Regiospecific oxidation of an alkyl group of aromatic amine to carbonyl group by DDQ in aq.medium

The regiospecific oxidation of alkyl group of both sterically hindered and unhindered aromatic amine to corresponding carbonyl compound was done in aq. medium by using DDQ. The optimized reaction protocol was found to be most simple, high yielding and novel method for oxidation of alkyl group of aromatic amine in to its carbonyl compound.     

Interaction of bathocuproine with metals (Ca, Mg, Al, Ag, and Au) studied by density functional theory

Electronic structure of the interface between a bathocuproine (BCP) molecule and metal surface was studied by density functional theory. The bond energy of BCP with metal surface increased with decreasing work function of metals, that is, Au, Ag, Al, Mg, and Ca in this order. The charge transfer also increased with decreasing metal work function. It was analyzed that the Fermi level and the lowest unoccupied molecular orbital of BCP are composed of both BCP and metal orbital component, and electron transport properties across the BCP and metal is discussed based on these analyses.     

Synthesis and thermal properties of mesomorphic 1,1'-bis[ω-(4'-cyano-4-biphenyloxy)alkyl] ferrocenes

A new series of 1,1'-disubstituted ferrocene compounds of the type [(η⁵-C₅H₄(CH₂)_nOC₆H₄C₆H₄CN]₂Fe (3a-d, n = 5, 6, 8, 11) incorporating a variable length alkyloxy cyanobiphenyl unit has been prepared and their mesomorphic properties have been investigated. Compounds 3b, c and d exhibit a thermotropic smectic C phase and 3c also exhibits a monotropic smectic A phase over a fairly wide range near ambient temperature.     

Steady-State dynamics of a linear structure weakly coupled to an essentially nonlinear oscillator

We present a theoretical study of the dynamics of the coupled system of Jiang, McFarland, Bergman, and Vakakis. It comprises a harmonically excited linear subsystem weakly coupled to an essentially nonlinear oscillator. We explored the rich dynamics exhibited by this coupled system by determining its periodic responses and their bifurcations. Not surprisingly, we found a lot of interesting dynamics over a broad frequency range: cyclic-fold, Hopf, symmetry-breaking, and period-doubling bifurcations; phase-locked motions; regions with multiple coexisting solutions; hysteresis; and chaos. We did not find any occurrence of energy transfer via modulation (also known as zero-to-one internal resonance); theoretically, the possibility of its occurrence was ruled out for systems with weak nonlinearity and damping. Finally, we investigated the ef fectiveness of the so-called nonlinear energy sink (NES) in vibration attenuation of forced linear structures. We found that the NES results in an increase in the vibration amplitude of the linear subsystem, especially when the damping is low, contrary to the claim made by Jiang et al. Also, we did not find any indication of nonlinear energy pumping or localization of energy in the NES, away from the directly forced linear subsystem, indicating that the NES is not ef fective for controlling the vibrations of forced linear structures.     

Raman spectroscopic investigation on the microenvironment of the liver tissues of Zebrafish (Danio rerio) due to titanium dioxide exposure

Nano titanium dioxide (nTiO₂), generally considered to be toxicologically inert, is manufactured in large quantities and extensively applied in consumer products. The small size and large surface area endow them with an active group or intrinsic toxicity. Advances in instrumentation are making Raman spectroscopy the tool of choice for an increasing number of (bio) chemical applications. One of the great advantages of this technique is its ability to provide information on the concentration, structure and interaction of biochemical molecules in their microenvironments within intact cells and tissues, non-destructively. Zebrafish (Danio rerio), one of the most important vertebrate model organisms used in developmental biology, are increasingly used in biomedical research, particularly as a model of human disease. In the present work, an attempt is made to study the effect of titanium dioxide, both nano and bulk, on the microenvironment of the liver tissues of Zebrafish using FT-Raman spectroscopy. The results of the present study suggest that TiO₂ exposure demonstrate a marked influence on the microenvironments of the liver tissues of Zebrafish. A shift to a higher wavenumber and an increase in the intensity of the band at ∼1087 cm⁻¹ in the TiO₂ exposed tissues suggest that some of the conformational changes resulting from the alkali recovery process takes place due to TiO₂ exposure. The decreased intensity ratio (I₃₂₂₀/I₃₄₀₀) observed in the titanium-exposed tissues suggests a decreased water domain size, which could be interpreted in terms of weaker hydrogen-bonded molecular species of water in the TiO₂ exposed tissues. The observed shift of COO⁻ bands to higher frequencies shows the disruption of salt bridges as a result of a change in the oppositely charged partners and due to the enhanced random coil conformation. The variation in the intensity ratio of the tyrosyl doublet (I₈₅₈/I₈₂₅) indicates variation in the hydrogen bonding of the phenolic hydroxyl group due to TiO₂ exposure. The results further suggest that the microenvironments are greatly altered due to titanium nano exposure when compared to titanium bulk. In conclusion, the results indicate that FT-Raman spectroscopy might be a useful tool for rapid assessment of nano particle biological interactions.     

Determination of penciclovir in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry: application to a clinical pharmacokinetic study

A rapid, specific and sensitive liquid chromatography tandem mass spectrometry (LC–MS/MS) method was developed for the determination of penciclovir in human plasma. The method involved simple, one‐step SPE procedure coupled with a C₁₈, 75 × 4.mm, 3µm column with a flow‐rate of 0.5 mL/min, and acyclovir was used as the internal standard. The Quattro Micro mass spectrometry was operated under the multiple reaction‐monitoring mode using the electrospray ionization technique. Using 250 µL plasma, the methods were validated over the concentration range 52.555–6626.181 ng/mL, with a lower limit of quantification of 52.55 ng/mL. The intra‐ and inter‐day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a clinical pharmacokinetic study in human volunteers. Copyright © 2010 John Wiley & Sons, Ltd.     

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.