Homogeneous Schr?dinger Operators on Half-Line

The differential expression L_m=-?_x²+(m²-1/4)x^-2{L_m=-\partial_x^2+(m^2-1/4)x^{-2}} defines a self-adjoint operator H _m on L ²(0, ∞) in a natural way when m ² ≥ 1. We study the dependence of H _m on the parameter m show that it has a unique holomorphic extension to the half-plane Re m > −1, and analyze spectral and scattering properties of this family of operators.     

Impulsive perturbations of a three-trophic prey-dependent food chain system

The dynamics of an impulsively controlled three-trophic food chain system with general nonlinear functional responses for the intermediate consumer and the top predator are analyzed using the Floquet theory and comparison techniques. It is assumed that the impulsive controls act in a periodic fashion, the constant impulse (the biological control) and the proportional impulses (the chemical controls) acting with the same period, but not simultaneously. Sufficient conditions for the global stability of resource and intermediate consumer-free periodic solution and of the intermediate consumer-free periodic solution are established, the latter corresponding to the success of the integrated pest management strategy from which our food chain system arises. In this regard, it is seen that, theoretically speaking, the control strategy can be always made to succeed globally if proper pesticides are employed, while as far as the biological control is concerned, its global effectiveness can also be reached provided that the top predator is voracious enough or the (constant) number of top predators released each time is large enough or the release period is small enough. Some situations which lead to chaotic behavior of the system are also investigated by means of numerical simulations.     

Upconversion luminescence of Er3+/Yb3+ co-doped nanolangasite synthesized by a modified Pechini route

Nanopowders of langasite (La₃Ga₅SiO₁₄) doped with 1 at.% Er³⁺ and 3 at.% Yb³⁺ were synthesized for the first time by a modified Pechini route and annealed in air at 700, 750, 800, 900, and 1,000?°C. The langasite powders were characterized by XRD, FTIR and luminescence techniques. Crystallization began at 750?°C and pure langasite phase was obtained for the samples annealed at 800 and 900?°C. Traces of LaGaO₃ and Ga₂O₃ were observed in the sample annealed at 1,000?°C. Bright green and red luminescence was observed for pumping at 973?nm whose intensity increased with annealing temperature due to the removal of the adsorbed impurities and the improvement of crystallinity.     

Nondestructive method for the calculation of bulk material composition by X‐ray fluorescence,using surface analysis on corroded bronze objects

The formation of patina on the surface of archeological bronze objects is a complex phenomenon, being influenced by various parameters induced by the environment and the alloy composition. Over several years, many attempts have been made to analyze the bulk composition of the alloys by nondestructive surface measurements. In this paper, we propose an analytical approach to evaluate the composition of bronze alloys using neural network analysis and X‐ray fluorescence spectrometry. Copyright © 2012 John Wiley & Sons, Ltd.     

Target structure induced suppression of the ionization cross section for very low energy antiproton-hydrogen collisions

Low energy antiprotons have been used previously to give benchmark data for theories of atomic collisions. Here we present measurements of the cross section for single, nondissociative ionization of molecular hydrogen for impact of antiprotons with kinetic energies in the range 2-11 keV, i.e., in the velocity interval of 0.3-0.65 a.u. We find a cross section which is proportional to the projectile velocity, which is quite unlike the behavior of corresponding atomic cross sections, and which has never previously been observed experimentally.     

Total oxidation of benzene using Cu-Cr mixed oxide as catalyst

Benzene total oxidation on a Cu-Cr supported catalyst was investigated using the work function method. Above 300°C, the majority of the oxygen species on the surface was O²⁻ in the absence or in the presence of hydrocarbon.     

Ranking fuzzy choice functions by their rationality indicators

In this paper we study two rationality indicators and two normality indicators of a fuzzy choice function. They express the degree of rationality or normality of this fuzzy choice function. This way we can establish a hierarchy in a given family of fuzzy choice functions with respect to their degree of rationality.     

相对论平均场理论对Pb同位素位移的研究

运用变形的相对论平均场理论研究了Pb同位素链的基态性质. 对关联的处理采用了BCS方法, 不成对核子的处理运用了“阻塞”法. 计算的结果很好地符合了实验上Pb的平均结合能, 中子分离能, 同位素位移. 接着从原子核的微观结构出发, 比较详细地研究了Pb链同位素位移出现反常扭折这一重要性质的物理机制.     

EDXRF versus INAA in a pollution control of soil

Summary Elemental concentrations of soil samples collected in the vicinity of a Romanian fertilizer plant were determined by EDXRF and long half-life INAA. Lower limits of detection, obtained for various elements in soil by EDXRF technique with radioactive excitation sources (²³⁸Pu and ²⁴¹Am) and a HPGe detector are presented. Spurious effects characteristic for Ge detector X-ray spectrometry are evaluated and discussed, and methods to overcome this drawback are suggested. Special care was taken to subtract from the spectra the Ge Ka