Anantharaman, M R; Mathew, George; Asha, Mary John; Swapna, Nair S; Joy, P A(IOP Publishing LTD, February 17, 2006)
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Abstract:
Fine particles of lithium ferrite were synthesized by the sol-gel method.
By subsequent heat treatment at different temperatures, lithium ferrites of
different grain sizes were prepared. A structural characterization of all the
samples was conducted by the x-ray diffraction technique. A grain size of
around 12 nm was observed for Li0.5Fe2.5O4 obtained through the sol-gel
method. Magnetic properties of lithium ferrite nanoparticles with grain size
ranging from 12 to 32 nm were studied. Magnetization measurements
showed that Li0.5Fe2.5O4 fine particles exhibit a deviation from the predicted
magnetic behaviour. The as-prepared sample of lithium ferrite showed a
maximum saturation magnetization of 75 emu g−1. Variation of coercivity is
attributed to the transition from multi-domain to single domain nature.
Dielectric permittivity and ac conductivity of all the samples were evaluated
as a function of frequency, temperature and grain size. Variation of
permittivity and ac conductivity with frequency reveals that the dispersion is
due to the Maxwell–Wagner type interfacial polarization
Sivakumar,S; Prathapachandra Kurup, M R(Department of Applied Chemistry, 2002)
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Abstract:
The primary aim of these investigations was to probe the spectroscopic, electrochemical, biological and single crystal X-ray diffraction studies of some selected transition metal complexes of 4N-monosubstituted thiosemicarbazones. Transition metal complexes with thiosemicarbazones exhibit a wide range of stereochemistries and possess potential biological activity. Metal complexes of thiosemicarbazones are proved to have improved pharmacological and therapeutic effects. The studies are conducted to bring about a fair understanding of the structure activity relationship and to develop certain effective and economical metal-based antimicrobial agents. Study showed that the thiosemicarbazones have antibacterial, antiviral and antiproliferative properties and hence used against tuberculosis, leprosy, psoriasis, rheumatism, trypanosomiasis and coccidiosis. Certain thiosemicarbazones showed a selective inhibition of HSV and HIV infections. The insolubility of most thiosemicarbazones in water causes difficulty in the oral administration in clinical practice. Transition metal complexes are found to have more activity than uncombined thiosemicarbazones. They exhibit a variety of denticity and can be varied by proper substitution. The stereochemistry assumed by the thiosemicarbazones during the coordination with transition metal ions depends on the factors such as preparative conditions and availability of additional bonding site in the ligand moiety and charge of the ligand. The resulting complexes exhibited a wide range of stereochemistries and have biomimic activity and potential application as sensors.
Sivakumar,S; Prathapachandra Kurup, M R(Department of Applied Chemistry, 2002)
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Abstract:
The primary aim of these investigations was to probe the spectroscopic, electrochemical, biological and single crystal X-ray diffraction studies of some selected transition metal complexes of 4N-monosubstituted thiosemicarbazones. Transition metal complexes with thiosemicarbazones exhibit a wide range of stereochemistries and possess potential biological activity. Metal complexes of thiosemicarbazones are proved to have improved pharmacological and therapeutic effects. The studies are conducted to bring about a fair understanding of the structure activity relationship and to develop certain effective and economical metal-based antimicrobial agents. Study showed that the thiosemicarbazones have antibacterial, antiviral and antiproliferative properties and hence used against tuberculosis, leprosy, psoriasis, rheumatism, trypanosomiasis and coccidiosis. Certain thiosemicarbazones showed a selective inhibition of HSV and HIV infections. The insolubility of most thiosemicarbazones in water causes difficulty in the oral administration in clinical practice. Transition metal complexes are found to have more activity than uncombined thiosemicarbazones. They exhibit a variety of denticity and can be varied by proper substitution. The stereochemistry assumed by the thiosemicarbazones during the coordination with transition metal ions depends on the factors such as preparative conditions and availability of additional bonding site in the ligand moiety and charge of the ligand. The resulting complexes exhibited a wide range of stereochemistries and have biomimic activity and potential application as sensors
Abdul,Rashid K K; Dr.Krishnan Nambisan, P N; Dr.Jacob, Chacko(Cochin University of Science and Technology, November , 1986)
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Abstract:
This thesis deals with the studies on the synthesis and characterisation of the complexes of embelin with manganese (II), cobalt(II), nickel (II), copper (II), zinc (II), cadmium (II), chromium (III), iron (III) lanthanum(III), praseodymium (III) neodymium (III) Samarium (III), gadolinium (III) dysprosium (III), yttrium (III) thorium (IV) and uranium (VI). Elemental analysis as well as spectral, thermal and magnetic data were used to ascertain the composition of the complexes and to establish the structures of the metal complexes. Wherever possible, the electronic spectra and magnetic data were used to predict the stereochemistry of the complexes.The thesis is divided into four chapters.
Description:
Division of Chemical
Oceanography, School of Marine Science, Cochin University of Science and Technology
Anantharaman, M R; Lisha, R; Hysen, T; Geetha, P; Avasthi, D K; Ramanujan, R V(IOP Publishing LTD, March 7, 2014)
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Abstract:
Metglas 2826 MB having a nominal composition of Fe40Ni38Mo4B18 is an
excellent soft magnetic material and finds application in sensors and memory
heads. However, the thin-film forms of Fe40Ni38Mo4B18 are seldom studied,
although they are important in micro-electro-mechanical systems/nano-electromechanical
systems devices. The stoichiometry of the film plays a vital role in
determining the structural and magnetic properties of Fe40Ni38Mo4B18 thin
films: retaining the composition in thin films is a challenge. Thin films of 52 nm
thickness were fabricated by RF sputtering technique on silicon substrate from a
target of nominal composition of Fe40Ni38Mo4B18. The films were annealed at
temperatures of 400 °C and 600 °C. The micro-structural studies of films using
glancing x-ray diffractometer (GXRD) and transmission electron microscope
(TEM) revealed that pristine films are crystalline with (FeNiMo)23B6 phase.
Atomic force microscope (AFM) images were subjected to power spectral
density analysis to understand the probable surface evolution mechanism during
sputtering and annealing. X-ray photoelectron spectroscopy (XPS) was
employed to determine the film composition. The sluggish growth of crystallites
with annealing is attributed to the presence of molybdenum in the thin film. The
observed changes in magnetic properties were correlated with annealing induced
structural, compositional and morphological changes
Binitha, N N; Dr.Sugunan, S(Cochin University of Science and Technology, October , 2006)
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Abstract:
Green chemistry boots eco-friendly,natural clays as catalysts in the chemical as well as in the pharmaceutical industry.Industry demands thermal stability,mechanical strength etc for the catalyst and there the modification methods becomes important.Pillaring tunes clays as efficient catalytic templates for shape selective organic synthesis.Here pillared clays are used as promising alternatives for the environmentally hazardous homogeneous catalysts in some industrially important Friedel-Crafts alkylation reactions of arenes with lower alchohols and higher olefins.The layer structure is enhanced upon pillaring and allows the nanocomposite formation with polyaniline to develop today’s nanoscale diameter devices.Present work gives an entry of pillared clays to the world of conducting composite nanofibers.
Description:
Department of Applied Chemistry,
Cochin University of Science and Technology
Manoj, N(American chemical society, August 7, 2006)
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Abstract:
A combined experimental and theoretical study of the absorption spectra of a group of closely related pyrylium
perchlorates 1-11 are presented. Minor changes in the position of the substituents lead to drastic changes in
the absorption spectra in this series of compounds. We have attempted to explain the observed changes using
the x,y-band notation developed by Balaban and co-workers. Absorption spectra of all compounds are compared
with results from time-dependent density functional theory (TDDFT) and Zerner’s intermediate neglect of
differential overlap (ZINDO/S) level calculations. Results of the calculations are in good agreement with
experimental observations and an interesting correlation between Balaban’s notations and the MO transitions
are obtained for simple derivatives. It is suggested that for more complex systems such as R- and â-naphthyl
substituted systems, the empirical method is not appropriate.
Antony,G; Dr.Ranganathan, N(Cochin University of Science and Technology, April , 1986)
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Abstract:
The study evolved from the basic
premise that the existing distribution
structure is not adequate or adaptive to
meet the needs of the expanding manufacturing
sector and the emerging mass market.
The hypothised causes of the problem are
the following: marketing channels
are not used for strategy differentiation
by manufacturers: there are too many intermediaries
in the channels; the distributive
institutions are not adaptive; and there
is very little control over the flow of
products through the channels. These
assumptions about the causes of the problem
have been translated into specific
hypotheses and tested with data. Empirical
analysis, while supporting some of these
hypotheses, challenges certain widely held
notions. The ensuing summary presents the
important findings, in the sequence in
which they are discussed in the study.
Description:
School of Management Studies,Cochin University of Science and Technology
Neson, Varghese; Dr.Syamaprasad,U(Cochin University of Science and Technology, May 2, 2012)
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Abstract:
This thesis Entitled Studies on transport and magnetic properties of nano particle doped mgb2 superconductor for technological applications.The thesis ahead focuses on the establishment of enhanced superconducting properties in bulk MgB2 via nano particle doping and its conversion into mono/multifilamentary wires. Further, an attempt has also been made to develop prototypes of MgB2 coil and conduction cooled current lead for technological applications. The thesis is configured into 6
chapters. The opening chapter gives an idea on the phenomenon of superconductivity, the various types of superconductors and its applications in different fields. The second chapter is an introduction on MgB2 superconductor and its relevance which includes crystal and electronic structure, superconducting mechanism, basic superconducting properties along with its present international status. The third chapter provides details on the preparation and characterization techniques followed through out the study on MgB2. Fourth chapter discusses the effect of processing temperature and chemical doping using nano sized dopants on the superconducting properties of MgB2• Fifth chapter deals with the optimization of processing parameters and novel preparation techniques for wire fabrication. Sixth chapter furnishes the preparation of multifilamentary wires with various filament configurations, their electromechanical properties and it also incorporates the development of an MgB2 coil and a general purpose conduction cooled current lead.
Description:
Applied Super conductivity Group,Material science and technology division,National Institute for Interdisciplinary Science and Technology
Pramod, Gopinath; Dr.Nampoori,V P N(Cochin University of Science and Technology, April , 2006)
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Abstract:
Developments in laser technology over the past few years have made it possible to do
experiments with focused intensities of IO"-102' Wcm'z. Short-pulse high-intensity
lasers are able to accelerate protons and heavier ions to multi-MeV energies during
their interaction with solid targets, gas jets and clusters. When such a laser radiation
is focused at the intensity above 10” Wcm'2, local electric field strength will be
almost equivalent to that within an atom. Hence, new nonlinear optical phenomena
will be expected in the field of light matter interaction. Most of the research in the
material interaction using high power lasers, especially related to plasma interaction,
has been directed to the short pulse x-ray generation- Nanosecond laser interactions
with solid targets also generate plasmas which emit radiation mainly in the optical
region, the understanding of which is far from satisfactory. This thesis deals with a
detailed study of some of the dynamical processes in plasmas generated by
nanosecond and femtosecond lasers
Description:
lntemational School of Photonics
Cochin University of Science and Technology
Sheena, Mathew; Dr.Poulose Jacob, K(Cochin University of Science and Technology, June , 2008)
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Abstract:
Internet today has become a vital part of day to day life, owing to the
revolutionary changes it has brought about in various fields. Dependence on
the Internet as an information highway and knowledge bank is exponentially
increasing so that a going back is beyond imagination. Transfer of critical
information is also being carried out through the Internet. This widespread use
of the Internet coupled with the tremendous growth in e-commerce and m-commerce
has created a vital need for infonnation security.Internet has also become an active field of crackers and intruders. The
whole development in this area can become null and void if fool-proof security
of the data is not ensured without a chance of being adulterated. It is, hence a
challenge before the professional community to develop systems to ensure
security of the data sent through the Internet.Stream ciphers, hash functions and message authentication codes play
vital roles in providing security services like confidentiality, integrity and
authentication of the data sent through the Internet. There are several ·such
popular and dependable techniques, which have been in use widely, for quite a
long time. This long term exposure makes them vulnerable to successful or
near successful attempts for attacks. Hence it is the need of the hour to
develop new algorithms with better security.Hence studies were conducted on various types of algorithms being
used in this area. Focus was given to identify the properties imparting security
at this stage. By making use of a perception derived from these studies, new algorithms were designed. Performances of these algorithms were then
studied followed by necessary modifications to yield an improved system
consisting of a new stream cipher algorithm MAJE4, a new hash code JERIM-
320 and a new message authentication code MACJER-320. Detailed analysis
and comparison with the existing popular schemes were also carried out to
establish the security levels.The Secure Socket Layer (SSL) I Transport Layer Security (TLS)
protocol is one of the most widely used security protocols in Internet. The
cryptographic algorithms RC4 and HMAC have been in use for achieving
security services like confidentiality and authentication in the SSL I TLS. But
recent attacks on RC4 and HMAC have raised questions about the reliability
of these algorithms. Hence MAJE4 and MACJER-320 have been proposed as
substitutes for them. Detailed studies on the performance of these new
algorithms were carried out; it has been observed that they are dependable
alternatives.
Description:
Department of Computer
Science, Cochin University of Science and Technology
Paul, Isaac; Dr.Chakravarti, R S; Thrivikraman,T(Cochin University of Science and Technology, November , 2004)
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Abstract:
The
main objective of this thesis was to extend some basic concepts and results in
module theory in algebra to the fuzzy setting.The concepts like simple module, semisimple module and exact sequences
of R-modules form an important area of study in crisp module theory. In this
thesis generalising these concepts to the fuzzy setting we have introduced
concepts of ‘simple and semisimple L-modules’ and proved some results which
include results analogous to those in crisp case. Also we have defined and
studied the concept of ‘exact sequences of L-modules’.Further extending the concepts in crisp theory, we have introduced the
fuzzy analogues ‘projective and injective L-modules’. We have proved many
results in this context. Further we have defined and explored notion of ‘essential
L-submodules of an L-module’. Still there are results in crisp theory related to the
topics covered in this thesis which are to be investigated in the fuzzy setting.
There are a lot of ideas still left in algebra, related to the theory of
modules, such as the ‘injective hull of a module’, ‘tensor product of modules’
etc. for which the fuzzy analogues are not defined and explored.
Description:
Department of Mathematics, Cochin University of Science and Technology