Pradeep Chandran, C; V P N Nampoori; Radhakrishnan, P(Cochin University of Science and Technology, January 10, 2016)
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Abstract:
We live in an Information age, which is marked by the onset of digital
revolution during or after the latter half of the 20th century. In this era, we saw
sweeping changes in digital computing and communication technology. We largely
depend on electronics and photonics for hardware requirements to aid this
technology. With the assistance of modern technology, electronic devices have
become an indispensable tool in our everyday life.
Inorganic semiconductor materials like silicon and gallium arsenide have been
exploited for the on-growing demands of digital revolution. Fifty years of continuous
research and technological advancements have pushed these materials to their
theoretical efficiency limit. On the other hand, the rapid advancement in technology
has created a huge electronic waste which pose a threat to the environment. The
scarcity of inorganic materials such as gallium and indium is an alarming factor and it
is estimated that these will run out completely in the next 20 years. The availability of
new suitable materials is crucial for the development of semiconductor technology.
With much promise of delivering low-cost and energy efficient materials, organic
semiconductors such as conjugated polymers and small molecules have opened up
new avenues for research. Despite the intense effort by scientists and researchers, the
performance and stability of organic devices have taken a back seat. Therefore an
immediate large-scale replacement of inorganic components by organic counterparts
are not foreseen in the near future. Although research is underway to improve the
performance of organic materials, it is important to constantly search for new
materials.Nature is a big treasure-trove of successfully conducted experiments by
natural selection. Inspired by its apparent simplicity and actual complexity,
researchers look out for natural materials or synthetic materials mimicked from
natural models, systems or elements. Bio-inspired photonics use natural design as
their inspiration to solve human problems and channel these solutions in new
directions. It is promising that natural and nature-inspired materials can achieve the
ambitious goal of ‘green’ technology for sustainable future.
Job,Kuriakose Aerankavil; Dr.Rani,Joseph(Cochin University of Science and Technology, November 30, 1996)
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Abstract:
The distribution of curing agents and fillers in the
constituents of an elastomer blend is an important factor
which determines the curing behaviour and vulcanizate
properties of the blend. The distribution of curatives and
fillers largely depends on the nature of elastomers. The
curatives tend to migrate preferentially to the rubber of
higher unsaturation and/or higher polarity, and reinforcing
fillers tend to get distributed in the low viscosity phase,
resulting in inferior mechanical properties of the blends.
The thesis suggests several methods for improving
mechanical properties of blends like NBR/butyl, NR/butyl,
NBR/EPDM and NR/.
Description:
Department of Polymer Science and Rubber
Technology, Cochin University of Science and Technology
Edwin, Xavier; Dr.Girijavallabhan,C P(Cochin University of Science & Technology, March , 1997)
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Abstract:
The present thesis is centered around the study of electrical and thermal
properties of certain selected photonic materials.We have studied the electrical conduction mechanism in various
phases of certain selected photonic materials and those associated with different phase
transitions occurring in them. A phase transition leaves its own impressions on the key
parameters like electrical conductivity and dielectric constant. However, the activation
energy calculation reveals the dominant factor responsible for conduction process.PA measurements of thermal diffusivity in certain other important photonic
materials are included in the remaining part of the research work presented in this
thesis. PA technique is a promising tool for studying thermal diffusivities of solid
samples in any form. Because of its crucial role and common occurrence in heat flow
problems, the thermal diffusivity determination is often necessary and knowledge of
thermal diffusivity can intum be used to calculate the thermal conductivity. Especially,knowledge of the thermal diffusivity of semiconductors is important due to its relation
to the power dissipation problem in microelectronic and optoelectronic devices which
limits their performances. More than that, the thermal properties, especially those of
thin films are of growing interest in microelectronics and microsystems because of the
heat removal problem involved in highly integrated devices. The prescribed chapter
of the present theis demonstrates how direct measurement of thermal diffusivity can be
carried out in thin films of interest in a simple and elegant manner using PA techniques.
Although results of only representative measurements viz; thermal diffusivity values in
Indium, Aluminium, Silver and CdS thin films are given here, evaluation of this
quantity for any photonic and / electronic material can be carried out using this
technique in a very simple and straight forward manner.
Description:
International School of Photonics,Cochin University of Science and Technology
Jasmine, Koshy; Dr.Padma, Nambisan(Cochin University Of Science And Technology, December 3, 2012)
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Abstract:
Commercially, Pleurotus spp. of mushroom are cultivated in bags. After mushroom cultivation, spent substrate remains as residual material. Proper recycling of spent substrate is beneficial for our economy. Spent substrate can be utilized for various other value added purposes through the proper knowledge of its components. Composition of various components depends on the activity of extracellular enzymes in the spent substrate. The present study was conducted to know the enzyme profile of some major extracellular enzymes - cellulase, hemicellulase (xylanase), pectinase and ligninase (lignin peroxidase and laccase) and to estimate cellulose, hemicellulose, pectin and lignin in the substrate. The use of spent substrate as a source of fibre and ethanol, and in the biodegradation of phenol by Pleurotus spp. was also investigated
Description:
Department of Biotechnology, Cochin University of Science and Technology
Balasubramani, N; Dr.Pillai, U T S(National Institute for Interdisciplinary Science and Technology (CSIR), 2009)
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Abstract:
MAGNESIUM ALLOYS have strong potential for weight reduction in a wide
range of technical applications because of their low density compared to other structural
metallic materials. Therefore, an extensive growth of magnesium alloys usage in the
automobile sector is expected in the coming years to enhance the fuel efficiency through
mass reduction. The drawback associated with the use of commercially cheaper Mg-Al
based alloys, such as AZ91, AM60 and AM50 are their inferior creep properties above
100ºC due to the presence of discontinuous Mg17A112 phases at the grain boundaries.
