Radhakrishnan, P; V P N Nampoori; Girijavallabhan, C P; Sajan, D George; Aji, A Anapara; K G K Warrier(Proceedings of SPIE, 2003)
[+]
[-]
Abstract:
In this paper, we report the measurements of thermal diffusivity of nano Ag metal dispersed ceramic alumina
matrix sintered at different temperatures using laser induced non-destructive photoacoustic technique. Measurements of
thermal diffusivity also have been carried out on specimens with various concentration of nano metal. Analysis of the
data is done on the basis of one-dimensional model of Rosencwaig and Gersho. The present measurements on the
thermal diffusivity of nano metal dispersed ceramic alumina shows that porosity has a great influence on the heat
transport and the thermal diffusivity value. The present analysis also shows that the inclusion of nano metal into
ceramic matrix increases its interconnectivity and hence the thermal diffusivity value. The present study on the samples
sintered at different temperature shows that the porosity of the ceramics varies considerably with the change in sintering
temperature. The results are interpreted in terms of phonon assisted heat transfer mechanism and the exclusion of pores
with the increase in sintering temperature
Girijavallabhan, C P; Radhakrishnan, P; V P N Nampoori; Sajan, D George; Aji, A Anapara; K G K Warrier(Proceedings of SPIE, 2003)
[+]
[-]
Abstract:
In this paper, we report the measurements of thermal diffusivity of nano Ag metal dispersed ceramic alumina
matrix sintered at different temperatures using laser induced non-destructive photoacoustic technique. Measurements of
thermal diffusivity also have been carried out on specimens with various concentration of nano metal. Analysis of the
data is done on the basis of one-dimensional model of Rosencwaig and Gersho. The present measurements on the
thermal diffusivity of nano metal dispersed ceramic alumina shows that porosity has a great influence on the heat
transport and the thermal diffusivity value. The present analysis also shows that the inclusion of nano metal into
ceramic matrix increases its interconnectivity and hence the thermal diffusivity value. The present study on the samples
sintered at different temperature shows that the porosity of the ceramics varies considerably with the change in sintering
temperature. The results are interpreted in terms of phonon assisted heat transfer mechanism and the exclusion of pores
with the increase in sintering temperature.
Bindhu, C V; Harilal, S S; Riju C, Issac; Geetha K, Varier; Nampoori, V P N; Vallabhan, C P G(World Scientific Publishing Company, 1995)
[+]
[-]
Abstract:
Measurement of thermal lensing signal as a function of laser power made in Rhodamine B solutions in methanol give clear evidence of two photon absorption process within certain concentration ranges when 488 nm Ar+ laser beam is used as the pump source. Only one photon process is found to occur when 514 nm and 476 nm beams are used as the pump.
The use of laser excitations at two wavelengths, 488 rim and 514 nm, produced by Argon ion laser in
two plants species, Vicia faba (faba bean) and Allium cepa L., is described to compare the mutagenicity and
the spectrum of chromosomal aberrations induced by laser at mitosis. The laser irradiation has been done
at two power levels 200 and 400 mW with power densities 2.25 mW cm 2 and 4.49 mW cm 2 and different
exposure times (10, 20, 30 and 40 min). The effect produced by laser is compared to those of UV rays and
y- radiations. Laser as in the case of other physical and chenucal mutagens causes a dose-dependent decrease
in mitotic chromosomal aberrations at these wavelengths. It is postulated that laser could be used as a new
radiation system for the induction of mutations.
A novel method of blending natural rubber with polyvinylchloride in the latex
stage was developed, Dioctyl phthalate (DOP) and Amine terminated natural rubber
(ATNR) were used as plasticisers, for improving the mechanical properties of
these blends. Properties of the latex stage blends were compared with those of
dry blends. Latex stage blends showed superior mechanical properties compared
to the blends prepared in the dry state. The ageing resistance, oil resistance and
processability were found to be improved by latex stage blending.
Sugunan, S; Bindhu, J; Disha; Jessey, V(Indian Journal of Chemistry, July , 1997)
[+]
[-]
Abstract:
The Lewis acidity of yttrium and dysprosium exchanged
zeolite Y and ZSM-5 has been determined by titration method
using Hammett indicators. The acidity of the Y form increases
with increase in concentration of the rare earth cation in the Y
zeolite. It is independent of the amount of the rare earth ion for
ZSM-5. The data have been correlated with the activity of these
zeolites for the esterification of butanol using acetic acid.
