Ramachandra, Sharma N; Dr.Madhavan Pillai, P(Cochin University of Science And Technology, March , 1988)
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Abstract:
Strychnine is the major alkaloid present in the seeds of _Strychnos, nuxvomica tree which grow naturally in this area. Strychnine has a very complex chemical structure and is known to stimulate all portions of the central nervous system with preference to the spinal cord. However, it is a powerful convulsant and death results from asphyxia. Consequently strychnine has no therapeutic application in the western system of medicine at present. The objective of this work, therefore, was to convert strychnine by microbial transformation into a product having more desirable pharmacological properties so that this locally available natural product may find some use in the preparation of a therapeutic agent.
Description:
Department of applied chemistry, Cochin University of Science And Technology
Ambika, G; Dr.Babu, Joseph K(Cochin University of Science And Technology, March , 1988)
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Abstract:
It has become clear over the last few years that many deterministic dynamical systems described
by simple but nonlinear equations with only a few variables can behave in an irregular or
random fashion. This phenomenon, commonly called deterministic chaos, is essentially due to the fact that we cannot deal with infinitely precise numbers. In these systems trajectories emerging from nearby initial conditions diverge exponentially as time evolves)and therefore)any small error in the initial measurement spreads with time considerably, leading to unpredictable and chaotic behaviour The thesis work is mainly centered on the asymptotic behaviour of nonlinear and nonintegrable dissipative dynamical systems. It is found that completely
deterministic nonlinear differential equations describing such systems can exhibit random or chaotic behaviour. Theoretical studies on this chaotic behaviour can enhance our understanding of various phenomena such as turbulence, nonlinear electronic circuits, erratic behaviour of heart and brain, fundamental molecular reactions involving DNA, meteorological phenomena, fluctuations in the cost of materials and so on. Chaos is studied mainly under two different
approaches - the nature of the onset of chaos and the statistical description of the chaotic state.
Description:
Department of physics, Cochin University of Science And Technology
Sunandakumari,V M; Dr.Ramanujam, N(Cochin University of Science And Technology, May , 1988)
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Abstract:
During recent years, the theory of differential inequalities has been extensively used to discuss singular perturbation problems and method of lines to partial differential equations. The present thesis deals with some differential inequality theorems and their applications to singularly perturbed initial value problems, boundary value problems for ordinary differential equations
in Banach space and initial boundary value problems for parabolic differential equations. The method of lines to parabolic and elliptic differential equations are also dealt The thesis is organised into nine chapters
Description:
Department of mathematics, Cochin University of Science And Technology
Mercy, Mani P; Dr.Ramachandra Kaimal, M(Cochin University of Science And Technology, June , 1988)
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Abstract:
The nonlinear dynamics of certain important reaction systems are discussed and analysed in this thesis. The interest in the theoretical and the experimental studies of chemical reactions showing oscillatory dynamics and associated properties is increasing very rapidly. An attempt is made to study some nonlinear phenomena exhibited by the well known chemical oscillator, the BelousovZhabotinskii reaction whose mathematical properties are much in common with the properties of biological oscillators. While extremely complex, this reaction is still much simpler
than biological systems at least from the modelling point of view. A suitable model [19] for the system is analysed and the researcher has studied the limit cycle behaviour of the system, for
different values of the stoichiometric parameter f, by keeping the value of the reaction rate (k6) fixed at k6 = l. The more complicated three-variable model is stiff in nature.
Description:
Department of mathematics and statistics, Cochin University of Science And Technology
Jayaraj, M K; Dr.Girijavallabhan,C P(Cochin University of Science and Technology, June 20, 1988)
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Abstract:
This thesis contains the author's work in preparing efficient EL phosphors, the details of fabrication of low voltage operated thin film EL (TFEL) devices and DC TFEL devices. Some of the important work presented here are related to the white light emitting ZnS:Cu,Pr,Cl phosphor which can be colour tuned by changing the excitation frequency, observation of energy transfer from Cu/Ag ions to rare earth ions in ZnS:(Cu/Ag), RE,Cl phosphors, development of TFEL device which can be operated below 50V, optimization of the device parameters for long life, high brightness in terms of the active and insulating layer thicknesses, observation of dependence of threshold voltage for the onset of emission on frequency of excitation when a novel dielectric Eu2O3 film was used as insulator and the devices with multicolor emission using ZnS doped with rare earth as active layer. Characterization based on other devices based on ZnS:Sm, ZnS:Pr, ZnS:Dy and their emission characteristics are also illustrated
Description:
Department of Physics, Cochin University of Science and Technology
Madhusoodanan, K N; Dr. Jacob, Philip(Cochin University of Science And Technology, November , 1988)
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Abstract:
This thesis work has mainly concentrated on the investigation of the ,optical and thermal properties of binary semiconducting chalcogenide glasses belonging to the AivB¥5x and AZBXEX families. The technique used for these studies is a relatively new one namely, the photoacoustic (PA) technique. This technique is based on the detection of acoustic signal produced in an enclosed volume when the sample is irradiated by an intensity modulated radiation. The signal produced depends upon the optical properties of the sample, and the thermal properties of the sample, backing material and the surrounding gas. For the present studies an efficient signal beam gas-microphone PA spectrometer, consisting of a high power
Xenon lamp, monochromator, light beam chopper, PA cell with microphone and lock-in amplifier, has been set up. Two PA cells have been fabricated: one for room temperature measurements and another for measurements at high temperatures. With the high temperature PA cell measurements can be taken upto 250°C. Provisions are incorporated. in both the cells to change the volume and to use different backing materials for the sample. The cells have been
calibrated by measuring the frequency response of the cells using carbon black as the sample
Description:
Department of physics, Cochin University of Science And Technology
Jose David, P; Dr.Paul, Vatakencherry A(Cochin University Of Science And Technology, February 17, 1989)
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Abstract:
In the present work different new approaches for the synthesis
of Vitamin A are investigated. In these synthetic schemes, all the
twenty carbon atoms of the target molecule are derived either fully
from components isolated from common essential oils or partially from
commercially available materials. By retrosynthetic analysis, Vitamin A molecule can be disconnected into a cyclic and a linear unit. Different methods for the synthesis of the linear and the cyclic components are described.
