Susarla, Raghuram; Dr.Anil, Bhardwaj(Cochin University Of Science And Technology, July , 2013)
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Abstract:
Comets are the spectacular objects in the night sky since the dawn of mankind. Due to
their giant apparitions and enigmatic behavior, followed by coincidental calamities, they
were termed as notorious and called as `bad omens'. With a systematic study of these
objects modern scienti c community understood that these objects are part of our solar
system. Comets are believed to be remnant bodies of at the end of evolution of solar
system and possess the material of solar nebula. Hence, these are considered as most
pristine objects which can provide the information about the conditions of solar nebula.
These are small bodies of our solar system, with a typical size of about a kilometer
to a few tens of kilometers orbiting the Sun in highly elliptical orbits. The solid body
of a comet is nucleus which is a conglomerated mixture of water ice, dust and some
other gases. When the cometary nucleus advances towards the Sun in its orbit the ices
sublimates and produces the gaseous envelope around the nucleus which is called coma.
The gravity of cometary nucleus is very small and hence can not in
uence the motion
of gases in the cometary coma. Though the cometary nucleus is a few kilometers in size
they can produce a transient, extensive, and expanding atmosphere with size several
orders of magnitude larger in space. By ejecting gas and dust into space comets became
the most active members of the solar system. The solar radiation and the solar wind
in
uences the motion of dust and ions and produces dust and ion tails, respectively.
Comets have been observed in di erent spectral regions from rocket, ground and
space borne optical instruments. The observed emission intensities are used to quantify
the chemical abundances of di erent species in the comets. The study of various physical
and chemical processes that govern these emissions is essential before estimating chemical
abundances in the coma. Cameron band emission of CO molecule has been used to derive
CO2 abundance in the comets based on the assumption that photodissociation of CO2
mainly produces these emissions. Similarly, the atomic oxygen visible emissions have
been used to probe H2O in the cometary coma. The observed green ([OI] 5577 A) to
red-doublet emission ([OI] 6300 and 6364 A) ratio has been used to con rm H2O as the
parent species of these emissions. In this thesis a model is developed to understand the
photochemistry of these emissions and applied to several comets. The model calculated
emission intensities are compared with the observations done by space borne instruments
like International Ultraviolet Explorer (IUE) and Hubble Space Telescope (HST) and
also by various ground based telescopes.
Description:
Space Physics Laboratory
Vikram Sarabhai Space Centre
Indian Space Research Organisation
Thiruvananthapuram
Pravinkumar,P A; Dr.Nair, K G(Cochin University of Science and Technology, March 18, 1985)
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Abstract:
With the advent of satellite communication and radio astronomy, the need for large and efficient reflector antennas had triggered a widespread investigation in reflector feed design techniques. Major improvements sought are reduction in spill-over, cross polarization losses and the enhancement of aperture efficiency. The search for such a feed culminated in the corrugated horn. The main idea behind the present work is to use the H-plane sectoral horns fitted with,corrugated flanges as feeds of a paraboloid and see how the secondary pattern
of the reflector antenna varies with different parameters of the feed. An offset paraboloid is used as the secondary reflector in order to avoid the adverse effect of aperture ‘blocking by the feed horn structure on the secondary radiation pattern. The measurements were repeated for three
different H-plane sectoral horns with the same set of corrugated flanges at various X-band frequencies. The following parameters of the whole system are studied: (a) Beam shaping. (b) Gain. (c) Variation of VSWR and (d) Cross polarization
Description:
Department of Physics, Cochin University of Science and Technology
Seena, E B; Dr.Prathapachandra Kurup,M R(Cochin University of Science and Technology, August 16, 2006)
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Abstract:
The work embodied in the thesis is divided into eight chapters. Chapter I gives a
brief introduction about metal complexes of thiosemicarbazones, including their
structural and bonding properties. Chapter 2 deals with the synthesis and single crystal
X-ray diffraction studies of various thiosemicarbazones used up for the present
investigations and various characterization techniques. Chapter 3 deals with synthesis,
spectral and structural studies of Cu(U) complexes with ONS donor thiosemicarbazones.
