Purification and Characterization of an Anti-cancer Enzyme Produced by Marine Vibrio Costicola Under A Novel Solid State Fermentation Process

L - Glutaminase, a therapeutically and industrially important enzyme, was produced from marine Vibrio costicola by a novel solid state fermentation process using polystyrene beads as inert support. The new fermentation system offered several advantages over the conventional systems, such as the yield of leachate with minimum viscosity and high specific activity for the target product besides facilitating the easy estimation of biomass. The enzyme thus produced was purified and characterised. It was active at physiological pH, showed high substrate specificity towards L - glutamine and had a Km value of 7.4 x 10-2 M. It also exhibited high salt and temperature tolerance indicating good scope for its industrial and therapeutic applications

Optimization of Lignin Peroxidase, Manganese Peroxidase, and Lac Production from Ganoderma lucidum Under Solid State Fermentation of Pineapple Leaf

This study was undertaken to isolate ligninase-producing white-rot fungi for use in the extraction of fibre from pineapple leaf agriwaste. Fifteen fungal strains were isolated from dead tree trunks and leaf litter. Ligninolytic enzymes (lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase (Lac)), were produced by solid-state fermentation (SSF) using pineapple leaves as the substrate. Of the isolated strains, the one showing maximum production of ligninolytic enzymes was identified to be Ganoderma lucidum by 18S ribotyping. Single parameter optimization and response surface methodology of different process variables were carried out for enzyme production. Incubation period, agitation, and Tween-80 were identified to be the most significant variables through Plackett-Burman design. These variables were further optimized by Box-Behnken design. The overall maximum yield of ligninolytic enzymes was achieved by experimental analysis under these optimal conditions. Quantitative lignin analysis of pineapple leaves by Klason lignin method showed significant degradation of lignin by Ganoderma lucidum under SSF

Characterization of rhodamine 6G doped polymer optical fiber by side illumination fluorescence

The length-dependent tuning of the fluorescence spectra of a dye doped polymer fiber is reported. The fiber is pumped sideways and the fluorescence is measured from one of the ends. The excitation of a finite length of dye doped fiber is done by a diode pumped solid state laser at a wavelength of 532 nm. The fluorescence emission is measured at various positions of the fiber starting from a position closer to the pumping region and then progressing toward the other end of the fiber. We observe that the optical loss coefficients for shorter and longer distances of propagation through the dye doped fiber are different. At longer distances of propagation, a decrease in optical loss coefficient is observed. The fluorescence peaks exhibit a redshift of 12 nm from 589 to 610 nm as the point of illumination progresses toward the detector end. This is attributed to the self-absorption and re-emission of the laser dye in the fiber.

Effect of silver nano particles on the fluorescence quantum yield of Rhodamine 6G determined using dual beam thermal lens method

Nano structured noble metals have very important applications in diverse fields as photovoltaics, catalysis, electronic and magnetic devices, etc. Here, we report the application of dual beam thermal lens technique for the determination of the effect of silver sol on the absolute fluorescence quantum yield (FQY) of the laser dye rhodamine 6G. A 532 nm radiation from a diode pumped solid state laser was used as the excitation source. It has been observed that the presence of silver sol decreases the fluorescence quantum efficiency. This is expected to have a very important consequence in enhancing Raman scattering which is an important spectrochemical tool that provides information on molecular structures. We have also observed that the presence of silver sol can enhance the thermal lens signal which makes the detection of the signal easier at any concentration.

Selective mode excitation in dye-doped DNA polyvinyl alcohol thin film

A solid-state laser based on a dye-doped deoxyribonucleic acid (DNA) matrix is described. A thin solid film of DNA has been fabricated by treating with polyvinyl alcohol (PVA) and used as a host for the laser dye Rhodamine 6G. The edge emitted spectrum clearly indicated the existence of laser modes and amplified spontaneous emission. Lasing was obtained by pumping with a frequency-doubled Nd:YAG laser at 532 nm. For a pump energy of 10 mJ/pulse, an intense line with FWHM ≈0.2 nm was observed at 566 nm due to selective mode excitation.