Rajeev Kumar,S; Chandrasekaran,M(Department of Biotechnology, June , 2001)
[+]
[-]
Abstract:
The present study is about the Pseudomonas sp. BTMS-51 isolated from the marine sediments of Cochin Coast. In the present study, it is concluded that marine bacteria are ideal candidates for immobilization using either Ca-alginate entrapment or physical adsorption on to synthetic inert supports and the process of
immobilization does not negatively influence them. Thus, Ca-alginate entrapment of the bacteria was found to be well suited for reuse of the biomass and extended
operational stability during continuous operation. Adherence of the bacterium to inertsupports was observed to be strong and it imparted minimal stress on the immobilized bacterium and allowed detachment and relocation on the supports
which enabled the formation of a dynamic equilibrium maintaining a stable cell
loading. This is particularly desirable in the industry for extended operational
stability and maintenance of consistently higher outputs. Marine Pseudomonas sp. BTMS-51 is ideal for industrial production of extra cellular L-glutaminase and immobilization on to synthetic inert support such as polyurethane foam could be an efficient technique, employing packed bed reactor for continuous production of the enzyme. Temperature and glutamine concentration had significant effects on enzyme production by cells immobilized on polyurethane foam (PUF).
Sabu,A; Chandrasekaran,M(Cochin University of Science and Technology, December , 1999)
[+]
[-]
Abstract:
This study presents the L-Glutaminase Production by Marine Fungi. Enzymes are involved in all aspects of biochemical conversion from the simple enzyme or fermentation conversion to the complex techniques in genetic engineering. Enzyme industry is one among the major industries of the world and there exists a great market for enzymes in general. Food industry is recognized as the largest consumer for commercial enzymes (Lon sane and Ramakrishna, 1989). In industry, enzymes are frequently used for process improvement, for instance to enable the utilization of new types of raw materials or for improving the physical properties of a material so that it can be more easily processed. They are the focal point of biotechnological processe. The marine biosphere is one of the richest of the earth's innumerable habitats, yet is one of the least well characterized. The marine biosphere covers more than two third of the world's surface, our knowledge of marine microorganisms, in particular fungi, is still very limited (Molitoris and Schumann, 1986). The results obtained in the present study the following conclusions are drawn. Beauveria bassiana isolated form marine sediment has immense potential as an Industrial organism for production of L-glutaminase as an extracellular enzyme employing either submerged fermentnation or solid state fermentation
Ritty J, Nedumpara; Geetha, K; Dann, V J; Vallabhan, C P G; Nampoori, V P N; Radhakrishnan, P(IOP Publishing, 2007)
[+]
[-]
Abstract:
We report unusual spectral narrowing and laser emission from polymer thin
films doped with Coumarin 540 dye. The laser emission from the polymer
films is found to be highly dependent upon the excitation length of the
medium. Even a short length of 1.75 mm of the dye doped film gave rise to
laser emission with FWHM of 0.3 nm for a pump intensity of 825 kW cm−2.
The partial reflections from the broad lateral surfaces of the free standing
films provided the optical feedback for the laser emission. Occurrence of
well-resolved equally spaced resonant modes confirmed the effect of a
Fabry–Perot-like optical cavity between the film surfaces.
V P N Nampoori; Radhakrishnan, P; Girijavallabhan, C P; Ritty, J Nedumpara; Geetha, K; Dann, V J(Journal of Optics A: Pure and Applied Optics, Institute of Physics Publishing, January 9, 2007)
[+]
[-]
Abstract:
We report unusual spectral narrowing and laser emission from polymer thin
films doped with Coumarin 540 dye. The laser emission from the polymer
films is found to be highly dependent upon the excitation length of the
medium. Even a short length of 1.75 mm of the dye doped film gave rise to
laser emission with FWHM of 0.3 nm for a pump intensity of 825 kW cm−2.
The partial reflections from the broad lateral surfaces of the free standing
films provided the optical feedback for the laser emission. Occurrence of
well-resolved equally spaced resonant modes confirmed the effect of a
Fabry–Perot-like optical cavity between the film surfaces.
Radhakrishnan, P; V P N Nampoori; Girijavallabhan, C P; Ritty, J Nedumpara; Geetha, K; Dann, V J(Journal of Optics A: Pure and Applied Optics, Institute of Physics Publishing, January 9, 2007)
[+]
[-]
Abstract:
We report unusual spectral narrowing and laser emission from polymer thin
films doped with Coumarin 540 dye. The laser emission from the polymer
films is found to be highly dependent upon the excitation length of the
medium. Even a short length of 1.75 mm of the dye doped film gave rise to
laser emission with FWHM of 0.3 nm for a pump intensity of 825 kW cm−2.
The partial reflections from the broad lateral surfaces of the free standing
films provided the optical feedback for the laser emission. Occurrence of
well-resolved equally spaced resonant modes confirmed the effect of a
Fabry–Perot-like optical cavity between the film surfaces
Litty, Irimpan; Bindu, Krishnan; Nampoori, V P N; Radhakrishnan, P(Optical Society of America, August 20, 2008)
[+]
[-]
Abstract:
We present the spectral and nonlinear optical properties of ZnO-SiO2 nanocomposites prepared by colloidal chemical synthesis. Obvious enhancement of ultraviolet (UV) emission of the samples is observed, and the strongest UV emission of a typical ZnO-SiO2 nanocomposite is over three times stronger than that of pure ZnO. The nonlinearity of the silica colloid is low, and its nonlinear response can be improved by making composites with ZnO. These nanocomposites show self-defocusing nonlinearity and good nonlinear absorption behavior. The observed nonlinear absorption is explained through two photon absorption followed by weak free carrier absorption and nonlinear scattering. The nonlinear refractive index and the nonlinear absorption increase with increasing ZnO volume fraction and can be attributed to the enhancement of exciton oscillator strength. ZnO-SiO2 is a potential nanocomposite material for the UV light emission and for the development of nonlinear optical devices with a relatively small limiting threshold.
Anna Dilfi, K F; Dr. Thomas, Kurian(Cochin University of Science & Technology, August , 2011)
[+]
[-]
Abstract:
Various compositions of linear low density polyethylene(LLDPE) containing bio-filler(either starch or dextrin)of various particle sizes were prepared.The mechanical,thermal,FTIR,morphological(SEM),water absorption and melt flow(MFI) studies were carried out.Biodegradability of the compositions were determined using a shake culture flask containing amylase producing bacteria(vibrios),which were isolated from marine benthic environment and by soil burial test. The effect of low quantities of metal oxides and metal stearate as pro-oxidants in LLDPE and in the LLDPE-biofiller compositions was established by exposing the samples to ultraviolet light.The combination of bio-filler and a pro-oxidant improves the degradation of linear low density polyethylene.The maleation of LLDPE improves the compatibility of the c blend components and thepro-oxidants enhance the photodegradability of the compatibilised blends.The responsibility studies on the partially biodegradable LLDPE containing bio-fillers and pro-oxidants suggest that the blends could be repeatedly reprocessed without deterioration in mechanical properties.
Description:
Dept.of Polymer Science and Rubber Technology,Cochin University of Science and Technology
Haddud,T A; Al-Mansoori,M H; Zamzuri,A K; Shaharudin,S; Abdullah,M K; Mahdi,M A(Microwave and Optical Technology Letters, April 20, 2005)
[+]
[-]
Abstract:
In this paper, the generation of a multiwavelength laser
source from a Brillouin -Erbium fiber laser in the long wavelength band
(L-band) region is experimentally demonstrated. The proposed laser
system utilizes a Fabrv-Perot cavity formed by fiber-loop mirrors.
Twenty-four lines of Brillouin-Stokes with line spacings of 10 GHz are
obtained in the L-band region
ABSTRACT: Linseed oil is used in the dual roles of the plasticizer and the fatty
acid component of the activator in nitrile rubber vulcanizates. The study shows
that the substitution can substantially improve the mechanical properties in
addition to other advantages such as increased cure rate, reduced leachability
and reduced compound cost.
Soorej M, Basheer; Dr. Chandrasekaran, M(Cochin University of Science and Technology, April , 2007)
[+]
[-]
Abstract:
The present study indicate the scope for the
utilization of the marine fungus Aspergillus awamori Nagazawa BTMFW 032 for
extracellular lipase production employing submerged fermentation. To the best of
our knowledge this is the first report on lipase production by a marine fungus
employing statistical modeling towards industrial production. The characterization
of purified lipase produced by A. awamori showed stability in organic solvents,
oxidizing agent and reducing agents, I,3-regiospecificity and hydrolytic activity.
These properties make this lipase an ideal candidate for biocatalysis in organic
media for the production of novel compounds such as biodiesel and sugar fatty
esters. 91.4 % reduction in oil and grease content in ayurvedic oil by the treatment
of A. awamori lipase indicates that there is a scope for this enzyme in the treatment
of oil effluents and bioremediation. There is ample scope for further research on
the biochemistry of the enzyme, structure elucidation and enzyme engineering
towards a wide range of further applications, besides enriching scientific
knowledge on marine enzymes.
Description:
Department of Biotechnology,
Cochin University of Science and Technology