Manju, Nair P; Dr. Sujatha, C.H(Cochin University of Science & Technology, June , 2014)
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Abstract:
Geochemical composition is a set of data for predicting the climatic condition existing in an ecosystem. Both the surficial and core sediment geochemistry are helpful in monitoring, assessing and evaluating the marine environment. The aim of the research work is to assess the relationship between the biogeochemical constituents in the Cochin Estuarine System (CES), their modifications after a long period of anoxia and also to identify the various processes which control the sediment composition in this region, through a multivariate statistical approach. Therefore the study of present core sediment geochemistry has a critical role in unraveling the benchmark of their characterization. Sediment cores from four prominent zones of CES were examined for various biogeochemical aspects. The results have served as rejuvenating records for the prediction of core sediment status prevailing in the CES
Reji,Srinivas; Sajan,K(Department of Marine Geology and Geophysics, School of marine Sciences, 2002)
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Abstract:
In this study, an attempt has been made to find the textural, geochemical, sedimentological characteristics of sediments and water phases of the kayamkulam estuary located in the Southwest coast of Kerala, besides the impact of gas based thermal power plant located at the northern part of the estuary. Estuaries are an important stage in the transport of the solid weathering product of the earth’s crust. These weathered products or sediments are complex mixtures of a number of solid phases that may include clays, silica, organic matter, metal oxides, carbonates, sulfides and a number of minerals. Studies on the aquatic systems revealed the fact that it posses severe ecological impairments due to heavy discharge of sediments from 44 rivers, the continued disposal of pollutants rich materials from industries, sewage channels, agricultural areas and retting yards
Hariharan,G N; Nambiar,C G(Department of Marine Geology & Geophysics, School of Marine Sciences, 2001)
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Abstract:
The present work deals with the texture, mineralogy and geochemistry of bedload sediments of the main stream of the Chaliyar basin, a typical small drainage system of the tropics enjoying heavy rain fall and moderate climate, located essentially in the Northern Kerala and flowing over the crystalline rocks (and their laterized duricrust) of the South Indian granulite terrain. As the Chaliyar is the major river draining the Wynad Gold Fields and is known for its placer gold occurrences, the thesis gives special emphasize on understanding the nature and distribution of detrital gold in sediments of the basin, while attempting to infer the provenance characteristics and factors involved in the evolution of sediments in general. Minerologically the chaliyar basin sands are quartzose. The quartz and feldspar contents in the coarse sand fraction of the basin range from 64 to 86% and 2 to 16% respectively. The Q/F ration ranges from 4 to 38 with a slight decrease in the lower reaches. Other minerals present include, hornblende, pyroxene and heavy minerals like opaques, garnet, rutile, biotite, spene, silliminite, zircon, apatite and monazite some of which are seen as inclusions in quartz. The major element composition of Chaliyar bedload sediments in the main channel and the headwater tributaries is related to the mineralogical and textual characteristics of sediments.
Soney Kurien, P; Dr.Nambiar,C G(Cochin University Of Science And Technology, May 2, 2000)
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Abstract:
This report deals essentially with the geochemistry and petrogenesis
of Perinthatta anorthosite. The work also addresses the geological setting
of the pluton in terms of its field relationships and petrography and the
structure and metamorphism of the region and examines its relation with
the associated plutons. For the sake of convenience, the thesis is divided
into six chapters
Description:
Department of Marine Geology and Geophysics, School of Marine Sciences, Cochin
University of Science and Technology
Siby,Varghese; Chandramohanakumar, N(National Institute of Oceanography & CUSAT, 2003)
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Abstract:
Rare earth elements have occupied an important role in marine geochemical research, particularly as used in the format of REE abundance patterns to describe the geochemical pathways in marine sedimentation and authigenesis. This study concentrates on the distribution pattern of Rare earth elements in the sediments, behavior of Eu and Ce with respect to their occurrence in multiple oxidation states. It also concentrate the depth wise variation of sediment REEs from near shore areas (30m) to deeper depths 200m) in the Arabian Sea. It includes the downcore variation of REEs and other trace elements in the sediment cores and a comparison between the REE distributions of Arabian Sea sediment with the sediments of Andaman Sea. The study gives a general introduction regarding the importance of RRE studies, its occurrence and abundance, electronic configuration, lanthanide contraction, oxidations states and REE supply to the ocean, seawater and sediments.
