Base-free green synthesis of copper(II) oxide nanoparticles using highly cross-linked poly(curcumin) nanospheres: synergistically improved antimicrobial activity

Research on Chemical Intermediates - Antimicrobial activity of metal containing formulas has drawn attention and been widely investigated. In this research, CuO/hc-pCUR nanocomposite composed of...     

Thermal buckling of functionally graded circular plates based on higher order shear deformation plate theory

In this research, thermal buckling of circular plates compose of functionally graded material (FGM) is considered. Equilibrium and stability equations of a FGM circular plate under thermal loads are derived, based on the higher order shear deformation plate theory (3rd order plate theory). Assuming that the material properties vary as a power form of the thickness coordinate variable z and using the variational method, the system of fundamental partial differential equations is established. A buckling analysis of a functionally graded circular plate (FGCP) under various types of thermal loads is carried out and the result are given in closed-form solutions. The results are compared with the critical buckling temperature obtained for FGCP based on first order (1st order plate theory) and classical plate theory (0 order plate theory) given in the literature. The study concludes that higher order shear deformation theory accurately predicts the behavior of FGCP, whereas the first order and classical plate theory overestimates buckling temperature.     

Large Eddy Simulation of Air Entrainment and Mixing in Reacting and Non-Reacting Diesel Sprays

Large eddy simulation is performed to investigate air entrainment and mixing in diesel sprays with and without combustion. The Spray A case of the Engine Combustion Network (ECN) is considered in the study, in which liquid n-Dodecane is injected at 1500 bar through a nozzle of 90 μm into a constant volume vessel with an ambient density of 22.8 kg/m³ and an ambient temperature of 900 K. Primary and secondary breakup processes of the liquid fuel are taken into account. The gas and liquid phases are modeled using Eulerian/Lagrangian coupling approach. Detailed chemical kinetics for n-Dodecane is employed to simulate the ignition process and the lifted flames. A chemistry coordinate mapping approach is used for speeding up the calculations. The effect of low temperature ignition (cool flame) on the evaporation process and on the liquid penetration length is analyzed. The effect of combustion heat release from the lifted flames on the vapor spreading in the radial direction and on the vapor transport in the streamwise direction (vapor penetration) is investigated.     

Investigation on rough rice drying kinetics at various thin layers of a deep bed

Moisture content gradients along the bed column are commonly neglected during simulation of deep-bed grain drying. In this study, rough rice drying kinetics at various thin layers of a deep bed was investigated. The experiments were conducted under different drying conditions and the data were compared with the values predicted by a previously developed non-equilibrium model for numerical simulation of grain drying. The moisture content gradients related to the rough rice column indicated that the higher the drying layer, the more was the moisture content at each drying time. The constant drying rate period was observed neither for any thin layers nor for the entire drying column. The drying rate of the lower layers continuously decreased with drying time, whereas that of the upper layers firstly increased and then decreased. The implemented model predicted drying process with a high accuracy at various layers. However, the values of maximum relative error (RE _max ) and mean relative error (MRE) increased as the air temperature increased, and reversely decreased with the air velocity. The higher values of MRE and RE _max were related to the layer 1 (0–5 cm bed height) at temperature of 60 °C and air velocity of 0.4 m s^?1, and the lower values belonged to the layer 4 (15–20 cm bed height) at temperature of 40 °C and air velocity of 0.9 m s^?1.     

Analytical Investigation of the Effect of Viscous Dissipation on Couette Flow in a Channel Partially Filled with a Porous Medium

An analytical study of viscous dissipation effect on the fully developed forced convection Couette flow through a parallel plate channel partially filled with porous medium is presented. A uniform heat flux is imposed at the moving plate while the fixed plate is insulated. In the fluid-only region the flow field is governed by Navier–Stokes equation while the Brinkman-extended Darcy law relationship is considered in the fully saturated porous medium. The interface conditions are formulated with an empirical constant β due to the stress jump boundary condition. Fluid properties are assumed to be constant and the longitudinal heat conduction is neglected. A closed-form solution for the velocity and temperature distributions and also the Nusselt number in the channel are obtained and the viscous dissipation effect on these profiles is briefly investigated.     

