Quasinormal modes of BTZ black hole and Hawking‐like radiation in graphene

The Bañados‐Teitelboim‐Zanelli (BTZ) black hole model corresponds to a solution of (2+1)‐dimensional Einstein gravity with negative cosmological constant, and by a conformal rescaling its metric can be mapped onto the hyperbolic pseudosphere surface (Beltrami trumpet) with negative curvature. Beltrami trumpet shaped graphene sheets have been predicted to emit Hawking radiation that is experimentally detectable by a scanning tunnelling microscope. Here, for the first time we present an analytical algorithm that allows variational solutions to the Dirac Hamiltonian of graphene pseudoparticles in BTZ black hole gravitational field by using an approach based on the formalism of pseudo‐Hermitian Hamiltonians within a discrete‐basis‐set method. We show that our model not only reproduces the exact results for the real part of quasinormal mode frequencies of (2+1)‐dimensional spinless BTZ black hole, but also provides analytical results for the real part of quasinormal modes of spinning BTZ black hole, and also offers some predictions for the observable effects with a view to gravity‐like phenomena in a curved graphene sheet.

     

Synthesis of dipyrrolo[2,3-a:1′,2′,3′-fg]acridin-12(1H)-ones

Acylation reactions of 4,6-dimethoxyindoles with glyoxyloyl chlorides were achieved by the use of graphite powder in 1,2-dichloroethane at reflux. The products were monoketones as a result of decarbonylation, rather than the expected 1,2-diketones. Treatment of these monoketones with base led to their cyclisation and elimination of methanol to afford the novel dipyrrolo[2.3-a:1′,2′,3′-fg]acridin-12(1H)-ones.     

A Fourier pseudospectral method for a generalized improved Boussinesq equation

In this article, we propose a Fourier pseudospectral method for solving the generalized improved Boussinesq equation. We prove the convergence of the semi‐discrete scheme in the energy space. For various power nonlinearities, we consider three test problems concerning the propagation of a single solitary wave, the interaction of two solitary waves and a solution that blows up in finite time. We compare our numerical results with those given in the literature in terms of numerical accuracy. The numerical comparisons show that the Fourier pseudospectral method provides highly accurate results. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 995–1008, 2015     

Determination of sulpha-drugs with ion-selective membrane electrodes--II

Two liquid-membrane electrodes, one sensitive to Cu(2+) and the other to Ag(+), were used for the determination of various sulpha-drugs with pK(a) > or = 6 (as the sodium salts) by potentiometric titration with CuSO(4) and AgNO(3). The construction and basic characteristics of these two electrodes are discussed.     

A numerical study of the semi‐classical limit for three‐coupled long wave–short wave interaction equations

We study numerically the semi‐classical limit for three‐coupled long wave–short wave interaction equations. The Fourier–Galerkin semi‐discretization is proved to be spectrally convergent in an appropriate energy space. We propose a split‐step Fourier method in the semi‐classical regime with the discussion of the meshing strategy, which is necessary to obtain correct numerical solution. Plane wave solution with weak and strong initial phases, solitary wave solution and Gaussian solution are considered to investigate the semi‐classical limit.     

The stability of magnetobipolarons in low-dimensional systems

We investigate the stability condition of large bipolarons confined in a parabolic potential containing certain parameters and a uniform magnetic field. The variational wave function is constructed as a product form of electronic parts, consisting of center of mass and internal motion, and a part of coherent phonons generated by Lee-Low-Pines transformation from the vacuum. An analytical expression for the bipolaron energy is found, from which the ground and excited-state energies are obtained numerically by minimization procedure. The bipolaron stability region is determined by comparing the bipolaron energy with those of two separate polarons, which is already calculated within the same approximation. It is shown that the results obtained for the ground state energy of bipolarons reduce to the existing works in zero magnetic field. In the presence of a magnetic field, the stability of bipolarons is examined, for three types of low-dimensional system, as function of certain parameters, such as the magnetic-field, the electron-phonon coupling constant, Coulomb repulsion and the confinement strength. Numerical solutions for the energy levels of the ground and first excited states are examined as functions of the same parameters. Received 7 March 2002 and Received in final form 22 April 2002 Published online 25 June 2002     

Performance assessment of the photon enhanced thermionic emitter and heat engine system

Journal of Thermal Analysis and Calorimetry - The aim of this research is to show the potential application of a photon enhanced thermionic emitter (PETE)–irreversible heat engine (HE) hybrid...     

LC-HRMS Profiling and Antidiabetic,Anticholinergic, and Antioxidant Activities of Aerial Parts of Kınkor (Ferulago stellata)

Kınkor (Ferulago stellata) is Turkish medicinal plant species and used in folk medicine against some diseases. As far as we know, the data are not available on the biological activities and chemical composition of this medicinal plant. In this study, the phytochemical composition; some metabolic enzyme inhibition; and antidiabetic, anticholinergic, and antioxidant activities of this plant were assessed. In order to evaluate the antioxidant activity of evaporated ethanolic extract (EEFS) and lyophilized water extract (WEFS) of kınkor (Ferulago stellata), some putative antioxidant methods such as DPPH· scavenging activity, ABTS^•+ scavenging activity, ferric ions (Fe³⁺) reduction method, cupric ions (Cu²⁺) reducing capacity, and ferrous ions (Fe²⁺)-binding activities were separately performed. Furthermore, ascorbic acid, BHT, and α-tocopherol were used as the standard compounds. Additionally, the main phenolic compounds that are responsible for antioxidant abilities of ethanol and water extracts of kınkor (Ferulago stellata) were determined by liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Ethanol and water extracts of kınkor (Ferulago stellata) demonstrated effective antioxidant abilities when compared to standards. Moreover, ethanol extract of kınkor (Ferulago stellata) demonstrated IC₅₀ values of 1.772 μg/mL against acetylcholinesterase (AChE), 33.56 ± 2.96 μg/mL against α-glycosidase, and 0.639 μg/mL against α-amylase enzyme respectively.     

2H-Indazolo[2,1-b]phthalazine-trione derivatives: Inhibition on some metabolic enzymes and molecular docking studies

In this study, substituted 2H-indazolo[2,1-b]phthalazine-1,6,11-trione compounds ( 4a–d ) obtained via one-pot three-component condensation reaction of aromatic aldehydes, cyclic 1,3-dione, and phthalhydrazide in ethanol catalyzed by Y(OTf)₃ showed satisfactory inhibitory effects against some important enzymes. Also, these molecules had K_i values in the row of 185.92 ± 36.03-294.82 ± 50.76 nM vs carbonic anhydrase I (CA I), 204.93 ± 46.90-374.10 ± 83.63 nM against human CA II, 937.16 ± 205.82-1021.83 ± 193.66 nM against α-glycosidase (α-Gly), respectively. For cholinesterase enzymes, the K_i values were found in the range of 47.26 ± 9.62-72.05 ± 19.47 nM against acetylcholinesterase (AChE) and 65.03 ± 9.88-102.83 ± 25.04 nM against butyrylcholinesterase (BChE), respectively. The inhibition effects of these compounds against enzymes whose name are AChE, BChE, α-Gly, hCA I, and hCA II, were compared with control molecules like tacrine, acarbose, and acetazolamide.