Luminescence from Surfactant-Free ZnO Quantum Dots Prepared by Laser Ablation in Liquid

Highly transparent, luminescent and biocompatible ZnO quantum dots were prepared in water, methanol, and ethanol using liquid-phase pulsed laser ablation technique without using any surfactant. Transmission electron microscopy analysis confirmed the formation of good crystalline ZnO quantum dots with a uniform size distribution of 7 nm. The emission wavelength could be varied by varying the native defect chemistry of ZnO quantum dots and the laser fluence. Highly luminescent nontoxic ZnO quantum dots have exciting application potential as florescent probes in biomedical applications.

Laser induced fluorescence of BaS: Sm phosphor and energy level splitting of Sm3+ ion

Fluorescence of BaS: Sm phosphor has been studied using a pulsed Nitrogen laser (337.1 nm) as the excitation source. The spectrum consists of a broad band in the region 540–660nm superposed by the characteristic Sm3+ lines. Energy level splitting pattern of Sm3+ due to crystal field effects has been calculated and relevent field parameters are evaluated. Analysis shows that Sm3+ takes up Ba2+ substitutional sites.

Studies on ASE, Lasing and NLO characteristics in Certain Laser Dyes

Observing the wide possibilities of fluorescent dyes, an exhaustive investigation is done in laser dyes mainly focusing on Coumarin 540 which has a very strong emission in the green region. The photophysics of the dye is studied in detail in a good number of solvent environments. The results of the amplified spontaneous emission and lasing behaviour in both dye solution and different polymer solid state matrices and the ptotostability of the these matrices are investigated using the photoacoustic technique and the same are also included in this thesis. The energy transfer behaviour in dye mixtures which could be utilized for laser studies and bio-analysis are also presented. The nonlinear characterization of Coumarin540 forms the last part of the experimental investigations presented in the thesis.

Fluorescenec Emission of SrS:Eu2+ Phosphor-Energy Level Splitting of Eu2+

A method of preparation of strontium sulphide phosphors doped with europium is given. Nitrogen laser excited fluorescence emission spectra of these phosphors in the visible region are recorded. A band with line structure in the region 350-430 nm and a new broad band at 460 nm are observed. The splitting pattern for the 6p levels of Eu 2+ are given.

Fluorescence Decay Characteristics of the Green Emission From CaF2:Ho3+

Variations in the decay times of the characteristic green emissions at 522.7, 551.3, 549.6, 547.6, 542.2, 540.2, 535.9 and 533.5nm from CaF2 :H03+ with concentration are studied at RT and LNT. A pulsed N2 laser beam of power density 1.5 MW cm-2 is used for the excitation. Temperature dependent concentration quenching of the decay times are observed for all the emission bands. But an increase in the decay time due to the reabsorption process is also observed for a few of the above bands.

Growth and characterisation of p-type delafossite transparent conducting thin films for heterojunction applications

