Synthesis and Spectral Characterization of Some New 4-(2,6-Diarylpyridin-4-yl)-2H-chromen-2-ones

Some new 4-(2,6-diarylpyridin-4-yl)-2H-chromen-2-one derivatives 5a–l have been synthesized by reacting 4-(3-oxo-3-arylprop-1-enyl)-2H-chromen-2-ones 3a–c with appropriate 1-(2-oxo-2-arylethyl)pyridinium bromide salt 4a–d in the presence of ammonium acetate in refluxing glacial acetic acid. The newly synthesized compounds have been characterized by elemental and spectral analysis.     

High-temperature oxidation studies of cold-sprayed Ni-20Cr and Ni-50Cr coatings on SAE 213-T22 boiler steel

The high-temperature oxidation behavior of cold-sprayed Ni-20Cr and Ni-50Cr coatings on SAE 213-T22 boiler steel has been investigated at 900 °C in air under cyclic heating and cooling conditions for 50 cycles. The kinetics of oxidation of coated and bare boiler steel has been established with the help of weight change measurements. It was observed that all the coated and bare steels obeyed parabolic rate law of oxidation. X-ray diffraction, FE-SEM/EDAX and X-ray mapping techniques were used to analyse the oxidation products of the coated and uncoated boiler steel. The uncoated steel suffered corrosion in the form of intense spalling and peeling of its oxide scale, which was perhaps due to the formation of unprotective Fe₂O₃ oxide scale. Both the coatings showed better resistance to the air oxidation as compared to the uncoated steel. The Ni-50Cr coating was found to be more protective than the Ni-20Cr-coated steel. The formation of oxides and spinels of nickel and chromium may be contributing to the development of air oxidation resistance in the coatings.     

Water mediated deprotective intramolecular hydroamination of N-propargylaminopyridines: synthesis of imidazo[1,2-a]pyridines

Metal-free synthesis of substituted imidazole [1,2-a]pyridines from deprotective N-(prop-2-yn-1-yl)pyridin-2-amines in water is elucidated. Electron releasing substituents on pyridine ring provided pure products in quantitative yields without separation by column chromatography.     

Bivariate Gonarov polynomials and integer sequences

Univariate Gonarov polynomials arose from the Gonarov interpolation problem in numerical analysis.They provide a natural basis of polynomials for working with u-parking functions,which are integer sequences whose order statistics are bounded by a given sequence u.In this paper,we study multivariate Gonarov polynomials,which form a basis of solutions for multivariate Gonarov interpolation problem.We present algebraic and analytic properties of multivariate Gonarov polynomials and establish a combinatorial relation with integer sequences.Explicitly,we prove that multivariate Gonarov polynomials enumerate k-tuples of integers sequences whose order statistics are bounded by certain weights along lattice paths in Nk.It leads to a higher-dimensional generalization of parking functions,for which many enumerative results can be derived from the theory of multivariate Gonarov polynomials.     

Itinerant electron metamagnetism and magnetocaloric effect in Dy(Co,Si)2

Itinerant electron metamagnetism in Dy(Co_1-xSi_x)₂ compounds was studied in the light of a recent theoretical model based on magnetovolume effect and spin fluctuations. The nature of the magnetic transition in these compounds was analyzed within the framework of this model. The magnetocaloric effect in these compounds has been calculated and correlated with the strength of itinerant electron metamagnetism. The domain wall pinning effect was found to be dominant at low temperatures.     

Reactivity of M(en)Cl2 (M = Pd/Pt,en = 1,2-diaminoethane) with N,N′-bis(salicylidene)-p-phenylenediamine: Binding with hexafluorobenzene

Schiff base N,N′-bis(salicylidene)-p-phenylenediamine (LH₂) complexed with Pt(en)Cl₂ and Pd(en)Cl₂ provided [Pt(en)L]₂ · 4PF₆ (1) and Pd(Salen) (2) (Salen = N,N′-bis(salicylidene)-ethylenediamine), respectively, which were characterized by their elemental analysis, spectroscopic data and X-ray data. A solid complex obtained by the reaction of hexafluorobenzene (hfb) with the representative complex 1 has been isolated and characterized as 3 (1 · hfb) using UV–Vis, NMR (¹H, ¹³C and ¹⁹F) data. A solid complex of hfb with a reported Zn-cyclophane 4 has also been prepared and characterized 5 (4 · hfb) for comparison with complex 3. The association of hfb with 1 and 4 has also been monitored using UV–Vis and luminescence data.     

Synergistically advancing Li storage property of hydrothermally grown 1D pristine MnO2 over a mesh-like interconnected framework of 2D graphene oxide

Journal of Solid State Electrochemistry - Here, we present a unique morphology comprising a blend of ultrafine 1D MnO2 and graphene oxide as an efficient anode material to overcome the issue of...     

A CLASS OF ENTIRE DIRICHLET SERIES AS AN FK-SPACE AND A FRECHET SPACE

In the present paper we consider a class of entire functions represented by Dirichlet series whose coefficients belong to a commutative Banach algebra and prove it to be a complex FK-space and a Frechet space.     

Hurst exponents for interacting random walkers obeying nonlinear Fokker-Planck equations

Anomalous diffusion of random walks has been extensively studied for the case of non-interacting particles. Here we study the evolution of nonlinear partial differential equations by interpreting them as Fokker-Planck equations arising from interactions among random walkers. We extend the formalism of generalized Hurst exponents to the study of nonlinear evolution equations and apply it to several illustrative examples. They include an analytically solvable case of a nonlinear diffusion constant and three nonlinear equations which are not analytically solvable: the usual Fisher equation which contains a quadratic nonlinearity, a generalization of the Fisher equation with density-dependent diffusion constant, and the Nagumo equation which incorporates a cubic rather than a quadratic nonlinearity. We estimate the generalized Hurst exponents.