Heat transfer characteristics of pulsated turbulent pipe flow

Heat Transfer characteristics of pulsated turbulent pipe flow under different conditions of pulsation frequency, amplitude and Reynolds number were experimentally investigated. The pipe wall was kept at uniform heat flux. Reynolds number was varied from 5000 to 29 000 while frequency of pulsation ranged from 1 to 8 Hz. The results show an enhancement in the local Nusselt number at the entrance region. The rate of enhancement decreased as Re increased. Reduction of heat transfer coefficient was observed at higher frequencies and the effect of pulsation is found to be significant at high Reynolds number. It can be concluded that the effect of pulsation on the mean Nusselt numbers is insignificant at low values of Reynolds number. Received on 29 June 1998     

On a certain finite difference scheme for a model for diffusion of biological populations

In this note, we present a numerical scheme for finding an approximate solution of an equation which can be viewed as a model for spatial diffusion of age-dependent biological populations. Discretization of the model yields a linear system with a block tridiagonal matrix. Our main concern will be discussion of stability for this scheme by examining the eigenvalues of the block tridiagonal matrix. Numerical results are presented.     

Theoretical analysis of an intermediate band in Sn-doped hematite with wide-spectrum solar response

Journal of Solid State Electrochemistry - Hematite α-Fe2O3 is exposed to be an efficient photocatalytic material for the photoelectrochemical water splitting process under visible light. In...     

Electro-organic synthesis of tetrahydroimidazo[1,2-a]pyridin-5(1H)-one via a multicomponent reaction

Molecular Diversity - Electro-synthesis through a one-pot three-component condensation of corresponding aldehydes, Meldrum’s acid, and 2-(nitromethylene)imidazolidine resulted in a series of...     

Electrochemical Sensing of Flutamide Contained in Plasma and Urine Matrices Using NiFe2O4/rGO Nanocomposite,as an Efficient and Selective Electrocatalyst

In this article, we report on the synthesis and new employment of magnetic nickelferrite oxide nanoparticles decorated reduced graphene oxide (NiFe₂O₄/rGO) to electrochemically sensing of flutamide. The preparation of this electrocatalyst was first assessed using various analytical instrumental techniques including FT‐IR spectroscopy, X‐ray diffraction spectroscopy, energy‐dispersive X‐ray spectroscopy, and field emission scanning and transmission electron microscopy. Besides, its electrochemical performance was investigated utilizing some electrochemical methods such as cyclic and differential pulse voltammetry, and also electrochemical impedance spectroscopy. The findings of this research are especially relevant for sensing flutamide in aqueous and biological samples. At the optimized conditions, the electrochemical sensor showed a linear range of 0.24–40.0 μmol L^?1, the detection limit of 0.05 μmol L^?1 flutamide, calibration sensitivity of 1.016 μA/μmol L^?1, and repeatability and reproducibility of 1.7 % and 4.1 %, respectively. The selectivity of the method was investigated in the presence of ions, and species can generally exist in the biological medium. The resulting data of the present work represented that this type of magnetic nanocomposites is suitable for selective detection of flutamide in real samples of plasma and urine. The recoveries obtained for flutamide analyses represented lower than 5.0 percent of relative error in these real samples.     

Modified hydrothermal synthesis and characterization of reduced graphene oxide-silver selenide nanocomposites with enhanced reactive oxygen species generation

A visible‐light photocatalyst containing Ag2Se and reduced graphene oxide (RGO) was synthesized by a facile sonochemical‐assisted hydrothermal method. X‐ray diffraction, scanning electron mi‐croscopy w...     

Synthesis,crystal structure,cholinesterase inhibitory activity,evaluation of insecticidal activities,and computational studies of new phosphonic acids

Molecular Diversity - In an attempt to obtain the modified and novel insecticides with low human toxicity, a series of novel mono-, bis-, and tetraphosphonic acid derivatives were designed and...     

Influences of adsorptions of some inorganic molecules on electronic,optical, and thermodynamic properties of Mg_(12)O_(12) nanocage: A computational approach

According to density functional theory,we investigate the effects of BF_3,BF_4,BCl_3,AlF_3,AlCl_3,AlBr_3,BeF_3,GaF_3,GaCl3,GaBr_3,NO_3,BS_2,BSO,BO_2,F_2,PF_5,PCl_5,and ASF_5 molecules on the geometric,electronic,linear,and nonlinear optical properties of an Mg_(12)O_(12)nanocage.The thermodynamic stability and feasibility of the adsorption process are investigated by analyzing the free energy.It is shown that the adsorptions of almost all molecules on the Mg_(12)O_(12)surface are exothermic.The calculations of the polarizability of these nanoclusters show that among the studied molecules,BeF_3 has the largest influence on the polarizability value(α≈315 a.u.,the unit a.u.is short for atomic unit).The static first hyperpolarizability(β_0)value is increased in the presence of these superhalogens.This increase is greatest for BeF_3 and BF_4 of which the highest value of the first hyperpolarizability(β_0≈5775 a.u.)is related to a BeF_3 c(e@Mg_(12)O_(12))nanocluster.The adsorption position is a key to estimating the value of increasing the first hyperpolarizability.