has been studied how a hardening friction treatment with a sliding hard-alloy indenter influences the chemical composition and roughness of the surface, the structure, the distribution of the ...microhardness and the density of dislocations in depth of the surface layer, the mechanical properties upon static tension and the features of deformation and fracture upon cyclic tension of the annealed low-carbon (0.17
wt.% C) steel grade 20. It has been found that friction hardening of the steel (an increase in the microhardness up to 4.25
GPa) is due to a considerable dispersion of the ferritic base (with the formation of alpha-phase fragments no less than 100
nm in size) and pearlite colonies (crushing and partial dissolution of cementite plates) under the action of a severe friction deformation; hardening is not connected with the carryover of separate particles of the hard alloy to the steel surface. A finite-element model describing the process of the friction treatment with a sliding cylindrical indenter has been constructed. This model was used to determine how the number of the indenter strokes, the friction coefficient, and the shear component of the deformation affect the value of the accumulated deformation. It has been shown that the friction treatment improves the strength characteristics of the steel upon static tension. The hardened surface layer is susceptible to further considerable hardening (an increase in the microhardness up to 5.6–5.9
GPa) at the initial stages of the cyclic deformation and, therefore, has some margin of plasticity. The plastic flow in the surface-hardened steel under cyclic loading is due to the formation of numerous bands of localized deformation. It has been found that the friction-hardened surface layer is more prone to cracking under cyclic loading. The methods by which cracking of the hardened layer can be diminished have been discussed.
An original method has been developed for the synthesis of 1,3-dyine derivatives of natural lembehyne B in high yields (50–67%) and with high selectivity (>98%). The key stage of the synthesis is new ...Ti-catalyzed cross-cyclomagnesiation of oxygenated and aliphatic 1,2-dienes induced by Grignard reagents. For studying the effect of the structure on the antitumor and neuritogenic activities, a series of lembehyne B analogues with different distances between the terminal hydroxy group and the 1,3-diyne moiety was prepared and tested for neuritogenic activity on mouse neuroblastoma Neuro 2A cells and for cytotoxicity, induction of apoptosis, and effects on the cell cycle using Jurkat, U937, K562, HeLa, and Hek293 tumor cell lines.
The effect of the nitriding temperature in electron beam plasma on the structural and phase composition of the surface layers of metastable austenitic stainless steels is studied. Conversion electron ...Mössbauer spectroscopy shows that nitriding at 350°C results in the transition of the austenite into the α (bcc) phase by the shear mechanism in the surface layers of a plate (tenths of a micron). A nitrogen supersaturated austenite and a mixture of nitrides with a predominant configuration of three nitrogen atoms in the environment of iron are formed in layers 1–5 μm thick. Nitriding at a temperature of 500°C and above leads to nitrogen supersaturated austenite decomposition, the escape of chromium and nitrogen from the matrix into nitrides CrN, Fe
4
N, and Fe
x
N, and the subsequent γ → α phase transformation.
Ribonuclease from Bacillus intermedius (binase) is a small basic protein with antitumour activity. The three‐dimensional structure of the binase mutant form Glu43Ala/Phe81Ala was determined at 1.98 Å ...resolution and its functional properties, such as the kinetic parameters characterizing the hydrolysis of polyinosinic acid and cytotoxicity towards Kasumi‐1 cells, were investigated. In all crystal structures of binase studied previously the characteristic dimer is present, with the active site of one subunit being blocked owing to interactions within the dimer. In contrast to this, the new mutant form is not dimeric in the crystal. The catalytic efficiency of the mutant form is increased 1.7‐fold and its cytotoxic properties are enhanced compared with the wild‐type enzyme.
This article presents the results of studies that the authors conducted proceeding from a hypothesis that an increase of crises phenomena in the global economy, uncertainty, and higher risk along ...with the growing use of digital smart technology apply radically new requirements on knowledge-intensive services in the energy sector. The sector of management consulting and engineering services, which constitute the backbone of knowledge-intensive services, is faced with a new role of providing a mix of services addressing the tasks of devising anticipatory actions amid uncertainty and crisis based on forecasting. Analysis of changes in business models and the content of services indicate their strong capacity for smart logistics of complex projects, knowledge transfer in cooperation with universities and innovation institutions, managing the development of flexible technological and product solutions, and competency development in network teams. This article offers a detailed elaboration of an up-to-date conceptual framework of engineering and management consulting; provides an overview of global trends; and presents a case study of collaboration problems that emerge in cross-disciplinary teams working on smart grid projects and projects of energy supply in cities based on smart grid technology. A model of proactive management and anticipatory personnel training in energy companies is proposed. This article describes the skillset needed for implementing a concept of integrated knowledge-intensive services for technological modernization and digitalization of the energy sector.
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