Numerical scheme with convergence for a generalized time‐fractional Telegraph‐type equation

In this work, we design and analyze a numerical scheme for solving the generalized time‐fractional Telegraph‐type equation (GTFTTE) which is defined using the generalized time fractional derivative (GTFD) proposed recently by Agrawal. The GTFD involves the scale and the weight functions, and reduces to the traditional Caputo derivative for a particular choice of the weight and the scale functions. The scale and the weight functions play an important role in describing the behavior of real‐life physical systems and thus we study the solution behavior of the GTFTTE by varying the weight and the scale functions in the GTFD. We investigate the solution profile of the GTFTTE under some of these choices. We also provide the stability and the convergence analysis of the proposed numerical scheme for the GTFTTE. We consider two test examples to perform numerical simulations.     

Synthesis, characterization and structure-property relationship studies of cobaloximes with dithienylglyoxime as the equatorial ligand

The synthesis of cobaloximes, X/RCo(dThgH)₂Py (X = Cl, R = Me, Et, n-Pr, n-Bu and Bn) has been described. All the complexes have been characterized by elemental analyses and NMR spectral studies. The molecular structures of ClCo(dThgH)₂Py, MeCo(dThgH)₂Py, EtCo(dThgH)₂Py and BnCo(dThgH)₂Py complexes are determined by X-ray crystallography. The electron withdrawing nature of 2-thienyl ring affects the NMR as well as electrochemical behavior of these complexes. The electrochemical reduction from Co(III) to Co(II) and from Co(II) to Co(I) are much easier in ClCo(dThgH)₂Py as compared to chlorocobaloximes with the other dioximes (gH, dmgH, dpgH, dmestgH). The molecular oxygen insertion in the Co−C bond of benzyl complex (6) has been examined and a comparison of its reaction rate with other similar cobaloximes is discussed. The structural features of a dioxy complex Bn(O₂)Co(dThgH)₂Py (7) have also been reported.     

Synthesis of Amylose‐b‐P2VP Block Copolymers

A new class of rod–coil block copolymers is synthesized by chemoenzymatic polymerization. In the first step, maltoheptaose, which acts as a primer for the synthesis of amylose, is attached to poly(2‐vinyl pyridine) (P₂VP). The enzymatic polymerization of maltoheptaose is carried out by phosphorylase to obtain amylose‐b‐P₂VP block copolymers. The block copolymer is characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, and wide‐angle X‐ray scattering techniques. The designed molecules combine the inclusion complexation ability of amylose with the supramolecular complexation ability of P₂VP and therefore this kind of rod–coil block copolymers can be used to generate well‐organized novel self‐assembled structures.

     

Biorational synthesis of iridomyrmecin diastereomers from catnip oil

4S,4aS,7S,7aR; 4R,4aS,7S,7aR; 4S,4aS,7S,7aS, and 4R,4aS,7S,7aS diastereomers of iridomyrmecin have been prepared in 5 steps from 4aS,7S,7aR and 4aS,7S,7aS-nepetalactones, major components of catnip oil. 4S,4aS,7S,7aR and 4R,4aS,7S,7aR-iridomyrmecin have been identified as defensive compounds from Iridomyrmex ants.     

Can microbes mediate nano-transformation?

A green low-cost and reproducible microbe (Lactobacillus) and baker’s yeast (Saccharomyces cerevisiae) mediated biosynthesis of metallic and oxide nanoparticles are reported. Silver and copper oxide nanoparticles are synthesized using Lactobacillus sp. and Saccharomyces cerevisiae. The synthesis is performed akin to room temperature in the laboratory ambience. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of metallic and oxide nanoparticles. Individual nanoparticles having the dimensions of 2–6 nm (metallic) and 10–20 nm (oxide) are found. A possible mechanism involved for the synthesis of metallic and oxide nanoparticles has also been proposed in which pH as well as the partial pressure of gaseous hydrogen (r-H₂) or redox potential of the culture solution seem to play an important role in the process.     

High pressure measurement with simple piston gauge in static condition

This paper describes the characterization of the newly developed piston gauge pressure standard at the National Physical Laboratory (NPL), with particular reference to its fall rate, engagement length of the piston and the deceleration rate for the measurement of hydraulic hydrostatic pressure up to 60 MPa. The low pressure effective area of the gauge derived from its dimensional measurements when compared with the value obtained by its direct calibration against NPL transfer pressure standard agrees within 0.025%. The pressure gauge is quite stable, reproducible and has a sensitivity of 3 ppm. Though the theoretically calculated value of the pressure coefficient is low as compared to the experimentally observed one in its absolute terms, the pressure dependent effective area agrees within ± 0.025% over whole of the pressure range which is well within the uncertainty statement of the two independent techniques used.     

Resolution and assignement of absolute configuration to the (+)- and (−)-cis and trans 3,4-diol metabolites of the anti-juvenile hormone precocene I

The cis and trans 3,4-diol metabolites of precocene I have been prepared inoptically pure form and their absolute configurations have been assigned by independent nmr and CD techniques.     

A ring-closing metathesis approach for the synthesis of (±)-pregabalin

Abstract  

Efficient utilization of a Mannich-type reaction and the ring-closing metathesis (RCM) approach that leads to a convenient synthesis of 3-(aminomethyl)-5-methylhexanoic acid (pregabalin) is described.     

Recent trends in ultra‐fast HPLC: New generation superficially porous silica columns

New generation columns, i.e. packed with superficially porous silica particles are available as trade names with following manufacturers: Halo, Ascentis Express, Proshell 120, Kinetex, Accucore, Sunshell, and Nucleoshell. These provide ultra‐fast HPLC separations for a variety of compounds with moderate sample loading capacity and low back pressure. Chemistries of these columns are C₈, C₁₈, RP‐Amide, hydrophilic interaction liquid chromatography, penta fluorophenyl (PFP), F5, and RP‐aqua. Normally, the silica gel particles are of 2.7 and 1.7 μm as total and inner solid core diameters, respectively, with 0.5‐μm‐thick of outer porous layer having 90 Å pore sizes and 150 m²/g surface area. This article describes these new generation columns with special emphasis on their textures and chemistries, separations, optimization, and comparison (inter and intra stationary phases). Besides, future perspectives have also been discussed.     

Digital microfluidics: a versatile tool for applications in chemistry, biology and medicine

Digital microfluidics (DMF) has recently emerged as a popular technology for a wide range of applications. In DMF, nanoliter to microliter droplets containing samples and reagents can be manipulated to carry out a range of discrete fluidic operations simply by applying a series of electrical potentials to an array of patterned electrodes coated with a hydrophobic insulator. DMF is distinct from microchannel-based fluidics as it allows for precise control over multiple reagent phases (liquids and solids) in heterogeneous systems with no need for complex networks of connections, microvalves, or pumps. In this review, we discuss the most recent developments in this technology with particular attention to the potential benefits and outstanding challenges for applications in chemistry, biology, and medicine.