An effective potential for heavy quark antiquark bound system

A heavy quark antiquark potential is suggested connecting asymptotic freedom and quark confinement in a unified way. Theα _g (q ²) calculated using Borel summation technique with three loop agrees with the two loopβ-function up tog ²/4π≅ 1.1 but changes appreciably afterg ²/4π=1.5. The potential so derived satisfactorily explains the and spectrum.     

Effect of Ti4+ ions doping on microstructure and dc resistivity of nickel ferrites

Nanostructured nickel ferrites (NiFe₂O₄) were prepared by doping with Ti⁴⁺ ions using solid-state reaction route. Lowest grain size of 55 nm was achieved in the specimens with 20 mole% TiO₂ doping. Magnetization in the specimens decreases with decreasing grain sizes. Lower volume fractions of ferrite phase due to dissociation of the magnetic phase into smaller particles by the disruption of super exchange interaction by the titanium substitution results a decrease in magnetizations. Coercivity showed an increasing trend. This was explained as arising due to multidomain/monodomain magnetic behavior of magnetic nanoparticles. Small polaron hopping conduction between Fe²⁺ and Fe³⁺ sites controls the dc electrical properties of the specimens. The presence of an interfacial amorphous phase between the sites is evident from Mott's analysis. Specimens containing 10 mole or more TiO₂ and sintered at 1350 °C contain NiTiO₃ as a secondary phase and show unusual dc conductivity.     

Design and simulation of FIR band pass and band stop filters using gravitational search algorithm

In this paper, a new optimization method named gravitational search algorithm (GSA) is adopted for designing optimal linear phase finite impulse response band pass (BP) and band stop (BS) digital filters. Other various population based evolutionary algorithms like real coded genetic algorithm, conventional particle swarm optimization, differential evolution (DE), bee swarm optimization have also been applied for the sake of comparative study of the same optimal designs. In GSA, particles are considered as objects and their performances are measured by their masses. All these objects attract each other by gravity forces, and these forces produce global movements of all objects towards the objects with heavier masses. GSA guarantees the exploitation step of the algorithm and it is apparently free from premature convergence. Extensive simulation results justify superior optimization capability of GSA over the afore-mentioned optimization techniques for the solution of the multimodal, non-differentiable, highly non-linear, and constrained filter design problems.     

Differential Evolution with Wavelet Mutation in Digital Finite Impulse Response Filter Design

This paper proposes one novel algorithm called differential evolution with wavelet mutation for the optimal design of linear phase finite impulse response filters. For comparative performance study, the Parks–McClellan algorithm and some evolutionary algorithms like the real coded genetic algorithm, conventional particle swarm optimization, and conventional differential evolution have also been applied.     

Structural and electrical properties of Na1/2La1/2TiO3 ceramics

Na_1/2La_1/2TiO₃ (NLT) ceramic was prepared by a high-temperature solid-state reaction technique. A preliminary structural analysis (XRD) suggested the formation of a single-phase orthorhombic structure. SEM micrograph of the material showed uniform grain distribution on the surface of the sample. The dielectric permittivity and the loss tangent of the sample were measured in a frequency range from 1 kHz to 1 MHz and a temperature range 28 °C to 525 °C. Electrical properties of the material were studied using an ac impedance spectroscopic technique. Detailed analysis of the impedance spectrum suggested that the electrical properties of the material are strongly temperature dependant. The Nyquist plots clearly showed the presence of both bulk and grain boundary effect in the compound. The activation energy was estimated to be 1.1 eV from the temperature variation of dc conductivity. The a.c. conductivity spectrum suggests a typical signature of ion conducting system. PACS 77.22.Ch; 77.22.Gm; 77.80.Bh; 77.22.Ej     

Sodium Perborate Tetrahydrate–Mediated Transformations of 2′-Hydroxychalcones to Flavanones,Flavones, and 3′, 5′-Diiodoflavone Under Mild,Environmentally Friendly Conditions

Sodium perborate tetrahydrate has been utilized as a nucleophilic catalyst for facile conversion of 2′-hydroxychalcones to flavanones in warm aqueous acetonitrile, and then these chalcones, upon oxidative cyclization in warm acetic acid with an excess of the same reagent, afforded flavones in acceptable yields. One-pot synthesis of 3′,5′-diiodoflavone has been accomplished by diacetoxyiodobenzene-catalyzed iodination of 2′-hydroxychalcone with tetra-n-butylammonium iodide in acetic acid in the presence of sodium perborate as a terminal oxidant.