An efficient Knoevenagel condensation of aldehydes with active methylene compounds over novel,robust CeZrO4−δ catalyst

Research on Chemical Intermediates - In the present work, we explored novel CeZrO4?δ as a catalyst for Knoevenagel condensation of aldehydes with reactive methylene compounds like...     

Proteins: sequence to structure and function--current status

In an era that has been dominated by Structural Biology for the last 30-40 years, a dramatic change of focus towards sequence analysis has spurred the advent of the genome projects and the resultant diverging sequence/structure deficit. The central challenge of Computational Structural Biology is therefore to rationalize the mass of sequence information into biochemical and biophysical knowledge and to decipher the structural, functional and evolutionary clues encoded in the language of biological sequences. In investigating the meaning of sequences, two distinct analytical themes have emerged: in the first approach, pattern recognition techniques are used to detect similarity between sequences and hence to infer related structures and functions; in the second ab initio prediction methods are used to deduce 3D structure, and ultimately to infer function, directly from the linear sequence. In this article, we attempt to provide a critical assessment of what one may and may not expect from the biological sequences and to identify major issues yet to be resolved. The presentation is organized under several subtitles like protein sequences, pattern recognition techniques, protein tertiary structure prediction, membrane protein bioinformatics, human proteome, protein-protein interactions, metabolic networks, potential drug targets based on simple sequence properties, disordered proteins, the sequence-structure relationship and chemical logic of protein sequences.     

A validated HPTLC method for determination of trans-caryophyllene from polyherbal formulations

Formulations of traditional medicines are usually made up of a complex mixture of herbs. However, effective quality control methods in order to select materials of the right quality are lacking. 'Amukkara choornam' is a polyherbal Siddha formulation used for gastritis, spleen enlargement, leucorrhoea, hiccups, anaemia, tuberculosis and kappa diseases. Trans-caryophyllene is an important constituent present in the ingredients of this formulation. In a literature survey, it was found that there is no such method for the quantification of trans-caryophyllene except gas chromatography or gas chromatography-mass spectroscopy (GC-MS). So, a high performance thin layer chromatography (HPTLC) method was developed and validated for the quantification of trans-caryophyllene in amukkara choornam. Pre-coated silica gel 60F-254 plates (10 × 10 cm2) were used for the analysis. The solvent system consisted of toluene-ethyl acetatate (9 : 3, v/v), and trans-caryophyllene was detected at 260 nm. The developed method was validated for linearity (R2 = 0.9996 ± 0.0034), limit of detection (LOD) (0.101 ng), limit of quantification (LOQ) (0.639 ng), accuracy (% recovery = 97.19 ± 1.204), and precision (CV < 5%, for both intra-day and inter-day precisions). The levels of trans-caryophyllene were found to be 3.5-4.10 μg per gram of herbal products.     

Biosorption of lead from aqueous solution by seed powder of Strychnos potatorum L.

In the present study, Pb(II) removal efficiency of Strychnos potatorum seed powder (SPSP) from aqueous solution has been investigated. Batch mode adsorption experiments have been conducted by varying pH, contact time, adsorbent dose and Pb(II) concentration. Pb(II) removal was pH dependent and found to be maximum at pH 5.0. The maximum removal of Pb(II) was achieved within 360 min. The Lagergren first-order model was less applicable than pseudo-second-order reaction model. The equilibrium adsorption data was fitted to Langmuir and Freundlich adsorption isotherm models to evaluate the model parameters. Both models represented the experimental data satisfactorily. The monolayer adsorption capacities of SPSP as obtained from Langmuir isotherm was found to be 16.420 mg/g. The FTIR study revealed the presence of various functional groups which are responsible for the adsorption process.     

Dynamic analysis of Markovian jumping impulsive stochastic Cohen–Grossberg neural networks with discrete interval and distributed time-varying delays

In this paper, the dynamic analysis problem is considered for a new class of Markovian jumping impulsive stochastic Cohen–Grossberg neural networks (CGNNs) with discrete interval and distributed delays. The parameter uncertainties are assumed to be norm bounded and the discrete delay is assumed to be time-varying and belonging to a given interval, which means that the lower and upper bounds of interval time-varying delays are available. Based on the Lyapunov–Krasovskii functional and stochastic stability theory, delay-interval dependent stability criteria are obtained in terms of linear matrix inequalities. Some asymptotic stability criteria are formulated by means of the feasibility of a linear matrix inequality (LMI), which can be easily calculated by LMI Toolbox in Matlab. A numerical example is provided to show that the proposed results significantly improve the allowable upper bounds of delays over some existing results in the literature.     

Ecofriendly and facile Nano ZnO catalyzed solvent-free enamination of 1,3-dicarbonyls

Nano zinc oxide (Nano-ZnO) was explored as a reusable catalyst for the enamination of 1,3-dicarbonyls using diverse amines. To make the process environmentally viable, the reaction was carried out under solvent-free conditions and found to give good yield of desired products. The catalyst was characterized by various analytical techniques such as UV-spectroscopy, XRD, and TEM. The catalyst was found to be reusable up to four catalytic cycles without any appreciable loss in activity.     

Superconductivity of Y–Ba–Cu–O and substituted systems

Superconductivity of Y-Ba-Cu-O system is studied in the composition 2:2:3 and 1:2:3 of Y:Ba:Cu. The effect of replacement of Y or Ba by divalent Sr and Ca, trivalent Ce and tetravalent Zr is studied. X-ray diffraction, SEM and TEM techniques are used for materials characterization. Superconducting transition temperatures are measured resistively. Rapid resistance drop observed above 230 K in Y-Ba-Sr-Cu-O and Y-Ba-Ca-Cu-O systems indicate the possible existence of superconductivity above 230 K. Substitution of Ce in place of Y is found to reduce the onset Tc from 95 K to 80 K. For the first time, replacement of Cu by Zr in Y-Ba-Cu-O has yielded the onset Tc of about 105 K.