Chapter 4 deals with synthesis and spectral studies of Ni(II) complexes \vith
2-hydroxyacetophenone N(4)-cyclohexyl thiosemicarbazone as the ligand. Chapter 5
includes synthesis and spectral studies of Mn(II) complexes. Chapter 6 deals with
synthesis, spectral and structural studies of Zn(II) complexes. Chapter 7 includes
synthesis and spectral studies of oxovanadium(IV) complexes. Chapter 8 deals with
synthesis, spectral and single crystal X-ray diffraction studies of dioxomolybdenum(VI)
complexes.
Description:
Department of Applied Chemistry, Cochin University of Science and
Technology
Renuka, T R; Paulose,C S(DEPARTMENT OF BIOTECHNOLOGY, June , 2003)
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Abstract:
The present work is an attempt to understand the role of acetylcholine
muscarinic M1 and M3 receptors during pancreatic regeneration and insulin
secretion. The work focuses on the changes in the muscarinic M1 and M3 receptors
in brain and pancreas during pancreatic regeneration. The effect of these receptor
subtypes on insulin secretion and pancreatic P-cell proliferation were studied in vitro
using rat primary pancreatic islet culture. Muscarinic Ml and M3 receptor kinetics
and gene expression studies during pancreatic regeneration and insulin secretion will
help to elucidate the role of acetylcholine functional regulation of pancreatic u-cell
proliferation and insulin secretion.The cholinergic system through muscarinic M1
and M3 receptors play an important role in the regulation of pancreatic (3-cell
proliferation and insulin secretion . Cholinergic activity as indicated by acetylcholine
esterase, a marker for cholinergic system, decreased in the brain regions -
hypothalamus, brain stem, corpus striatum, cerebral cortex and cerebellum during
pancreatic regeneration. Pancreatic muscarinic M1 and M3 receptor activity increased during proliferation indicating that both receptors are stimulatory to (3-cell division. Acetylcholine dose dependently increase EGF induced DNA synthesis in pancreatic islets in vitro, which is inhibited by muscarinic antagonist atropine confirming the role of muscarinic receptors. Muscarinic M1 and M3 receptor antagonists also block acetycholine induced DNA synthesis suggesting the importance of these receptors in regeneration. Acetylcholine also stimulated glucose induced insulin secretion in vitro which is inhibited by muscarinic M1 and M3 receptor antagonists. The muscarinic receptors activity and their functional balance in the brain and pancreas exert a profound influence in the insulin secretion and also regeneration of pancreas
Savitha, Balakrishnan; Dr. Paulose, C S(Cochin University of Science and Technology, January , 2008)
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Abstract:
The present study describes that acetylcholine through muscarinic Ml and
M3 receptors play an important role in the brain function during diabetes as a function
of age. Cholinergic activity as indicated by acetylcholine esterase, a marker for
cholinergic function, decreased in the brain regions - the cerebral cortex, brainstem
and corpus striatum of old rats compared to young rats. in diabetic condition, it was
increased in both young and old rats in cerebral cortex, and corpus striatum while in
brainstem it was decreased. The functional changes in the muscarinic receptors were
studied in the brain regions and it showed that muscarinic M I receptors of old rats
were down regulated in cerebral cortex while in corpus striatum and brainstem it was
up regulated. Muscarinic M3 receptors of old rats showed no significant change in
cerebral cortex while in corpus striatum and brainstem muscarinic receptors were
down regulated. During diabetes, muscarinic M I receptors were down regulated in
cerebral cortex and brainstem of young rats while in corpus striatum they were up
regulated. In old rats, M I receptors were up regulated in cerebral cortex, corpus
striatum and in brainstem they were down regulated. Muscarinic M3 receptors were
up regulated in cerebral cortex and brainstem of young rats while in corpus striatum
they were down regulated. In old rats, muscarinic M l receptors were up regulated in
cerebral cortex, corpus striatum and brainstem. In insulin treated diabetic rats the
activity of the receptors were reversed to near control. Pancreatic muscarinic M3
receptor activity increased in the pancreas of both young and old rats during diabetes.
