Laser Spectra and Efficiencies of Pyrazolo Derivatives of Coumarins

Abstract

Of the new laser dyes of coumarin series reported earlier, pyrazolo derivatives have been further studied. The paper reports their laser spectra and efficiencies in various solvents compared to a standard coumarin laser dye C₅₁₅. One of the derivatives shows comparable output under optimum concentration conditions as compared to the standard.     

Infra-red spectra of fluoroxylenes

The infra-red spectra of four fluoroxylenes (1, 2, 6-, 1, 2, 3-, 1, 3, 4-and 1, 2, 5-isomers) have been recorded in the 2–15 µ region on a Perkin-Elmer Model 21 spectrophotometer. From among the bands recorded, those which could be correlated to the fundamental vibration of the constituent benzene and methyl groups are discussed in detail and compared with particular reference to the type of substitutions.     

Collectively compact sets of operators and almost periodic functions

A characterization of collectively compact sets of linear operators on the Banach algebra of almost periodic functions is obtained by using Gelfand-Naimark theory. Properties of collectively compact sets are then used to prove that the Fourier coefficients of an almost periodic function are approximately the eigenvalues of Fredholm type integral operators.     

Thermal Studies of Metal-quinone Complexes Role of Aqua Coligations with Copper(II) in Coordination of 2-hydroxy-1,4-naphthoquinone

Copper(II) complexes of lawsone (2-hydroxy-1,4-naphthaquinone, Lw) with variety of aqua ligation viz. Cu-1, [Cu(Lw)₂(H₂O)]₂; Cu-2, [Cu(Lw)₂(H₂O)₂] and Cu-3, [Cu(Lw)₂(H₂O)₂]₂ have been synthesized. The role of water as counter ligand on coordination propensity of redox active lawsone in naphthoquinone/naphthosemiquinone (NQ/NSQ) forms is quantified by studies of pyrolytic reactions, using non-isothermal TG and DTA techniques, coupled with IR studies. Mixed (NQ) (NSQ) ligation in Cu-1 and Cu-3 required energy of activation, E_a ∼67 kJ mol⁻¹ of (NQ) and ∼41 kJ mol⁻¹ of (NSQ). Comparable energies of aqua ligand (∼43 kJ mol⁻¹) with NSQ ligand in Cu-1 and Cu-3, dictate charge distributions in lawsone coordinations. A large difference between E_a of aqua and p-NQ ligand indicates coordination of lawsone in its fully oxidised quinone form in Cu-2. From thermoanalytical studies schematic oxidative decomposition mechanisms are proposed for Cu-1 and Cu-3. From pyrolytic reactions enthalpies are estimated by DTA technique. This revised version was published online in August 2006 with corrections to the Cover Date.     

Differentiation of neurons from neural precursors generated in floating spheres from embryonic stem cells

Background  

Neural differentiation of embryonic stem (ES) cells is usually achieved by induction of ectoderm in embryoid bodies followed by the enrichment of neuronal progenitors using a variety of factors. Obtaining reproducible percentages of neural cells is difficult and the methods are time consuming.     

Ferrocene‐substituted 3,3′‐diindolylmethanes with improved anticancer activity

A series of ferrocene‐substituted derivatives ( 2a , 2b , 2c , 2d , 2e , 2f , 2g ) of the known drug 3,3′‐diindolylmethane ( DIM ) were prepared and tested for their in vitro antitumor activity. The derivatives 2a (featuring indole moiety), 2b (featuring 2‐methylindole moiety) and 2f (featuring 5‐nitroindole moiety) were growth‐inhibiting in vitro at lower concentrations than DIM in various tumor cells including pancreas cancer (BcPC‐3), three DIM‐resistant cancer cell lines (518 A2, KB‐V1/Vbl, HT‐29), triple‐negative breast cancer (MDA‐MB‐231) and prostate cancer (PC‐3). Derivatives 2a , 2b and 2f were the most active compounds of this series, qualifying as drug candidates for various cancer diseases. Copyright © 2016 John Wiley & Sons, Ltd.     

Enhancing performance of particle swarm optimization through an algorithmic link with genetic algorithms

Evolutionary Algorithms (EAs) are emerging as competitive and reliable techniques for several optimization tasks. Juxtapositioning their higher-level and implicit correspondence; it is provocative to query if one optimization algorithm can benefit from another by studying underlying similarities and dissimilarities. This paper establishes a clear and fundamental algorithmic linking between particle swarm optimization (PSO) algorithm and genetic algorithms (GAs). Specifically, we select the task of solving unimodal optimization problems, and demonstrate that key algorithmic features of an effective Generalized Generation Gap based Genetic Algorithm can be introduced into the PSO by leveraging this algorithmic linking while significantly enhance the PSO’s performance. However, the goal of this paper is not to solve unimodal problems, neither is to demonstrate that the modified PSO algorithm resembles a GA, but to highlight the concept of algorithmic linking in an attempt towards designing efficient optimization algorithms. We intend to emphasize that the evolutionary and other optimization researchers should direct more efforts in establishing equivalence between different genetic, evolutionary and other nature-inspired or non-traditional algorithms. In addition to achieving performance gains, such an exercise shall deepen the understanding and scope of various operators from different paradigms in Evolutionary Computation (EC) and other optimization methods.     

Biscoumarins - New Laser Dyes in Coumarin Series

With a view to extend the tunability range using new derivatives in the coumarin series of dyes, a novel series have been synthesized, viz. the biscoumarins where two coumarin nuclei are coupled. These are studied for their lasing characteristics, optical spectra and quantum efficiencies. Laser spectra of these dyes in various solvents are also studied. Tunability range of these dyes have been found to cover blue green region of the spectrum and though there is shift to longer wavelength as compared to monocoumarins, extending the tunability range, it is not as much as would be normally expected with extended conjugation involving two coumarin nucled.