Litty, Irimpan; Deepthy, A; Bindu, Krishnan; Kukreja, L M; Nampoori, V P N; Radhakrishnan, P(Elsevier, 2008)
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Abstract:
In the present work, we report the third order nonlinear optical properties of ZnO thin films deposited using self assembly, sol gel process as well as pulsed laser ablation by z scan technique. ZnO thin films clearly exhibit a negative nonlinear index of refraction at 532 nm and the observed nonlinear refraction is attributed to two photon absorption followed by free carrier absorption. Although the absolute nonlinear values for these films are comparable, there is a change in the sign of the absorptive nonlinearity of the films. The films developed by dip coating and pulsed laser ablation exhibit reverse saturable absorption whereas the self assembled film exhibits saturable absorption. These different nonlinear characteristics in the self assembled films can be mainly attributed to the saturation of linear absorption of the ZnO defect states.
Sreeraj, M; Sumam, Mary Idicula(IEEE, December 7, 2012)
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Abstract:
The span of writer identification extends to broad
domes like digital rights administration, forensic expert decisionmaking
systems, and document analysis systems and so on. As the
success rate of a writer identification scheme is highly dependent
on the features extracted from the documents, the phase of
feature extraction and therefore selection is highly significant for
writer identification schemes. In this paper, the writer
identification in Malayalam language is sought for by utilizing
feature extraction technique such as Scale Invariant Features
Transform (SIFT).The schemes are tested on a test bed of 280
writers and performance evaluated
Chloroprene rubber was blended with whole tire reclaimed rubber
(WTR) in presence of different levels of a coupling agent Si69 [bis-
(3-(triethoxysilyl)propy1)tetrasuIfide] and the cure characteristics and
mechanical properties were studied. The rate and state of cure were
also affected by the coupling agent. While the cure time was increased,
the cure rate and scorch time were decreased with increasing silane
content. Tensile strength, tear strength, and abrasion resistance were
improved in the presence of coupling agent. Compression set and
resilience were adversely affected in presence of silane-coupling agent.Aging studies showed that the blends containing the coupling agent
were inferior to the unmodified blends.
Blends of nitrile rubber and reclaimed rubber containing different levels of a
coupling agent, Si 69 (bis(3- triethoxysilyl propyl)(tetrasulphide) were prepared
and the cure characteristic's and mechanical properties were studied. Optimum
loading of Si-69 was found to be a function of blend ratio. 3 phi- of Si 69 in a
70:30. Blend was found to be the optimum combination with respect to the
mechanical properties. The rate and state of cure were also affected bv the
conp/ing agent. Tensile strength, tear strength and abrasion resistance were
improved in the presence of coupling agent. While the state of cure improved,
the cure rate and scorch time decreased with increasing silane content. Ageing
studies showed that the blends containing the coupling agent were inferior to
the unmodified blends.
Santhi, A; Umadevi, M; Ramakrishnan, V; Radhakrishnan, P; Nampoori, V P N(Elsevier, 2004)
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Abstract:
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.
Kanakavalli,Susarla S; Dr.Balakrishnan, K P(Cochin University of Science and Technology, March 10, 1987)
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Abstract:
The extraction and use of metals has been the mainstay for the sustained development and progress of a nation. Metals, though fairly stable in the natural environment are found in trace quantities in water bodies. Attention has therefore been focused to identify the metals that impair the water quality. In the last few decades the concern about the fate of these metals in the aquatic system has been gaining momentum, particularly in the industrial belts. The disasters caused by metal poisoning in recent times have prompted an indepth study of the interaction of metals with aquatic biota. Kerala, basically an agriculture oriented state has witnessed the upsurgence of various industries as a part of the nationwide economic development programme. Cochin has been identified as the industrial capital of the state.The present study is an attempt towards a better understanding of the metal-phytoplankton interactions with special reference to the physiological changes in the species. various parameters such as temperature, salinity, pH, nutrients, number of cells, photosynthetic pigments, carbohydrates, protein and lipid are studied to highlight the complexity of metal..phytoplankton interaction
Description:
School of Environmental Studies,
Cochin University of Science and Technology
Dhanya,P R; Dr.Saleena, Mathew(Cochin University of Science And Technology, October 16, 2012)
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Abstract:
Unprocessed seafood harbor high number of bacteria, hence are more prone to
spoilage. In this circumstance, the use of spice in fish for reduction of microorganism can
play an important role in seafood processing. Many essential oils from herbs and spices are
used widely in the food, health and personal care industries and are classified as GRAS
(Generally regarded as safe) substances or are permitted food additives. A large number of
these compounds have been the subject of extensive toxicological scrutiny. However, their
principal function is to impart desirable flavours and aromas and not necessarily to act as
antimicrobial agents. Given the high flavour and aroma impact to plant essential oils, the
future for using these compound as food preservatives lies in the careful selection and
evaluation of their efficacy at low concentrations but in combination with other chemical
preservatives or preservation processes. For this reason they are worth of study alone or in
combination with processing methods in order to establish if they could extend the shelf-life
of foods.
In this study, the effect of the spices, clove, turmeric, cardamom, oregano, rosemary
and garlic in controlling the spoilage and pathogenic bacteria is investigated. Their effect on
biogenic amine formation in tuna especially, histamine, as a result of bacterial control is also
studied in detail. The contribution of spice oleoresin in the sensory and textural parameters
is investigated using textural profile analysis and sensory panel. Finally, the potential of
spices in quality stabilization and in increasing the shelf–life of tuna during frozen storage is
analysed
Description:
School of Industrial Fisheries
Cochin University of Science and Technology
Jayaraj, M K(Electrochemical Society, July 18, 2007)
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Abstract:
ZnGa2O4:Dy3+ phosphor thin films were deposited on quartz substrates by radio frequency rf magnetron sputtering and the effect
of substrate temperature on its structural and luminescent properties was investigated. Polycrystalline film could be deposited even
at room temperature. The crystalline behavior, Zn/Ga ratio, and surface morphology of the films were found to be highly sensitive
to substrate temperature. Under UV illumination, the as-deposited films at and above 300°C gave white luminescence even
without any postdeposition treatments. The photoluminescent PL emission can be attributed to the combined effect of multicolor
emissions from the single luminescence center Dy3+ via host-sensitization. Maximum PL emission intensity was observed for the
film deposited at 600°C, and the CIE chromaticity coordinates of the emission were determined to be x,y = 0.34, 0.31 .
Sajan, D George; Augustine, S; Mathai, E; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(WILEY-VCH Verlag GmbH&Co, 2003)
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Abstract:
An open cell configuration has been employed for the photoacoustic measurement of the thermal diffusivity of undoped Bi2Se3 crystals and Bi2Se3 crystals doped with various concentrations of Te. The amplitude of the photoacoustic signal obtained under heat transmission configuration as a function of chopping frequency is used to evaluate the numerical value of thermal diffusivity, α. Doped samples show a substantial reduction in the value of α compared to undoped samples. The variations in the thermal diffusivity of the doped samples are explained in terms of the phonon assisted heat transfer mechanism. It is seen that α is very sensitive to structural variations arising from doping. The experimentally observed results are correlated with X-ray diffraction studies.
Anantharaman, M R; Hysen, T; Saravanan, S; Deepa, S; Ramanujan, R V; Avasthi, D K; Kulkarni, S D; Joy, P A(IOP Publishing LTD, May 5, 2006)
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Abstract:
Magnetic properties of nano-crystalline soft magnetic alloys have usually
been correlated to structural evolution with heat treatment. However,
literature reports pertaining to the study of nano-crystalline thin films are
less abundant. Thin films of Fe40Ni38B18Mo4 were deposited on glass
substrates under a high vacuum of ≈ 10−6 Torr by employing resistive
heating. They were annealed at various temperatures ranging from 373 to
773K based on differential scanning calorimetric studies carried out on the
ribbons. The magnetic characteristics were investigated using vibrating
sample magnetometry. Morphological characterizations were carried out
using atomic force microscopy (AFM), and magnetic force microscopy
(MFM) imaging is used to study the domain characteristics. The variation of
magnetic properties with thermal annealing is also investigated. From AFM
and MFM images it can be inferred that the crystallization temperature of
the as-prepared films are lower than their bulk counterparts. Also there is a
progressive evolution of coercivity up to 573 K, which is an indication of the
lowering of nano-crystallization temperature in thin films. The variation of
coercivity with the structural evolution of the thin films with annealing is
discussed and a plausible explanation is provided using the modified random
anisotropy model
Rani, Joseph(Wiley InterScience, December 13, 2004)
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Abstract:
Prevulcanized natural rubber latex was prepared
by the heating of the latex compound at 55°C for
different periods of time (2, 4, 6, 8, and 10 h). The changes in
the colloidal stability and physical properties were evaluated
during the course of prevulcanization. The prevulcanized
latex compounds were stored for 300 days, and the
properties were monitored at different storage intervals (0,
20, 40, 60, 120, 180, 240, and 300 days). During prevulcanization,
the mechanical stability time increased, and the viscosity
remained almost constant. The tensile strength increased
during storage for a period of 20 days. The degree of
crosslinking, modulus, elongation at break, and chloroform
number were varied with the time of storage.
The cure characteristics and mechanical properties of short nylon fiber- styrene
/whole tyre reclaim (SBR/WTR) composites with and without
an interfacial bonding agent based on 4,4 diphenyl methane diisocyanate and
polyethylene glycol (MDI/PEG) have been studied. An 80:40 blend of SBR/
WTR reinforced with 20 phr of short nylon fiber has been selected and the MDI/
PEG ratio has been changed from 0.67:1 to 2:1. The minimum and maximum
torques increased with isocyanate concentration. The scorch time and cure time
showed an initial reduction. The cure rate showed an initial improvement.
Tensile strength, tear strength and abrasion resistance increased with MDI/PEG
ratio, these values were higher in longitudinal direction. Resilience and
compression set increased with isocyanate concentration.
Sugunan, S; Renuka, N K(Indian Journal of Chemistry, April , 2002)
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Abstract:
Physico-chemical characterization of DY203/V2O5 systems prepared through wet impregnation method has been carried
out using various techniques like EDX, XRD, FTIR. thermal studies, BET surface area, pore volume and pore size
distribution analysis. The amount of vanadia incorporated has been found to influence the surface properties of dysprosia.
The spectroscopic results combining with X-ray analysis reveal that vanadia species exist predominantly as isolated
amorphous vanadyl units along with crystalline dysprosium orthovanadate. Basicity studies have been conducted by
adsorption of electron acceptors and acidity and acid strength distribution by temperature programmed desorption of
ammonia. Cyclohexanol decomposition has been employed as a chemical probe reaction to examine the effect of vanadia on
the acid base property of Dy2O3. Incorporation of vanadia titrates thc Lewis acid and base sites of Dy2O3, while an
enhancement of Bronsted acid sites has been noticed. Data have been correlated with the catalytic activity of these oxides
towards the vapour phase methylation of phenol
Cilla Abraham; Dr.Radhakrishnan,C K(Cochin University Of Science And Technology, November , 2012)
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Abstract:
The main objective of the present work is to acquire information
regarding the growth responses of P. monodon larvae (from PZ1 upto PL1)
to various mono specific and mixed diets. Evaluate the nutritional quality of
selected species of micro algae viz. Chaetoceros calcitrans, Dunaliella
salina, Isochrysis galbana and Nannochloropsis salina, larvae at three cell concentrations 10x104 cells/ml, 25x104 cells/ml and
50x104 cells/ml.
The P. monodon larvae were transported, at the Nauplius stage, to the
laboratory. The larvae were stocked at density of 150 larvae per litre in 5 litre
FRP tanks with 3 litres of sea water. The algal cell density given to the larvae
varied. The larval stages were fed with increasing densities of algae to
evaluate the relationship between the food densities, ingestion rates,
development and growth of the larvae. The water quality parameters, the
percentage of survival rate, the growth estimation and the algal cell count
were done. Each experiment was carried out in triplicate with a control group
of larvae fed with Chaetoceros calcitrans. For the estimation standard
procedures were used.to P. monodon
Description:
Dept. of Marine Biology,
Microbiology and Biochemistry.
Cochin University of
Science and Technology
Bikash Chandra, Mohapatra; Dr.Rengarajan, K(Cochin University Of Science And Technology, August , 1993)
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Abstract:
The research investigations on pollution, particularly in coastal/
estuarine environments are recent ones and started only in 1970s. Hence
the informations available are fragmentary and scattered. They throw
some light only on either the concentration of heavy metals in water
or in sediment or in organisms. No concerted efforts have been made
to consolidate and correlate the results between the environment and
biota. Literature on the level of concentration of heavy metals in different
tissues of organisms with regard to their availability in the living media,
their ratio, their inter—relationship, tolerance limit of organisms, etc. are
very few or rather nil.
in view of the importance enumerated above, the candidate has
selected the topic "Effects of some heavy metals copper, zinc and lead
on certain tissues of E E (Hamilton and Buchanan) in different
environments" for detailed studies and to understand systematically (i)
the source of effluents and wastes, (ii) the concentration of heavy metals
copper, zinc and lead in water, in sediments and in tissues of the test
animal, (iii) their effects, (iv) capacity of tolerance and accumulation
in different tissues of the animal, and (V) the "Bioaccumulation Factor",
etc.
Description:
Department Of Marine Sciences, Cochin University Of Science And Technology
Ashokakumaran, Unnithan K; Dr.Menon,N R; Dr.Kuttyamma, V J(Cochin University Of Science And Technology, August , 1997)
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Abstract:
The present research programme envisages a comparative study of the effects of
two piscicides of plant origin, viz., mahua oil cake, a derivative from the plant fig
Iatifolia and croton seed, a product from the plant Croton tiglium. Although some reports
on the effects of mahua oil cake and croton seed on fresh water pond culture systems are
available, information on their effect on brackishwater culture systems are rather scanty
This was the guiding principle for launching the present study It is hoped that the findings
will enable aquaculturists to make use of the piscicides in a more rational and efficient
way, and will go a long way towards realising the maximum return liom culture systems
without hampering the environment.
The thesis is presented in seven chapters such as Introduction, Review of
literature, Materials and Methods, Results, Discussion, Summary and Bibliography
Description:
School of Marine Sciences. Cochin University of Science and
Technology