No abstract

No abstract

The influences of Polycarpaea corymbosa (PC) and Desmodium triflorum (DT) leaf extracts on the corrosion behavior of mild steel (MS) in 1.0 M HCl was investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The effect of temperature on the corrosion behavior of MS in 1.0 M HCl with the addition of plant extracts was studied in the temperature range of 300 K-320 ± 1 K. The results revealed that PC and DT were excellent green inhibitors and the inhibition efficiencies obtained from weight loss and electrochemical experiments were in good agreement. Inhibition efficiencies up to 91.78 % for PC and 92.99 % for DT were obtained. Potentiodynamic polarization studies revealed that both the inhibitors behaved as mixed-type inhibitors. Adsorption behavior of these green inhibitors on the MS surface was found to obey the Langmuir adsorption isotherm. The thermodynamic parameter values of free energy of adsorption (DG ads ) and enthalpy of adsorption (DH ads ) revealed that each inhibitor was adsorbed on the MS surface via both chemisorption and physisorption mechanisms. The adsorption mechanism of inhibition was supported by FT-IR, UV-Visible, WAXD and SEM-EDS.

4-Chlorophenyl acrylate (CPA) was prepared by reacting 4-chlorophenol and acryloyl chloride in the presence of triethylamine in ethyl acetate solution. Poly(4-chlorophenyl acrylate) and copoly(4-chlorophenyl acrylate-methyl acrylate) were synthesized by the free radical polymerization in ethyl acetate at 70°C. All the polymers were characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopic techniques. The composition of the copolymers was determined by the 1 H-NMR spectroscopic technique, that is, by integrating the aromatic peaks corresponding to the 4-chlorophenyl acrylate unit against the carbomethoxy group in the methyl acrylate unit. The reactivity ratios were calculated by Fineman-Ross, Kelen-Tudos (K-T), and the extended Kelen-Tudos methods. The values of r 1 and r 2 obtained by these methods were in close agreement with each other; that is, r 1 (CPA) ϭ 0.64 and r 2 (MA) ϭ 0.13 by the K-T method. The number-average molecular weight (M n ϭ 1.55 ϫ 10 3 ), the weight-average molecular weight (M w ϭ 8.39 ϫ 10 3 ), and the polydispersity index (M w /M n ϭ 5.42) of poly(CPA) were determined by gel permeation chromatography (GPC). Thermal properties of the polymers were studied in a nitrogen atmosphere using thermogravimetric analysis (TGA). As the CPA increases in the copolymer, thermal stability of the copolymer increases (e.g., 90% weight loss occurs at 480°C for 20 mol % CPA, whereas the same weight loss occurs at 571°C for 80 mol % CPA). Acrylic binders, based on the CPA-MA-BA terpolymer, of different glass transition temperatures were prepared for applications in leather industry as top coat and base coat materials. These acrylic emulsions were cast into thin films, and their characteristics were tested for physical properties. These acrylic emulsions were applied as a base coat on leather, and the compositions having T g values of 1.08 and 9.25°C were found to have excellent properties as base coats for leather when compared with commercial samples.

No abstract

BackgroundNatural products isolated from plant sources have been demonstrated as potential candidates against several ailments. The scientific investigations on the underlying principles of phytotherapy can pave way for the convergence of traditional medicines and modern science and technologies.ResultsQuercetin 3-O-(2′′-acetyl)-glucoside obtained from ethyl acetate fraction of Cleome viscosa is studied against inflammatory of carrageenan-induced rat paw edema ( in vivo) and microbial activity on ( in vitro). The structure of the glycoside is confirmed by means of hydrogen-1 nuclear magnetic resonance spectroscopy, carbon nuclear magnetic resonance spectroscopy, attached proton test, and mass spectrum. The flavonoid glycoside showed significant anti-inflammatory activity of on carrageenan-induced rat paw edema ( in vivo) and anti-microbial activity ( in vitro) on Staphylococcus aureus (gram positive) and Escherichia coli (gram negative). The anti-inflammatory effect of the flavonoid glycoside may be due to the inhibition of prostaglandin synthesis. Selective toxicity with flavonoid glycoside towards the gram-positive bacteria was found on S. aureus.ConclusionsThe present study reveals the anti-inflammatory and antimicrobial activities of an isolated quercetin 3-O-(2′′-acetyl)-glucoside from a natural source ( C. viscosa).

The inhibition effect of 2,3-dihydroxyflavone on the corrosion of mild steel in 100-600 ppm aqueous hydrochloric acid solution has been investigated by weight loss and electrochemical impedance spectroscopy. The corrosion inhibition efficiency increases with increasing concentration and time. The effect of temperature on the corrosion behavior of mild steel in 1 M HCl with addition of inhibitor was studied at the temperature range of 300-330 K. UV-Vis, FTIR, and surface analysis (SEM) was also carried out to establish the corrosion inhibitive property of this inhibitor in HCl solution. The adsorption of this inhibitor on the mild steel surface obeys the Langmuir adsorption isotherm. Electrochemical studies reveal that the inhibitor is a cathodic type.

No abstract