The photon absorption edge in superconductors and gapped 1D systems

Opening of a gap in the low-energy excitations spectrum affects the power-law singularity in the photon absorption spectrum $A(\Omega)$. In the normal state, the singularity, $A(\Omega)\propto [D/(\Omega-\Omega_{\rm th})]^\alpha$, is characterized by an interaction-dependent exponent $\alpha$. On the contrary, in the supeconducting state the divergence, $A(\Omega)\propto (D/\Delta)^\alpha(\Omega-\tilde{\Omega}_{\rm th})^{-1/2}$, is interaction-independent, while threshold is shifted, $\tilde{\Omega}_{\rm th}=\Omega_{\rm th}+\Delta$; the ``normal-metal'' form of $A(\Omega)$ resumes at $(\Omega-\tilde{\Omega}_{\rm th})\gtrsim \Delta\exp(1/\alpha)$. If the core hole is magnetic, it creates in-gap states; these states transform drastically the absorption edge. In addition, processes of scattering off the magnetic core hole involving spin-flip give rise to inelastic absorption with one or several {\it real} excited pairs in the final state, yielding a structure of peaks in $A(\Omega)$ at multiples of $2\Delta$ above the threshold frequency. The above conclusions apply to a broad class of systems, e.g., Mott insulators, where a gap opens at the Fermi level due to the interactions.Comment: 6 pages, 5 figures; published versio

Calculation of Field Characteristics in Periodic Nanostructures from Composite Elements with Activated Plasmon Modes

Modeling of the electromagnetic field of the optical frequency in periodic structures composed of parallel conducting nanorods as well as composite spherical nanoparticles with an excitonogenic envelope in hexagonal 2d-lattices - in the quasistatic approximation and the FDTD method. The qualitative agreement of these approaches is shown when calculating field characteristics in lattices of cylindrical elements

CHANGES OF THE SERUM ENZYME LEVEL IN PATIENTS WITH LIVER CARCINOMA

No abstrac

Impurities, Quantum Interference and Quantum Phase Transitions in s-wave superconductors

We study the effects of quantum interference in impurity structures consisting of two or three magnetic impurities that are located on the surface of an s-wave superconductor. By using a self-consistent Bogoliubov-de Gennes formalism, we show that quantum interference leads to characteristic signatures not only in the local density of states (LDOS), but also in the spatial form of the superconducting order parameter. We demonstrate that the signatures of quantum interference in the LDOS are qualitatively, and to a large extent quantitatively unaffected by the suppression of the superconducting order parameter near impurities, which illustrates the robustness of quantum interference phenomena. Moreover, we show that by changing the interimpurity distance, or the impurities' scattering strength, the s-wave superconductor can be tuned through a series of first order quantum phase transitions in which the spin polarization of its ground state changes. In contrast to the single impurity case, this transition is not necessarily accompanied by a $\pi$-phase shift of the order parameter, and can in certain cases even lead to its enhancement. Our results demonstrate that the superconductor's LDOS, its spin state, and the spatial form of the superconducting order parameter are determined by a subtle interplay between the relative positions of the impurities and their scattering strength

Diazatriphenylenes and their thiophene analogues: Synthesis and applications

This review highlights the recent advances in the field of the synthesis of diazatriphenylenes and their structural analogues, such as phenanthrenes, fused with the thiophene ring, and naphthalenes, condensed with two thiophene rings. Also applications of these compounds are considered. © ARKAT USA, Inc.The research was financially supported by the Russian Science Foundation (Project No. 16-13-10435) and the Russian Foundation for Basic Research (research project №. 17-03-00011-А)

5-(Methylidene)barbituric acid as a new anchor unit for dye-sensitized solar cells (DSSC)

Novel dyes bearing a 5-(methylidene)barbituric acid moiety as a new acceptor/anchor fragment were obtained and exhibited remarkable photophysical properties, according to a preliminary assessment of their sensitization activity as elements for dye-sensitized solar cells. © ARKAT-USA, Inc

(E)-2-(hydroxystyryl)-3-phenylquinazolin-4(3H)-ones: Synthesis, photochemical and luminescent properties

The new (E)-2-(hydroxyarilethenyl)-3-phenylquinazolin-4(3H)-ones with various substituents in phenyl fragment were synthesized. The effect of electron donor and acceptor substituents (±M) in quinazolinones on luminescence intensity and dual emission in 550-650-nm wavelength range was shown. The fact of the reversible photo/thermal E-Z isomerization for several substances was established. The (E)-2-(5-chloro-2-hydroxystyryl)-3-phenylquinazolin-4(3H)-one had shown the best combination of photochemical (E-Z isomerization) and photophysical properties. The (E)-2-(2-hydroxy-5-morpholinostyryl)-3-phenylquinazolin-4(3H)-one had revealed the best ESIPT-luminescence (Φrel = 5.3 %). © Arkat. All Rights Reserved.Russian Foundation for Basic Research, RFBR: 18-03-00112This work was supported by the Russian Foundation for Basic Research (grant 18-03-00112). Analytical studies were carried out using equipment of the Center for Joint Use SSpectroscopy and ?nalysis of Organic Compounds ? at the Postosvky Institute of Organic Synthesis of the Russian Academy of Sciences (Ural Branch)

An improved protocol for the preparation of 5, 11-dialkyl-6, 12-di(hetero)aryl-5, 11-dihydroindolo[3, 2-b]carbazoles and synthesis of their new 2, 8-dicyano-/2, 8-bis(benzo[d]thiazol-2-yl)-substituted derivatives

A number of 5, 11-dialkyl-6, 12-di(hetero)aryl-5, 11-dyhydroindolo[3, 2-b]carbazoles has been synthesized by modified method based on HBr catalyzed condensation of (hetero)aromatic aldehydes with indole in MeCN solution affording 5, 6, 11, 12-tetrahydroindolo[3, 2-b]carbazoles, that have been aromatized with I2 in DMF solution for 1 h at reflux, followed by alkylation of 5, 11-dihydro compounds. New 2, 8-dicyano-(10 examples) as well as 2, 8-bis(benzo[d]thiazol-2-yl)-substituted (5 examples) derivatives of these 5, 11-dyhydroindolo[3, 2-b]carbazoles have been obtained through their initial C2, 8-formylation, followed by treatment of dialdehydes with excess of hydroxylamine and dehydration of the formed aldoximes with acetic anhydride or by interaction with excess of 2-aminothiophenol in DMSO solution, respectively. © 2018 Arkat. All rights reserved.This research study was supported financially by the Russian Science Foundation (Project No. 16-13-10435)