Surendran,K P; Bijumon, P V; Mohanan, P; Sebastian,M T(Department of Electronics, April 14, 2005)
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Abstract:
The MgAl2O4 ceramics were prepared by the conventional
solid-state ceramic route and the dielectric properties
studied in the microwave frequency region (3–13 GHz).
The phase purity and crystal structure were identified using
the X-ray diffraction technique. The MgAl2O4 spinel ceramics
show interesting microwave dielectric properties (εr = 8.75,
Qux f = 68 900 GHz (loss tangent = 0.00017 at 12.3 GHz),
τf =−75 ppm/◦C). The MgAl2O4 has high negative τf, which
precludes its immediate use in practical applications. Hence
the microwave dielectric properties of MgAl2O4 spinels were
tailored by adding different mole fractions of TiO2. The
εr and Q factor of the mixed phases were increased with
the molar addition of TiO2 into the spinel to form mixtures
based on (1−x)MgAl2O4-xTiO2 (x = 0.0−1.0). For x = 0.25 in (1−x)MgAl2O4-xTiO2, the microwave quality factor
reaches a maximum value of Qux f = 105 400 GHz (loss tangent
= 0.00007 at 7.5 GHz) where εr and τf are 11.035 and
−12 ppm/◦C, respectively. The microwave dielectric properties
of the newly developed 0.75MgAl2O4-0.25TiO2 dielectric is
superior to several commercially available low loss dielectric
substrates.
Roshini, Thumpakara K; Dr.Prathapan, S(Cochin University of Science & Technology, November , 2007)
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Abstract:
The synthesis and reactions of simple derivatives of 2(3H)- and 3(2H)furanones
have attracted considerable attention in recent years, primarily in
connection with development of routes to antitumor agents that contain this
ring as central structural unit. They also serve as useful synthetic building
blocks for lactones and furans and are the precursors of a wide variety of
biologically important heterocyclic systems. Although a number of syntheses
of furanones were known they were in many cases limited to specific
substitution pattems. The development of altemative strategies for the
preparation of these heterocycles is therefore of considerable importance or
continues to be a challenge.We propose to develop new and general approaches to the synthesis of
furanone ring systems from simple and readily available starting materials
since we were interested in examining their rich photochemistry. The
photochemical reactivity of Beta,gama-unsaturated lactams and lactones is a subject of current interest. Some of the prominent photoreaction pathways of
unsaturated lactones include decarbonylation, solvent addition to double
bonds, decarboxylation, migration of aryl substituents and dimerisation. lt
was reported earlier that the critical requirement for clean photochemical
cleavage of the acyl-oxygen bond is the presence ofa double bond adjacent to
the ether oxygen and 2(3H)-furanones possessing this structural requirement
undergo facile decarbonylation. But related phenanthrofuranones are isolated
as photostable end products upon irradiation. Hence we propose to synthesis a
few phenanthro-2(3H)-furanones to study the effect of a radical stabilising
group at 3-position of furanone ring on photolysis. To explore the tripletmediated
transformations of 2(3H)-furanones in polar and nonpolar solvents a
few 3,3-bis(4-chlorophenyl)-5-aryl-3H-furan-2-ones and 3,3-di(p-tolyl)-5-aryl-
3H-furan-2-ones were synthesised from the corresponding
dibenzoylstyrene precursors by neat thermolysis. Our aim was to study the
nature of intermediates involved in these transformations.We also explored the possibility of developing a new and general
approach to the synthesis of 3(2H)-furanones from simple and readily
available starting materials since such general procedures are not available.
The protocol developed by us employs readily available phenanthrenequinone
and various 4-substituted acetophenones as starting materials and provides
easy access to the required 3(2H)-furanone targets. These furanone
derivatives have immense potential for further investigations .We also aimed the synthesis of a few dibenzoylalkene-type systems
such as acenaphthenone-2—ylidene ketones and phenanthrenone-9-ylidene
ketones. These systems were expected to undergo thermal rearrangement to
give furanones and spirofuranones. Also these systems can be categorised as
quinonemethides which are valuable synthetic intermediates.
Description:
Department of Applied Chemistry, Cochin University of Science
and Technology
Pyroja, S; Paulose,C S(Department of Biotechnology, Faculty of Science, April , 2002)
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Abstract:
The work is an attempt to understand the role of 5-HT, 5-HT1A and 5-HT2C receptors in the regulation of liver cell proliferation using in vivo and in vitro models. The work also focuses on the brain serotonergic changes associated with hapatocyte proliferation and apoptosis to delineate its regulatory function. The investigation of mechanisms involving different models of hepatocyte proliferation contributes to our knowledge about serotonergic regulation of cell growth, apoptosis and carcinogenesis of liver. The study reveals that the alteration of the 5-HT1A and 5-HT2C receptor function and gene expression in the brain stem, cerebral cortex and hypothalamus play an important role in the sympathetic regulation of cell proliferation, neoplastic transformation and apoptosis. The functional balance between 5-HT1A and 5-HT2C receptor plays an important role in regulating hepatocyte proliferation, neoplastic transformation and hepatic apoptosis. The regulatory role of 5-HT1A and 5-HT2C receptor during neoplastic transformation and apoptosis could lead to possible therapeutic intervention in the treatment of cancers and have immense clinical importance.
Baby,Jacob; Dr.Sankaranarayanan, K C(Cochin University of Science and Technology, March 1, 1985)
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Abstract:
An attempt is made to identify the causes for the decline of Kerala’s agricultural export performance. The study evaluates the policies of the government and programmes of the organization assigned with the task of development of export trade of specific commodities. The researcher recommends a plan of action with long term perspective and suggests appropriate strategies for the export development of the traditional and nontraditional agricultural items. T he thesis also review trends in the world trade of the major exports from Kerala
Description:
Department of Applied Economics, Cochin University of Science and Technology