Laluraj, C M; Dr.Muraleedharan Nair, S(Cochin University of Science and Technology, February , 2009)
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Abstract:
The metals present in the surface sediments have high demand on a
global perspective, and the main reservoir of these elements is believed to be
the ocean floor. A lot of studies on metals are going on throughout the world
for its quantification and exploitation. Even though, some preliminary
attempts have been made in selected areas for the quantitative study of
metals in the western continental shelf of India, no comprehensive work has
been reported so far. The importance of this study also lies on the fact that
there has not been a proper evaluation of the impact of the Great Tsunami of
2004 on the coastal areas of the south India. In View of this, an attempt has
been made to address the seasonal distribution, behavior and mechanisms
which control the deposition of metals in the sediments of the western
continental shelf and Cochin Estuary, an annex to this coastal marine region.Surface sediment samples were collected seasonally from two
subenvironemnts of southwest coast of India, (continental shelf of Kerala and
Cochin estuarine system), to estimate the seasonal distribution and geochemical
behavior of non-transition, transition, rare-earth elements, Th and U. Bottom
water samples were also taken from each station, and analysed for temperature,
salinity and dissolved oxygen, hence the response of redox sensitive elements to
oxygen minimum zone can be addressed. In addition, other sedimentary
parameters such as sand, silt, clay fractions, CaCO3 and organic carbon content
were also estimated to evaluate the control factors on level of metals present in
the sediment. The study used different environmental data analysis techniques
to evaluate the distribution and behavior of elements during different seasons.
This includes environmental parameters such as elemental normalisation,
enrichment factor, element excess, cerium and europium anomalies and
authigenic uranium.
Description:
Department of Chemical Oceanography,Cochin University of Science and Technology
Lasitha, S; Dr.Radhakrishna, M(Cochin University of Science and Technology, September , 2007)
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Abstract:
This work aims to study the variation in subduction
zone geometry along and across the arc and the fault pattern within the subducting
plate. Depth of penetration as well as the dip of the Benioff zone varies considerably
along the arc which corresponds to the curvature of the fold- thrust belt which varies
from concave to convex in different sectors of the arc. The entire arc is divided into 27
segments and depth sections thus prepared are utilized to investigate the average dip
of the Benioff zone in the different parts of the entire arc, penetration depth of the
subducting lithosphere, the subduction zone geometry underlying the trench, the arctrench
gap, etc.The study also
describes how different seismogenic sources are identified in the
region, estimation of moment release rate and deformation pattern. The region is
divided into broad seismogenic belts. Based on these previous studies and seismicity
Pattern, we identified several broad distinct seismogenic belts/sources. These are l)
the Outer arc region consisting of Andaman-Nicobar islands 2) the back-arc Andaman Sea 3)The Sumatran fault zone(SFZ)4)Java onshore region termed as Jave Fault Zone(JFZ)5)Sumatran fore arc silver plate consisting of Mentawai fault(MFZ)6) The offshore java fore arc region 7)The Sunda Strait region.As the Seismicity is variable,it is difficult to demarcate individual seismogenic sources.Hence, we employed a moving window method having a window length of 3—4° and with 50%
overlapping starting from one end to the other. We succeeded in defining 4 sources
each in the Andaman fore arc and Back arc region, 9 such sources (moving windows)
in the Sumatran Fault zone (SFZ), 9 sources in the offshore SFZ region and 7 sources
in the offshore Java region. Because of the low seismicity along JFZ, it is separated
into three seismogenic sources namely West Java, Central Java and East Java. The
Sunda strait is considered as a single seismogenic source.The deformation rates for
each of the seismogenic zones have been computed. A detailed error analysis of
velocity tensors using Monte—Carlo simulation method has been carried out in order
to obtain uncertainties. The eigen values and the respective eigen vectors of the
velocity tensor are computed to analyze the actual deformation pattem for different
zones. The results obtained have been discussed in the light of regional tectonics, and
their implications in terms of geodynamics have been enumerated.ln the light of recent major earthquakes (26th December 2004 and 28th March
2005 events) and the ongoing seismic activity, we have recalculated the variation in
the crustal deformation rates prior and after these earthquakes in Andaman—Sumatra
region including the data up to 2005 and the significant results has been presented.ln this
chapter, the down going lithosphere along the subduction zone is modeled using the
free air gravity data by taking into consideration the thickness of the crustal layer, the
thickness of the subducting slab, sediment thickness, presence of volcanism, the
proximity of the continental crust etc. Here a systematic and detailed gravity
interpretation constrained by seismicity and seismic data in the Andaman arc and the
Andaman Sea region in order to delineate the crustal structure and density heterogeneities a Io nagnd across the arc and its correlation with the seismogenic behaviour is presented.
Description:
Department of Marine Geology & Geophysics,
Cochin University of Science and Technology
Santosh,Kumar Pandey; Dr.Chakravarti, R S(Cochin University of Science and Technology, June , 2010)
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Abstract:
This thesis entitled Geometric algebra and einsteins electron: Deterministic field theories .The work in this thesis clarifies an important part of Koga’s theory.Koga also developed a theory of the electron incorporating its gravitational field, using his substitutes for Einstein’s equation.The third chapter deals with the application of geometric algebra to Koga’s approach of the Dirac equation. In chapter 4 we study some aspects of the work of mendel sachs (35,36,37,).Sachs stated aim is to show how quantum mechanics is a limiting case of a general relativistic unified field theory.Chapter 5 contains a critical study and comparison of the work of Koga and Sachs. In particular, we conclude that the incorporation of Mach’s principle is not necessary in Sachs’s treatment of the Dirac equation.
Description:
Department of Mathematics, Cochin University of Science
and Technology
Arts,K Purushotham; Radhakrishna,M(Department of Marine Geology and Geophysics,School of Marine Sciences, 2002)
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Abstract:
The main objective of the present study is to model the gravity fields in terms of lithospheric structure below the western continental margin of India (WCMI) identify zones of crustal mass anomalies and attempt to infer the location of Ocean Continent transition in the Arabian Sea. In this study, the area starting from the western shield margin to the region covering the deep oceanic parts of the Arabian Sea which is bounded by Carlsberg and Cerg and Central Indian ridges in the south, eastern part of the Indus Cone in the west and falling between 630E and 800E longitudes, and 50N - 240N latitudes has been considered. The vast amount of seismic reflection and refraction data in the form of crustal velocities, basement configuration and crustal thicknesses available for the west coast as well as the eastern Arabian Sea has been utilized for this purpose
Saly, Thomas N; Dr. Hridayanathan, C(Cochin University of Science and Technology, May , 2001)
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Abstract:
The fishing industry the world over is passing through a critical situation.The landings of marine fishes seemed to have reached saturation in major fishing areas of the world.As a general rule fisheries employing fishing gear and techniques used by small scale and artisanal fishermen either from shore or from onboard small fishing craft come under small-scale fisheries.This study on gill nets of Kerala, the fishing method depended upon by maximum fishermen of the state focuses on the importance of this selective and low energy fishing method in the marine fishing sector of the state.The study opens with the conceptual framework by briefly reviewing the crisis in the marine fisheries sector. Maximum fishermen depend upon gill net, which is, an important selective and low energy fishing gear. A review of relevant literature on aspects such as material, selectivity and techno-economic efficiency together with scope and main objectives of the study form the major part of the compass of the introductory chapter.This survey provided the inputs for selection of centres. The chapter presents the basis for selection of sample centres, sample units and methodology for field and experimental study.The subject matter of the fourth chapter is a basic study on gear aterials. The weathering resistance, which is an important criterion to assess the material performance, was studied for polyamide monofilament in comparison to polyamide multifilament and polyethylene twisted monofilament.The study provides supporting evidence of oxidation and characteristic C-O stretching in polyethylene and cyclic lactam .formation and presence of OH in polyamide.The study indicates that small mesh gill netting can be encouraged as a selective fishing method in the inshore waters with restrained use of 30 and 32 mm mesh sizes. The economic efficiency was assessed using standard indices such as rate of return, internal rate of return, pay back period, fishery income, energy efficiency and factor productivity. The effect of size and cost of capital and cost of production on the economics of operation is also discussed in this chapter. It was observed that level of technology did not have direct effect on economic performance.
Description:
Industrial Fisheries,
Cochin University of
Science and Technology
Anoo Anna, Anthony; Dr.Mary,Joseph T(Cochin University of Science and Technology, October , 2011)
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Abstract:
The literature on the involvement of developing countries in trade has focused on the effects of different aspects of globalization on firms, regions and countries. The study attempts to examine how an export based industry, locallyembedded and originated on the basis of regional strengths has been inserted into the global trade framework. Though the unit of analysis is the manufacturing export firm in the region of Kannur, it represents the entire home textile export
industry from the state of Kerala, as close to 90% of fabric exports in home furnishing material, textiles for upholstery and decoration and stitched or fused, and branded made ups are from the region. From a global perspective, how developing countries face newer trade restrictions and overcome non quota barriers by firm and region specific activities within a value chain framework is a major research area, which has already contributions from the Ludhiana woolen
cluster (Tewari,1999 ) and the Tirupur cluster in India (Cawthorne, 1995). The study contributes to the value chain literature by examining the governance and upgrading as well as how firms benefit from linkages. India has a number of export oriented agglomerations or regions where firms have been serving export markets for many years. In many cases it is no longer the supply side policy actions that determine how they are able to penetrate new markets or expand existing market share. Based on this study it becomes possible to understand how the global value chain operates in these different industries to examine whether there is a danger of immiserisation of growth or low road growth
Description:
School of Management Studies, Cochin University of Science and Technology
Jayanarayanan, S; Dr. Paulose, C S(Cochin University Of Science And Technology, December 21, 2012)
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Abstract:
The present study was designed to investigate the protective effect of
curcumin and vitamin D3 in the functional regulation of glutamatergic NMDA and
AMPA receptors in streptozotocin (STZ) induced diabetic rats. Alterations in
glutamatergic neurotransmission in the brain were evaluated by analyzing the
glutamate content, glutamate receptors - NMDA and AMPA receptors binding
parameters and gene expression, GAD and GLAST gene expression.
Immunohistochemistry studies using confocal microscope were carried out to
confirm receptor density and gene expression results of NMDA and AMPA
receptors. The role of glutamatergic receptors in pancreas was studied using the
following parameters; glutamate content, GLAST expression, glutamate receptors
- NMDA and AMPA receptor binding and gene expression. Increasing evidence in
both experimental and clinical studies suggests that oxidative stress plays a major
role in the pathogenesis of diabetes. In the present study SOD assay and GPx gene
expression were done to evaluate the activity of antioxidant enzymes in the brain
regions and pancreas. NeuroD1 and Pdx1 gene expression were performed in
pancreas of experimental rats to evaluate pancreatic islet survival. Gene
expression profiles of caspase 8, Bax, and Akt in brain regions and pancreas were
studied to understand the possible mechanism behind curcumin and vitamin D3
mediated neuroprotection and islet survival. Gene expression studies of
vitamin D3 receptor localisation in the pancreas was done to understand the
mechanism of vitamin D3 in insulin secretion. Curcumin and vitamin D3 mediated
insulin secretion via Ca2+ release were studied using confocal microscope.
Description:
Department of Biotechnology
Cochin University of Science and Technology
Sosamma,Cherian; Dr.George, Philip(Cochin University of Science And Technology, May , 1984)
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Abstract:
Alpha glucan phosphorylase plays a very
significant role in glycolysis. The inhibition and
activation of this enzyme have significant effect on
the rate of glycolysis. The rate of glycolysis is
also determined by the interconversion between the
active 3 and inactive Q forms of phosphorylase by
two specific enzymes called phosphorylase phosphatase
and phosphorylase kinase. The allosteric properties
and interconversion mechanism reported for
well—studied animal muscle phosphorylases do not
fall under a general pattern. Studies using
purified phosphorylase from marine sources are scanty.
Detailed studies using specialised tissues from more
marine animals are necessary to find the factors that
control the properties and activities of the enzyme.
This thesis is an attempt in this direction. The
thesis deals with a detailed study of the control of
the phosphorylase by both allosterism and
interconversion between the g and b forms from four
different aquatic animals of different habitat. Phosphorylase frm the four different animal muscles were purified either partially or completely and the kinetic and control properties were studied.
Description:
School of marine sciences, Cochin University of Science And Technology
Suresh, M; Dr.Pillai, U T S(Cochin University of Science and Technology, April , 2012)
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Abstract:
Demand on magnesium and its alloys is increased significantly in the automotive industry because of their great potential in reducing the weight of components, thus resulting in improvement in fuel efficiency of the vehicle. To date, most of Mg products have been fabricated by casting, especially, by die-casting because of its high productivity, suitable strength, acceptable quality & dimensional accuracy and the components produced through sand, gravity and low pressure die casting are small extent. In fact, higher solidification rate is possible only in high pressure die casting, which results in finer grain size. However, achieving high cooling rate in gravity casting using sand and permanent moulds is a difficult task, which ends with a coarser grain nature and exhibit poor mechanical properties, which is an important aspect of the performance in industrial applications. Grain refinement is technologically attractive because it generally does not adversely affect ductility and toughness, contrary to most other strengthening methods. Therefore formation of fine grain structure in these castings is crucial, in order to improve the mechanical properties of these cast components.
Therefore, the present investigation is “GRAIN REFINEMENT STUDIES ON Mg AND Mg-Al BASED ALLOYS”. The primary objective of this present investigation is to study the effect of various grain refining inoculants (Al-4B, Al- 5TiB2 master alloys, Al4C3, Charcoal particles) on Pure Mg and Mg-Al alloys such as AZ31, AZ91 and study their grain refining mechanisms. The second objective of this work is to study the effect of superheating process on the grain size of AZ31, AZ91 Mg alloys with and without inoculants addition. In addition, to study the effect of grain refinement on the mechanical properties of Mg and Mg-Al alloys. The thesis is well organized with seven chapters and the details of the studies are given below in detail.
Description:
Materials Science and Technology Division, National Institute for Interdisciplinary Science and Technology (NIIST), CSIR
John Kurian,P; Radhakrishna,M(Department of Marine Geology and Geophysics, School of Marine Sciences, 2000)
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Abstract:
The primary aim of the present study is to acquire a large amount of gravity data, to prepare gravity maps and interpret the data in terms of crustal structure below the Bavali shear zone and adjacent regions of northern Kerala. The gravity modeling is basically a tool to obtain knowledge of the subsurface extension of the exposed geological units and their structural relationship with the surroundings. The study is expected to throw light on the nature of the shear zone, crustal configuration below the high-grade granulite terrain and the tectonics operating during geological times in the region. The Bavali shear is manifested in the gravity profiles by a steep gravity gradient. The gravity models indicate that the Bavali shear coincides with steep plane that separates two contrasting crustal densities extending beyond a depth of 30 km possibly down to Moho, justifying it to be a Mantle fault. It is difficult to construct a generalized model of crustal evolution in terms of its varied manifestations using only the gravity data. However, the data constrains several aspects of crustal evolution and provides insights into some of the major events.
Jomon Jacob, P; Dr.Prathapan, S(Cochin University of Science And Technology, January 30, 2013)
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Abstract:
the thesis entitled “Ground and Excited
State Electron Transfer Reaction Between a few Anthracene
Appended Tertiary Amines and Suitable Electron Acceptors”
portrays our attempts to explore the solvent, concentration and
temperature effect of the reaction between a few (anthracen-9-
yl)methanamines with electron acceptors like DMAD, DBA and
DBE. We have also studied the effect of solvent and percentage
fluorescence quenching in the photoinduced electron transfer
reactions of these ‘donor-spacer-acceptor’ systems. Finally we
look in to the intramolecular electron transfer reactions of a few
tertiary amine appended dibenzobarrelenes and
bisdibenzobarrelenes
Description:
Department
of Applied Chemistry, Cochin University of Science and Technology
Premachandran,S K; Dr.Joy, George(Cochin University of Science And Technology, January , 1981)
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Abstract:
The thesis presents the results of the investigations on the crystallisation ‘behaviour, detect
structure end electrical properties of certain organic crystals---phthslic snhydride end potsssiun scid phthalate Hollow crystals of phthalic snhydride were grown from vapour. the norpholog of these hollow crystals were studied in detail and s. mechanism for their growth has been proposed. A closed crystal—vapour system was used to study the basal plane growth of the
whiskers and the sequential growth, observed, confirmed the mechanism suggested for hollow crystals. The dendritic crystals of phthslic enhydride were grown, both iron
the melt and solution. The observed morphologies of these dendrites ere described. Bpherulites of phthalic anhydride have been grown by the artificial initiation of nucleation, from melt and solution. The variation of the substructure oi’ these spherulites with the growth tenperature wee
investigated. The spherulitic filll having ribbon substructure were etched to reveal dislocations. A mechanism for the formation of the observed etch pattern has been suggested. the slip occurring in these ribbons were studied and the results are presented
Description:
Department of physics, Cochin University of Science And Technology
Vanaja, K A; Dr.Jayalekshmi, S(Cochin University of Science and Technology, May , 2011)
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Abstract:
In the present studies, various copper delafossite materials viz; CuAlO2,
CuGaO2, CuFeO2 , CuGa1-xFexO2, CuYO2 and CuCaxY1-xO2 were synthesised by
solid state reaction technique. These copper delafossite materials were grown in
thin film form by rf magnetron sputtering technique. In general copper
delafossites exhibit good optical transparency. The conductivity of the CuYO2
could be improved by Ca doping or by oxygen intercalation by annealing the film in oxygen atmosphere. It has so far been impossible to improve the p-type
conductivity of CuGaO2 significantly by doping Mg or Ca on the Ga site. The ptype
conductivity is presumed to be due to oxygen doping or Cu Vacancies [6].
Reports in literature show, oxygen intercalation or divalent ion doping on Ga
site is not possible for CuGaO2 thin films to improve the p-type conductivity.
Sintered powder and crystals of CuFeO2 have been reported as the materials
having the highest p-type conductivity [14, 15] among the copper and silver
delafossites. However the CuFeO2 films are found to be less transparent in the
visible region compared to CuGaO2. Hence in the present work, the solid
solution between the CuGaO2 and CuFeO2 was effected by solid state reaction,
varying the Fe content. The CuGa1-xFexO2 with Fe content, x=0.5 shows an
increase in conductivity by two orders, compared to CuGaO2 but the
transparency is only about 50% in the visible region which is less than that of
CuGaO2 The synthesis of α−AgGaO2 was carried out by two step process which
involves the synthesis of β-AgGaO2 by ion exchange reaction followed by the
hydrothermal conversion of the β-AgGaO2 into α-AgGaO2. The trace amount of
Ag has been reduced substantially in the two step synthesis compared to the
direct hydrothermal synthesis. Thin films of α-AgGaO2 were prepared on silicon
and Al2O3 substrates by pulsed laser deposition. These studies indicate the
possibility of using this material as p-type material in thin film form for
transparent electronics. The room temperature conductivity of α-AgGaO2 was
measured as 3.17 x 10-4 Scm-1and the optical band gap was estimated as 4.12 eV.
A transparent p-n junction thin film diode on glass substrate was fabricated
using p-type α-AgGaO2 and n-ZnO.AgCoO2 thin films with 50% transparency in the visible region were deposited
on single crystalline Al2O3 and amorphous silica substrates by RF magnetron
sputtering and p type conductivity of AgCoO2 was demonstrated by fabricating
transparent p-n junction diode with AgCoO2 as p-side and ZnO: Al as n-side
using sputtering. The junction thus obtained was found to be rectifying with a
forward to reverse current of about 10 at an applied voltage of 3 V.The present
study shows that silver delafossite thin films with p-type conductivity can be
used for the fabrication of active devices for transparent electronics applications.
Description:
Department of Physics,
Cochin University of Science and Technology
Nisha, M; Jayaraj, M K(Department of Physics, December , 2006)
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Abstract:
The increasing interest in the interaction of light with electricity and
electronically active materials made the materials and techniques for producing
semitransparent electrically conducting films particularly attractive. Transparent
conductors have found major applications in a number of electronic and
optoelectronic devices including resistors, transparent heating elements,
antistatic and electromagnetic shield coatings, transparent electrode for solar
cells, antireflection coatings, heat reflecting mirrors in glass windows and many
other. Tin doped indium oxide (indium tin oxide or ITO) is one of the most
commonly used transparent conducting oxides. At present and likely well into
the future this material offers best available performance in terms of
conductivity and transmittivity combined with excellent environmental stability,
reproducibility and good surface morphology.
Although partial transparency, with a reduction in conductivity, can be obtained
for very thin metallic films, high transparency and simultaneously high
conductivity cannot be attained in intrinsic stoichiometric materials. The only
way this can be achieved is by creating electron degeneracy in a wide bandgap
(Eg > 3eV or more for visible radiation) material by controllably introducing
non-stoichiometry and/or appropriate dopants. These conditions can be
conveniently met for ITO as well as a number of other materials like Zinc oxide,
Cadmium oxide etc.
ITO shows interesting and technologically important combination of properties
viz high luminous transmittance, high IR reflectance, good electrical
conductivity, excellent substrate adherence and chemical inertness. ITO is a key
part of solar cells, window coatings, energy efficient buildings, and flat panel
displays. In solar cells, ITO can be the transparent, conducting top layer that lets
light into the cell to shine the junction and lets electricity flow out. Improving
the ITO layer can help improve the solar cell efficiency. A transparent
ii
conducting oxide is a material with high transparency in a derived part of the
spectrum and high electrical conductivity. Beyond these key properties of
transparent conducting oxides (TCOs), ITO has a number of other key
characteristics. The structure of ITO can be amorphous, crystalline, or mixed,
depending on the deposition temperature and atmosphere. The electro-optical
properties are a function of the crystallinity of the material. In general, ITO
deposited at room temperature is amorphous, and ITO deposited at higher
temperatures is crystalline. Depositing at high temperatures is more expensive
than at room temperature, and this method may not be compatible with the
underlying devices.
The main objective of this thesis work is to optimise the growth conditions of
Indium tin oxide thin films at low processing temperatures. The films are
prepared by radio frequency magnetron sputtering under various deposition
conditions. The films are also deposited on to flexible substrates by employing
bias sputtering technique. The films thus grown were characterised using
different tools. A powder x-ray diffractometer was used to analyse the
crystalline nature of the films. The energy dispersive x-ray analysis (EDX) and
scanning electron microscopy (SEM) were used for evaluating the composition
and morphology of the films. Optical properties were investigated using the UVVIS-
NIR spectrophotometer by recording the transmission/absorption spectra.
The electrical properties were studied using vander Pauw four probe technique.
The plasma generated during the sputtering of the ITO target was analysed using
Langmuir probe and optical emission spectral studies.
Valsala Kumari, C K; Dr.Joy, George(Cochin University of Science and Technology, 1984)
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Abstract:
During the past few decades, a wide spread interest in the structural, optical, electrical and other physical properties of the transition metal dichalcogenide
layer compounds has evolved. The members of this family of compounds can be regarded as stronglybonded two dimensional chalcogen-metal-chalcogen layers
which are loosely coupled to one another by the weak van der Waal's forces. Because of this type of bonding, the crystals are easily cleavable along the basal plane and show highly anisotropic properties. This thesis contains the growth and the study of the physical properties of certain tin dichalcogenide
crystals (SnS2 and Snsea). Tin disulphide and tin diselenide crystallize in the hexagonal CdI2 type crystalstructure. This structure consists of layers of tin
atoms sandwiched between two layers of chalcogen atoms. Aitin atom is surrounded by six chalcogen atoms octahedrally. In the layers the atoms are held together by covalent bonding and in between the layers there is
van der Waal's bonding.
Description:
Department of Physics, Cochin University of Science and Technology
Valsala Kumari, C K; Dr.Joy, George(Cochin University of Science and Technology, September 20, 1984)
[+]
[-]
Abstract:
During the past few decades, a wide spread interest in the structural, optical, electrical and
other physical properties of the transition metal dichalcogenide layer compounds has evolved. The members of this family of compounds can be regarded as strongly bonded two dimensional chalcogen-metal~chalcogen layers which are loosely coupled to one another by the weak ven
der Waal's forces. Because of this type of bonding, the crystals are easily cleavable along the basal plane and show highly anisotropic properties. This thesis contains the growth and the study
of the physical properties of certain tin dichalcogenide crystals (SnS2 and SnSe2). Tin disulphide and tin diselenide crystallize in the hexagonal CdI2 type crystal structure. This structure consists of layers of tin atoms sandwiched between two layers of chalcogen atoms. A tin atom is surrounded by six chalcogen atoms octahedrally.In the layers the atoms are held together by
covalent bonding and in between the layers there is van der Waal's bonding.
Description:
Department of Physics, Cochin University of Science and Technology
George, Peter; Dr.Joy, George(Cochin University Of Science And Technology, July 11, 1986)
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Abstract:
Over the past years there has been considerable interest in the
growth of single crystals both from the point of view of basic research
and technological application. With the revolutionary emergence
of solid state electronics which is based on single crystal technolo8Ys
basic and applied studies on crystal growth and characterization
_have gained a-more significant role in material science. These studies
are being carried out for single crystals not only of semiconductor
and other electronic materials but also of metals and insulators.
Many organic crystals belonging to the orthorhombic class exhibit
ferroelectric, electrooptic, triboluminescent and piezoelectric properties.
Diammonium Hydrogen Citrate (DAHC) crystals are reported to
be piezoelectric and triboluminescent /1/. Koptsik et al. /2/ have
reported the piezoelectric nature of Citric Acid Monohydrate (CA)
crystals. And since not much work has been done on these crystals,
it has been thought useful to grow and characterize these crystals.
This thesis presents a study of the growth of these crystals
from solution and their defect structures. The results of the microindentation and thermal analysis are presented. Dielectric, fractographic, infrared (IR) and ultraviolet (UV) studies of DAHC crystals are also reported
Description:
Department of Physics, Cochin University
of Science and Technology
Kunjomana, A G; Dr.Elizabeth, Mathai(Cochin University Of Science And Technology, August 10, 1992)
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Abstract:
The physical properties of solid matter are
basically influenced by the existence of lattice defects;
as a result the study of crystal defects has assumed
a central position in solid state physics and materials
science. The study of dislocations ixa single crystals
can yield a great deal of information on the mechanical
properties of materials. In order to secure a full understanding
of the processes taking place in semiconducting
materials, it is important to investigate the microhardness
of these materials-—the most reliable method of
determining the fine structure of crystals, the revelation
of micro—inhomogenities in the distribution of impurities,
the effect of dislocation density on the mechanical
properties of crystals etc. Basically electrical conductivity
in single crystals is a defect controlled phenomenon
and hence detailed investigation of the electrical properties
of these materials is one of the best available
methods for the study of defects in them. In the present
thesis a series of detailed studies carried out in Te—Se
system, Bi2Te3 and In2Te3 crystals using surface topographical,
dislocation and microindentation analysis as well as
electrical measurements are presented
Description:
Department of
Physics, Cochin University of Science and Technology
Ajimsha, R S; Jayaraj, M K(Department of Physics, February , 2008)
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Abstract:
Transparent conducting oxides (TCO’s) have been known and used for technologically important applications for more than 50 years. The oxide materials such as In2O3, SnO2 and impurity doped SnO2: Sb, SnO2: F and In2O3: Sn (indium tin oxide) were primarily used as TCO’s. Indium based oxides had been widely used as TCO’s for the past few decades. But the current increase in the cost of indium and scarcity of this material created the difficulty in obtaining low cost TCO’s. Hence the search for alternative TCO material has been a topic of active research for the last few decades. This resulted in the development of various binary and ternary compounds. But the advantages of using binary oxides are the easiness to control the composition and deposition parameters. ZnO has been identified as the one of the promising candidate for transparent electronic applications owing to its exciting optoelectronic properties. Some optoelectronics applications of ZnO overlap with that of GaN, another wide band gap semiconductor which is widely used for the production of green, blue-violet and white light emitting devices. However ZnO has some advantages over GaN among which are the availability of fairly high quality ZnO bulk single crystals and large excitonic binding energy. ZnO also has much simpler crystal-growth technology, resulting in a potentially lower cost for ZnO based devices.
