Glutathione as green corrosion inhibitor for 6061Al-SiC(p) composite in HCl medium: electrochemical and theoretical investigation

This research deals with the inhibition activity of glutathione in 0.5 M HCl on the corrosion behavior of 6061Al-SiC_(p) composite. Glutathione is an eco-friendly water-soluble inhibitor. Polarization results reveal the cathodic inhibitor behavior of glutathione (Gt). The inhibition performance of Gt increases by increasing its concentration and lowering the medium temperature. The decrease in the corrosion current density and increase in inhibition efficiency on increasing Gt concentration reveal the attenuation of composite corrosion. Experimental results indicate the mixed adsorption with predominantly physisorption of Gt molecules adsorption on the composite surface following Langmuir adsorption isotherm. The impedance measurements indicate the rise in polarization resistance with an increase in Gt concentration, showing the control of composite corrosion. The surface analysis of the corroded and inhibited composite samples using a scanning electron microscope and atomic force microscope supports Gt molecules’ adsorption. The quantum chemical calculations confirm the conclusions of the experimental studies.

     

An experimental investigation of separating flow on a convex surface

The mean and turbulent characteristics of an incompressible turbulent boundary layer developing on a convex surface under the influence of an adverse pressure gradient are presented in this paper.The turbulence quantities measured include all the components of Reynolds stresses, auto-correlation functions and power spectra of the three components of turbulence. The results indicate the comparative influence of the convex curvature and adverse pressure gradient which are simultaneously acting on the flow. The investigation provides extensive experimental information which is much needed for a better understanding of turbulent shear flows.Nomenclature a, b constants in equation for velocity defect profile (Fig. 6) - c _f skin-friction coefficient (= _w/F _1/2 U ₁ ² ) - E(k ₁) one-dimensional wave number spectra - f frequency in Hz - G Clauser's equilibrium parameter = (H–1)/H(c _f /2) - H shape parameter (= ₁/ ₂) - k ₁ wave number (=2f/U) - L _u, L _v, L _w length scales of u, v and w fluctuations - p _s static pressure on the measurement surface - p _w reference tunnel wall static pressure - q ² total turbulent kinetic energy - R radius of curvature of the convex surface - R() auto-correlation function - T _u, T _v, T _w time scales of u, v and w fluctuations - U local mean velocity - U ₁ local free stream velocity - U _* friction velocity - u, v, w velocity fluctuations in x, y and z directions respectively - X streamwise coordinate measured along the surface from A (Fig. 1b) - x streamwise coordinate measured along the surface reckoned from station 9 - y coordinate normal to the surface - z spanwise coordinate - ₁/ _w · dp/dx - - boundary layer thickness - ₁ displacement thickness - ₂ momentum thickness - ₃ energy thickness - kinematic viscosity - density - time delay - _w wall shear stress     

Chemisorption Synthesis of the Ion-Polymeric Heteronuclear Gold(III)–Bismuth(III) Complex ([Au{S2CN(C3H7)2}2]3[Bi2Cl9])n Based on [Bi2{S2CN(C3H7)2}6]: 13C MAS NMR,Supramolecular Structure,and Thermal Behavior

Russian Journal of Coordination Chemistry - Chemisorption synthesis on the basis of the binuclear compound [Bi2{S2CN(C3H7)2}6] (I) and preparative isolation of the ion-polymeric heteronuclear...     

Some classes of Kenmotsu manifolds with respect to semi-symmetric metric connection

In this paper, we study conharmonic curvature tensor in Kenmotsu manifolds with respect to semi-symmetric metric connection and also characterize conharmonically flat, conharmonically semi-symmetric and φ-conharmonically flat Kenmotsu manifolds with respect to semi-symmetric metric connection.     

Hydrogenation and hydrogenolysis of furfural and furfuryl alcohol catalyzed by ruthenium(II) bis(diimine) complexes

