On a lower bound of commutativity degree

The commutativity degree of a finite group G, denoted by Pr(G), is the probability that a randomly chosen pair of elements of G commute. The object of this paper is to derive a lower bound for Pr(G) and study some of its consequences towards characterizing G.     

New di- and triorganotin(IV) complexes of tripodal Schiff base ligand containing three imidazole arms: Synthesis, structural characterization, anti-inflammatory activity and thermal studies

Some new tri- and diorganotin(IV) complexes of the general formula, R₃Sn(H₂L) and R′₂Sn(HL) [where R = Me, n-Pr, n-Bu and Ph; R′ = Me, n-Bu, Ph and n-Oct; H₃L = Schiff base (abbreviated as tren(4-Me-5-ImH)₃) derived from condensation of tris(2-aminoethyl)amine (tren) and 4-methyl-5-imidazolecarboxaldehyde (4-Me-5-ImH)] have been synthesized. The coordination behaviour of Schiff base towards organotin(IV) moieties is discussed on the basis of infrared and far-infrared, ¹¹⁹Sn Mössbauer and multinuclear (¹H, ¹³C and ¹¹⁹Sn) magnetic resonance (NMR) spectroscopic studies. Thermal studies of all of the synthesized organotin(IV) complexes have been carried out using TG, DTG and DTA techniques. The residues thus obtained from pyrolysis of the studied complexes have been characterized by X-ray powder diffraction analysis and IR. The newly synthesized complexes have been tested for their anti-inflammatory activity and toxicity (LD₅₀).     

Ligand-stabilized metal nanoparticles in organic solvent

This critical review reports the fundamental behavior of metal nanoparticles in different organic solvents, i.e., metal organosol. An overview on metal organosol and then their smart synthetic approaches, characterization, and potential applications in the fields of catalysis and spectroscopy with special emphasis on SERS are embodied. Aspects of organosol fabrication, stabilization, morphology control, growth mechanisms, and physical properties as mono- and bimetallic nanoparticles are discussed. The article inspires the repetitive usage of metal nanoparticles as stable deliverable organic and molecular compounds.     

Cosmology with the intergalactic medium

We discuss a few new results which points out the importance of the intergalactic medium as a diagnostic for the formation and evolution of galaxies in the Universe. We discuss the recent studies to determine the power spectrum of fluctuation from QSO-absorption line studies, and then some feedback processes from early galaxies which influence the intergalactic medium.     

Non-intrusive refractometer sensor

An experimental realization of a simple non-intrusive refractometer sensor is demonstrated in this communication. The working principle of the sensor is based on intensity modulation of the back-reflected light when output light from an optical fibre end focusses onto air-medium interface. The change in the refractive index of the medium affects the reflectance of the incident light signal and thus modulates the back-reflected signal. Refractive index variation as small as 0.002 RIU can be measured using the present technique. The advantages of the technique are its simplicity, cost efficiency and usefulness in monitoring refractive indices of acidic solutions.     

Separation of enzymes by sequential macroaffinity ligand-facilitated three-phase partitioning

Pectinase and cellulase were separated from a commercial enzyme preparation called Pectinex Ultra SP-L. This was carried out using a process called macroaffinity ligand-facilitated three-phase partitioning (MLFTPP). In this method, a water-soluble polymer is floated as an interfacial precipitate by adding ammonium sulfate and tert.-butanol. The polymer (appropriately chosen) in the presence of an enzyme for which it shows affinity, selectively binds to the enzyme and floats as a polymer-enzyme complex. In the first step, pectinase was purified (with alginate as the polymer) 13-fold with 96% activity recovery. In the second MLFTPP step, using chitosan, cellulase was purified 16-fold with 92% activity recovery. Both preparations showed a single band on sodium dodecylsulfate-polyacrylamide gel electrophoresis. This illustrative example shows that the strategy of sequential MLFTPP can be used to separate important biological activities from a crude broth.     

Propagation of cylindrical shock waves in a rotating atmosphere under the action of monochromatic radiation

Summary  A model of cylindrical shock waves is discussed in a non-uniform rotating atmosphere under the action of monochromatic radiation. We have assumed that the radiation flux moves through a rotating gas with constant intensity and the energy is absorbed only behind the shock wave which moves in opposite direction to the radiation flux.