Estimates of the supremum of a class of stationary random processes

Under the conditions guaranteeing the uniform convergence of the spectral representations, we obtain estimates for the distribution of its supremum. We obtain estimates for the supremum of a real stationary process for which the corresponding spectral processes belong to the space Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No.12, pp. 1628–1637, December, 1991.     

Manganese doping of In1−xGaxAsyP1-y films in liquid-phase epitaxy

The manganese doping of In_1–xGa_xAs_yP_1-y(0 y 1) films grown by liquid-phase epitaxy has been investigated. A study has been made of the influence of the solid-solution composition and of the method of introducing the manganese into the solution melt on the electrical properties of the films, and also on the surface morphology, the optical absorption edge, and the mismatch of the film and substrate lattice constants. It is shown that the hole density in the films decreases with decreasing y. The reasons for this are the decrease in the distribution coefficient of the acceptor manganese (from 0.3 to 0.001), the increase in the degree of compensation of the acceptors with donors (from 0.2 to 0.9), and the increase in the acceptor ionization energy. The composition of the InGaAsP:Mn film and the morphology of its surface depend on the method of preparation of the melt, this being explained by the strong interaction of the manganese atoms with the other components of the liquid phase.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 26–34, January, 1992.We thank T. G. Druzhinin, Ya. I. Otman, and V. B. Yabzhanov for helping with the experiments.     

New water-soluble calix[4]arene-bis(benzocrown-6) for caesium-sodium separation by nanofiltration-complexation

Calix-bis(benzocrown-6) 6 and 7 were converted into the water-soluble receptors 9, 10, 12 and 15 by introducing hydroxy, carboxy, sulfato or diethanolamino groups at the para position of the phenolic ring and/or on the benzo-ether moieties. The complexation properties of these ionophores were studied for all alkali cations in methanolic and aqueous media. Stability constants were calculated by UV-Vis spectroscopy. All ligands showed a more or less affinity for the larger cations, depending on the nature and the position of the substituents grafted on the benzo-ether chain only or both on the calixarene ring and the benzo-ether loop. For selective Cs⁺/Na⁺ separation, the efficiency of the ligands was evaluated by means of a nanofiltration system. In comparison with the known tetrahydroxylated bis-crown-6 calix[4]arene 1, compounds 9, 12 and 15 represent the most selective ligands for the Cs⁺ cation in a moderate salted medium ([NaNO₃]=85 g/L).     

Retention behaviour of peptides in capillary electrochromatography using an embedded ammonium in dodecacyl stationary phase

A highly water-soluble new cyclodextrin (CD) derivative 2-O-acetonyl-2-O-hydroxypropyl-beta-CD (2-AHP-beta-CD) was synthesized and tested as an effective chiral selector for the capillary zone electrophoretic resolution (Rs) of several basic and acidic analytes. The primary purpose of the research was to explore the capability of the 2-AHP-beta-CD as chiral selectors on comparison with the neutral CDs such as beta-CD, DM-beta-CD and HP-beta-CD. Substitution with 2-O-acetonyl-2-O-hydroxypropyl group at the secondary hydroxyl sites of the CD is aimed at influencing the magnitude and selectivity of analyte-CD interactions. The chiral resolution was strongly influenced by the concentration of the CDs and buffer pH. 2-AHP-beta-CD showed the best enantiomer resolution properties among the tested compounds, while the other CDs showed inferior or no performances at all.     

Structure of the products of the reaction of 9,10-dimethylacridinium salts with aromatic o-hydroxy aldehydes

The reaction of 9,10-dimethylacridinium methosulfate with aromatic o-hydroxy aldehydes in alcohol in the presence of piperidine gives 10-methyl-4-(10-methyl-9-acridanylidenemethyl)-spiro[acridan-9,2-chromans]. The structure of the compounds obtained was established by means of the PMR, UV, and IR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 539–544, April, 1973.     

Versatile reactions of a para-bromophenylacetylide iron(II) derivative and X-ray structure of the fluoro analogue. Synthesis of new redox-active organoiron(II) synthons

The synthesis of the new (η²-dppe)(η⁵-C₅Me₅)Fe---CC---1,3-(C₆H₄X) (m-2a/2b; X=F/Br) and (η²-dppe)(η⁵-C₅Me₅)Fe---CC---1,4-(C₆H₄I) (2c) complexes, as well as the solid-state structure of the known (η²-dppe)(η⁵-C₅Me₅)Fe---CC---1,4-(C₆H₄F) (2a) complex are described. The catalytic coupling reactions of the bromo complexes with various alkynes were next investigated. Starting from the known (η²-dppe)(η⁵-C₅Me₅)Fe---CC---1,4-(C₆H₄Br) complex (2b), the synthesis of the (η²-dppe)(η⁵-C₅Me₅)Fe---CC---1,4-(C₆H₄)---CC---H complex (6d) and of the corresponding silyl-protected precursors (η²-dppe)(η⁵-C₅Me₅)Fe---CC---1,4-(C₆H₄)CC---SiR₃ (6b/6c; R=ⁱPr/Me) are reported. By use of lithium---bromine exchange reactions on 2b, the silyl- (7a; E=Si; R=Me) and tin- (7b–7d; E=Sn; R=Me, Bu, Ph) substituted analogues (η²-dppe)(η⁵-C₅Me₅)Fe---CC---1,4-(C₆H₄)ER₃ are also isolated. The spectroscopic and electrochemical characterisations of all these new Fe(II)/Fe(III) redox-active building blocks are presented and the electronic substituent parameters for the “(η²-dppe)(η⁵-C₅Me₅)Fe---CC” group are determined by means of ¹⁹F-NMR.     

Direct structure determination using residual dipolar couplings: reaction-site conformation of methionine sulfoxide reductase in solution

Residual dipolar couplings (RDC) from partially aligned molecules provide long-range structural data and are thus particularly well adapted to rapid structure validation or protein fold recognition. Extensive measurements in two alignment media can also provide precise de novo structure from RDC alone. We have applied a novel combination of these approaches to the study of methionine sulfoxide reductase (MsrA) from Erwinia chrysanthemi, a 27 kDa enzyme essential for repairing oxidative stress damage. The tertiary fold was initially validated by comparing backbone RDC to expected values from the crystal structure of the homologous MsrA from Escherichia coli. Good agreement was found throughout the chain, verifying the overall topology of the molecule, with the exception of the catalytically important peptide P196-L202, where strong and systematic RDC violation was observed. No evidence for local differential mobility in this region was detected, implying that the structure of the strand differs in the two molecules. We have therefore applied the de novo approach meccano to determine the conformation of this peptide using only RDC. A single conformation is found that is in agreement with all measured data. The aligned peptide can be docked onto the expected covalence of the rest of the template molecule while respecting its strictly defined relative orientation. In contrast to the structure of MsrA from E. coli, the reactive side chain of Cys200 is oriented toward the interior of the molecule and therefore closer to the catalytic Cys53, obviating the need for previously proposed conformational reorganization prior to formation of this disulfide intermediate. This analysis requires only backbone assignment and uses unambiguously assigned and readily measurable structural data, thereby greatly economizing investigation time compared to established nuclear Overhauser effect- (nOe-) based structure calculation methods.     

Stability of single-mode oscillations synchronized by an external signal in A multimode cyclotron-resonance maser monotron

Conclusions Premodulation of the electron beam by an external signal and appropriate choice of parameters for a synchronized CRM monotron increase the starting values of the parameters I_s proportional to the beam current and the Q's of competing modes. In maximum-efficiency regimes (for optimal beam current and externalsignal frequency), the stability of single-mode oscillations in a CRM monotron is ensured for any competing-mode Q's, regardless of the values of the parameters,, , X, or n.Scientific-Research Institute of Radio Physics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 19, No. 3, pp. 453–459, March, 1976.     

Photostimulated kinetic effects in semiconductors

It is shown that the presence of intense laser radiation can result in the origination of spreading of kinetic effects even in a degenerate monopolar semiconductor with an isotropic energy spectrum, where the magnitude of such photostimulated effects can exceed the magnitude of corresponding effects in the absence of radiation, due to the thermal spread of current carriers in the energies or anisotropies of isoenergetic surfaces. Photostimulated Ettingshausen, Peltier, and transverse magnetoresistive effects are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 121–129, February, 1976.     

Multi-State Second-Order Nonlinear Optical Switches Incorporating One to Three Benzazolo-Oxazolidine Units: A Quantum Chemistry Investigation

This contribution employs quantum chemistry methods to describe the variations of the second nonlinear optical responses of molecular switches based on benzazolo-oxazolidine (BOX) units, connected by π-linkers, along their successive opening/closing. Under the fully closed forms, all of them display negligible first hyperpolarizability (β) values. When one BOX is opened, which is sketched as C→O, a push–pull π-conjugated segment is formed, having the potential to enhance β and to set the depolarization ratio (DR) to its one-dimensional-like value (DR = 5). This is observed when only one BOX is open, either for the monoBOX species (C→O) or for the diBOX (CC→CO) and triBOX (CCC→CCO) compounds, i.e., when the remaining BOXs stay closed. The next BOX openings have much different effects. For the diBOXs, the second opening (CO→OO) is associated with a decrease of β, and this decrease is tuned by controlling the conformation of the π-linker, i.e., the centrosymmetry of the whole compound because β vanishes in centrosymmetric compounds. For the triBOXs, the second opening gives rise to a Λ-shape compound, with a negligible change of β, but a decrease of the DR whereas, along the third opening, β remains similar and the DR decreases to the typical value of octupolar systems (DR = 1.5).