471 research outputs found

    MANAGEMENT’S PERCEPTION OF STOCK DIVIDEND DISTRIBUTION IN AN EMERGING CAPITAL MARKET: THE CASE OF KUWAIT

    Get PDF
    The purpose of this study is to investigate perceptions of top managers of Kuwaiti companies regarding factors the affect their companies’ decision to distribute stock dividend ( SD ). A questionnaire listing 32 reasons that could explain companies’ decisions to declare SDs was distributed to a sample of 120 randomly selected top managers from 100 Kuwaiti companies and 73 responses were received (representing a 61% response rate ). Participants were classified according to: ( 1 )business sector ( investment, real estate, banking, service, and industrial ) and ( 2 ) size of SDs ( small ( less than 25% ) and large ( 25% or more )). Nonparametric statistical tests were employed to analyze the data.Stock Dividends, Importance Ratings, Trading Liquidity, Institutional Investors

    Microwave-assisted Synthesis Of Palladium Nanoparticles Supported On Copper Oxide In Aqueous Medium As An Efficient Catalyst For Suzuki Cross-coupling Reaction

    Get PDF
    We report here a reliable green method for the synthesis of palladium nanoparticles supported on copper oxide as a highly active and efficient catalyst for Suzuki cross-coupling reaction. The experimental synthetic approach is based on microwave-assisted chemical reduction of an aqueous mixture of palladium and copper salt simultaneously using hydrazine hydrate as reducing agent. The catalyst was fully characterized using various techniques showing well-dispersed palladium nanoparticles. The catalytic activity and recyclability of the prepared catalyst were experimentally explored in the ligand-free Suzuki cross-coupling reaction with a diverse series of functionalized substrates. The synthesized Pd/CuO catalyst shows many advantages beside its high catalytic efficiency such as the recyclability of up to five times with negligible loss of catalytic activity, short reaction times, use of environmentally benign solvent systems, and mild reaction conditions

    Facile Synthesis Of Reduced Graphene Oxide-supported Pd/Cuo Nanoparticles As An Efficient Catalyst For Cross-coupling Reactions

    Get PDF
    The present communication reports a scientific investigation of a simple and versatile synthetic route for the synthesis of palladium nanoparticles decorated with copper oxide and supported on reduced graphene oxide (rGO). They are used as a highly active catalyst of Suzuki, Heck, and Sonogashira cross coupling reactions with a remarkable turnover number of 7000 and a turnover frequency of 85000 h-1. The Pd-CuO nanoparticles supported on reduced graphene oxide nanosheets (Pd-CuO/rGO) exhibit an outstanding performance through a high catalytic activity towards cross coupling reactions. A simple, reproducible, and reliable method is used to prepare this efficient catalyst using microwave irradiation synthetic conditions. The synthesis approach requires a simultaneous reduction of palladium and copper nitrates in presence of graphene oxide (GO) nanosheets using hydrazine hydrate as a strong reducing agent. The highly active and recyclable catalyst has many advantages including mild reaction conditions and short reaction durations in an environmentally benign solvent system. Moreover, the catalyst prepared can be recycled for up to five times with nearly identical high catalytic activity. Furthermore, the high catalytic activity and the recyclability of the catalyst prepared are due to the strong catalyst-support interaction. The defect sites of the reduced graphene oxide (rGO) act as nucleation centers that enable anchoring of both Pd and CuO nanoparticles and hence, minimize the possibility of agglomeration which leads to a severe decrease of the catalytic activity

    Spectrophotometric Study of Acid-Base Equilibria in Non-Aqueous Solvents

    Get PDF
    The equilibrium constants for the reaction of 2,6-dichloro-4- -nitrophenol, 2,6-dinitrophenol, 2,5-dinitrophenol and 2,4-dinitrophenol with some aliphatic amines of different structures have been determined spectrophotometrically in chlorobenzene, ethyl acetate and carbon tetrachloride as solvents. The data show that such reactions in inert solvents lead essentially to ion-pairs of the type BH+ ... A- where, HA and B represent the phenol and ·amine molecule, respectively. This conclusions was found to be in agreement with that obtained by other workers. In chlorobenzene as a solvent, the basic strengths fall in the order mono < di- < tri-n- . -butyl amine, while in ethyl acetate the order of basic strengths becomes: mono-> di-> tri-n-butyl amine. These results are discussed from the point of view of solvation as an important role in the determination of the relative strengths of butylamines, as well as the extent to which dinitrophenols are affected by chelation between the phenolic OH and ortho-nitro group. However, in chlorobenzene and ethyl acetate as solvents, the relative basic strengths of pyridine and aniline derivatives remain independent of the solvent when bromophenol blue is used as a reference acid. The of KBH+A- values for aniline derivatives proved to be more suitable for judging the effect of the substituent than the basic strength in aqueous solution

    Opportunistic Multiple Access for Cognitive Radio Networks

    Full text link

    Mathematica as an Efficient Tool to Optimize the Kinetic Study of Ethyl Acetate Hydrolysis

    Get PDF
    Mathematica is a powerful program for computing both numeric and algebraic calculations as well as graphing two- and three-dimensional curves and surfaces. It is used increasingly in many fields of science now such as physics, engineering, chemistry and even biology because of the fast interaction of mathematics with almost the fields of science nowadays. We report here, optimizing the kinetic data for the hydrolysis of ethyl acetate through caustic soda via using Mathematica

    Enhanced Water Electrolysis: Effect Of Temperature On The Oxygen Evolution Reaction At Cobalt Oxide Nanoparticles Modified Glassy Carbon Electrodes

    Get PDF
    Water splitting producing hydrogen and oxygen gases appears promising in view of the increasing need of renewable energy sources and storage strategies. Investigation of stable and highly efficient electrocatalysts for oxygen evolution reaction (OER) is targeted in this study at cobalt oxide nanoparticle modified glassy carbon (nano-CoOx/GC) electrodes. The effect of the preparation (Tp) and measuring temperature (Tm) on the electrocatalytic activity of nano-CoOx/GC towards the OER is investigated under various operating conditions. Linear sweep voltammetry (LSV), cyclic voltammetry (CV) as well as SEM and XRD techniques were used to probe the electrocatalytic and morphological characteristics of nano-CoOx prepared under various conditions. Increasing Tp and/or Tm results in improving the kinetics and electrocatalytic activity of the proposed anodes towards the OER as demonstrated in the value of the onset potential of the OER and the OER currents recorded at a fixed potential. The morphology as well as the surface characterization of the prepared catalyst are reported herein and evaluated

    Hydrothermal Synthesis Of Graphene Supported Pd/Fe 3 O 4 Nanoparticles As Efficient Magnetic Catalysts For Suzuki Cross – Coupling

    Get PDF
    This research reports a reproducible, reliable, and efficient method for preparing palladium nanoparticles dispersed on a composite of Fe3O4 and graphene as an active catalyst with high efficiency for being used in Suzuki cross – coupling reactions. Graphene supported Pd/Fe3O4 nanoparticles (Pd/Fe3O4 /G) exhibit a remarkable catalytic performance towards Suzuki coupling reactions. Moreover, the prepared catalyst recyclability was up to nine times without losing its high catalytic activity. The catalyst was prepared using hydrothermal synthesis; the prepared catalyst is magnetic in order to facilitate catalyst separation out of the reaction medium after reaction completion simply through using a strong magnet. This approach offers unique advantages including recyclability, mild reaction conditions, and reproducibility. Furthermore, the magnetic properties of the prepared catalyst made a huge enhancement to the ability to purify the reaction products from catalyst and other side products. The high catalytic performance and recyclability of the prepared catalyst are due to the strong interaction between the catalyst and the support. Moreover, the reduced GO nanosheets have defect sites acting as nucleation centers to anchor the Pd and Fe3O4 nanoparticles and hence minimize the harmful effect of potential agglomeration and subsequently the anticipated decrease in the catalyst catalytic activity as a direct impact for this unfavorable agglomeration
    • …
    corecore