Charlotte,B V; P G Kurup(Department of Physical Oceanography, School of Marine Sciences, 2004)
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Abstract:
The study is undertaken with an objective to investigate the linkage between air-sea fluxes in the Indian Ocean and monsoon forcing. Since the monsoon activity is linked to fluxes, the variability of surface marine meteorological fields under the variable monsoon conditions is also studied. The very objective of the present study is to document various sea surface parameters of the Indian Ocean and to examine the anomalies found in them. Hence it is attempted to relate the anomaly to the variability of monsoon over India, highlighting the occasion of contrasting monsoon periods. The analysis of anomalies of surface meteorological fields such as SST, wind speed and direction, sea level pressure and cloud cover for contrasting monsoons are also studied. During good monsoon years, the pressure anomalies are negative indicating a fall in SLP during pre-monsoon and monsoon months. The interaction of the marine atmosphere with tropical Indian Ocean and its influence on ISMR continue to be an area of active research.
Antu K, Antony; Raghu, K G(Cochin University of Science and Technology, December , 2014)
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Abstract:
Diabetes mellitus is a heterogeneous metabolic disorder characterized by hyperglycemia
with disturbances in carbohydrate, protein and lipid metabolism resulting from defects in
insulin secretion, insulin action or both. Currently there are 387 million people with
diabetes worldwide and is expected to affect 592 million people by 2035. Insulin
resistance in peripheral tissues and pancreatic beta cell dysfunction are the major
challenges in the pathophysiology of diabetes. Diabetic secondary complications (like
liver cirrhosis, retinopathy, microvascular and macrovascular complications) arise from
persistent hyperglycemia and dyslipidemia can be disabling or even life threatening.
Current medications are effective for control and management of hyperglycemia but
undesirable effects, inefficiency against secondary complications and high cost are still
serious issues in the present prognosis of this disorder. Hence the search for more
effective and safer therapeutic agents of natural origin has been found to be highly
demanding and attract attention in the present drug discovery research. The data
available from Ayurveda on various medicinal plants for treatment of diabetes can
efficiently yield potential new lead as antidiabetic agents. For wider acceptability and
popularity of herbal remedies available in Ayurveda scientific validation by the
elucidation of mechanism of action is very much essential. Modern biological techniques
are available now to elucidate the biochemical basis of the effectiveness of these
medicinal plants. Keeping this idea the research programme under this thesis has been
planned to evaluate the molecular mechanism responsible for the antidiabetic property of
Symplocos cochinchinensis, the main ingredient of Nishakathakadi Kashayam, a wellknown
Ayurvedic antidiabetic preparation. A general introduction of diabetes, its
pathophysiology, secondary complications and current treatment options, innovative
solutions based on phytomedicine etc has been described in Chapter 1.
The effect of Symplocos cochinchinensis (SC), on various in vitro biochemical targets
relevant to diabetes is depicted in Chapter 2 including the preparation of plant extract.
Since diabetes is a multifactorial disease, ethanolic extract of the bark of SC (SCE) and its
fractions (hexane, dichloromethane, ethyl acetate and 90 % ethanol) were evaluated by in
vitro methods against multiple targets such as control of postprandial hyperglycemia,
insulin resistance, oxidative stress, pancreatic beta cell proliferation, inhibition of protein
glycation, protein tyrosine phosphatase-1B (PTP-1B) and dipeptidyl peptidase-IV (DPPxxi
IV). Among the extracts, SCE exhibited comparatively better activity like alpha
glucosidase inhibition, insulin dependent glucose uptake (3 fold increase) in L6
myotubes, pancreatic beta cell regeneration in RIN-m5F and reduced triglyceride
accumulation in 3T3-L1 cells, protection from hyperglycemia induced generation of
reactive oxygen species in HepG2 cells with moderate antiglycation and PTP-1B
inhibition. Chemical characterization by HPLC revealed the superiority of SCE over other
extracts due to presence of bioactives (beta-sitosterol, phloretin 2’glucoside, oleanolic
acid) in addition to minerals like magnesium, calcium, potassium, sodium, zinc and
manganese. So SCE has been subjected to oral sucrose tolerance test (OGTT) to evaluate
its antihyperglycemic property in mild diabetic and diabetic animal models. SCE showed
significant antihyperglycemic activity in in vivo diabetic models.
Chapter 3 highlights the beneficial effects of hydroethanol extract of Symplocos
cochinchinensis (SCE) against hyperglycemia associated secondary complications in
streptozotocin (60 mg/kg body weight) induced diabetic rat model. Proper sanction had
been obtained for all the animal experiments from CSIR-CDRI institutional animal ethics
committee. The experimental groups consist of normal control (NC), N + SCE 500 mg/kg
bwd, diabetic control (DC), D + metformin 100 mg/kg bwd, D + SCE 250 and D + SCE
500. SCEs and metformin were administered daily for 21 days and sacrificed on day 22.
Oral glucose tolerance test, plasma insulin, % HbA1c, urea, creatinine, aspartate
aminotransferase (AST), alanine aminotransferase (ALT), albumin, total protein etc. were
analysed. Aldose reductase (AR) activity in the eye lens was also checked. On day 21,
DC rats showed significantly abnormal glucose response, HOMA-IR, % HbA1c,
decreased activity of antioxidant enzymes and GSH, elevated AR activity, hepatic and
renal oxidative stress markers compared to NC. DC rats also exhibited increased level of
plasma urea and creatinine. Treatment with SCE protected from the deleterious alterations
of biochemical parameters in a dose dependent manner including histopathological
alterations in pancreas. SCE 500 exhibited significant glucose lowering effect and
decreased HOMA-IR, % HbA1c, lens AR activity, and hepatic, renal oxidative stress and
function markers compared to DC group. Considerable amount of liver and muscle
glycogen was replenished by SCE treatment in diabetic animals. Although metformin
showed better effect, the activity of SCE was very much comparable with this drug.
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The possible molecular mechanism behind the protective property of S. cochinchinensis
against the insulin resistance in peripheral tissue as well as dyslipidemia in in vivo high
fructose saturated fat diet model is described in Chapter 4. Initially animal were fed a
high fructose saturated fat (HFS) diet for a period of 8 weeks to develop insulin resistance
and dyslipidemia. The normal diet control (ND), ND + SCE 500 mg/kg bwd, high
fructose saturated fat diet control (HFS), HFS + metformin 100 mg/kg bwd, HFS + SCE
250 and HFS + SCE 500 were the experimental groups. SCEs and metformin were
administered daily for the next 3 weeks and sacrificed at the end of 11th week. At the end
of week 11, HFS rats showed significantly abnormal glucose and insulin tolerance,
HOMA-IR, % HbA1c, adiponectin, lipid profile, liver glycolytic and gluconeogenic
enzyme activities, liver and muscle triglyceride accumulation compared to ND. HFS rats
also exhibited increased level of plasma inflammatory cytokines, upregulated mRNA
level of gluconeogenic and lipogenic genes in liver. HFS exhibited the increased
expression of GLUT-2 in liver and decreased expression of GLUT-4 in muscle and
adipose. SCE treatment also preserved the architecture of pancreas, liver, and kidney
tissues. Treatment with SCE reversed the alterations of biochemical parameters, improved
insulin sensitivity by modifying gene expression in liver, muscle and adipose tissues.
Overall results suggest that SC mediates the antidiabetic activity mainly via alpha
glucosidase inhibition, improved insulin sensitivity, with antiglycation and antioxidant
activities.
Priya Rani, M; Dr. Padmakumari Amma, K. P.; Dr. Raghu, K. G.(Cochin University of Science & Technology, June , 2014)
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Abstract:
Plants and microorganisms provide the pharmaceutical industry with some of the most important sources of components for the research of new medications This thesis involves the study of three medicinal plants belonging to three different important families viz, Cyperus rotundus (Cyperaceae), Stereospermum colais (Bignoniaceae) as well as the well known medicinal plant Zingiber officinale (Zingiberaceae) as the third. The first chapter gives an overview of biologically active natural products with special reference to antioxidant, antidiabetic, anti-inflammatory and antimicrobial molecules from terrestrial sources. Chapter 2 of the thesis deals with the isolation of phytochemical constituents of the medicinal plant Cyperus rotundus and its antioxidant and radical scavenging potential. Chapter 3 of the thesis describes the studies on the roots of Stereospermum colais,
A Bignoniaceae plant belonging to the genus Stereospermum which is used extensively. Chapter 3 of the thesis describes the studies on the roots of Stereospermum colais, a Bignoniaceae plant belonging to the genus Stereospermum which is used extensively in Ayurveda. Chapter 4 describes the biological potential of rhizomes of Zingiber officinale. Ethyl acetate extract of ginger (EAG) possessed antioxidant activity as is evident from the results of various in vitro assays compared to other extracts .In conclusion, medicinal plants Cyperus rotundus and Stereospermum colais have been analysed for their phytochemical constituents. Also, the positive results obtained from biological activity studies such as antioxidant, anti-inflammatory and antimicrobial activity on the isolated compounds/extracts add on to the medicinal properties of these plants. Apart from that, ethyl acetate extract of Zingiber officinale (ginger) rhizomes has been shown to have very good biological potential including glucose lowering and adipocyte differentiation inhibitory effect.
Sobha, A; Dr.Syamaprasad,U(Cochin University of Science And Technology, December , 2002)
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Abstract:
It is important that long superconducting tape must have
desired strain tolerance (less reduction of Jc with applied strains) and
stress tolerance (less reduction of JC in applied stresses) for its use as
coils and magnets. Ag addition to the BPSCCO system has many
advantages with its physical and chemical inertness to the system,
reduces the processing temperature, and promotes the grain growth,
grain alignment and connectivity. All these not only enhance the
critical current density of the tapes but also improve the mechanical
properties. But the published results show very much scattering on the
type of Ag additive to be selected, method of addition and its optimum
percentage. Also there are some negative reports in this regard. The
present work has been undertaken to study the effect of silver addition
in different forms (Ag powder, Ag2O, AgNO3) on the superconducting
and mechanical properties of (Bi,Pb)-2223/Ag tapes and to find out a
suitable form of Ag additive and its optimum percentage to have better
superconducting and mechanical properties. Also it is the aim of the
present work is to optimise the process parameters needed to prepare
(Bi,Pb)-2223/Ag multifilamentary tapes of length ~ 12 m in solenoid
and pancake coil forms with good critical current density and
homogeneity of J C along the length of the tapes.
Description:
Department of physics, Cochin University of Science And Technology
Radhakrishnan, M K; Dr.Joy, George(Cochin University of Science And Technology, February , 1981)
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Abstract:
The Thesis consist of the study of the electrical properties of antimony trisulphide films and the electrical behaviour of different metal contacts to antimony trisulphide films. Since the thermal evapouration of the compound antimony trisulphide as such mayresult in nonstoichiometric compound films , sb2s3 films in the present work were mostly prepared by the three temperature method ,keeping the substrate at different temperature ranging from 3031 to 4231 and evapourating antimony and sulphur simultaneously from separate sources.
Description:
Department of Physics, Cochin University of Science And Technology
Urmila, K. S; Dr. Pradeep, B.(Cochin University of Science and Technology, August 6, 2016)
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Abstract:
The use of energy in our day to day life has grown exponentially and
conserving energy to meet the world’s escalating energy demands is the need of
the hour. During the past decade there is a heightened awareness all over the
world that the production costs of energy from coal, oil and natural gas is
increasingly higher and at the same time the energy technologies involving their
use are contributing to a serious rise in the greenhouse gases in the environment
and a consequent global warming. As a result, more attention is focused on the
utilization of clean energy technologies, especially solar energy which has a
great potential to meet a large fraction of world’s energy demands using
photovoltaics (PV). The heart of the PV system that efficiently convert sunlight
directly into electricity through photovoltaic effect is the solar cell - originally
developed for space applications in the 1950s, are now used in consumer
products, mounted on roofs of houses or assembled into large power stations.
Sudha Kartha, C; Pramitha, Vayalamkuzhi; Rani, Joseph; Sreekumar, K(Optical Society of America, June 13, 2011)
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Abstract:
An investigation on the panchromaticity of a silver-doped poly(vinyl alcohol)/acrylamide photopolymer
system is presented in this paper. Frequency-doubled Nd:YAG (532 nm) and Arþ (488 nm) lasers were
used for the characterization of the films. Previous studies using an He–Ne laser (632:8 nm) showed that
plane-wave transmission grating with a high diffraction efficiency of 75% could be stored in the optimized
film. From the present study, it was noted that transmission gratings with 70% diffraction efficiency
could be recorded using Arþ and Nd:YAG lasers, thereby elucidating the possibility of using the developed
photopolymer system as a competent panchromatic recording medium
Joseph, K S; Dr.George, Joy(Cochin University of Science and Technology, 1983)
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Abstract:
In this thesis the preparation and properties of thin films of certain semiconducting sulphides (sulphides of tin, copper and indium) are reported. As single source evaporation does not yield satisfactory films of these compounds for a variety of reasons, reactive evaporation of the metal in a sulphur atmosphere has been used for film preparation. It was found that for each metal sulphide a stoichimetric interval of fluxes and substrate temperature exists for the formation of the compound in accordance with the analysis of Guenther. The first chapter of the thesis gives a resume of the basic principles of semiconductor physics relevant to the work reported here. In the second chapter is discussed in detail the reactive evaporation techniques like ordinary reactive evaporation, activated reactive evaporation and reactive ion plating. Third chapter deals with the experimental techniques used in this study for film preparation and characterization. In the next seven chapters is discussed the preparation and properties of the compound films studied. The last chapter gives a general theory of the formation of compound films in various deposition techniques in terms of the kinetic energy of the film forming particles. It must be mentioned here that this is of fundamental importance to thin film deposition and is virtually untouched in the literature
Description:
Department of Physics, Cochin University of Science and Technology