Abdul Khader, K M; Dr.Mohandas, A(Cochin University of Science & Technology, 1999)
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Abstract:
Instead of developing easily degradable, and low-priced insecticides, we are
going after highly sophisticated chemicals. Here, an attempt is being made to develop
safer formulations of insecticides of botanical origin.
Different parts of the plants were chosen based on their use in countryside and
villages The dried plant materials were extracted with petroleum ether, and were
applied on Tribolium castaneum. The results were statistically analysed.
The active principles from Croton tigilium and Leea sambucina, the most
potential plants, were isolated using Column Chromatography, TLC, and Hydrolysis.
The isolated principles were analysed spectroscopically ( UV-Vis., IR, NMR,
and MS ) to identify their chemical nature. The active principles from Leea and
Croton were identified as a cholisterate derivative and a phorbol derivative
respectively.
In order to ascertain the environmental combatibility of the principles,
degradation by soil bacteria was studied.
The isolated principles were made into three type of formulations using
stabilizers .The formulations were applied on Snake gourd semilooper, Pulse beetle,
and mosquito larvae. Also the biocidal activity of the formulations was studied.
Both Leea derivative and Croton derivative could be formulated effectively
and were effective against a variety of pests. They are eco-friendly, as there is no
artificial chemicals involved.
Description:
School of Environmental Studies,
Cochin University of Science And Technology
Gibinkumar, T R; Dr.Boopendranath, M R(Cochin University of Science & Technology, July , 2008)
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Abstract:
In the context of Indian fisheries there is a paucity of information on bycatch, in general, and bycatch reduction technologies, in particular. In this study, a detailed investigation on trawl bycatch and bycatch reduction measures is attempted with a view to evolve optimized BRDs for improving selectivity of commercial shrimp trawls. The objectives of the study included design and development of hard bycatch reduction devices (BRDs), comparative evaluation of hard bycatch reduction devices, for selective trawling, bycatch characterisation of the trawl landings, off Central Kerala; and investigations on status of the existing trawling systems operated off Central Kerala.
Description:
School of Industrial Fisheries, Cochin University of Science and Technology
Aneesh Kumar, K.V.; Dr.Meenakumari,B; Dr Remesan, M. P(Cochin University of Science And Technology, November , 2013)
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Abstract:
The main objectives of the present study have been
studies on the operational performance of tuna longline in
Lakshadweep Sea
studies on the efficiency of hooks in the longline operation
studies on the efficiency of baits in the longline operation
studies on bycatch in longline operation
studies on predation on the longline catch and the hook loss
encountered during the fishing operation
Description:
Fishing Technology Division
Central Institute of Fisheries Technology
CIFT Junction, P. O. Matsyapuri
(Indian Council of Agricultural Research)
Geetha K, Varier; Issac, Riju C; Harilal, S S; Bindhu, C V; Nampoori, V P N; Vallabhan, C P G(Elsevier, 1997)
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Abstract:
The laser produced plasma from the multi-component target YBa2CU3O7 was analyzed using Michelson interferometry and time resolved emission spectroscopy. The interaction of 10 ns pulses of 1.06 mum radiation from a Q-switched Nd:YAG laser at laser power densities ranging from 0.55 GW cm-2 to 1.5 GW cm-2 has been studied. Time resolved spectral measurements of the plasma evolution show distinct features at different points in its temporal history. For a time duration of less than 55 ns after the laser pulse (for a typical laser power density of 0.8 GW cm-2, the emission spectrum is dominated by black-body radiation. During cooling after 55 ns the spectral emission consists mainly of neutral and ionic species. Line averaged electron densities were deduced from interferometric line intensity measurements at various laser power densities. Plasma electron densities are of the order of 1017 cm-3 and the plasma temperature at the core region is about 1 eV. The measurement of plasma emission line intensities of various ions inside the plasma gave evidence of multiphoton ionization of the elements constituting the target at low laser power densities. At higher laser power densities the ionization mechanism is collision dominated. For elements such as nitrogen present outside the target, ionization is due to collisions only.
Geetha K, Varier; Dr.Nampoori,V P N(Cochin University of Science and Technology, April 28, 1998)
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Abstract:
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
Description:
International School of Photonics, Cochin University of Science & Technology
Sajimol Augustine, M; Dr.Jayalekshmi, S(Cochin University Of Science And Technology, December 20, 2012)
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Abstract:
Fluorescence is a powerful tool in biological research, the relevance of
which relies greatly on the availability of sensitive and selective fluorescent
probes. Nanometer sized fluorescent semiconductor materials have attracted considerable attention in recent years due to the high luminescence intensity, low
photobleaching, large Stokes’ shift and high photochemical stability. The optical
and spectroscopic features of nanoparticles make them very convincing
alternatives to traditional fluorophores in a range of applications. Efficient surface
capping agents make these nanocrystals bio-compatible. They can provide a novel
platform on which many biomolecules such as DNA, RNA and proteins can be
covalently linked. In the second phase of the present work, bio-compatible,
fluorescent, manganese doped ZnS (ZnS:Mn) nanocrystals suitable for bioimaging
applications have been developed and their cytocompatibility has been
assessed. Functionalization of ZnS:Mn nanocrystals by safe materials results in
considerable reduction of toxicity and allows conjugation with specific
biomolecules. The highly fluorescent, bio-compatible and water- dispersible
ZnS:Mn nanocrystals are found to be ideal fluorescent probes for biological
labeling
Description:
Department of Physics, Cochin University of Science and
Technology
Sabir, M; Dr.Babu, Joseph K(Cochin University of Science and Technology, 1978)
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Abstract:
The present thesis deals with the studies on certain aspects of pathological higher field theories .It brings to light some new abnormalities and new samples of abnormal theories and also puts forward a novel approach towards the construction of trouble free theories
Description:
Department of Science, Cochin University of Science and Technology
Sini, P J; Dr.Saramma, A V(Cochin University of Science and Technology, February , 2012)
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Abstract:
Considering the importance of diversity of micro algae in our ecosystem and new invasion of many organisms, an attempt was made to monitor the Cochin estuary along the south west coast of India for the qualitative distribution of phytoplankton and to study the growth kinetics and allelopathic effect of the phaeocystis sp. Isolated from the cochin estuary. Phaeocystis blooms are common only in high latitude environments and they rarely occur in low latitude environments such as tropics and subtropics. As phaeocystis is grouped under harmful alga ,in the present study the factors causing the blooms formation in the ecosystem. The nutrient concentration of the water body along with other physiochemical parameters that includes temperature salinity and ph play an important role in triggering the bloom of phaeocystis .The phaeocystis harbor specific bacterial flora associated with it and they exert an important role in the growth ,haemolytic activity and the bloom phases of the alga. The harmful alga mainly depends on the production of alleopathic compounds for the establishment of bloom in the marine environments .These physiological properties of the phaecystis were considered for the study, along with the role of nutrients in the allelopathic and hemolytic activity
Description:
Department of Marine Biology,Microbiology and Biochemistry
School of Marine Sciences, Cochin University of Science and Technology
Gregorios, Mathew; Dr. Jacob, Philip(Cochin University of Science and Technology, December , 1998)
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Abstract:
In this thesis, we present the results of our investigations on the photoconducting
and electrical switching properties of selected chalcogenide glass systems. We have used
XRD and X-ray photoelectron spectroscopy (XPS) analysis for confinuing the amorphous
nature of these materials and for confirming their constituents respectively.Photoconductivity is the enhancement in electrical conductivity of materials
brought about by the motion of charge carriers excited by absorbed radiation. The
phenomenon involves absorption, photogeneration, recombination and transport processes
and it gives good insight into the density of states in the energy gap of solids due to the
presence of impurities and lattice defects. Photoconductivity measurements lead to the
determination of such important parameters as quantum efficiency, photosensiti\'ity,
spectral sensitivity and carrier lifetime. Extensive research work on photoconducting
properties of amorphous semiconductors has resulted in the development of a variety of
very sensitive photodetectors. Photoconductors are finding newer and newer uses eyery