The catalytic activity of ruthenium(II) bis(diimine) complexes cis‐[Ru(6,6′‐Cl₂bpy)₂(OH₂)₂](Z)₂ ( 1 , Z = CF₃SO₃; 2 , Z = (3,5‐(CF₃)₂C₆H₃)₄B, i.e. BArF) and cis‐[Ru(4,4′‐Cl₂bpy)₂(OH₂)₂](Z)₂ ( 3 , Z = CF₃SO₃; 4 , Z = BArF) for the hydrogenation and/or the hydrogenolysis of furfural (FFR) and furfuryl alcohol (FFA) was investigated. The molecular structures of cis‐[Ru(4,4′‐Cl₂bpy)₂(CH₃CN)₂](CF₃SO₃)₂ ( 3 ′) and dimeric cis‐[(Ru(4,4′‐Cl₂bpy)₂Cl)₂](BArF)₂ ( 5 ) were characterized by X‐ray crystallography. The structures are consistent with the anticipated reduction in steric hindrance about the ruthenium centers in comparison with corresponding complexes containing 6,6′‐Cl₂bpy ligands. While compounds 1 , 2 , 3 , 4 are all active and highly selective catalysts for the hydrogenation of FFR to FFA under modest reaction conditions, 3 and 4 showed decreased activity. This is best explained in terms of reduced Lewis acidity of the Ru²⁺ centers and reduced steric hindrance about the metal centers of catalysts 3 and 4 . cis‐[Ru(6,6′‐Cl₂bpy)₂(OH₂)₂](BArF)₂ ( 2 ) also displayed high catalytic efficiency for the hydrogenation of FFA to tetrahydrofurfuryl alcohol. Presumably, this is because coordination of C═C bonds of FFA to the ruthenium center is poorly inhibited by non‐coordinating BArF counterions. Interestingly, cis‐[Ru(6,6′‐Cl₂bpy)₂(OH₂)₂](CF₃SO₃)₂ ( 1 ) showed some catalytic activity in ethanol for the hydrogenolysis of FFA to 2‐methylfuran, albeit with fairly modest selectivity. Nonetheless, these results indicate that ruthenium(II) bis(diimine) complexes need to be further explored as catalysts for the hydrogenolysis of C―O bonds of FFR, FFA, and related compounds. Copyright © 2012 John Wiley & Sons, Ltd.     

Cyclic-deformation behavior of notched mild-steel plates in plane stress

Notched rectangular SAE 1015 mild-steel plates were subjected to controlled cyclic nominal stresses or strains in a closed-loop servo-controlled fatigue-testing machine. Resistance strain gages were used to measure strains at the notch roots. These strains showed that large mean strains and strain ranges prevailed at these notches, though nominal strains were fully reversed and small. Inelastic stress- and strain-concentration factors calculated at various cycles were used to check the accuracy of the Neuber relation between these concentration factors and elastic stress-concentration factor. Limitations of this relation and characteristic notch-strain behavior mentioned above are discussed with reference to the peculiarities of the stress-strain relationships of this material.     

Structural Conformation of a Novel Piperidine-4-One Derivative: 1-Acryloyl-3-Methyl-2,6-Dip-Tolylpiperidine-4-One

Abstract  

The novel 3-methyl-2,6-dip-toylpiperidine-4-one was acylated by 3-chloropropanoychloride and subjected for dehydrohalogenation. The synthesized compound was characterized by spectroscopic techniques and finally confirmed by X-ray diffraction studies. The molecule crystallizes in the monoclinic crystal class in the space group C ₂/c with cell parameters a = 18.538(2) ?, b = 9.9050(1) ?, c = 22.954(2) ?, β = 94.486(8)° and Z = 8. The piperidine ring adopts a twist boat conformation.     

A concise synthetic strategy to functionalized chromenones via [5+1] heteroannulation and facile C-N/C-S/C-O bond formation with various nucleophiles

A highly efficient strategy to 2,3-substituted chromen-4H-ones has been developed. The methodology involves unexpected intramolecular heteroannulation of readily accessible substituted 2-hydroxy-ω-nitroacetophenone with carbon disulfide in the presence K₂CO₃ followed by methylation with methyl iodide. These chromenones were further reacted with various nucleophiles such as amines, thiols, and alkoxide resulting in the facile C-N, C-S, and C-O bond formation. The scope and generality have been discussed.     

Oxidation of ethanolamines by sodium N‐bromobenzenesulfonamide in alkaline buffer medium: A kinetic and mechanistic study

The kinetics of oxidation of ethanolamines, monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA), by sodium N‐bromobenzenesulfonamide or bromamine‐B (BAB) in alkaline buffer medium (pH 8.7–12.2) has been studied at 40°C. The three reactions follow identical kinetics with first‐order in [oxidant] and fractional‐order each in [substrate] and [OH^?]. Under comparable experimental conditions, the rate of oxidation increases in the order: DEA > TEA > MEA. The added reaction product, benzenesulfonamide, retards the reaction rate. The addition of halide ions and the variation of ionic strength of the medium have no significant effect on the rate. The dielectric effect is negative. The solvent isotope effect k′(H₂O)/k′(D₂O) ≈ 0.92. Activation parameters for the composite reaction and for the rate‐limiting step were computed from the Eyring plots. Michaelis‐Menten type of kinetics is observed. The formation and decomposition constants of ethanolamine‐BAB complexes are evaluated. An isokinetic relationship is observed with β = 430 K indicating that enthalpy factors control the rate. For each substrate, a mechanism consistent with the kinetic data has been proposed. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 480–490, 2001     

Stability in the presence of degeneracy and error estimation

Received February 10, 1997 / Revised version received June 6, 1998 Published online October 9, 1998