One-pot synthesis of 2-substituted quinoxalines using K10-montmorillonite as heterogeneous catalyst

An efficient one-pot synthesis of 2-substituted quinoxalines from 1,2-diamines and phenacyl bromides is developed using K10-montmorillonite (K10 clay) as a catalyst at 50 °C in acetonitrile medium. This method offers an easy route for the synthesis of substituted quinoxalines in high yields. A plausible mechanism is proposed in which quinoxalines are formed via dehydration–dehydrohalogenation–cyclization sequence. Further, the K10 clay catalyst is recovered by simple filtration and reused six times without any loss in its catalytic activity.     

2,3-Di(phenylsulfinyl)-1,3-butadiene via a double [2,3]-sigmatropic rearrangement of the bis-sulfenate ester of 2-butyne-1,4-diol.

a one-step conversion of butyne-1,4-diol (1) to 2,3-di(phenylsulfinyl)-1,3-butadiene (4) and the conversion of this bis-sulfoxide to the sulfoxide-sulfone 6 and the bis-sulfone 5 are reported.     

A nonlinear partial least squares algorithm using quadratic fuzzy inference system

We introduce a new nonlinear partial least squares algorithm ‘Quadratic Fuzzy PLS (QFPLS)’ that combines the outer linear Partial Least Squares (PLS) framework and the Takagi–Sugeno–Kang (TSK) fuzzy inference system. The inner relation between the input and the output PLS score vectors is modeled by a quadratic TSK fuzzy inference system. The performance of the proposed QFPLS method is tested and compared against four other well‐known partial least squares methods (Linear PLS (LPLS), Quadratic PLS (QPLS), Linear Fuzzy PLS (LFPLS), and Neural Network PLS (NNPLS)) on various different types of randomly generated test data. QFPLS outperformed competitors based on two comparison measures: the output variables cumulative per cent variance captured by the PLS latent variables and the root mean‐square error of prediction (RMSEP). Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of bismuth on liquid-phase epitaxy (LPE) grown GaAs layer using Ga–As–Bi melt

GaAs epitaxial layers of high structural quality have been realised from Ga–As–Bi melt using liquid-phase epitaxy (LPE). LPE grown GaAs epitaxial layer using bismuth solvent on GaAs substrate has been found to be of good structural perfection as compared to layers using gallium solvent. The temperature-dependent PL spectra of GaAs layer, grown from Ga+Bi mixed solvent has shown that the use of bismuth does not change the band energy. ECV depth profile of heavily zinc-doped epitaxial layer shows uniform doping in the GaAs layer grown using gallium solvent as compared to the layer grown using bismuth solvent.     

Investigation of O7+ swift heavy ion irradiation on molybdenum doped indium oxide thin films

Molybdenum (0.5 at%) doped indium oxide thin films deposited by spray pyrolysis technique were irradiated by 100 MeV O⁷⁺ ions with different fluences of 5×10¹¹, 1×10¹² and 1×10¹³ ions/cm². Intensity of (222) peak of the pristine film was decreased with increase in the ion fluence. Films irradiated with the maximum ion fluence of 1×10¹³ ions/cm² showed a fraction of amorphous nature. The surface microstructures on the surface of the film showed that increase in ion fluence decreases the grain size. Mobility of the pristine molybdenum doped indium oxide films was decreased from ～122 to 48 cm²/V s with increasing ion fluence. Among the irradiated films the film irradiated with the ion fluence of 5×10¹¹ ions/cm² showed relatively low resistivity of 6.7×10^?4 Ω cm with the mobility of 75 cm²/V s. The average transmittance of the as-deposited IMO film is decreased from 89% to 81% due to irradiation with the fluence of 5×10¹¹ ions/cm².     

Conformer selection and intensified dynamics during catalytic turnover in chymotrypsin

Intensified searching: In enzymes, conformational dynamics are linked to the catalytic reaction coordinate. A novel analytical approach was used to monitor catalysis-linked dynamics in chymotrypsin, revealing that in some enzymes, catalysis is promoted by intensified, but undirected conformational sampling after substrate binding.     

Michael addition of indoles to β-nitrostyrenes catalyzed by HY zeolite under solvent-free conditions

Michael addition of indoles to β-nitrostyrenes is reported using HY zeolite as catalyst under mild reaction conditions. This methodology allows the synthesis of various indole derivatives in good to high yields at 50 °C under solvent-free conditions. The short reaction time and achieving high yield of the desired products are the main advantages of the present work. The catalyst can be easily recovered and reused for six successive runs without considerable changes in yields. This Michael addition catalyzed by HY zeolite is operationally simple and can be considered as a greener protocol as it avoids the use of corrosive acids and toxic reagents.     

Bactericidal Effect of Poly(Acrylamide/Itaconic Acid)–Silver Nanoparticles Synthesized by Gamma Irradiation Against Pseudomonas Aeruginosa

Antimicrobial activity of silver nanoparticles is gaining importance due its broad spectrum of targets in cell compared to conventional antimicrobial agents. In this context, silver nanoparticles were synthesized by gamma irradiation-induced reduction method of acrylamide and itaconic acid with irradiation dose up to 70 kGy. Silver nanoparticles were examined by Fourier-transform infrared, scanning electron microscopic images (SEM), and ultraviolet–visible spectrophotometer. The particle size was determined by X-ray diffraction, transmission electron microscopy (TEM), and dynamic light scattering. The antibacterial effect was studied by disk diffusion method against some bacterial pathogenic strains. Silver nanoparticles showed promising activity against Pseudomonas aeruginosa and slightly active against Escherichia coli, methicillin-resistant Staphylococcus aureus, and Klebsiella pneumonia. The bactericidal effect of silver nanoparticles was tested against P. aeruginosa. The killing rate of P. aeruginosa was found to be 90 % of viability at (100 μl/ml) of silver nanoparticles. Exposure of P. aeruginosa cells to silver nanoparticles caused fast loss of 260 nm absorbing materials and release of potassium ions. The TEM and SEM observation showed that silver nanoparticles may destroy the structure of bacterial cell membrane in order to enter the bacterial cell resulting in the leakage of the cytoplasmic component and the eventual death.