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
Sindhu, Issac; Dr.Girish Kumar, K(Cochin University of Science & Technology, February , 2011)
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Abstract:
Voltammetric sensors are an important class of electrochemical sensors in which the analytical information is obtained from the measurement of current obtained as a result of electrochemical oxidation/reduction.This current is proportional to the concentration of the analyte.Chemically modified electrodes(CMEs) have great significance as important analytical tools for the electrochemical determination of pharmaceuticals.The modification of electrode results in efficient determination of electro-active biomolecules at very lower potential without its major interferences.The operation mechanism of CMEs depends on the properties of the modifier materials that are used to promote selectivity towards the target analytes.Modified electrodes can be prepared by deposition of various compounds such as organic compounds ,conducting polymers,metal oxides,etc. on the various electrode surfaces.The thesis presents the development ,electrochemical characterization and analytical application studies of eight voltammetric sensors developed for six drugs viz.,Ambroxol,Sulfamethoxazole,PAM Chloride, Lamivudine,Metronidazole and Nimesulide.The modification techniques adopted as part of the present work include Multiwalled Carbon Nanotube(MWCNT) based modification.Electropolymerisation and Gold Nanoparticle (AuNP) based modifications.
Description:
Dept.of Applied Chemistry,Cochin University of Science & Technology
Remalakshmy,Poduval; Girish Kumar,K(Department of applied chemistry, 2006)
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Abstract:
In this study Fabrication of Potentiometric sensors for the determination of certain metal ions, presents the synthesis and characterization of seven ionophores, their use in the fabrication of potentiometric sensors and the results and discussion of fourteen sensors developed for the determination of five transition metal ions. As part of the present investigations a total of fourteen potentiometric sensors have been developed and fabricated. A three fold approach has been taken in developing he sensors, PVC plasticized membrane sensor, carbon paste electrode and chemically modified carbon paste electrode. All the sensors are highly useful in the determination of metal ions such as manganese, nickel, copper, mercury and lead. A through analytical study has been carried out with respect to each other developed. Based on these studies, optimum conditions have been developed for the quantitative determinations of the selected metal ions using the sensors. Systematic application studies have also been carried out for all the developed sensors and the results revealed that the presently developed sensors are far superior than most of the sensors reported.
Beena, S; Dr.Girish Kumar, K(Cochin University of Science and Technology, May , 2010)
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Abstract:
In many fields such as earth science biology, environment and electronics, the knowledge about elemental distributions and chemical speciation is important. The determination of metal levels especially the toxic ones both in the environment and in biological materials are increasingly demanded by the society.Ion selective sensors have become one of the most effective ad powerful means for analytical scientists for the trace level monitoring of metal ions. The wide range of applications ,low material requirements and simplicity of analytical procedure have not only brought ion-selective electrodes in to the lime light of analytical chemistry,but have promoted their use as tools for physiologists,medical researchers,biologists,geologists,environmental protection specialists etc.Potentiometric ion-selective sensors have been developed for the determination of lanthanide ions such as La3+,Nd3+,Pr3+,Sm3+, and Gd3+.The sensors fabricated include both PVC membrane sensor and chemically modified carbon paste sensor. A set of 10 sensors have been developed. The response parameters of all the sensors have been studied and the sensors were applied as an indicator electrode in the potentiometric titration and for the determination of metal ions in real samples.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Nandakumar, M P; Dr.Chandrasekaran,M(Cochin University Of Science And Technology, January 17, 1991)
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Abstract:
Recently’ recognition cnf immobilization ‘technology
for the rapid conversion of several substrates into metabolites
and repeated reuse of the biocatalysts have drawn the
attention of the fermentation scientists and technologists to
try these new technologies for the rapid production of pnxkmt
and enhancement of the efficiencies of the systems
Hence in the present study rice was selected,as a
substrate since it is a rich source of starch, available and
cultivated throughout the year almost in all part of our
country. Rice although known for its use as a staple food in
many forms as rice, idli, dosai etc., has not been used in
industry extensively. However, it ii; a potential resource
for’ the production of alcohol, high protein food anui for
sugar and sugar syrups as it is evidenced by the few reports
mentioned in the review of literature.