In vitro studies using carbachol and antagonists for muscarinic Ml and M3 receptor
subtypes confirmed the specific receptor mediated neurotransmitter changes during
diabetes. Calcium imaging studies revealed muscarinic M I mediated Ca2
+ release
from the pancreatic islet cells of young and old rats. Electrophysiological studies
using EEG recording in young and old rats showed a brain activity difference during diabetes. Long term low dose STH and INS treated rat brain tissues were used for
gene expression of muscarinic Ml, M3, glutamate NMDARl, mGlu-5,alpha2A, beta2,
GABAAa1 and GABAB, DAD2 and 5-HT 2C receptors to observe the neurotransmitter
receptor functional interrelationship for integrating memory, cognition and
rejuvenating brain functions in young and old. Studies on neurotransmitter receptor
interaction pathways and gene expression regulation by second messengers like IP3
and cGMP in turn will lead to the development of therapeutic agents to manage
diabetes and brain activity.From this study it is suggested that functional improvement of
muscarinic Ml, M3, glutamate NMDAR1, mGlu-5, alpha2A, beta2, GABAAa1 and GABAB,
DAD2 and 5-HT 2C receptors mediated through IP3 and cGMP will lead to therapeutic
applications in the management of diabetes. Also, our results from long term low dose
STH and INS treatment showed rejuvenation of the brain function which has clinical
significance in maintaining healthy period of life as a function of age.
Description:
Department of Biotechnology,
Cochin University of Science and Technology
Sherin, Antony; Dr. Paulose, C S(Cochin University of Science & Technology, May , 2010)
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Abstract:
In the present study, a detailed investigation on the alterations of
muscarinic M1, M3, α7 nicotinic acetylcholine receptor (α7 nAchR), GABA
receptors and its subtypes; GABAAα1 and GABAB in the brain regions of
streptozotocin induced diabetic and insulin induced hypoglycemic rats were
carried out. Gene expression of acetylcholine esterase (AChE), choline
acetyltransferase (ChAT), GAD, GLUT3, Insulin receptor, superoxide dismutase
(SOD), Bax protein, Phospholipase C and CREB in hypoglycemic and
hyperglycemic rat brain were studied. Muscarinic M1, M3 receptors, AChE,
ChAT, GABAAα1, GABAB, GAD, Insulin receptor, SOD, Bax protein and
Phospholipase C expression in pancreas was also carried out. The molecular
studies on the CNS and PNS damage will elucidate the therapeutic role in the
corrective measures of the damage to the brain during hypoglycemia and
hyperglycemia.
Description:
Department of Biotechnology,Cochin University of Science and Technology
Gireesh,G; Dr. Paulose, C S(Cochin University of Science & Technology, January , 2007)
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Abstract:
The present work is to understand the alterations of total Muscarinic and
Muscarinic MI receptors in brain and pancreatic islets of Streptozotocin induced
diabetic rats. The work focuses on the evaluation of the antihyperglycemic activity
of aqueous extracts of Aegle marmelose and Costus pictus leaves in vivo and the
changes in the total Muscarinic and Muscarinic MI receptors during diabetes and
after the treatment with insulin. The insulin secretory activity of Aegle marmelose
and Costus pictus leaf extracts and the effect of cholinergic receptor agonist were
investigated in vitro using rat primary pancreatic islet culture. Muscarinic MI
receptor kinetics and gene expression during diabetes and regulation of insulin
secretion by Aegle marmelose and Costus pie/us leaf extracts will help us to
elucidate the role of Muscarinic and Muscarinic MI receptors in hyperglycemia
and the regulatory activity of these plant extracts on insulin secretion through
Muscarinic receptors.
Description:
Department of
Biotechnology, Cochin University of Science and Technology
Reas Khan, S; Dr. Paulose, C S(Cochin University of Science and Technology, April , 2007)
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Abstract:
The present work is to understand the alterations of total muscarinic.
muscarinic MI and glutamate receptors in the brain regions of pilocarpine induced
epileptic rats. The work focuses on the evaluation of the anti epileptic activity of
extracts of Bacopa monnieri, Bacoside A and Carbamazepine in vivo. The
molecular changes in the muscarinic M I receptors in the pre- and post-treated
epileptic model with Bacopa monnieri, Bacoside A and Carbamazepine were also
studied. These studies will help us to elucidate the functional role of muscarinic
and glutamate receptors in epilepsy.
Description:
Department of Biotechnology, Cochin University of
Science and Technology
Radhakrishnan, P; Dr.Sathianandan, K(Cochin University of Science and Technology, April 30, 1985)
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Abstract:
Laser-induced damage is the principal limiting constraint in the design and operation of high-power laser systems used in fusion and other high-energy laser applications. Therefore, an understanding of the mechanisms which cause the radiation damage to the components employed
in building a laser and a knowledge of the damage threshold of these materials are of great importance in designing a laser system and to operate it without appreciable degradation in performance. This thesis, even though covers three distinct problems for investigations using a dye Q-switched multimode Nd:glass laser operating at 1062 nm and emitting 25 ns (FWHM) pulses, lays its main thrust on damage threshold studies on thin films. Using the same glass
laser two-photon excited fluorescence in rhodamine 6G and generation and characterisation of a carbon plasma have also been carried out. The thesis is presented in seven chapters.
Description:
Department of Physics, Cochin university of Science and Technology
Radhakrishnan, P; Dr.Sathianandan, K(Cochin University Of Science And Technology, April 30, 1985)
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Abstract:
Laser-induced damage is the principal limiting
constraint in the design and operation of high-power laser
systems used in fusion and other high-energy laser applications.
Therefore, an understanding of the mechanisms
which cause the radiation damage to the components employed
in building a laser and a knowledge of the damage threshold
of these materials are of great importance in designing a
laser system and to operate it without appreciable degradation
in performance. This thesis, even though covers
three distinct problems for investigations using a dye
Q-switched multimode Nd:glass laser operating at 1062 nm
and emitting 25 ns (FWHM) pulses, lays its main thrust on
damage threshold studies on thin films. Using the same glass
laser two-photon excited fluorescence in rhodamine 6G and
generation and characterisation of a carbon plasma have also
been carried out.
Description:
Department of Physics, Cochin University Of Science And Technology
Anitha, M; Dr. Paulose, C S(Cochin University of Science and Technology, July , 2012)
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Abstract:
This thesis Entitled Neuronal degeneration in streptozotocin induced diabetic rats: effect of aegle marmelose and pyridoxine in pancreatic B cell proliferation and neuronal survival. Diabetes mellitus, a chronic metabolic disorder results in neurological dysfunctions and structural changes in the CNS. Antioxidant therapy is a challenging but necessary dimension in the management of diabetes and neurodegenerative changes associated with it. Our results showed regional variation and imbalance in the expression pattern of dopaminergic receptor subtypes in diabetes and its role in imbalanced insulin signaling and glucose regulation. Disrupted dopaminergic signaling and increased hyperglycemic stress in diabetes contributed to the neuronal loss. Neuronal loss in diabetic rats mediated through the expression of pattern of GLUT-3, CREB, IGF-1, Akt-1, NF,B, second messengers- cAMP, cGMP, IP3 and activation of apoptotic factors factors- TNF-a,caspase-8. Disrupted dopaminergic receptor expressions and its signaling in pancreas contributed defective insulin secretion in diabetes. Activation of apoptotic factors- TNF- a,caspase-8 and defective functioning of neuronal survival factors, disrupted second messenger signaling modulated neuronal viability in diabetes. Hyperglycemic stress activated the expression of TNF-a,caspase-8, BAX and differential expression of anti oxidant
enzymes- SOD and GPx in liver lead to apoptosis. Treatment of diabetic rats with insulin, Aegle marmelose and pyridoxine significantly reversed the altered dopaminergic neurotransmission, GLUT3, GLUT2, IGF-1 and second messenger signaling. Antihyperglycemic and antioxidant activity of Aegle marmelose and pyridoxine enhanced pancreatic B cell proliferation, increased insulin synthesis and secretion in diabetic rats. Thus our results conclude the neuroprotective and regenerating ability of Aegle marmelose and pyridoxine which in turn has a novel therapeutic role in the management of diabetes.
Description:
Center for neuroscience, Department of Biotechnology, Cochin University of Science and Technology