Although rare earth-based magnesium alloys show better mechanical properties, it is not
economically viable to use these alloys in auto industries. Recently, many new Mg-Al
based alloy systems have been developed for high temperature applications, which do not
contain the Mg17Al12 phase. It has been proved that the addition of a high percentage of
zinc (which depends upon the percentage of Al) to binary Mg-Al alloys also ensures the
complete removal of the Mg17Al12 phase and hence exhibits superior high temperature
properties.ZA84 alloy is one such system, which has 8%Zn in it (Mg-8Zn-4Al-0.2Mn, all
are in wt %) and shows superior creep resistance compared to AZ and AM series alloys.
These alloys are mostly used in die casting industries. However, there are certain large
and heavy components, made up of this alloy by sand castings that show lower
mechanical properties because of their coarse microstructure. Moreover, further
improvement in their high temperature behaviour through microstructural modification is
also an essential task to make this alloy suitable for the replacement of high strength
aluminium alloys used in automobile industry. Grain refinement is an effective way to
improve the tensile behaviour of engineering alloys. In fact, grain refinement of Mg-Al
based alloys is well documented in literature. However, there is no grain refiner
commercially available in the market for Mg-Al alloys. It is also reported in the literature
that the microstructure of AZ91 alloy is modified through the minor elemental additions
such as Sb, Si, Sr, Ca, etc., which enhance its high temperature properties because of the formation of new stable intermetallics. The same strategy can be used with the ZA84
alloy system to improve its high temperature properties further without sacrificing the
other properties. The primary objective of the present research work, “Studies on
grain refinement and alloying additions on the microstructure and
mechanical properties of Mg-8Zn-4Al alloy” is twofold:
1. To investigate the role of individual and combined additions of Sb and Ca on
the microstructure and mechanical properties of ZA84 alloy.
2. To synthesis a novel Mg-1wt%Al4C3 master alloy for grain refinement of
ZA84 alloy and investigate its effects on mechanical properties.
Maya,K S; Dr.Rani,Joseph(Cochin University of Science & Technology, July , 2007)
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Abstract:
Precipitated silica is the most promising alternative for carbon black in tyre tread compounds due to its improved performance in terms of rolling resistance and wet grip.But its poor processability is a serious limitation to its commercial application.This thesis suggests a novel route for the incorporation of silica in rubbers,i.e.,precipitation of silica in rubber latex followed by coagulation of the latex to get rubber-silica maseterbatch.Composites with in situ precipitated silica showed improved processability and mechanical properties,when compared to conventional silica composites.
Description:
Department of Polymer Science and Rubber
Technology, Cochin University of Science and Technology
Shylaraj, K S; Dr.Chandrasekaran,M(Cochin University of Science And Technology, August 27, 1998)
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Abstract:
In the light of the very huge demand for natural ephedrine and
pseudoephidrine, a search for an angiosperm plant containing the alkaloid ephedrine
was made and could locate Sida spp. of malvaceae family. Sida is a large genus of,
herbs and shrubs distributed throughout the tropics. About a dozen species occur in
India. The medicinally important species known are S.rhombrfolia S.cordata and
S.spinosa (Anon, 1972). Among the various species, S.rh0mbIfolia is the most widely
used one in the traditional system of medicine. An attempt was made in the present
study to develop an ideal bioprocess for the in vitro production of ephedrine from the
cell culture system of Sida rhombrfolia Linn. ssp. retusa. The callus and suspension
culture were initiated and attempts were made to enhance the yield positively by
employing various strategies like mutagenesis, immobilization and addition of
precursors, elicitors and penneabilizing agents.
Description:
Department of Biotechnology
Cochin University of Science and Technology
Bindhu, C V; Dr.Girijavallabhan,C P(Cochin University of Science and Technology, June 22, 1998)
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Abstract:
In the pre—laser era it was difficult to believe that the optical properties of a medium
depend upon the intensity of the radiation incident on it. The basis for this conclusion is
that the electric field strength associated with the conventional light sources used before
the advent of lasers was much smaller than (103 V/cm) the field sttrengths of atomic or
interatomic fields (2 107 —- 10” V/cm). The radiation with such low intensity is not able
to affect atomic fields to the extent of changing optical parameters. The invention of laser
in 1960 was a turning point. The high degree of coherence of the laser radiation provides
high spatial concentration of optical power. With the availability of the femtosecond lasers
it has become possible to get extremely high peak powers 2 1013 W/cmz). At such high
fields, the relationship between electric ‘polarization P and the electric field strength E ceases
to be linear and several nonlinear effects begin to occur. Nonlinear absorption, a branch
of nonlinear optics, refers to the interaction between radiation and matter accompanied by
absorption of more than one photon. Nonlinear absorption has acquired great importance
after the invention of high power lasers.
One of the objectives of the present work is to investigate the nonlinear absorption processes
occurring in fullerene, selected organic solvents and laser dyes. Fullerenes and laser
dyes were chosen because of their highly nonlinear behaviour. Fullerenes, the most beautiful
among molecules, offer fascinating field of research owinglto their significant structural
properties. As toluene, benzene and carbon disulphide are themost widely used solvents for
fullerenes, it seems important to study the nonlinear properties of these liquids as well. Like
fullerenes, laser dyes also possess highly delocalized 7r electrons which are responsible for their
nonlinear absorption. Dye lasers were the fulfillment of an experimenter’s pipe dream - to
have a laser that is easily tunable over a wide range of wavelengths. A better understandingof the photophysical properties of laser dyes can significantly enhance the development and
technology of dye lasers. We studied the nonlinear absorption properties of two rhodamine
dyes to have some insight into their nonlinear optical properties.
Description:
International School of Photonics, Cochin University of Science & Technology
Lailamma,Jose; Dr.Rani,Joseph(Cochin University of Science and Technology, January 30, 1996)
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Abstract:
The main objective of the present study was to
explore ways of making latex products more cost effective
and versatile. Polyethylene glycol was identified as a
surface active agent in latex compounds which improves the
filler-polymer interaction and also distributes the filler
more uniformly. The use of such surface active agents can
develop filled latex products with improved mechanical
properties at a lower cost. In this study dispersions of carbon black and silica were successfully added to NR latex under high speed stirring without destabilizing latex.
Description:
Department
of Polymer Science and Rubber Technology, Cochin University of Science and Technology
Mary,Joseph; Dr.George, K E(Cochin University of Science and Technology, March 19, 1998)
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Abstract:
The primary aim of this work has been to develop a cost effective
process that can be operated at room temperature for developing latex
reclaim with superior mechanical properties. With this objective in mind
the researcher proposes to study the reclaiming action of four different chemicals on
latex products waste. Waste latex products are chosen because it has a
higher potential to generate good quality rubber hydrocarbon since all
latex products are based on either high quality concentrated latex or
creamed latex. Moreover, all latex products are only lightly crosslinked
and not masticated and hence not mechanically degraded. The author also
proposes to fully explore the possible application of latex reclaim in various
fields..
Description:
Department of Polymer
Science and Rubber Technology, Cochin University of
Science and Technology
Madhavan Nanpoothiri, K; Dr.Ashok, Pandey(Cochin University Of Science And Technology, July 8, 1997)
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Abstract:
The thesis comprises a set of experiments mainly focused on the
improvement of L-glutamic acid fennentation. Much attention has been given to
use of locally available raw materials, culturing the organism on inert solid
substrates and also immobilization of the bacterial cells from the view point of long
term utilization of biocatalyst and continuous operation of the stabilized system.
Studies were also carried out for the down stream processing for the extraction and
purification of L-glutamic acid. An attempt was made to study the morphological
features of the microorganism including the cell premeability. In relation with the
accumulation of glutamic acid within the cells an approach was made to study the
behaviour of the Brevibacterium cells when they are exposed to hyper osmotic
environment. Attempts were also made to study the requirement of iron and
production of siderophores by this microbial strain. The search for a suitable
nitrogen source for glutamate fermentation ended with a promising result that they
got a potent urease activity and it can be utilized for many biotransfonnation
studies.
The entire thesis is presented in three sections, viz. introductory section,
experimental section and the concluding section
Description:
Department Of Biotechnology,Cochin University Of Science And Technology
Sunny, M C; Dr.George, K E(Cochin University of Science & Technology, July , 2006)
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Abstract:
Plasticized poly(vinyl chloride) (pPVC), although a major player in the medical field, is at present facing lot of criticism due to some of its limitations like the leaching out of the toxic plasticizer, di ethylhexyl phthalate (DEHP) to the medium and the emission of an environmental pollutant,dioxin gas,at the time of the post use disposal of PVC Products by incineration. Due to these reasons, efforts are on to reduce the use of pPVC considerably in the medical field and to find viable alternative materials. The present study has been undertaken in this context to find a suitable material for the manufacture of medical aids in place of pPVC. The main focus of this study has been to find out a non-DEHP material as plasticizer for pPVC and another suitable material for the complete repalcement of pPVC for blood/ blood component storage applications.Two approaches have been undertaken for this purpose-(1)the controversial plasticizer, DEHP has been partially replaced by polymeric plasticizers(2) an alternative material, namely, metallocene polyolefin (mPO) has been used and suitably modified to match the properties of flexible PVC used for blood and blood component storage applications.
Description:
Department of Polymer Science and
Rubber Technology, Cochin University of Science and Technology