The monoterpenes, geraniol and citral, major constituents of
palmarosa and lemongrass oils, have the required basic carbon framework
for consideration as starting materials for the synthesis of Vitamin A.
The potential of these easily available naturally occurring compounds
as promising starting materials for Vitamin A synthesis is demonstrated.
Organoselenium and organosulfur mediated functional group transformations
for the synthesis of the functionalised conjugated C10 linear components
(ie., the dimethyloctatriene derivatives) are reported. The classical
approaches as well as the attempted preparation of cyclic C10 and C13
units employed in the present study as intermediates for Vitamin A
synthesis are described. The utility of commercially available materials namely 2-acetylbutyrolactone and levulinic acid in -the preparation of C5 intermediates for Vitamin A synthesis is demonstrated.
Description:
Department Of Applied Chemistry
Cochin University Of Science And Technology
Babu, Sundar S; Dr.Thrivikraman, T(Cochin University Of Science And Technology, March 21, 1989)
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Abstract:
It is believed that every fuzzy generalization should be
formulated in such a way that it contain the ordinary set
theoretic notion as a special case. Therefore the definition of fuzzy topology in the line of C.L.CHANG E9]
with an arbitrary complete and distributive lattice as the
membership set is taken. Almost all the results proved and presented in this thesis can, in a sense, be called generalizations of corresponding results in ordinary set theory and set topology. However the tools and the methods have to be in many of the cases, new. Here an attempt is made to solve the problem of complementation in the lattice of fuzzy
topologies on a set. It is proved that in general, the
lattice of fuzzy topologies is not complemented. Complements
of some fuzzy topologies are found out. It is observed that
(L,X) is not uniquely complemented. However, a complete
analysis of the problem of complementation in the lattice
of fuzzy topologies is yet to be found out
Description:
Depantment of Mathematics and Statistics
Cochin University of Scince
and Technology
Rajeev, Kumar K; Dr.Sathianandan, K(Cochin University of Science and Technology, June 20, 1989)
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Abstract:
A brief account of the several methods used for the production of thin films is presented in this Chapter. The discussions stress on the important methods used for the fabrication of a-si:H thin films. This review' also reveals ‘that almost all the general methods, like vacuum evaporation, sputtering,
glow discharge and even chemical methods are currently employed for the production of a-Si:H thin films. Each method has its own advantages and disadvantages. However, certain methods are generally preferred. Subsequently a detailed account of the method used here for the preparation of amorphous silicon thin films and their hydrogenation is presented. The metal chamber used for the electrical and dielectric measurements is also described. A brief mention is made-on the electrode
structure, film area and film geometry.
Description:
Division of Thin Film, Department
of Physics, Cochin University of Science and Technology
Navil Kumar, R; Dr.Girijavallabhan,C P(Cochin University Of Science And Technology, June 28, 1989)
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Abstract:
In the present thesis a series of exhaustive
investigations have been carried out on a number of crystalline
samples with special reference tx> the jphase transitions
exhibited by them. These include single crystals
of pure, doped or deuterated specimens of certain ammonium
containing crystals viz., (NH )34H(SO4)2, (NH4)2HPO4,
(NH4)2Cr2O7 znui NH4H2PO4. ac/dc electrical conductivity,
dielectric constant, ionic thermocurrent as wwifil as photoacoustic
measurements have been carried out on most of
them over a wide range of temperature. In addition investigations
have been carried out in pure and doped single
crystals of NaClO3 and NaNO3 using ionic thermocurrent
measurements and these are presented here. Special attention
has been paid to reveal the mechanism of electrical conduction
in various phases of "these crystals and to evaluate
the different parameters involved in the conduction as well
as phase transition process.
The thesis contains ten chapters ‘
Description:
Department of Physics, Cochin
University of Science and Technology
Abraham,P K; Dr.Sathianandan, K(Cochin University of Science and Technology, July , 1989)
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Abstract:
This thesis Entitled Electrical switching studies on the thin flims of polyfuran and polyacrylonitrile prepared by plasma polymerisation and vacuum evaporated amorphous silicon.A general introduction to the switching and allied phenomena is presented. Subsequently, developments of switching in thin films are described. The Mott transition is qualitatively presented. The working of a switching transitor is outlined and compared to the switching observed in thin films. Characteristic parameters of switching such as threshold voltage, time response to a, voltage pulse, and delay time are described. The various switching configurations commonly used are discussed. The mechanisms used to explain the switching behaviour like thermal, electrothermal and purely electronic are reviewed. Finally the scope, feasibility and the importance of polymer thin films in switching are highlighted.
Description:
Department of Physics, Division of Thin Film, Cochin University of Science and Tecnology