Triple-Diffusive Mixed Convection in a Porous Open Cavity

The triple-diffusive mixed convection heat and mass transfer of a mixture is analyzed in an enclosure filled with a Darcy porous medium. The mass transfer buoyancy effects due to concentration gradients of the dispersed components (pollutant components) are taken into account using the Boussinesq approximation model. The governing equations are transformed into a non-dimensional form, and six groups of non-dimensional parameters, including Darcy–Rayleigh number, Peclet number, two Lewis numbers for pollutant components 1 and 2 and two buoyancy ratio parameters for pollutant components 1 and 2, are introduced. The governing equations are numerically solved for various combinations of non-dimensional parameters using the finite element method. The effect of each group of non-dimensional parameters on the pollutant distribution and the heat transfer in the cavity is discussed. The results indicate that the presence of one pollutant component can significantly affect the pollutant distribution of the other component. When the Lewis number of a pollutant component is small, the increase in the bouncy ratio parameter of the proposed component always increases the Nusselt and Sherwood numbers in the cavity.     

Efficient and selective oxidation of alcohols in water employing palladium supported nanomagnetic Fe3O4@hyperbranched polyethylenimine (Fe3O4@HPEI.Pd) as a new organic–inorganic hybrid nanocatalyst

Palladium immobilized magnetic nanoFe₃O₄@hyperbranched polyethylenimine (Fe₃O₄@HPEI.Pd) was prepared according to a simple and cost effective pathway and it was employed as a new efficient and selective organic–inorganic hybrid nanocatalyst for the aqueous oxidation of primary and secondary alcohols to their corresponding products in good yields applying oxone (potassium hydrogen monopersulfate) and H₂O₂ as an oxidant at room temperature. Moreover, the catalytic system was reused at least 13 times without significant loss of activity. The complete characterization of this efficient nanocatalyst was investigated by FTIR, UV–Vis, TEM, SEM, XRD, TGA, VSM, ICP and EDX techniques.     

Reaction of dimethylplatinum(II) complexes with PhCH2CH2Br: Comparative reactivity with CH3CH2Br and PhCH2Br and synthesis of Pt(IV) complexes

Oxidative addition of 2‐phenylethylbromide (PhCH₂CH₂Br) to dimethylplatinum(II) complexes [PtMe₂(NN)] ( 1a , NN = 2,2′‐bipyridine (bpy); 1b , NN = 1,10‐phenanthroline (phen)) afforded the new organoplatinum(IV) complexes [PtMe₂(Br)(PhCH₂CH₂)(bpy)], as a mixture of trans ( 2a ) and cis ( 3a ) isomers, and [PtMe₂(Br)(PhCH₂CH₂)(phen)], as a mixture of trans ( 2b ) and cis ( 3b ) isomers, respectively. The new Pt(IV) complexes were readily characterized using multinuclear (¹H and ¹³C) NMR spectroscopy and elemental microanalysis. The crystal structure of 2a was further determined using X‐ray crystallography indicating an octahedral geometry around the platinum centre. A comparison of reactivity of RCH₂Br reagents (R = CH₃, Ph or PhCH₂) in their oxidative addition reactions with complex 1a , with an emphasis on the effects of the R groups of alkyl halides, was also conducted using density functional theory.     

Phosphated tungstate: An efficient new solid phosphoric acid catalyst for the synthesis of heterocyclic nitrones

Phosphated tungstate as a new, reusable and efficient solid phosphoric acid catalyst was synthesized and used to promote the reaction of diaminoglyoxime with various aromatic aldehydes. The prepared phosphated tungstate was characterized using various techniques including X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy and thermal analysis. A wide variety of heterocyclic nitrones were obtained under mild reaction conditions and in high yields by using the prepared catalyst.     

Hollow fibre-supported graphene oxide nanosheets modified with a deep eutectic solvent to be used for the solid-phase microextraction of silver ions

A deep eutectic solvent (DES) of choline chloride and thiourea was synthesised, immobilised on the surface of graphene oxide (GO) nanosheets and reinforced inside the pores of the hollow fibre (DES-GO-HF). Then, solid-phase microextraction flame atomic absorption spectrometry was designed for separation, preconcentration and determination of trace amounts of silver. Various parameters affecting the extraction recovery of the analyte, such as pH, sample volume, type of DES, extraction time, length of the hollow fiber, nature, as well as the volume and concentration of the eluent, were investigated and optimised. Under optimum conditions, the method showed good linearity in the concentration range of 1.0–40.0 µg L^?1 with the determination coefficient of (r²) 0.9990 for silver. The method was very sensitive and has limits of detection and quantification (defined as 3S_b/m and 10S_b/m) of 0.2 and 0.7 µg L^?1, respectively. The method was successfully applied for the determination of Ag(I) in water, wastewater, ore and hair samples. The accuracy of the method was evaluated through the recovery experiments and the analysis of certified reference materials.