Most of the TCO’s are n-type semiconductors and are utilized as transparent electrodes in variety of commercial applications such as photovoltaics, electrochromic windows, flat panel displays. TCO’s provide a great potential for realizing diverse range of active functions, novel functions can be integrated into the materials according to the requirement. However the application of TCO’s has been restricted to transparent electrodes,
ii
notwithstanding the fact that TCO’s are n-type semiconductors. The basic reason is the lack of p-type TCO, many of the active functions in semiconductor originate from the nature of pn-junction. In 1997, H. Kawazoe et al reported the CuAlO2 as the first p-type TCO along with the chemical design concept for the exploration of other p-type TCO’s. This has led to the fabrication of all transparent diode and transistors.
Fabrication of nanostructures of TCO has been a focus of an ever-increasing number of researchers world wide, mainly due to their unique optical and electronic properties which makes them ideal for a wide spectrum of applications ranging from flexible displays, quantum well lasers to in vivo biological imaging and therapeutic agents. ZnO is a highly multifunctional material system with highly promising application potential for UV light emitting diodes, diode lasers, sensors, etc. ZnO nanocrystals and nanorods doped with transition metal impurities have also attracted great interest, recently, for their spin-electronic applications
This thesis summarizes the results on the growth and characterization of ZnO based diodes and nanostructures by pulsed laser ablation. Various ZnO based heterojunction diodes have been fabricated using pulsed laser deposition (PLD) and their electrical characteristics were interpreted using existing models. Pulsed laser ablation has been employed to fabricate ZnO quantum dots, ZnO nanorods and ZnMgO/ZnO multiple quantum well structures with the aim of studying the luminescent properties.
Sreeja, R; Dr.Jayaraj, M K(Cochin University Of Science And Technology, July 6, 2011)
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Abstract:
Nonlinear optics has been a rapidly growing field in recent decades since the
invention of lasers. The systematic progress in the laser technology increases our
efficiency in the generation and control of coherent optical radiations. Nonlinear
optics is based on the study ofeffects and phenomena related to the interaction of
intense coherent light radiation with matter. Compared to other light sources laser radiation can provide high directionality, high monochromaticiry, high brightness
and high photon degeneracy. At such a very intense incident beam, the matter
responds in a nonlinear manner to the incident radiation fields, which endows the
media :1 characteristic to change the refractive index or absorption coe fflcient of the
media or the wavelength, or the frequency of the incident electromagnetic waves.
This thesis encompasses the fabrication of nonlinear optical devices based on
semiconductor and metal nanostructures. The presented work focus on the
experimental and theoretical discussions on nonlinear optical effects especially
nonlinear absorption and refraction exhibitted by metal and semiconductor nanostructures
Description:
Optoelectronic Devices Laboratory
Department of Physics
Cochin University of Science and Technology
Joy, C M; Dr.Balakrishnan, K P(Cochin University of Science and Technology, April , 1989)
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Abstract:
The thesis entitled Growth Response of Phytoplankton Exposed to Industrial Effluents in River Periyar. The present investigation has been conducted in two phases: field observation and algal assays. The monthly distribution of hydrographic features is represented graphically. The sampling year has been divided into three seasons: monsoon (June to September), postmonsoon (October to January) and premonsoon (February to May). The data were analysed using Student's t-test to find whether there was any significant difference between surface and bottom samples. The spatial variation of the variables was assessed by Page's L (trend) test (Ray Meddis, 1975). The standard procedure for algal toxicity test (Ward and Parrish, 1982) was followed throughout the study. Statistical analysis (Page's L (trend) test) showed that there was no significant difference in Secchi disc transparency between the stations. The field observations as well as the laboratory assays confirm that the rate of discharge in river Periyar during premonsoon is insufficient to effect dilution of wastewater received in the industrial zone.
Description:
School of Environmental Studies,
Cochin University of Science
and Technology.