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
Jacob, George; Dr. Mohanan, P(Cochin University of Science & Technology, June , 1998)
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Abstract:
The thesis is the outcome of the experimental and theoretical investigations on a new compact drum-shaped microstrip antenna. A new compact antenna suitable for personal communication system(PCS), Global position System(GPS) and array applications is developed and analysed. The generalised cavity model and spatial fourier transform technique are suitably modified for the analysis of the antenna. The predicted results are compared with experimental results and excellent agreement is observed. The experimental work done by the author in related fields are incorporated as three appendices in this thesis. A single feed dual frequency microstrip antenne is presented in appendix A.Appendix B describes a new broadband dual frequeny microstrip antenna. The bandwidth enhancement effect of microstrip antennas through dielectric resonator loading is demonstarted in Appendix C.
Description:
Department of Electronics,
Cochin University of Science and Technology
Harikumar, P S; Dr. Sivasankara Pillai, V N(Cochin University of Science and Technology, 1990)
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Abstract:
The primary aim of these investigations was to probe the elecnuchemical
and material science aspects of some selected metal phthalocyanines(MPcs).Metal phthalocyanines are characterised by a unique planar molecular structure. As a single
class of compounds they have been the subject of ever increasing number of physicochemical and
technological investigations. During the last two decades the literature on these compounds was
flooded by an outpour of original publications and patents. Almost every branch of materials science
has benefited by their application-swface coating, printing, electrophotography, photoelectrochemistry,
electronics and medicine to name a few.The present study was confined to the electrical and electrochemical properties of cobalt,
nickel, zinc. iron and copper phthalocyanines. The use of soluble Pes as corrosion inhibitor for
aluminium was also investigated.In the introductory section of the thesis, the work done so far on MPcs is reviewed. In this
review emphasis is given to their general methods of synthesis and the physicochemical properties.In phthalocyanine chemistry one of the formidable tasks is the isolation of singular species.
In the second chapter the methods of synthesis and purification are presented with necessary
experimental details.The studies on plasma modified films of CoPe, FePc, ZnPc. NiPc and CuPc are also presented.Modification of electron transfer process by such films for reversible redox systems
is taken as the criterion to establish enhanced electrocatalytic activity.Metal phthalocyanines are p- type semiconductors and the conductivity is enhanced by
doping with iodine. The effect of doping on the activation energy of the conduction process is
evaluated by measuring the temperature dependent variation of conductivity. Effect of thennal
treatment on iodine doped CoPc is investigated by DSC,magnetic susceptibility, IR, ESR and
electronic spectra. The elecnucatalytic activity of such doped materials was probed by cyclic
voltammetry.The electron transfer mediation characteristics of MPc films depend on the film thickness.
The influence of reducing the effective thickness of the MPc film by dispersing it into a conductive
polymeric matrix was investigated. Tetrasulphonated cobalt phthalocyanine (CoTSP) was
electrostatically immobilised into polyaniline and poly(o-toluidine) under varied conditions.The studies on corrosion inhibition of aluminium by CoTSP and CuTSP and By virtue of their anionic character they are soluble in water and are strongly adsorbed on aluminium.
Hence they can act as corrosion inhibitors. CoTSP is also known to catalyze the reduction of
dioxygen.This reaction can accelerate the anodic dissolution of metal as a complementary reaction.
The influence of these conflicting properties of CoTSP on the corrosion of aluminium was studied
and compared with those of CuTSP.In the course of these investigations a number of gadgets like cell for measuring the electrical
conductivity of solids under non-isothermal conditions, low power rf oscillator and a rotating disc
electrode were fabricated.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology