Facile,eco-friendly,one-pot protocol for the synthesis of indole-imidazole derivatives catalyzed by amino acids

An efficient, convenient green approach for the synthesis of indole-based 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles by multicomponent reaction of substituted 2-arylindole-3-carbaldehydes, benzil, substituted anilines, and ammonium acetate using catalytic amino acid (glycine) in ethanol is described. Several amino acids have also been evaluated as organic catalysts for these reactions. The structures of the compounds have been established on the basis of infrared, mass, and ¹H NMR spectral data. The mild reaction conditions, inexpensive/economical reagents, and good yield show the usefulness of this approach.     

A simplified UV spectrometric method for determination of peroxide value in thermally oxidized canola oil

The aim of present study was to develop a simple method on UV spectrometer for the determination of peroxide value (PV) of the frying oil. The basis of the PV determination was the stoichiometric reaction of triphenylphosphine (TPP) with the hydroperoxides present in frying oil to produce triphenylphosphine oxide (TPPO), which exhibits a readily measurable absorption band at 240 nm by ultraviolet region. The PV ranged between 0.15 and 11.66 meq. of active oxygen per kilogram of oil as the canola oil was heated from 0 to 12 h in the fryer at 180 °C. The proposed method was correlated with official AOCS titration method and best correlation coefficient (R² = 0.99525) was achieved, proving that there is no significant difference in the results. Therefore, developed method could serve as an alternative to the titration method, for the determination of PV in frying oils.     

Global QSAR models of skin sensitisers for regulatory purposes

Background

The new European Regulation on chemical safety, REACH, (Registration, Evaluation, Authorisation and Restriction of CHemical substances), is in the process of being implemented. Many chemicals used in industry require additional testing to comply with the REACH regulations. At the same time EU member states are attempting to reduce the number of animals used in experiments under the 3 Rs policy, (refining, reducing, and replacing the use of animals in laboratory procedures). Computational techniques such as QSAR have the potential to offer an alternative for generating REACH data. The FP6 project CAESAR was aimed at developing QSAR models for 5 key toxicological endpoints of which skin sensitisation was one.

Results

This paper reports the development of two global QSAR models using two different computational approaches, which contribute to the hybrid model freely available online.

Conclusions

The QSAR models for assessing skin sensitisation have been developed and tested under stringent quality criteria to fulfil the principles laid down by the OECD. The final models, accessible from CAESAR website, offer a robust and reliable method of assessing skin sensitisation for regulatory use.

     

A first‐order system least‐squares finite element method for the Poisson‐Boltzmann equation

The Poisson‐Boltzmann equation is an important tool in modeling solvent in biomolecular systems. In this article, we focus on numerical approximations to the electrostatic potential expressed in the regularized linear Poisson‐Boltzmann equation. We expose the flux directly through a first‐order system form of the equation. Using this formulation, we propose a system that yields a tractable least‐squares finite element formulation and establish theory to support this approach. The least‐squares finite element approximation naturally provides an a posteriori error estimator and we present numerical evidence in support of the method. The computational results highlight optimality in the case of adaptive mesh refinement for a variety of molecular configurations. In particular, we show promising performance for the Born ion, Fasciculin 1, methanol, and a dipole, which highlights robustness of our approach. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Assessing soil pollution from a municipal waste dump in Islamabad, Pakistan: a study by INAA and AAS

INAA and AAS techniques have been employed to determine 40 elements in soil of a municipal waste dump in sector H-11, Islamabad. Background soil was also analyzed to study the extent of contamination of the dump site soil. Most of the major elements in these soils represented the geochemical composition of the soil in this area. The enrichment factors for quantified elements identified high Sb and Mg contents that could be attributed to the presence of PET and food materials in the waste. Geo-accumulation Index (I _geo), Pollution Index (PI) and the Integrated Pollution Index (IPI) have also been calculated for all elements. The values for these indices show that municipal waste has distorted the soil ambiance and the soil of waste dump site is slightly to moderately polluted as compared to the background soil. The dump soil was found to be moderately polluted by the elements Ba, Br, Ga, Rb, Zn, Ni and Pb. Significantly high Cu, Mg and Sb contamination was observed for the waste soil that is likely to pose an environmental issue if current waste disposal procedures are continuously employed.     

