Ship-in-a-bottle synthesis of 2,4,6-triphenylthiapyrylium cations encapsulated in zeolites Y and beta: a novel robust photocatalyst

The 2,4,6-triphenylthiapyrylium ion has been obtained imprisoned inside the supercages of the tridirectional, large pore zeolites Y and beta via ship-in-a-bottle synthesis from chalcone and acetophenone in the presence of hydrogen sulfide. The resulting solids are efficient and robust photocatalysts that are able to degrade phenol and aniline in water with a higher efficiency than the P-25 TiO2 standard. Preliminary tests have shown that these encapsulated dye materials are also efficient photocatalysts for the oxidative degradation of malodorous sulfurcontaining molecules.

Propionylation of anisole to 4-methoxypropiophenone over zeolite H-beta

The results of a detailed study of the propionylation of anisole over various medium and large pore zeolites such as H-ZSM-5, H-beta, H-Na-beta. H-mordenite. H-Y and H-RE- Y are presented and discussed. In addition, homogenous catalysts and amorphous Si02-Al2O3 are also included for comparison, The catalyst and process parameters are optimised to enhance the conversion of propionyl chloride(PC) and selectivity to 4-methoxypropiophenone(4-MOPP).

Performance characteristics of positive and negative delayed feedback on chaotic dynamics of directly modulated InGaAsP semiconductor lasers

The chaotic dynamics of directly modulated semiconductor lasers with delayed optoelectronic feedback is studied numerically. The effects of positive and negative delayed optoelectronic feedback in producing chaotic outputs from such lasers with nonlinear gain reduction in its optimum value range is investigated using bifurcation diagrams. The results are confirmed by calculating the Lyapunov exponents. A negative delayed optoelectronic feedback configuration is found to be more effective in inducing chaotic dynamics to such systems with nonlinear gain reduction factor in the practical value range.

Control of bistability in a directly modulated semiconductor laser using delayed optoelectronic feedback

We show numerically that direct delayed optoelectronic feedback can suppress hysteresis and bistability in a directly modulated semiconductor laser. The simulation of a laser with feedback is performed for a considerable range of feedback strengths and delays and the corresponding values for the areas of the hysteresis loops are calculated. It is shown that the hysteresis loop completely vanishes for certain combinations of these parameters. The regimes for the disappearance of bistability are classified globally. Different dynamical states of the laser are characterized using bifurcation diagrams and time series plots.

On Finite Mixture of Pareto and Beta Distnbutions

Department of Statistics, Cochin University of Science and Technology

Extracellular beta-Glucosidase production by marine Aspergillus sydowii BTMFS 55

The beta-glucosidase enzyme purified from the marine fungus, Aspergillus sydowii BTMFS 55 showed a good yield of enzyme production under solid state fermentation. The statistical optimization of the media components revealed that moisture content, concentration of peptone and inoculum are the major parameters which supported the maximal enzyme production. The purified enzyme showed low pH activity and stability, glucose tolerance and activation by ethanol. It could produce ethanol from wheat bran and rice straw by simultaneous saccharification and fermentation with yeast.The glucosidase purified from Aspergillus sydowii BTMFS 55 shows great potential for several biotechnological applications such as the production of bio-ethanol from agricultural biomass and improvement in the aromatic character of wines and fruit juices through the hydrolysis of flavour glucosidic precursors. There is immense scope for the application of this marine fungus in the biofuel production besides in other industries provided further studies are pursued in exploiting this enzyme and the organism particularly scale up studies with respect to application. There is also ample scope for cloning of the gene encoding beta-glucosidase in domesticated hosts such as Pichia pastoris or S. cerevisiae that can produce ethanol directly from cellulosic biomass.

Effect of Delayed Icing on the Microbiological Quality of Hilsa Toli

Effect of delayed icing on the microbial quality and shelf-life of Hilsa toll was studied . Fish iced in rigor condition had a shelf-life of 11 days irrespective of the state of rigor . Fish procured from the landing centre had a shelf-life of only 8 days . It showed the presence of coagulase positive staphylococci, faecal streptococci and E. coli. Total bacterial count was low in all the samples and it increased after spoilage