In the present studies, various copper delafossite materials viz; CuAlO2, CuGaO2, CuFeO2 , CuGa1-xFexO2, CuYO2 and CuCaxY1-xO2 were synthesised by solid state reaction technique. These copper delafossite materials were grown in thin film form by rf magnetron sputtering technique. In general copper delafossites exhibit good optical transparency. The conductivity of the CuYO2 could be improved by Ca doping or by oxygen intercalation by annealing the film in oxygen atmosphere. It has so far been impossible to improve the p-type conductivity of CuGaO2 significantly by doping Mg or Ca on the Ga site. The ptype conductivity is presumed to be due to oxygen doping or Cu Vacancies [6]. Reports in literature show, oxygen intercalation or divalent ion doping on Ga site is not possible for CuGaO2 thin films to improve the p-type conductivity. Sintered powder and crystals of CuFeO2 have been reported as the materials having the highest p-type conductivity [14, 15] among the copper and silver delafossites. However the CuFeO2 films are found to be less transparent in the visible region compared to CuGaO2. Hence in the present work, the solid solution between the CuGaO2 and CuFeO2 was effected by solid state reaction, varying the Fe content. The CuGa1-xFexO2 with Fe content, x=0.5 shows an increase in conductivity by two orders, compared to CuGaO2 but the transparency is only about 50% in the visible region which is less than that of CuGaO2 The synthesis of α−AgGaO2 was carried out by two step process which involves the synthesis of β-AgGaO2 by ion exchange reaction followed by the hydrothermal conversion of the β-AgGaO2 into α-AgGaO2. The trace amount of Ag has been reduced substantially in the two step synthesis compared to the direct hydrothermal synthesis. Thin films of α-AgGaO2 were prepared on silicon and Al2O3 substrates by pulsed laser deposition. These studies indicate the possibility of using this material as p-type material in thin film form for transparent electronics. The room temperature conductivity of α-AgGaO2 was measured as 3.17 x 10-4 Scm-1and the optical band gap was estimated as 4.12 eV. A transparent p-n junction thin film diode on glass substrate was fabricated using p-type α-AgGaO2 and n-ZnO.AgCoO2 thin films with 50% transparency in the visible region were deposited on single crystalline Al2O3 and amorphous silica substrates by RF magnetron sputtering and p type conductivity of AgCoO2 was demonstrated by fabricating transparent p-n junction diode with AgCoO2 as p-side and ZnO: Al as n-side using sputtering. The junction thus obtained was found to be rectifying with a forward to reverse current of about 10 at an applied voltage of 3 V.The present study shows that silver delafossite thin films with p-type conductivity can be used for the fabrication of active devices for transparent electronics applications.

Investigations on Nonlinear and Radiative Properties of Certain Phatonic Materials

Light in its physical and philosophical sense has captured the imagination of human mind right from the dawn of civilization. The invention of lasers in the 60’s caused a renaissance in the field of optics. This intense, monochromatic, highly directional radiation created new frontiers in science and technology. The strong oscillating electric field of laser radiation creates a. polarisation response that is nonlinear in character in the medium through which it passes and the medium acts as a new source of optical field with alternate properties. It was in this context, that the field of optoelectronics which encompasses the generation, modulation, transmission etc. of optical radiation has gained tremendous importance. Organic molecules and polymeric systems have emerged as a class of promising materials of optoelectronics because they offer the flexibility, both at the molecular and bulk levels, to optimize the nonlinearity and other suitable properties for device applications. Organic nonlinear optical media, which yield large third-order nonlinearities, have been widely studied to develop optical devices like high speed switches, optical limiters etc. Transparent polymeric materials have found one of their most promising applicationsin lasers, in which they can be used as active elements with suitable laser dyes doped in it. The solid-matrix dye lasers make possible combination of the advantages of solid state lasers with the possibility of tuning the radiation over a broad spectral range. The polymeric matrices impregnated with organic dyes have not yet widely used because of the low resistance of the polymeric matrices to laser damage, their low dye photostability, and low dye stability over longer time of operation and storage. In this thesis we investigate the nonlinear and radiative properties of certain organic materials and doped polymeric matrix and their possible role in device development

Short Communication: Polystyrene-an inert carrier for L·glutaminase production by marine Vibrio costico/a under selld-state fermentation

Polystyrene beads, impregnated with mineral salts/glutamine medium as inert support, were used to produce L-glutaminase from Vibrio costicola by solid-state fermentation. Maximum enzyme yield, 88 U/g substrate, was after 36 h. Glucose at 10 g/kg enhanced the enzyme yield by 66%. The support system allowed glutaminase to be recovered with higher specific activity and lower viscosity than when a wheat-bran system was used