Suja, Haridas; Dr.Sugunan, S(Cochin University of Science & Technology, January , 2002)
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Abstract:
The present project was a systematic investigation of the
physico-chemical properties and catalytic activity of some transition metal promoted
sulphated zirconia systems. The characterisation and catalytic activity results were
compared with that of pure Zr02 and simple sulphated zirconia systems. Sulphated
zirconia samples were prepared by a controlled impregnation technique. In the case of
metal incorporated systems, a single step impregnation was carried out using required
amounts of sulphuric acid and metal salt solutions. As a preliminary step, optimisation of
calcination temperature and sulphate content was achieved. For further studies, the
optimised sulphate loading of 10 ml per gram of hydrous zirconium oxide and a
calcination temperature of 700°C was employed. Metal incorporation had a positive
influence on the physico-chemical properties. Vapour phase cumene conversion served as
a test reaction for acidity. Some industrially important reactions like Friedel-Crafts
reaction, phenol hydroxylation, nitration, etc. were selected to test the catalytic activity of
the prepared systems.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Sreeja Rani, K; Prathapan,S; Sugunan, S(Department of Applied Chemistry,Faculty of Science, 2002)
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Abstract:
Catalysis is an essential technology in manufacturing industries. The investigation based on supported vanadia catalysts and it’s sulfated analogues. Vanadia is a transition metal oxide and is used in oxidation reactions in chemical industry. It is more active and selective catalysts on suitable supports. The work deals with preparation of vanadia incorporated tin oxide and zirconia systems by wet impregnation. Physico-chemical characterization using instrumental techniques like BET etc. The surface acidic properties were determined by the ammonia TPD studies, Perylene absorption studies and Cumene conversion reaction. The catalytic activities of the prepared systems are tested by Friedel-Crafts benzylation of arenes and Bechmann rearrangement of Cyclohexanol oxime. Here the rector reactions are relatively rare. So to test the application of the catalyst systems for the selective oxidation of cyclohexanol to cyclohexanone and finally evaluate the catalytic activity of the systems for the vapour phase oxidative dehydrogenation of Ethylbenzene, which leads to the formation of
Industrially important compound ‘styrene’ is another objective of this work
Chitra, R Nayak; Dr.Kuriakose, V C(Cochin University of Science and Technology, October , 2008)
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Abstract:
The main goal of this thesis is to study the dynamics of Josephson
junction system in the presence of an external rf-biasing.A system of
two chaotically synchronized Josephson junction is studied.The change in the dynamics of the system in the presence of at
phase difference between the applied fields is considered. Control of
chaos is very important from an application point of view. The role
Of phase difference in controlling chaos is discussed.An array of three Josephson junctions
iS studied for the effect of phase difference on chaos and synchronization
and the argument is extended for a system of N Josephson junctions. In the presence of a phase difference between the external
fields, the system exhibits periodic behavior with a definite phase relationship
between all the three junctions.Itdeals with an
array of three Josephson junctions with a time delay in the coupling
term. It is observed that only the outer systems synchronize while
the middle system remain uncorrelated with t-he other two. The effect
of phase difference between the applied fields and time-delay on
system dynamics and synchronization is also studied. We study the influence of an applied ac biasing on a serniannular
Josephson junction. It is found the magnetic field along with the
biasing induces creation and annihilation of fluxons in the junction.
The I-V characteristics of the junction is studied by considering the
surface loss term also in the model equation. The system is found to
exhibit chaotic behavior in the presence of ac biasing.
Description:
Department of Physics,
Cochin University of Science and Technology
Lucy,Joseph; Dr.Sivasankara Pillai, V N(Cochin University Of Science And Technology, December 10, 1987)
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Abstract:
Ion-exchange chromatography has emerged
as a practical and rapid method of separation and
analysis. A review of literature on chelating
resins reveals that eventhough investigations on
highly selective resins are intensively pursued
from early 1940s, such resins are still insufficiently
used in analytical chemistry and process
technology. This is mainly due to the complexity
of their synthesis and high cost. In this context,
it is worthwhile to develop novel chelating resins
which are specific or at least selective towards
a group of metal ions. Synthesis, characterization
and analytical applications of two such resins are
presented in this thesis.
Description:
Department of Applied Chemistry, Cochin University of
Science and Technology
Lakshmi,M; Sudha Kartha, C(Department of Physics, 2001)
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Abstract:
Chemical bath deposition (CBD)is one of the simplest, very convient and probably the cheapest method for thin film preparation. Photovoltaic is the cleanest and the most efficient mode of conversion of energy to electrical power. Silicon is the most popular material in this field. The present study on chemical bath deposited semiconducting copper selenide and iron sulfide thin films useful for photovoltaic applications. Semiconducting thin films prepared by chemical deposition find applications as photo detectors, solar control coatings and solar cells. Copper selenide is a p-type semiconductor that finds application in photovolitics. Several heterojunction systems such as Cu2-xSe/ZnSe (for injection electro luminescence), Cu2Se/AgInSe2 and Cu2Se/Si (for photodiodes), Cu2-xSe/CdS, Cu2-xSe/CdSe, CuxSe/InP and Cu2-xSe/Si for solar cells are reported. A maximum efficiency of 8.3% was achieved for the Cu2-xSe/Si cell, various preparation techniques are used for copper selenide like vacuum evaporation, direct reaction, electrodeposition and CBD. Instability of the as-prepared films was investigation and is accounted as mainly due to deviation from stoichiometry and the formation of iron oxide impurity. A sulphur annealing chamber was designed and fabricated for this work. These samples wee also analysed using optical absorption technique, XPS (X-ray Photoelectron Spectroscopy) and XRD.(X-Ray Diffraction).The pyrite films obtained by CBD technique showed amorphous nature and the electrical studies carried out showed the films to be of high resistive nature. Future work possible in the material of iron pyrite includes sulphur annealing of the non-stochiometric iron pyrite CBD thin films in the absence of atmospheric oxygen
Praseetha, P; Dr. Titus K Mathew(Cochin University of Science and Technology, September 13, 2015)
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Abstract:
Cosmology deals with the studies on the structure and evolution
of the universe. The model of the universe formulated by Friedmann,
Lemaitre, Robertson andWalker known as the standard model
(FLRW model) of the universe, which is based on the Einstein's theory
of gravity, turned out to be the accepted model because of the
various observational supports. The major observational supports
to this model are the explanation for the Hubble's law, primordial
nucleosynthesis, microwave back ground radiation etc.
Recent observations on Type Ia supernovae by teams led by S
Perlmutter, Brian P Schmidt and Adam G Riess led to the discovery
that the present universe is expanding in an accelerated manner. The
exotic form of matter which causes the acceleration is termed as dark
energy which produce negative pressure. Understanding the nature
and evolution of dark energy is a challenge for the cosmologists. In
addition to the evidences from supernovae, the anisotropy in CMBR
spectra, large scale structures and Baryon acoustic oscillations are
also supporting the discovery.
To explain dark energy, various theoretical models have been proposed.
One such model is the CDM model, in which the universe
is assumed to be composed of dark energy and dark matter. In this
model, Einstein's cosmological constant is considered as dark energy.
It has a constant equation of state; ! = p
= 1: The model predicts
the values of cosmological parameters such as the Hubble parameter,
transition redshift and present deceleration parameter, having a very
good agreement with the observational constraints. But this model
has two major
aws, which are:
1. Cosmological constant problem:- Theoretically predicted value
of dark energy density as the vacuum constant is,
1074GeV 4; while the observed value is 1047GeV 4: The
predicted value is greater than the observed value by 120 orders
of magnitude. This discrepancy between the theoretical
and observational values is known as the cosmological constant
problem.
2. Cosmological coincidence problem:- Energy densities of dark energy
and dark matter are found to be of the same order even
though their evolutionary nature are di erent. This is known as
the coincidence problem which is not explained by the CDM
model.
These led to the proposals of dynamical dark energy models by considering
that the equation of state parameter is evolving with the expanding
universe. Scalar models of dark energy such as Quintessence,
K-essence, Phantom model, Chaplygin gas model and holographicdark energy model are examples of dynamic dark energy models.
Holographic dark energy model is based on the holographic principle
developed by Susskind and 't Hooft. The principle says that
the degrees of freedom of a system resides on its surface rather than
in its volume. The total energy inside a region of size L must not
exceed the mass of a black hole of the same size. The holographic
dark energy density can then be formulated as, = 3c2M2
plL2 (1)
where 3c2 is a numerical constant, M2
pl = 8 G is the reduced Planck
mass. Possible choices for L; the IR cut-o , are Hubble horizon, particle
horizon and event horizon. The choices for the IR cut-o whether
it be Hubble horizon or particle horizon will not support an accelerating
universe, while the third choice, the event horizon, violates
causality. Another alternative for the IR cut-o is the Ricci scalar,
which was rst introduced by Gao et al. Later modi ed holographic
Ricci dark energy was proposed by Granda and Oliveros.
In the present thesis, the modi ed Ricci dark energy is studied
by considering its interaction with the dark matter present in the
universe. Owing to the lack of knowledge about the microscopic origin
of such an interaction, phenomenological interaction forms of nongravitational
nature is assumed.
Sandhya, R; Dr.Prathapan, S(Cochin University Of Science And Technology, November 11, 2013)
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Abstract:
the thesis entitled “STUDIES
ON DEVELOPING A FACILE ROUTE FOR THE SYNTHESIS OF
HIGHLY SUBSTITUTED QUINOLINE AND INDOLE
DERIVATIVES” portrays our attempt to revisit the mechanism of 1,3-
dipolar additions with a view to establishing whether it follows a
concerted pathway or a stepwise reaction sequence through the formation
of a zwitterionic intermediate, which will definitely contribute to the better use of this technique. Furthermore, we propose to develop novel
routes for the synthesis of quinoline and indole derivatives with predefined
substitution pattern.
The thesis is devided into four chapters
Description:
Department of Applied Chemistry, Cochin
University of Science and Technology
Sarun, P M; Dr.Syamaprasad,U(National lnstitute for Interdisciplinary Science and Technology, June , 2010)
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Abstract:
The objective of the present work is to study the effect of rare-earth (RE)
doping on the superconducting properties of (Bi,Pb)-2212 system and to develop
novel superconductors in the system with improved properties, especially,
the self- and in-field critical current densities so as to use them for practical
applications. This dissertation describes a range of findings in Bi-based
superconductor using the cationic substitution of rare earth (RE) elements.
Most of the experiments reported here take advantage of the difference in the
valency and ionic radii of dopant and doping site.
Muraleedharan,Pillai S; Dr.Girijavallabhan,C P(Cochin University of Science And Technology, March , 1984)
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Abstract:
The subject of electroluminescence has currently acquired great importance because of its potential applications in display systems of a wide variety. A large number of scientists working in commercial, governmental as well as academic institutions all over the world are at present
engaged in the intense effort to develop new and efficient phosphor materials and electroluminescent devices. This thesis presents the work carried out by the author in this
field during the past few years. The studies discussed in this thesis are mostly confined to
the development of some new phosphor materials, their uses in powder and thin film electroluminescent devices and to their electrical and spectral characteristics. Care has been taken to bring' out the physics involved in all the above aspects of the phenomenon
Description:
Department of physics, Cochin University of Science And Technology
Bindhumol, I; Dr. Madhavan Nampoothiri, K(Cochin University of Science and Technology, May 22, 2012)
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Abstract:
The thesis mainly discussed the isolation and identification of a probiotic Lactobacillus plantarum, fermentative production of exopolysaccharide by the strain, its purification, structural characterisation and possible applications in food industry and therapeutics. The studies on the probiotic characterization explored the tolerance of the isolated LAB cultures to acid, bile, phenol, salt and mucin binding. These are some of the key factors that could satisfy the criteria for probiotic strains .
The important factors required for a high EPS production in submerged fermentation was investigated with a collection of statistical and mathematical approach. Chapter 5 of the thesis explains the structural elucidation of EPS employing spectroscopic and chromatographic techniques. The studies helped in the exploration of the hetero-polysaccharide sequence from L. plantarum MTCC 9510. The thesis also explored the bioactivities of EPS from L. plantarum. As majority of chemical compounds identified as anti-cancerous are toxic to normal cells, the discovery and identification of new safe drugs has become an important goal of research in the biomedical sciences. The thesis has explored the anti-oxidant, anti-tumour and immunomodulating properties of EPS purified from Lactobacillus plantarum. The presence of (1, 3) linkages and its molecular weight presented the EPS with anti-oxidant, anti-tumour and immunomodulating properties under in vitro conditions.
Description:
Division of Biotechnology,National Institute for Interdisciplinary science and Technology, Thiruvananthapuram