Catalytic Properties and Structure of Palladium Surface Layer Formed in the Course of a Self-Oscillatory Reaction of Methane Oxidation

Kinetics and Catalysis - The self-oscillatory mode of methane oxidation over Pd foil at temperature of 400°C for 1 h caused the formation of a surface layer containing bulky porous...     

On the spectral stability in subspaces for difference schemes with nonlocal boundary conditions

We consider an initial-boundary value problem for the heat equation with nonlocal boundary conditions containing a parameter γ > 1. The spectrum of the main differential operator contains some number (depending on γ) of eigenvalues lying in the left complex half-plane, which results in the instability of the problem with respect to the initial data. For difference schemes approximating the original problem, we obtain a criterion for stability in the subspaces generated by stable harmonics.     

Effect of the velocity-dependent potentials on the energy eigenvalues of the Morse potential

We investigate the effect of the isotropic velocity-dependent potentials on the bound state energy eigenvalues of the Morse potential for any quantum states. When the velocity-dependent term is used as a constant parameter, ρ(r) = ρ ₀, the energy eigenvalues can be obtained analytically by using the Pekeris approximation. When the velocity-dependent term is considered as an harmonic oscillator type, ρ(r) = ρ ₀ r ², we show how to obtain the energy eigenvalues of the Morse potential without any approximation for any n and ℓ quantum states by using numerical calculations. The calculations have been performed for different energy eigenvalues and different numerical values of ρ ₀, in order to show the contribution of the velocity-dependent potential on the energy eigenvalues of the Morse potential.     

Statistical characteristics of acoustic signals reflected from maritime vessels during contintuous emission

The paper presents the results of experimental studies of fluctuations in echo signals from maritime vessels under conditions of near echo ranging with continuous targeted emission and reception at a frequency of 80 kHz. Data have been obtained on the fluctuation intensity, distribution functions, spectra, and time coherency fluctuations of echo signals at various vessel velocities for different reflecting and scattering areas of vessel hulls, different areas of the scattering layer of air bubbles formed at the hull of a moving vessel, and the cloud of air bubbles remaining behind the stern after a vessel has passed.     

An HPTLC method for the determination of oleandrin in Nerium plant extracts and its application to forensic toxicology

JPC – Journal of Planar Chromatography – Modern TLC - The study reported in this paper was aimed to develop an accurate, specific, and precise high-performance thin-layer chromatography...     

The investigation of acid effect on chemical polymerization of indole

The present study investigates the effects of Lewis acid and protonic acid on the chemical polymerization of indole using electrical conductivity measurements and nuclear magnetic resonance, UV–visible, and Fourier transform infrared spectroscopy techniques. These effects are explained by theoretical calculations on the basis of molecular mechanic (MM+) and semi-empirical Austin Model 1 methods. As a result, it has been shown that indole interacts with proton and Lewis acids by the way of different mechanisms. Theoretical research has demonstrated that while BF₃, a Lewis acid, adds to the N atom in the indole, which has a basic character due to its lone-pair electrons, proton, H⁺ adds to the indole ring on C₃ atom. These additions affect both the polymerization of indole and the conductivity of polyindole. Polyindole conductivity is increased by BF₃ addition and decreased by H⁺ addition.     

Synthesis and Characterization of Poly(allyl methacrylate) Obtained by Free Radical Initiator

Allyl methacrylate was polymerized in CCl₄ solution by α,α′‐azoisobutyronitrile at 50, 60, and 70°C. The kinetic curves were auto‐accelarated types at 60 and 70°C, but almost linear at 50°C. Arrhenius activation energy was 77.5 kJ/mol. The polymer was insoluble in common organic solvents. It was characterized by FT‐IR, NMR, DSC, TGA and XPS methods. About 98–99% of allyl side groups were remained as pendant even after completion of the polymerization. The spectroscopic and thermal results showed that polymerization is not a cyclopolymerization type, but may have end group cyclization. The high molecular weight is the main cause of a polymer being insoluble even in the early stage of the polymerization. Molecular weight of 1.1×10⁶ for a soluble polymer fraction was measured by light scattering method. The Tg of polymer was 94°C, and after curing at 150–200°C, increased to 211°C. The thermal pyrolysis of polymer at about 350°C gave an anhydride by linkage type degradation, and side group cyclization. The XPS analysis showed the presence of radical fragments of AIBN (initiator) and CCl₄ (solvent) associated with oligomers.     

Stability criterion for a family of nonlocal difference schemes

We consider finite-difference schemes for the heat equation with nonlocal boundary conditions that contain a real parameter γ. A stability criterion for finite-difference schemes with respect to the initial data was earlier obtained for |γ| ≤ 1. In the present paper, we consider the case in which γ ∈ (−cosh π,−1) and the original differential problem is stable, while the stability conditions for the finite-difference schemes substantially depend on γ. We obtain estimates for the energy norm of the solution of the finite-difference problem via the same norm of the initial data and prove the equivalence of the energy norm and the grid L ₂-norm.