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
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
Jayan,Thomas; Sivasankara Pillai,V N(Department of Applied Chemistry,Faculty of Science, 1995)
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Abstract:
The thesis deals with the preparation of chemical, optical, thermal and electrical characterization of five compounds, namely metal free naphthalocyanine, vanadyl napthalocyanine, zinc naphlocyanine, europium dinaphthalocyanine, and europium diphthalocyanine in the pristine and iodine-doped forms. Two important technological properties of these compounds have been investigated. The electrical properties are important in applications sensors and semiconductor lasers. Opto-thermal properties assume significance for optical imaging and data recording. The electrical properties were investigated by dc and ac techniques. This work has revealed some novel information on the conduction mechanism in five macrocyclic compounds and their iodine-doped forms. Also useful data on the thermal diffusivity of the target compounds have been obtained by optical techniques.
Narayanan, P; Dr.Sivasankara Pillai, V N(Cochin University of Science and Technology, September , 1992)
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Abstract:
Metal phthalocyanines have some unique optical
properties which are exploited for dyeing fibers and films
used in applicationslike dye lasing and optical information
storage. Aggregation of dye molecules modifies their
absorption and emission spectra with concomitant
degradation in their energy transfer characteristics. MPcs
as such have poor processability and are seldom used in
solid matrices. The finest energy transfer characteristics
are shown by the monomers of metal phthalocyanines. In the
third chapter of this thesis the studies on two series of
metal phthalocyanines are repoted
Description:
Department of Applied Chemistry, Cochin University of Science And Technology
Anoop, N A; Dr. Sreekumar, K(Cochin University Of Science And Technology, September 12, 2013)
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Abstract:
High energy materials are essential ingredients in both rocket and explosive
formulations. These can be vulnerable due to maltreatment. During gulf war, several
catastrophic accidents have been reported from their own payload munitions. The role of
energetic binders here was to wrap the explosive formulations to convert it into insensitive
munitions. With the aid of energetic binders, the explosive charges are not only protected
from tragic accidents due to fire, bullet impact, adjacent detonation, unplanned
transportation, but also form total energy output presumption.
The use of energetic binders in rocket propellants and explosive charges has been
increased after the Second World War. Inert binders in combination with energetic
materials, performed well as binders but they diluted the final formulation. Obviously the
total energy output was reduced. Currently, the research in the field of energetic polymers is
an emerging area, since it plays crucial role in insensitive munitions.
The present work emphasises on the synthesis and characterization of oxetanes,
oxiranes and polyphosphazene based energetic polymers. The thesis is structured into six
chapters. First part of chapter 1 deals with brief history of energetic polymers. The second
part describes a brief literature survey of energetic polymers based on oxetanes and oxiranes.
Third and fourth parts deal with energetic plasticizers and energetic polyphosphazenes.
Finally, the fifth part deals with the various characterization techniques adopted for the
current study and sixth part includes objectives of the present work.
Description:
Department Of Applied Chemistry,
Cochin University Of Science And Technology
Meril, Mathew; Dr.Sudha Kartha,C(Cochin University of Science & Technology, January , 2009)
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Abstract:
In the present work, structural, optical and electrical properties of indium
sulfide are tuned by specific and controlled doping. Silver, tin, copper and chlorine
were used as the doping elements. In2S3 thin films for the present study were prepared
using a simple and low cost “Chemical Spray Pyrolysis (CSP)” technique. This
technique is adaptable for large-area deposition of thin films in any required shape and
facilitates easiness of doping and/or variation of atomic ratio. It involves spraying a
solution, usually aqueous, containing soluble salts of the constituents of the desired
compound onto a heated substrate. Doping process was optimized for different doping
concentrations. On optimizing doping conditions, we tuned the structural, optical and
electrical properties of indium sulfide thin films making them perform as an ideal
buffer layer.