day. CdS, CdSe. Sb2S3, Se, ZnO etc, are typical photoconducting materials which are used
in devices like vidicons, light amplifiers, xerography equipment etc.Electrical switching is another interesting and important property possessed by
several Te based chalcogenides. Switching is the rapid and reversible transition between a
highly resistive OFF state, driven by an external electric field and characterized by a
threshold voltage, and a low resistivity ON state, Switching can be either threshold type
or memory type. The phenomenon of switching could find applications in areas like
infonnation storage, electrical power control etc. Investigations on electrical switching in
chalcogenide glasses help in understanding the mechanism of switching which is
necessary to select and modify materials for specific switching applications.Analysis of XRD pattern gives no further infonuation about amorphous materials
than revealing their disordered structure whereas x-ray photoelectron spectroscopy,XPS)
provides information about the different constituents present in the material. Also it gives binding energies (b.e.) of an element in different compounds and hence b.e. shift from the
elemental form.Our investigations have been concentrated on the bulk glasses, Ge-In-Se, Ge-Bi-Se
and As-Sb-Se for photoconductivity measurements and In-Te for electrical switching. The
photoconducting properties of Ge-Sb-Se thin films prepared by sputtering technique have
also been studied. The bulk glasses for the present investigations are prepared by the melt
quenching technique and are annealed for half an hour at temperatures just below their
respective glass transition temperatures. The dependence of photoconducting propenies on
composition and temperature are investigated in each system. The electrical switching
characteristics of In-Te system are also studied with different compositions and by varying
the temperature.
Description:
Department of Instrumentation,
Cochin University of Science and Technology
Sreekanth, Varma J; Dr.Jayalekshmi, S(Cochin University of Science and Technology, September , 2012)
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Abstract:
Light emitting polymers (LEP) have drawn considerable attention because of their numerous potential applications in the field of optoelectronic devices. Till date, a large number of organic molecules and polymers have been designed and devices fabricated based on these materials. Optoelectronic devices like polymer light emitting diodes (PLED) have attracted wide-spread research attention owing to their superior properties like flexibility, lower operational power, colour tunability and possibility of obtaining large area coatings. PLEDs can be utilized for the fabrication of flat panel displays and as replacements for incandescent lamps. The internal efficiency of the LEDs mainly depends on the electroluminescent efficiency of the emissive polymer such as quantum efficiency, luminance-voltage profile of LED and the balanced injection of electrons and holes. Poly (p-phenylenevinylene) (PPV) and regio-regular polythiophenes are interesting electro-active polymers which exhibit good electrical conductivity, electroluminescent activity and high film-forming properties. A combination of Red, Green and Blue emitting polymers is necessary for the generation of white light which can replace the high energy consuming incandescent lamps. Most of these polymers show very low solubility, stability and poor mechanical properties. Many of these light emitting polymers are based on conjugated extended chains of alternating phenyl and vinyl units. The intra-chain or inter-chain interactions within these polymer chains can change the emitted colour. Therefore an effective way of synthesizing polymers with reduced π-stacking, high solubility, high thermal stability and high light-emitting efficiency is still a challenge for chemists. New copolymers have to be effectively designed so as to solve these issues. Hence, in the present work, the suitability of a few novel copolymers with very high thermal stability, excellent solubility, intense light emission (blue, cyan and green) and high glass transition temperatures have been investigated to be used as emissive layers for polymer light emitting diodes.
Description:
Division for Research in Advanced Materials
Department of Physics, Cochin University of Science and Technology
Shynu, S V; Vasudevan, K(Cochin University of Science & Technology, October , 2006)
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Abstract:
In this work,we investigate novel designs of compact electronically reconfigurable dual frequency microstrip antennas with a single feed,operating mainly in L-band,without using any matching networks and complicated biasing circuitry.These antennas have been designed to operate in very popular frequency range where a great number of wireless communication applications exist.Efforts were carried out to introduce a successful,low cost reconfigurable dual-frequency microstrip antenna design to the wireless and radio frequency design community.
Description:
Department of Electronics,
Cochin University of Science and Technology