URI: | http://dyuthi.cusat.ac.in/purl/1083 |
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Sreedharan Nair M N 1982.pdf | (107.8Kb) |
Abstract: | This thesis is devoted to theoretical studies on the properties of hadrons on the basis of bag models. It contains some applications of the traditional.HIT bag model to the spectroscopy and decay of hadrons. The inadequacies of the model are brought out and a new version of the model, called the variable pressure bag model, is developed. Some of the Phenomenological applications of this model are discussed and the predictions are compared with experiment. |
Description: | Department of Physics, Cochin University of Science & Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3337 |
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Dyuthi-T1323.pdf | (6.568Mb) |
Abstract: | Semiconductor photocatalysis has received much attention during last three decades as a promising solution for both energy generation and environmental problems. Heterogeneous photocatalytic oxidation allows the degradation of organic compounds into carbon dioxide and water in the presence of a semiconductor catalyst and UV light source. The •OH radicals formed during the photocatalytic processes are powerful oxidizing agents and can mineralise a number of organic contaminants. Titanium dioxide (TiO2), due to its chemical stability, non-toxicity and low cost represents one of the most efficient photocatalyst. However, only the ultraviolet fraction of the solar radiation is active in the photoexcitation processes using pure TiO2 and although, TiO2 can treat a wide range of organic pollutants the effectiveness of the process for pollution abatement is still low. A more effective and efficient catalyst therefore must be formulated. Doping of TiO2 was considered with the aim of improving photocatalytic properties. In this study TiO2 catalyst was prepared using the sol-gel method. Metal and nonmetal doped TiO2 catalysts were prepared. The photoactivity of the catalyst was evaluated by the photodegradation of different dyes and pesticides in aqueous solution. High photocatalytic degradation of all the pollutants was observed with doped TiO2. Structural and optical properties of the catalysts were characterized using XRD, BET surface area, UV-Vis. DRS, CHNS analysis, SEM, EDX, TEM, XPS, FTIR and TG. All the catalysts showed the anatase phase. The presence of dopants shifts the absorption of TiO2 into the visible region indicating the possibility of using visible light for photocatalytic processes. |
Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3687 |
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Dyuthi-T1653.pdf | (3.853Mb) |
Abstract: | To meet the challenges related to the chemical industry,development of efficient catalysts is necessary.The mesoporous materials like SBA-15 are considered as good catalyst candidates of 21st century.SBA-15 mesoporous materials are catalytically inactive,but allow the dispersion of catalytically active phases into the framework.So these materials can be considered as an interesting alternative for preparing catalytically active metal nanoparticles in-situ into it.In the present work various transition metals are incorporated to improve the catalytic activity of SBA-15 material.The fundamental aspects of the preparation,characterization and the activity studies are briefly viewed in this thesis. Systematic investigation of the physico-chemical properties and catalytic activity studies of the prepared materials were carried out and presented in this Study. |
Description: | Department of Applied Chemistry,Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2787 |
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Dyuthi-T0808.pdf | (4.177Mb) |
Abstract: | Scientists throughout the world are in search of a better methodology to reduce the use of environmentally hazardous chemicals common in industries .A significant contribution in this field is given by different redox catalysts in oxidation reactions. The oxidation of organic substrates represents one of the most important industrial chemical reactions, explaining the significant efforts invested in the research and development of new heterogeneous catalysts with increased activities and selectivities in these type reactions[l-4|. Hence liquid phase reactions like epoxidation of cylcohexene and hydroxylation of phenol were carried out with a new outlook in the challenge using CeO2/TiO;; and CuO/TiO2 catalysts denoted as TiO2-Ce as TiO2-Cu respectively in this work. Also different wt% of metals incorporated titania catalysts like 3, 6, 9 wt% CeO2/TiO; and CuO/TiO;were subjected to the present study .The interaction between metal oxides and the oxide supports have attracted much attention because of the wide applications of supported metal oxide systems[7,8]. It is well known that supported oxides of transition metals are widely used as catalysts for various reactions. Titania as well its metal modified catalysts systems afford high activity and selectivity in the liquid phase epoxidation of cyclohexene[9]. Cyclohexene epoxide is obtained as the major product during the reaction with small amounts of allylic substitution products.This chapter gives an idea about the liquid phase oxidation reactions like epoxidation of cylcohexene and hydroxylation of phenol in which many industrially important products are formed. Here discusses about the redox properties of the ceria and copper incorporated titania catalysts.The epoxidation of cyclohcxene is carried out efficiently over the prepared systems with the selective formation of cyclohexane epoxide. This reaction hints that it might be possible to create cleaner nylon chemistry. The total acidity of the prepared systems plays an important role in determining the catalytic activity in the dehydrogenation of cyclohexane and cyclohexene. The total acidity of the prepared systems plays an important role in determining the catalytic activity in the dehydrogenation of cyclohexane and cyclohexene. |
Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3068 |
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Dyuthi-T1042.pdf | (10.05Mb) |
Abstract: | The present project was a systematic investigation of the physico-chemical properties and catalytic activity of some transition metal promoted sulphated zirconia systems. The characterisation and catalytic activity results were compared with that of pure Zr02 and simple sulphated zirconia systems. Sulphated zirconia samples were prepared by a controlled impregnation technique. In the case of metal incorporated systems, a single step impregnation was carried out using required amounts of sulphuric acid and metal salt solutions. As a preliminary step, optimisation of calcination temperature and sulphate content was achieved. For further studies, the optimised sulphate loading of 10 ml per gram of hydrous zirconium oxide and a calcination temperature of 700°C was employed. Metal incorporation had a positive influence on the physico-chemical properties. Vapour phase cumene conversion served as a test reaction for acidity. Some industrially important reactions like Friedel-Crafts reaction, phenol hydroxylation, nitration, etc. were selected to test the catalytic activity of the prepared systems. |
Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2254 |
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Dyuthi-T0572.pdf | (9.474Mb) |
Abstract: | Catalysis is an essential technology in manufacturing industries. The investigation based on supported vanadia catalysts and it’s sulfated analogues. Vanadia is a transition metal oxide and is used in oxidation reactions in chemical industry. It is more active and selective catalysts on suitable supports. The work deals with preparation of vanadia incorporated tin oxide and zirconia systems by wet impregnation. Physico-chemical characterization using instrumental techniques like BET etc. The surface acidic properties were determined by the ammonia TPD studies, Perylene absorption studies and Cumene conversion reaction. The catalytic activities of the prepared systems are tested by Friedel-Crafts benzylation of arenes and Bechmann rearrangement of Cyclohexanol oxime. Here the rector reactions are relatively rare. So to test the application of the catalyst systems for the selective oxidation of cyclohexanol to cyclohexanone and finally evaluate the catalytic activity of the systems for the vapour phase oxidative dehydrogenation of Ethylbenzene, which leads to the formation of Industrially important compound ‘styrene’ is another objective of this work |
URI: | http://dyuthi.cusat.ac.in/purl/20 |
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Dyuthi-T0020.pdf | (11.65Mb) |
Abstract: | The main goal of this thesis is to study the dynamics of Josephson junction system in the presence of an external rf-biasing.A system of two chaotically synchronized Josephson junction is studied.The change in the dynamics of the system in the presence of at phase difference between the applied fields is considered. Control of chaos is very important from an application point of view. The role Of phase difference in controlling chaos is discussed.An array of three Josephson junctions iS studied for the effect of phase difference on chaos and synchronization and the argument is extended for a system of N Josephson junctions. In the presence of a phase difference between the external fields, the system exhibits periodic behavior with a definite phase relationship between all the three junctions.Itdeals with an array of three Josephson junctions with a time delay in the coupling term. It is observed that only the outer systems synchronize while the middle system remain uncorrelated with t-he other two. The effect of phase difference between the applied fields and time-delay on system dynamics and synchronization is also studied. We study the influence of an applied ac biasing on a serniannular Josephson junction. It is found the magnetic field along with the biasing induces creation and annihilation of fluxons in the junction. The I-V characteristics of the junction is studied by considering the surface loss term also in the model equation. The system is found to exhibit chaotic behavior in the presence of ac biasing. |
Description: | Department of Physics, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2904 |
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Dyuthi-T0900.pdf | (4.928Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1018 |
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Lucy Joseph 1988.pdf | (259.8Kb) |
Abstract: | Ion-exchange chromatography has emerged as a practical and rapid method of separation and analysis. A review of literature on chelating resins reveals that eventhough investigations on highly selective resins are intensively pursued from early 1940s, such resins are still insufficiently used in analytical chemistry and process technology. This is mainly due to the complexity of their synthesis and high cost. In this context, it is worthwhile to develop novel chelating resins which are specific or at least selective towards a group of metal ions. Synthesis, characterization and analytical applications of two such resins are presented in this thesis. |
Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3614 |
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Dyuthi-T1572.pdf | (4.488Mb) |
Abstract: | Chemical bath deposition (CBD)is one of the simplest, very convient and probably the cheapest method for thin film preparation. Photovoltaic is the cleanest and the most efficient mode of conversion of energy to electrical power. Silicon is the most popular material in this field. The present study on chemical bath deposited semiconducting copper selenide and iron sulfide thin films useful for photovoltaic applications. Semiconducting thin films prepared by chemical deposition find applications as photo detectors, solar control coatings and solar cells. Copper selenide is a p-type semiconductor that finds application in photovolitics. Several heterojunction systems such as Cu2-xSe/ZnSe (for injection electro luminescence), Cu2Se/AgInSe2 and Cu2Se/Si (for photodiodes), Cu2-xSe/CdS, Cu2-xSe/CdSe, CuxSe/InP and Cu2-xSe/Si for solar cells are reported. A maximum efficiency of 8.3% was achieved for the Cu2-xSe/Si cell, various preparation techniques are used for copper selenide like vacuum evaporation, direct reaction, electrodeposition and CBD. Instability of the as-prepared films was investigation and is accounted as mainly due to deviation from stoichiometry and the formation of iron oxide impurity. A sulphur annealing chamber was designed and fabricated for this work. These samples wee also analysed using optical absorption technique, XPS (X-ray Photoelectron Spectroscopy) and XRD.(X-Ray Diffraction).The pyrite films obtained by CBD technique showed amorphous nature and the electrical studies carried out showed the films to be of high resistive nature. Future work possible in the material of iron pyrite includes sulphur annealing of the non-stochiometric iron pyrite CBD thin films in the absence of atmospheric oxygen |
URI: | http://dyuthi.cusat.ac.in/purl/941 |
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Dyuthi-T0021.pdf | (10.53Mb) |
Description: | Department of Mathematics, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2349 |
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Dyuthi-T0621.pdf | (503.3Kb) |
Description: | Theory Division Department of Physics |
URI: | http://dyuthi.cusat.ac.in/purl/5016 |
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Dyuthi-T2083.pdf | (3.615Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1601 |
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Dyuthi-T0022.pdf | (3.541Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1659 |
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Dyuthi-T0023.pdf | (3.315Mb) |
Abstract: | Cosmology deals with the studies on the structure and evolution of the universe. The model of the universe formulated by Friedmann, Lemaitre, Robertson andWalker known as the standard model (FLRW model) of the universe, which is based on the Einstein's theory of gravity, turned out to be the accepted model because of the various observational supports. The major observational supports to this model are the explanation for the Hubble's law, primordial nucleosynthesis, microwave back ground radiation etc. Recent observations on Type Ia supernovae by teams led by S Perlmutter, Brian P Schmidt and Adam G Riess led to the discovery that the present universe is expanding in an accelerated manner. The exotic form of matter which causes the acceleration is termed as dark energy which produce negative pressure. Understanding the nature and evolution of dark energy is a challenge for the cosmologists. In addition to the evidences from supernovae, the anisotropy in CMBR spectra, large scale structures and Baryon acoustic oscillations are also supporting the discovery. To explain dark energy, various theoretical models have been proposed. One such model is the CDM model, in which the universe is assumed to be composed of dark energy and dark matter. In this model, Einstein's cosmological constant is considered as dark energy. It has a constant equation of state; ! = p = 1: The model predicts the values of cosmological parameters such as the Hubble parameter, transition redshift and present deceleration parameter, having a very good agreement with the observational constraints. But this model has two major aws, which are: 1. Cosmological constant problem:- Theoretically predicted value of dark energy density as the vacuum constant is, 1074GeV 4; while the observed value is 1047GeV 4: The predicted value is greater than the observed value by 120 orders of magnitude. This discrepancy between the theoretical and observational values is known as the cosmological constant problem. 2. Cosmological coincidence problem:- Energy densities of dark energy and dark matter are found to be of the same order even though their evolutionary nature are di erent. This is known as the coincidence problem which is not explained by the CDM model. These led to the proposals of dynamical dark energy models by considering that the equation of state parameter is evolving with the expanding universe. Scalar models of dark energy such as Quintessence, K-essence, Phantom model, Chaplygin gas model and holographicdark energy model are examples of dynamic dark energy models. Holographic dark energy model is based on the holographic principle developed by Susskind and 't Hooft. The principle says that the degrees of freedom of a system resides on its surface rather than in its volume. The total energy inside a region of size L must not exceed the mass of a black hole of the same size. The holographic dark energy density can then be formulated as, = 3c2M2 plL2 (1) where 3c2 is a numerical constant, M2 pl = 8 G is the reduced Planck mass. Possible choices for L; the IR cut-o , are Hubble horizon, particle horizon and event horizon. The choices for the IR cut-o whether it be Hubble horizon or particle horizon will not support an accelerating universe, while the third choice, the event horizon, violates causality. Another alternative for the IR cut-o is the Ricci scalar, which was rst introduced by Gao et al. Later modi ed holographic Ricci dark energy was proposed by Granda and Oliveros. In the present thesis, the modi ed Ricci dark energy is studied by considering its interaction with the dark matter present in the universe. Owing to the lack of knowledge about the microscopic origin of such an interaction, phenomenological interaction forms of nongravitational nature is assumed. |
URI: | http://dyuthi.cusat.ac.in/purl/5163 |
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Dyuthi-T2197.pdf | (2.575Mb) |
Abstract: | the thesis entitled “STUDIES ON DEVELOPING A FACILE ROUTE FOR THE SYNTHESIS OF HIGHLY SUBSTITUTED QUINOLINE AND INDOLE DERIVATIVES” portrays our attempt to revisit the mechanism of 1,3- dipolar additions with a view to establishing whether it follows a concerted pathway or a stepwise reaction sequence through the formation of a zwitterionic intermediate, which will definitely contribute to the better use of this technique. Furthermore, we propose to develop novel routes for the synthesis of quinoline and indole derivatives with predefined substitution pattern. The thesis is devided into four chapters |
Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3745 |
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Dyuthi-T1708.pdf | (4.224Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5280 |
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Dyuthi T-2316.pdf | (7.804Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5317 |
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Dyuthi T-2353.pdf | (10.52Mb) |
URI: | http://dyuthi.cusat.ac.in/xmlui/purl/1982 |
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Dyuthi-T0460.pdf | (7.131Mb) |
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