Gegenbauer spectral method for time‐fractional convection–diffusion equations with variable coefficients

In this paper, we study the numerical solution to time‐fractional partial differential equations with variable coefficients that involve temporal Caputo derivative. A spectral method based on Gegenbauer polynomials is taken for approximating the solution of the given time‐fractional partial differential equation in time and a collocation method in space. The suggested method reduces this type of equation to the solution of a linear algebraic system. Finally, some numerical examples are presented to illustrate the efficiency and accuracy of the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.     

Solution structure of a seven coordinated manganese(II) complex via electrospray ionization mass spectrometry

The mononuclear complex [Mn(tptz)(CH₃COO)(OH₂)₂]NO₃ (1) was investigated by electrospray ionization mass spectrometry in aqueous solution at pH 4.5. Electrospray ionization mass spectrometry shows that mononuclear and dinuclear manganese cationic species are present in solution, probably in equilibrium with neutral 1. An experiment showed that the most important reaction in the presence of oxone (2KHSO₅·KHSO₄·K₂SO₄) is decoordination.     

Photocatalytic activity of ZnO nanoparticles prepared via submerged arc discharge method

ZnO nanostructures were synthesized through arc discharge of zinc electrodes in deionized (DI) water. X-ray diffraction (XRD) analysis of the prepared nanostructures indicates formation of crystalline ZnO of hexagonal lattice structures. Transmission electron microscopy (TEM) images illustrate rod-like as well as semi spherical ZnO nanoparticles with 15–20 nm diameter range, which were formed during the discharge process with 5 A arc current. The average particle size was found to increase with the increasing arc current. X-ray photoelectron spectroscopy (XPS) analysis confirms formation of ZnO at the surface of the nanoparticles. Surface area of the sample prepared at 5 A arc current, measured by BET analysis, was 34 m²/g. Photodegradation of Rhodamine B (Rh. B) shows that the prepared samples at lower currents have a higher photocatalytic activity due to larger surface area and smaller particle size.     

EPR and UV-vis studies of the nitric oxide adducts of bacterial phenylalanine hydroxylase: effects of cofactor and substrate on the iron environment

Phenylalanine hydroxylase from Chromobacterium violaceum (cPAH), which catalyzes phenylalanine oxidation to tyrosine, is homologous to the catalytic domain of eukaryotic PAHs. Previous crystallographic and spectroscopic studies on mammalian PAH conflict on whether O2 binds to the open-coordination site or displaces the remaining water ligand to yield either a six- or a five-coordinate iron, respectively. The abilities of nitric oxide to behave as an oxygen mimic and a spectroscopic probe of ferrous iron are used to investigate the geometric and electronic effects of cofactor and substrate binding to cPAH by electron paramagnetic resonance (EPR) and UV-vis spectroscopies. A rhombic distortion observed for the ternary complex is due to two factors: a decrease in the Fe-NO angle and an alteration in the equatorial ligand geometry. Both factors are consistent with NO displacing the sole remaining water ligand to yield a five-coordinate iron center. Hyperfine broadening of the EPR resonances of the nitrosyl complexes by 17O-enriched water is observed in the absence of substrates or presence of cofactor only (binary complex), demonstrating that water is bound to the Fe(II). However, in the presence of substrate and cofactor (ternary complex), the EPR resonances of the nitrosyl complex are not broadened by 17O-enriched water, indicating the displacement of water by NO to afford a five-coordinate iron. Furthermore, the increased intensity in the 500-600 nm range of the UV-vis spectrum of the ternary nitrosyl complex indicates an increased overlap between the in-plane NO 2pi and d(x2-y2) and d(xz) orbitals, which corroborates a five-coordinate iron.     

Brillouin-Raman comb fiber laser with cooperative Rayleigh scattering in a linear cavity

We demonstrate a multiple-wavelength Brillouin comb laser with cooperative Rayleigh scattering that uses Raman amplification in dispersion-compensating fiber. The laser resonator is a linear cavity formed by reflector at each end of the dispersion-compensating fiber to improve the reflectivity of the Brillouin Stokes comb. Multiple Brillouin Stokes generation has been improved in terms of optical signal-to-noise ratio and power-level fluctuation between neighboring channels. Furthermore, the linewidth of the Brillouin Stokes is uniform within the laser output bandwidth.     

On the supplier diversification under binomial yield

In a recent article, Fadiloglu et al. study an EOQ inventory model with multiple suppliers and binomial yields and conclude that sole sourcing is always optimal. This finding is contrary to the literature advocating diversification of the supply base in the presence of uncertainty. In this note, we present an alternative and more elegant proof of the optimality of sole sourcing in the EOQ model with binomial yield. Our approach extends this result to a general structure for the fixed order cost and provides more insights into the problem.     

Some results on information properties of coherent systems

This paper considers information properties of coherent systems when component lifetimes are independent and identically distributed. Some results on the entropy of coherent systems in terms of ordering properties of component distributions are proposed. Moreover, various sufficient conditions are given under which the entropy order among systems as well as the corresponding dual systems hold. Specifically, it is proved that under some conditions, the entropy order among component lifetimes is preserved under coherent system formations. The findings are based on system signatures as a useful measure from comparison purposes. Furthermore, some results on the system's entropy are derived when lifetimes of components are dependent and identically distributed. Several illustrative examples are also given.     

A novel method for the cyclotron production no-carrier-added <Superscript>93m</Superscript>Mo for nuclear medicine

Amongst the various radioisotopes of molybdenum, ^93mMo in its no-carrier added form might be a potential candidate radionuclide in the field of nuclear medicine due to its suitable half-life (T _1/2 = 6.85 h) and for its intense gamma line at 263.14 keV. Aim of the presented study is to compare the calculated cross sections for the production of ^93mMo incident proton energy up to 30 MeV, theoretical calculation of production yield and calculation of target thickness requirement. Also, deposition of ⁹³NbO₂ on Cu substrate was carried out via two special sedimentation methods for the production of ^93mMo and a simple and selective extraction of molybdenum was described.