Description:
Department of Physics,
Cochin University of Science and Technology
Sinu, C R; Vijay, Nair, G; Radhakrishnan, K V(Cochin University of Science And Technology, November 22, 2014)
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Abstract:
The thesis entitled “Exploration of Novel Organic Reactions Catalyzed by
Nucleophilic Heterocyclic Carbenes (NHCs)” embodies the results of the
investigations carried out to explore the synthetic potential of N–heterocyclic carbenes
(NHCs) as organocatalyst towards various electrophiles for the synthesis of heterocyclic
and carbocyclic systems. Recent investigations in the generation of homoenolates by the
addition of NHCs to conjugated aldehydes have made it possible to study the reactivity of
this unique three carbon synthon.
Krishnan Kartha, K; Dr. Ajayaghosh, A(Cochin University Of Science And Technology, January 8, 2014)
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Abstract:
Gelation provides a unique medium, which often induces
organization of molecules resulting in the modulation of their
optical, morphological and electronic properties thereby opening a
new world of fascinating materials with interesting physical
properties at nano- meso- and macroscopic levels. Supramolecular
gels based on linear π-systems have attracted much attention due to
their inherent optical and electronic properties which find
application in organic electronics, light harvesting and sensing. They
exhibit reversible properties due to the dynamic nature of noncovalent
forces. As a result, studies on such soft materials are
currently a topic of great interest. Recently, researchers are actively
involved in the development of sensors and stimuli-responsive
materials based on self-assembled π-systems, which are also called
smart materials.
The present thesis is divided into four chapters
Description:
Photosciences and Photonics
Chemical Sciences and Technology Division
CSIR-National Institute for Interdisciplinary Science and
Technology (CSIR-NIIST), Trivandrum
Sindu,T K; Sankaran, P G(COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY, December , 2002)
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Abstract:
In the present environment, industry should provide the products of high quality. Quality of products is judged by the period of time they can successfully perform their intended functions without failure. The cause of the failures can be ascertained through life testing experiments and the times to failure due to different cause are likely to follow different distributions. Knowledge of this distribution is essential to eliminate causes of failures and thereby to improve the quality and the reliability of products. The main accomplishment expected to the study is to develop statistical tools that could facilitate solution to lifetime data arising in such and similar contexts
Madhu, K M; Dr.Chandrasekaran,M(Cochin University of Science and Technology, April , 2007)
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Abstract:
The beta-glucosidase enzyme purified from the marine fungus, Aspergillus
sydowii BTMFS 55 showed a good yield of enzyme production under solid state
fermentation. The statistical optimization of the media components revealed that
moisture content, concentration of peptone and inoculum are the major parameters
which supported the maximal enzyme production. The purified enzyme showed low
pH activity and stability, glucose tolerance and activation by ethanol. It could produce
ethanol from wheat bran and rice straw by simultaneous saccharification and
fermentation with yeast.The glucosidase purified from Aspergillus sydowii BTMFS 55
shows great potential for several biotechnological applications such as the production
of bio-ethanol from agricultural biomass and improvement in the aromatic character
of wines and fruit juices through the hydrolysis of flavour glucosidic precursors.
There is immense scope for the application of this marine fungus in the biofuel
production besides in other industries provided further studies are pursued in
exploiting this enzyme and the organism particularly scale up studies with respect to
application. There is also ample scope for cloning of the gene encoding beta-glucosidase
in domesticated hosts such as Pichia pastoris or S. cerevisiae that can produce ethanol
directly from cellulosic biomass.
Description:
Department of Biotechnology,
Cochin University of Science and Technology
Beena,Mary John; Sudha Kartha, C(Department of Physics, January , 2008)
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Abstract:
Holographic technology is at the dawn of quick evolution in various new
areas including holographic data storage, holographic optical elements, artificial
intelligence, optical interconnects, optical correlators, commerce, medical practice,
holographic weapon sight, night vision goggles and games etc. One of the major
obstacles for the success of holographic technology to a large extent is the lack of
suitable recording medium.
Compared with other holographic materials such as dichromated gelatin
and silver halide emulsions, photopolymers have the great advantage of recording
and reading holograms in real time and the spectral sensitivity could be easily
shifted to the type of recording laser used by simply changing the sensitizing dye.
Also these materials possess characteristics such as good light sensitivity, real
time image development, large dynamic range, good optical properties, format
flexibility, and low cost. This thesis describes the attempts made to fabricate
highly economic photopolymer films for various holographic applications.
In the present work, Poly (vinyl alcohol) (PVA) and poly (vinyl chloride)
(PVC) are selected as the host polymer matrices and methylene blue (MB) is used
as the photosensitizing dye. The films were fabricated using gravity settling
method. No chemical treatment or pre/post exposures were applied to the films.
As the outcome of the work, photopolymer films with more than 70% efficiency, a
permanent recording material which required no fixing process, a reusable
recording material etc. were fabricated.
Varkey,K P; Dr.Vijayakumar, K P(COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY, August , 1999)
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Abstract:
The study on the fabrication and characterization of spray pyrolysed cadmium sulphide homojunction solar cells. As an alternative to the conventional energy source, the PV technology has to be improved. Study about the factors affecting the performance of the existing solar cells and this will result in the enhancement of efficiency of the cells. At the same time it is equally important to have R&D works on developing new photovoltaic devices and processes which are less expensive for large scale production. CdS is an important binary compound semiconductor, which is very useful in the field of photovoltaics. It is very easy to prepare large area CdS thin films. In order to fabricate thin film homojunction cadmium sulphide cells, prepared and characterized SnO2 thin film as the lower electrode, p-CdS as the active layer and n-CdS as window layer. Cadmium material used for the fabrication of homojunction solar cells is highly toxic. The major damage due to continued exposure to low levels of cadmium are on the kidneys, lungs and bones. The real advantage of spray pyrolysis process is that there is no emission of any toxic gases during the deposition. Very low concentration of the chemicals is needed in this process. The risk involved from this material is very low, though they are toxic. On large scale usage it may become necessary that the cells after their life, should be bought back by the companies to retrieve chemicals like cadmium. This will reduce environmental problem and also the material wastage
Sebastian, P J; Dr.Sathianandan, K(Cochin University Of Science And Technology, November 25, 1981)
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Abstract:
Eventhough a large number of schemes have been proposed and develoned for N9 laser ouined dye lasers the
relatively low efficiency compelled the scientists to
device new methods to improve the system efficiencs.
Energy transfer mechanism has been shown to he a convenien
tool for the enhancement of efficiency of dye lasers. Th
p resent work covers a detailed study of the performance
characteristics of a N2 laser pumped dye laser in the con—
ventional mode and also, when pumped by the energy transfer
mechanism. For .th.e present investigations a dye laser
pumped by a'N2 laser (A4200 kw peak power) was fabricated.
The grating at grazing incidence was used as the beam expanding
device; A t its best performance the system was
giving an output peak power of l5 kW for a 5 X lC"3H/l Rh—€
solution in methanol. T he conversion efficiency was 7.5;
The output beam was having 3 divergence of 2 mrad and bandwidth
o.9 A. Suitable modifications were suggested for
obtaining better conversion efficiency and bandwidth.
Description:
Department of Physics,
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
Sareena, John; Dr.Girish Kumar, K(Cochin University of Science and Technology, December , 2007)
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Abstract:
Potentiometric chemical sensors,an important class of electro-chemical sensors are widely used in pharmaceutical analysis because of its inherent advantages.The present study was aimed at fabrication of potentiometric sensors for the drugs mebendazole,pefloxacin,ambroxol,sildenafil citrate,dextro-methorphan and tetracycline.A total of 18 sensors have been developed for the determination of theses drugs.The major step in the fabrication of the sensor was the preparation of the ion association.Two types of sensors viz:PVC membrane sensor and carbon paste electode (CPE) were fabricated.The response characteristics of the different sensors fabricated were studied.Various response parameters studied include response time,selectivity and the effect of pH.The developed sensors were also employed for the determination of the drugs in pharmaceutical formulations and also for the recovery of the drug from urine samples.The selectivity studies reveal that the developed sensors are highly selective to the drug even in prescence of foreign ions.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology