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 |
URI: | http://dyuthi.cusat.ac.in/purl/3851 |
Files | Size |
---|---|
Dyuthi-T1778.pdf | (5.398Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1693 |
Files | Size |
---|---|
Dyuthi-T0033.pdf | (5.331Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1843 |
Files | Size |
---|---|
Dyuthi-T0203.pdf | (3.638Mb) |
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 |
URI: | http://dyuthi.cusat.ac.in/purl/3483 |
Files | Size |
---|---|
Dyuthi-T1447.pdf | (6.177Mb) |
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 |
URI: | http://dyuthi.cusat.ac.in/purl/3392 |
Files | Size |
---|---|
Dyuthi-T1369.pdf | (9.181Mb) |
Description: | Department of Polymer Science and Rubber Technology, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2695 |
Files | Size |
---|---|
Dyuthi-T0747.pdf | (4.052Mb) |
Abstract: | The thesis deals with the different properties and characteristics of oil of lemon grass.. The oil of lemongrass (Cymbopogon flexuosus) is one of the most important essential oils. It will continue to be one of the "big ten" of our essential oils1. Lemongrass oil is obtained from certain species of grasses of the genus cymbopogon. The genus consists of about 80 species, 10 to 12 of which are known to occur in India. Lemongrass is a stoloniferous plant. The plant grows wild in many tropical andsemitropical parts of Asia, Africa and in parts of Central America and South America. For the extraction of the oil however only cultivated lemongrass is employed. The trade distinguishes two Principal types of lemongrass oil, viz. the East Indian Oil and West Indian Oil. There was much confusion, years ago, about the taxonomy of the plants which yield theEast Indian and West Indian types of lemongrass oil, however Stapf2 ended the long controversy of identifying the plant yielding the East Indian type oil as Cymbopogon flexuosus (D.C.) Stapf and the plant yielding the West Indian type oil as Cymbopogon citrates (D.C.) stapf. The 2 plants have_been named variously also Andropogon nardus var. Flexuosus Hack or A. citratus D.C. respectively |
Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3314 |
Files | Size |
---|---|
Dyuthi-T1314.pdf | (3.994Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1017 |
Files | Size |
---|---|
Pushpakumari K N 1988.pdf | (227.4Kb) |
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 |
URI: | http://dyuthi.cusat.ac.in/purl/3517 |
Files | Size |
---|---|
Dyuthi-T1490.pdf | (7.191Mb) |
Abstract: | Recent studies with prawns indicate that their growth, metamorphosis, maturation and moulting are affected by the typo and level of lipids supplied in the diets. Despite the recognition of the importance of lipids in the diets of prawns there is no information on the essentiality and quantitative lipid requirements of Indian penaeid prawns. Therefore during the present study about 24 laboratory experiments were conducted to determine the essentiality and dietary requirements of total lipids, phoapholipida, fatty acids cholestrol, and to ascertain the nutritional value of natural lipid sources for the larvae, post-larvae tad juveniles of one of the most suitable cultivable species of panaeid prans. All the experiments were conducted in the laboratory following standard procedures, using isonitrogen and approaximately isocaloric purified diets. Changes were made in tha ingridients as required for specific requirements. For the larvae diets of particle size < 37) were fed, For the postlarvae and juveniles pellet feed was given. while data on survival and growth of larvae and pout-larvae 1-10 were recorded, data were collected on the survival, growth, food conversion ratio, protein efficiency ratio and biochemical composition at the body for post-larva 11-25 and juveniles. The influence ot fatty acid pattern of dietary lipid sources on the fatty acids profile of prawns were also studied in the case of juvenile prawns. Analysis of variance andleast significant differences test were employed to determine the significant differences between treatments in the observed parameters with the help of a newlett Packard master computer. |
Description: | Central marine fisheries research institute, Cochin University of Science And Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3297 |
Files | Size |
---|---|
Dyuthi-T1275.pdf | (14.17Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1205 |
Files | Size |
---|---|
Manohar Sivaram Chandge1987.PDF | (403.8Kb) |
URI: | http://dyuthi.cusat.ac.in/purl/2180 |
Files | Size |
---|---|
Dyuthi-T0532.pdf | (3.735Mb) |
Abstract: | The current water treatment technology is oriented towards the removal of contaminants, mostly organic compounds, by activated carbon. Activated carbons are classified as Granular Activated Carbons (GAC) and Powdered Activated Carbons (PAC) on the basis of the particle size of the carbon granules. Powdered carbons are generally less expensive than granular carbon, operating costs with powdered carbon could be lower. Though powdered activated carbon has many advantages over granular carbon, its application in large-scale separation process is limited by difficulty in recovery and regeneration. Deposition of magnetic iron oxide on carbon particles provides a convenient way of recovering the spent carbon from process water. The study deals with the preparation and physico-chemical characterization of magnetic iron oxide loaded activated carbons. The evaluation of absorption properties of magnetic iron oxide loaded activated carbon composites. The target molecules studied were phenol, p-nitro phenol and methylene blue. The feasibility of magnetic separation of iron oxide loaded activated carbons were studied and described in this thesis. |
