Analysis of unsteady mixed convection of Cu–water nanofluid in an oscillatory,lid-driven enclosure using lattice Boltzmann method

Journal of Thermal Analysis and Calorimetry - The unsteady physics of laminar mixed convection in a lid-driven enclosure filled with Cu–water nanofluid is numerically investigated. The top...     

Excellent alkene epoxidation catalytic activity of macrocyclic‐based complex of dioxo‐Mo(VI) on supermagnetic separable nanocatalyst

A phenoxybutane‐based Schiff base complex of cis‐dioxo‐Mo(VI) was supported on paramagnetic nanoparticles and characterized using powder X‐ray diffraction, infrared, diffuse reflectance and atomic absorption spectroscopies, scanning and transmission electron microscopies and vibrating sample magnetometry. The separable nanocatalyst was tested for the selective epoxidation of cyclohexene, cyclooctene, styrene, indene, α‐pinene, 1‐octene, 1‐heptene, 1‐dodecene and trans‐stilbene using tert‐butyl hydroperoxide (80% in di‐tert‐butyl peroxide–water, 3:2) as oxidant in chloroform. The catalyst was efficient for oxidation of cyclooctene with 100% selectivity for epoxidation with 98% conversion in 10 min. We were able to separate magnetically the nanocatalyst using an external magnetic field and used the catalyst at least six successive times without significant decrease in conversion. The turnover frequency of the catalyst was remarkable (2556 h^?1 for cyclooctene). The proposed nanomagnetic catalyst has advantages in terms of catalytic activity, selectivity, catalytic reaction time and reusability by easy separation.     

Fabrication of nanostructure M/ZnO (M = V,Bi, and Cu) semiconductors: Synthesis,structural and photocatalytic study

Vanadium, bismuth, and copper loaded ZnO crystals were synthesized and characterized by FTIR, XRD, DRUV, SEM-EDS, and BET techniques. XRD and adsorption–desorption analysis shows that the structure of ZnO remains intact after various modifications, while spectral technique shows the successful immobilizing of the metal on the support. The effect of loaded metals (V, Bi, and Cu) of the same concentration on the photocatalytic and structural characteristics of metal loaded ZnO nanoparticles (NPs) were then investigated. The obtained band gap values were in the 3.33–3.37 eV range. The photoefficiency of this nanosized M/ZnO in photodegradation of Malachite Green (MG) was studied.     

Reply to “Comments on “Fuzzy fractional order sliding mode controller for nonlinear systems,Commun Nonlinear Sci Numer Simulat 15 (2010) 963–978” ”

The aim of this letter is to confirm the achievements in [1] and answer all the mentioned comments in [2]. Meanwhile some other drawbacks in the comment paper [2] are also presented in this paper.     

One-pot synthesis of novel (E)-3-(3,8a-dihydro-2H-oxazolo[3,2-a]pyridin-2-ylidene)chroman-2-one derivatives

An efficient synthetic procedure for the preparation of novel (E)-3-(3,8a-dihydro-2H-oxazolo[3,2-a]pyridin-2-ylidene)chroman-2-one derivatives was developed. A sequential one-pot, two-step tandem reaction starting from 3-(2-bromoacetyl)-2H-chromen-2-one derivatives synthesized, pyridine, and naphthols in the presence of triethylamine proceeded smoothly in acetonitrile under reflux conditions. In this process, 2-oxo-2H-chromen-3-yl)ethyl)pyridinium bromide derivatives as intermediate produced in situ, followed by Michael addition of naphthoxide anion and intramolecular cylization, resulted the corresponding products in good to high yields. All of the compounds were obtained in high purity without any use of more purification.     

A Novel Kinetic Approach for Photocatalytic Degradation of Azo Dye with CdS and Ag/CdS Nanoparticles Fixed on a Cement Bed in a Continuous‐Flow Photoreactor

Azo dyes are one of the synthetic dyes that have been used in many textile industries. Azo dye and their intermediate products are toxic, carcinogenic, and mutagenic to aquatic life. Removal of azo dyes is one of the main challenges before releasing the wastes discharged by textile industries. Photocatalytic degradation of azo dyes by nanoparticles is one of the environment‐friendly methods used for the removal of dyes from textile effluents. Therefore, this study focused on degradation of azo dye, Direct Red 264. Photocatalytic degradation of DR 264 azo dye was investigated using CdS and Ag/CdS nanoparticles immobilized on a cement bed in a continuous‐flow photoreactor under UV‐C exposure. The effect of the parameters of type and mass of catalyst, temperature, flow rate, dye concentration, and light intensity were evaluated for azo dye removal. Under optimal conditions, photocatalytic degradation of DR 264 azo dye using Ag/CdS nanoparticles immobilized on a cement bed in a continuous‐flow photoreactor obtained an efficiency of 99.99%. A developed kinetic model was proposed based on the intrinsic elementary reactions. The proposed model is in a good agreement with the Langmuir–Hinshelwood (L–H) equation. The pseudo–steady‐state approximation has considered for the concentration of hydroxyl radicals associated with the L–H model under certain conditions and explains consistently the dependence of the apparent kinetic parameter, k_obs (the reaction rate constant), and K_R (the adsorption equilibrium constant) with the light intensity. Based on the model, k_obs for Ag/CdS was greater than the CdS nanoparticles.     

Heat and mass transfer and thermodynamic analysis of power-law fluid flow in a porous microchannel

Journal of Thermal Analysis and Calorimetry - Transfer of heat and mass and thermodynamic irreversibilities are investigated in a porous, parallel-plate microreactor in which the working fluid is...