Of the several microorganisms available, Bacillus sp,
is a known candidate for the production of amylases. Hence
in the present study Bacillus sp, was desired for its known
efficiencies in starch conversion
Description:
Department
of Applied Chemistry, Cochin University of Science and
Technology
Nirmala, Antherjanam N; Dr.Jathavedan, M(Cochin University of Science And Technology, December , 1987)
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Abstract:
In this thesis the author has presented qualitative studies of certain Kdv equations with variable coefficients. The well-known KdV equation is a model for waves propagating on the surface of shallow water of constant depth. This model is considered as fitting into waves reaching the shore. Renewed attempts have led to the derivation of KdV type equations in which the coefficients are not constants. Johnson's equation is one such equation. The researcher has used this model to study the interaction of waves. It has been found that three-wave interaction is possible, there is transfer of energy between the waves and the energy is not conserved during interaction.
Description:
Department of mathematics, Cochin University of Science And Technology
Boban, Thomas; Dr.Krishna Pillai, M G(Cochin University of Science and Technology, December , 1989)
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Abstract:
This thesis deals with preparing stoichiometric crystalline thin films of InSe and In2Se3 by elemental evapouration and their property investigation.In the present study three temperature( or Elemental evapouration) method is utilized for the deposition of crystalline thin films . The deposition mechanism using three temperature method deals’ with condensation of solids on heated surfaces when the critical supersaturation of the vapour phase exceeds a certain limit. The critical values of the incident flux are related to substrate temperature and the interfacial energies of the involved vapours. At a favorable presence of component atoms in the vapour phase these can react and condense onto a substrate even at a elevated temperature. In the studies conducted the most significant factor is the formation of single compositional film namely indium mono selenide in the In –se system of compounds .Further this work shows the feasibility of thin film photovoltaic junctions of the schottky barrier type
Description:
Department of Physics, Cochin University of Science and Technology
Mohanachandran, K; Dr.Sathianandan, K(Cochin University Of Science And Technology, April 2, 1983)
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Abstract:
Due to the great versatility of the properties
of polymer thin films, special interest has been taken in
recent years on their preparation and electrical properties.
The present thesis is entirely devoted to the study of the
formation, structure and electrical properties of plasma»
polymerised polyacrylonitrile (PAN) thin films. Eventhough
the studies are confined to a single polymer film, the
results in general are applicable to similar polar polymer
films.
Description:
Department of Physics,Cochin University Of Science And Technology
Mohanan, P; Dr.Nair, K G(Cochin University of Science And Technology, March , 1985)
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Abstract:
The flange technique, suggested by Reynolds72
is simple technique to improve antenna characteristics.
Using flange technique we can trim the antenna
characteristic by suitably adjusting the flange parameters75.
Later corrugated flanges87 are used for beam shaping. The
important parameters of the corrugated flanges are (a) flange
angle, (b) flange width, (c) flange position, (d) conductivity
of the flange, (e) amplitude excitation of the flange
elements, (f) period of corrugation etc. Compared to a
compound horn the flange technique offers great convenience
in trimming antenna characteristics.
Horns are commonly used as a feed in radar and
satellite communications. A large number of work had been
done to improve the characteristics of horn antennas. It is
an established fact that grooved walls on the inner surface
of a horn can improve the antenna characteristics44.
Corrugated comb surface can be used for the circular
polarization98, tilt of polarization99 etc. This suggests
the possibility to combine these two phenomena and to
obtain a resultant beam. This thesis presents the result
of an investigation to study the possibility of controlling
different antenna characteristics like polarization, beam
shaping, matching etc, using corrugated flange techniques.
Description:
Department of physics, Cochin University of Science And Technology