URI: | http://dyuthi.cusat.ac.in/purl/971 |
Files | Size |
---|---|
Dyuthi-T0035.pdf | (8.577Mb) |
Abstract: | In 1931 Dirac studied the motion of an electron in the field of a magnetic monopole and found that the quantization of electric charge can be explained by postulating the mere existence of a magnetic monopole. Since 1974 there has been a resurgence of interest in magnetic monopole due to the work of ‘t’ Hooft and Polyakov who independently observed that monopoles can exist as finite energy topologically stable solutions to certain spontaneously broken gauge theories. The thesis, “Studies on Magnetic Monopole Solutions of Non-abelian Gauge Theories and Related Problems”, reports a systematic investigation of classical solutions of non-abelian gauge theories with special emphasis on magnetic monopoles and dyons which possess both electric and magnetic charges. The formation of bound states of a dyon with fermions and bosons is also studied in detail. The thesis opens with an account of a new derivation of a relationship between the magnetic charge of a dyon and the topology of the gauge fields associated with it. Although this formula has been reported earlier in the literature, the present method has two distinct advantages. In the first place, it does not depend either on the mechanism of symmetry breaking or on the nature of the residual symmetry group. Secondly, the results can be generalized to finite temperature monopoles. |
Description: | Department of Physics, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3242 |
Files | Size |
---|---|
Dyuthi-T1216.pdf | (2.455Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5259 |
Files | Size |
---|---|
Dyuthi T-2295.pdf | (2.182Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1142 |
Files | Size |
---|---|
Balachandran T 1981.PDF | (327.4Kb) |
Abstract: | Plankton community, drawn from a vary wide variety of animal phyla, formed the basic food supply of marine life and indicators of water mass. The term meroplankton generally referred to that portion of the zooplankton which is transient in nature, remaining rest of their lives in the nektonic or benthic environment. This group was selected for intensive studies, considering the role of meroplankton in the economy of the sea and the scarcity of literature on them from the Indian Ocean. The preser .udy besides providing information regarding the fixation and preservation !e _ iniques and biochemical aspects of tropical meroplankton, also consolidates information regarding their zoogeography in the Indian Ocean region, with a view to amplifying the limited information available from this area. The distribution studies are based on the collections made during the International Indian Ocean Expedition (1960-65), whereas the material for preservation and biochemical studies was collected from the coastal waters during 1968-1978. Salient features:- 2% of formaldehyde buffered with 2% borax, added to the plankton in the ratio of 9:1 was found the best fixative. On fixation the plankton underwent shrinkage due to loss of 15 to 87% water. Addition of antioxidants prevented colour fading. Narcotization by different specific reagents prior to fixation reduced distortions due to violent reaction and improved morphological conditions. One percent formaldehyde solution in sea water buffered with borax or neutralised with calcium carbonate perfectly preserved majority of meroplankton. Equally good was one percent propylene phenoxetol buffered with borax. Biochemical compostion of vaioous taxa showed variations according to their age class, size groups metamorphosing stage, feeding mechanism, type of organism fed and time of collection. General distribution studies of 4 meroplankton taxa - Anthozoan larvae, cirripedia larvae, sipunculoid larvae and gastropod larvae stowed abundance in the coastal areas especially during the SW monsoon period. Based on the larval distribution different zoo-geographical areas in the Indian Ocean are differentiated. |
Description: | School of Marine Science, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3447 |
Files | Size |
---|---|
Dyuthi-T1434.pdf | (11.07Mb) |
Abstract: | Studies on transition metal complexes have achieved a great interest due to their versatile applications.The convenient route for synthesis,the nature of ligands and stability of metal complexes has significant contributions in their applications in medicine,biology,catalysis and photonics.The present work deals wth the synthesis and characterization of metal complexes of some tridentate acylhydrazones .Hydrazones are promising ligands in coordination chemistry with interesting binding modes and applications.The acylhydrazones chosen for the current study are capable of forming complexes in different forms through tautomerism. |
Description: | Department of Applied Chemistry,Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2791 |
Files | Size |
---|---|
Dyuthi-T0812.pdf | (4.912Mb) |
Description: | Dept.of Applied Chemistry, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2153 |
Files | Size |
---|---|
Dyuthi-T0512.pdf | (3.547Mb) |
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 |
URI: | http://dyuthi.cusat.ac.in/purl/2194 |
Files | Size |
---|---|
Dyuthi-T0544.pdf | (8.355Mb) |
Dyuthi Digital Repository Copyright © 2007-2011 Cochin University of Science and Technology. Items in Dyuthi are protected by copyright, with all rights reserved, unless otherwise indicated.