EM-Wave Diffraction by a Finite Plate with Dirichlet Conditions in the Ionosphere of Cold Plasma

In the current communication, the problem of plane wave diffraction by a conductible plate of finite length in the presence of cold plasma is investigated. The boundary-value problem corresponding to this model is formulated by Fourier transform which then leads to the Wiener?Hopf equation. The resulting equation has been solved by the Wiener?Hopf procedure in a standard way. The separated field (diffracted field) is analyzed in an anisotropic medium using asymptotic expansion and modified stationary phase method. The problem can be made simple by assuming ε₂→0, where ε₂ is the element of permittivity tensor. This happens, if the operating frequency is assumed to be very large as compared to ω_c (cyclotron frequency) while it is of same order of ω_p (the plasma frequency). The case ε₁ =1, ε₂→0 leads to the results for soft plate of finite length in an isotropic medium. Graphical study is performed to investigate the behavior of separated field for various physical parameters for isotropic and anisotropic media.     

Conduction of heat in a semi-infinite solid with an exponential-type initial temperature profile: temperature and heat flux solutions due to an instantaneous laser source

A closed-form model for the computation of temperature and heat-flux distribution in a semi-infinite solid with an exponentially-decaying, initial-temperature profile is investigated. The solutions are presented for the case of an instantaneous laser source which is absorbed partially in the surface layers followed by an exponential decay with position in the material itself. The appropriate dimensionless parameters are identified and the reduced temperature and heat flux solutions are presented in the graphic form as a function of these parameters. Some limiting cases of practical interest are also discussed. It is demonstrated that the present analysis covers the classical case of no heat generation in the solid as well as some new solutions.     

Lithium‐Salt‐Containing High‐Molecular‐Weight Polystyrene‐block‐Polyethylene Oxide Block Copolymer Films

Ionic conductivity in relation to the morphology of lithium‐doped high‐molecular‐weight polystyrene‐block‐polyethylene oxide (PS‐b‐PEO) diblock copolymer films was investigated as solid‐state membranes for lithium‐ion batteries. The tendency of the polyethylene (PEO) block to crystallize was highly suppressed by increasing both the salt‐doping level and the temperature. The PEO crystallites completely vanished at a salt‐doping ratio of Li/EO>0.08, at which the PEO segments were hindered from entering the crystalline unit of the PEO chain. A kinetically trapped lamella morphology of PS‐b‐PEO was observed, due to PEO crystallization. The increase in the lamella spacing with increasing salt concentration was attributed to the conformation of the PEO chain rather than the volume contribution of the salt or the previously reported increase in the effective interaction parameter. Upon loading the salt, the PEO chains changed from a compact/highly folded conformation to an amorphous/expanded‐like conformation. The ionic conductivity was enhanced by amorphization of PEO and thereby the mobility of the PEO blocks increased upon increasing the salt‐doping level.     

Antimicrobial activities of essential oil and methanol extract of Coriaria nepalensis

Plant extracts and products have been used for centuries in traditional medicine; for most of them, in addition to the scant scientific credibility, the chemical composition and spectrum of activity are yet to be explored. To put forward this effort and to identify novel antimicrobial agents, the inhibitory activities of methanolic extract and essential oil from Coriaria nepalensis against various microorganisms including pathogenic yeast, and Gram-positive and negative bacteria were evaluated. Chemical compositions of C. nepalensis methanolic extract and essential oil were analysed by gas chromatography-mass spectrometry. In vitro susceptibility tests against all the tested isolates were performed in terms of minimum inhibitory concentration (MIC), and well diffusion assay using standard protocols. All microorganisms tested were profoundly found susceptible to both the C. nepalensis extract and oil with MIC values of 1.3-2.1?mg?mL?1 (Gram-positive bacteria), 1.4-2.2?mg?mL?1 (Gram-negative bacteria) and 0.9-1.6?mg?mL?1 (yeasts). The extent of inhibition was shown more by methanolic extract than by essential oil. This study is the first to report the antimicrobial activity of extracts obtained from the C. nepalensis. It can be concluded that the observed antimicrobial characteristics of C. nepalensis indicate that it might be a promising antimicrobial agent.