Liquid crystal parameters through image analysis

A technique which combines image analysis and polarising optical microscope (POM) is a useful tool for the physical investigation of discotic liquid crystals, such as hexabutoxytriphenylene and hexahexyloxytriphenylene. This investigation includes the phase transitions, optical properties and order parameter as a function of temperature. Textures of discotic liquid crystals are captured as a function of temperature using POM. These microscopic textures are analysed using MATLAB software to compute statistical parameters, Legendre moments, optical parameters and order parameters of discotic liquid crystal samples. Compared with other techniques in the literature, the proposed methodology is a reliable and very simple technique for the physical investigation of liquid crystals.     

Liquid crystalline banana‐shaped monomers derived from 2,7‐naphthalene: synthesis and properties

Three banana‐shaped monomers, i.e. 2,7‐naphthalene bis[4‐(4‐allyloxyphenylazo)‐benzoate], 2,7‐naphthalene bis[4‐(4‐allyloxy‐3‐fluorophenylazo)benzoate] and 2,7‐naphthalene bis{4‐[4‐(10‐undecenyloxy)phenylazo]benzoate}, containing azobenzene as side arms, 2,7‐dihydroxynaphthalene as central units and terminal double bonds as polymerisable functional groups, were synthesised and their mesophase behaviour investigated. Polarizing optical microscopy and DSC measurements reveal that all compounds exhibit nematic mesophases. The absorption spectrum of the trans‐azobenzene groups displays a high‐intensity π–π* transition at about 365 nm and a low‐intensity n–π* transition at around 450 nm for all compounds. Hence, photochromism can be achieved by the introduction of the azo linkage to banana‐shaped liquid crystals molecules.     

A new form of discotic metallomesogens: the synthesis of metal-bridged triphenylene discotic dimers

Discotic metallomesogens are becoming increasingly important due to their electronic and optoelectronic properties. Preliminary results on the synthesis and characterization of a new form of discotic metallomesogens in which a Hg atom is covalently linked with two substituted triphenylene moieties are presented.     

Novel monofunctionalized electron-deficient anthraquinone-based discotic liquid crystals

A series of electron-deficient 1-hydroxy-2,3,5,6,7-pentaalkoxyanthra-9,10-quinones has been synthesized. All nine members of the series were found to be liquid crystalline, forming columnar mesophases over a broad temperature range. Such supramolecular building blocks can be used for the preparation of novel discotic dimers, oligomers, polymers and metallomesogens.     

Advances in RNA Interference Technology and Its Impact on Nutritional Improvement, Disease and Insect Control in Plants

This review highlights the advances in the knowledge of RNA interference (RNAi) and discusses recent progress on the functionality of different components RNAi machinery operating in the organisms. The silencing of genes by RNA interference has become the technology of choice for investigation of gene functions in different organisms. The refinement in the knowledge of the endogenous RNAi pathways in plants along with the development of new strategies and applications for the improvement of nutritional value of important agricultural crops through suppression of genes in different plants have opened new vistas for nutritional security. The improvement in the nutritional status of the plants and reduction in the level of toxins or antinutrients was desired for long, but the available technology was not completely successful in achieving the tissue specific regulation of some genes. In the recent years, a number of economically important crop plants have been tested successfully for improving plant nutritional value through metabolic engineering using RNAi. The implications of this technology for crop improvement programs, including nutritional enrichment, reduction of antinutrients, disease, and insect control have been successfully tested in variety of crops with commercial considerations. The enhancement of the nutraceutical traits for the desired health benefits in common crop plants through manipulation of gene expression has been elaborated in this article. The tremendous potential with RNAi technology is expected to revolutionize the modern agriculture for meeting the growing challenges is discussed.     

Asymptotic synchronization of continuous/discrete complex dynamical networks by optimal partitioning method

The synchronization problem for both continuous and discrete‐time complex dynamical networks with time‐varying delays is investigated. Using optimal partitioning method, time‐varying delays are partitioned into l subintervals and generalized results are derived in terms of linear matrix inequalities (LMIs). New delay‐dependent synchronization criteria in terms of LMIs are derived by constructing appropriate Lyapunov–Krasovskii functional, reciprocally convex combination technique and some inequality techniques. Numerical examples are given to illustrate the effectiveness and advantage of the proposed synchronization criteria. © 2014 Wiley Periodicals, Inc. Complexity 21: 193–210, 2015     

Micelles catalyzed one pot regio- and chemoselective synthesis of benzo[a]phenazines and naphtho[2,3-d]imidazoles ‘in H2O’

An efficient, novel, and concise one pot regio- and chemoselective synthesis of benzo[a]phenazines (4) and naphtho[2,3-d]imidazoles (8) has been accomplished in excellent yields by nucleophilic substitution reaction of 2,3-dichloro-1,4-naphthoquinone (1) with o-phenylenediamine (2) and benzamidines (7) respectively ‘in H₂O’ using base and micelles (SDS) as catalyst. Analog reaction of 2,3-dichloro-1,4-naphthoquinone (1) with 2-aminobenzenethiol (9) under identical conditions led to formation of a mixture of benzo[b]phenothiazine (10), benzo[a]phenothiazine (11), and benzo[a]-1,4-benzothiazino-3,2-phenothiazine (12) in 17%, 23%, and 57% yields, respectively.     

Evolution of coercivity and its angular dependence in CoFe nanostructures subjected to field cooling

Evolution of coercivity and its angular dependence in CoFe nanostructures subjected to field cooling has been investigated in this work. Spherical CoFe grains with an average diameter of 30 nm were grown on a silicon substrate using electron beam evaporation. Further, the as‐deposited sample was subjected to field cooling. The morphology and topography of the sample before and after field cooling were characterized by atomic force microscopy and SEM. Magnetic force microscopy indicated that there is a good uniformity of magnetization throughout the sample after field cooling. Vibrating sample magnetometer measurements indicate that the coercivity in CoFe nanostructures is dependent on shape of the nanostructures. Copyright © 2013 John Wiley & Sons, Ltd.     

An efficient one pot method for synthesis of carboxylic acids from nitriles using recyclable ionic liquid [bmim]HSO4

Environmentally benign ionic liquid [bmim]HSO₄ was found suitable for conversion of nitriles into carboxylic acids under mild conditions with excellent purity.