Cobalt-modified nickel–zinc catalyst for electrooxidation of methanol in alkaline medium

Cobalt-modified nickel-zinc catalyst CuNi(Zn)Co is prepared on a copper substrate by using electrodeposition. Its catalytic efficiency for methanol oxidation is studied with cyclic voltammetry, chronoamperometry, and chronopotentiometry techniques. The surface morphology and chemical composition of catalyst are characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The oxidation kinetic parameters activation energy (Ea), active species on the surface (Γ), and rate constant (k) are determined from cyclic voltammograms which are performed at different methanol concentrations and temperatures. The results show that Ni(Zn)Co catalyst has higher catalytic activity than Ni, Co, and NiZn coatings as a composite catalyst for a promising choice of methanol electrooxidation in the alkaline medium.     

Stereoselective synthesis of optically active cyclopenta[c]pyrans and cyclopenta[c]furans by the intramolecular Pauson–Khand reaction

An intramolecular Pauson–Khand reaction of enynes derived from homoallyl, homopropargyl, and allyl alcohols is described. 2-Heteroaryl-substituted homoallyl, homopropargyl, and allyl alcohols are easily and efficiently resolved through enzymatic resolution in high ee (91–99%) and with a known stereochemistry. Each enantiomerically enriched enyne derived from homoallyl and homopropargyl alcohols affords the conformationally most stable diastereomeric cyclopenta[c]pyran ring system as the sole product, whereas enantiomerically enriched enynes derived from allyl alcohols give a diastereomeric cis:trans mixture of the cyclopenta[c]furan ring system.     

Some relations between certain inequalities concerning analytic and univalent functions

By making use of the well-known assertions in [S.S. Miller, P.T. Mocanu, Differential Subordinations, Theory and Applications, Marcel Dekker, New York-Basel, 2000] and [M. Nunokawa, On the order of strongly starlikeness of strongly convex functions, Proc. Japan Acad. Ser. A Math. Sci. 69 (7) (1993) 234–237], several useful results of certain inequalities dealing with analytic and univalent functions are obtained and then certain consequences of them are also indicated.     

Stability of Ritz procedure for nonlinear two-point boundary value problem

In this paper we establish the stability of Ritz procedure in sense of Michlin and Tucker for a class of nonlinear two-point boundary value problems which has been considered by Varga, Schultz and Ciarlet in [1].     

Synthesis,crystal structure and catalytic activity for H2O2 disproportionation of the manganese(II) coordination polymer {[Mn(O2C(CF2)8CO2)(phen)2]H2O}n (phen = 1,10-phenanthroline)

The title polymeric complex {[Mn(O₂C(CF₂)₈CO₂)(phen)₂]H₂O}_n was synthesized through the reaction of 1,10-phenanthroline, perfluorosebacic acid and MnCO₃ · H₂O. The molecular structure was characterized by X-ray diffraction, elemental analysis, thermal gravimetry, IR and UV–Vis spectroscopy and its catalytic activity has been studied. X-ray structure analysis shows that each Mn(II) ion is octahedrally coordinated by two bidentate phenanthroline ligands and the carboxylate oxygen atoms from two symmetry related perfluorosebacate ligands, which are coordinated in cisoid positions. The structure consists of polymeric chains, with the perfluorosebacato ligand bridging the Mn(II) ions in a monodentate fashion. Crystallographic characterization shows a supramolecular structure involving hydrogen bonds, π–π and π-ring interactions. The catalytic results indicated that the complex has reasonably good activity towards the disproportionation of hydrogen peroxide into water and dioxygen in methanol and it does not exhibit saturation kinetics with the substrate. The initial reaction rates and their temperature and base dependencies were investigated by monitoring the dioxygen evolution. Kinetic studies revealed a first-order dependence on the catalyst concentration. Activation parameters have been calculated at 301 K.     

FT-IR spectra, vibrational assignments, and density functional calculations of imidazo[1,2-a]pyridine molecule and its Zn(II) halide complexes

The geometry, frequency, and intensity of the vibrational bands of imidazo[1,2-a]pyridine (which is abbreviated as impy) were obtained by the density functional theory (DFT) calculations with BLYP, B3LYP, and B3PW91 functionals and 6-31G(d) basis set. The optimized geometric bond lengths and bond angles are in good agreement with the available X-ray data. The infrared spectrum of imidazo[1,2-a]pyridine was computed by the DFT method in order to reproduce the vibrational wavenumbers and intensities with an accuracy, which allows reliable vibrational assignments. Total energy distribution and isotopic shifts have been calculated in order to help for the perfect assignment of the vibrational modes. The zinc halide complexes Zn(impy)₂X₂ [X = Cl, Br, and I] have also been synthesized. The compounds were characterized using the elemental analysis, FT-IR spectra, and quantum chemical calculations. The geometry optimization of Zn(impy)₂X₂ yields distorted tetrahedral environment around Zn ion.     

Novel phthalocyanines with naphthalenic substituents

Phthalocyanines with four naphthyl-malonic ester groups on the periphery were synthesized by cyclotetramerization of 4-(1,1-dicarbethoxy-2-(1-naphthyl)-ethyl)-phthalonitrile. The new compounds were characterized by spectroscopic methods. The electronic spectra exhibit intense π–π* transitions from the naphthyl moiety together with the characteristic Q and B bands of the phthalocyanine core. The electrochemical properties of the 2,9,17,23-tetra-(1,1-(dicarbethoxy)-2-(1-naphthyl)-ethyl) phthalocyaninato copper(II) complex were studied by cyclic voltammetry.     

Style goods pricing with demand learning

For many industries (e.g., apparel retailing) managing demand through price adjustments is often the only tool left to companies once the replenishment decisions are made. A significant amount of uncertainty about the magnitude and price sensitivity of demand can be resolved using the early sales information. In this study, a Bayesian model is developed to summarize sales information and pricing history in an efficient way. This model is incorporated into a periodic pricing model to optimize revenues for a given stock of items over a finite horizon. A computational study is carried out in order to find out the circumstances under which learning is most beneficial. The model is extended to allow for replenishments within the season, in order to understand global sourcing decisions made by apparel retailers. Some of the findings are empirically validated using data from U.S. apparel industry.