Santhosh, Shenoy D; Anantharaman, M R(COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY, July , 2004)
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Abstract:
The present work is an attempt to understand the characteristics of high energy ball milling on the structural, electrical and magnetic properties of some normal spinets in the ultra fine regime, Magnetism and magnetic materials have been a fascinating subject for the mankind ever since the discovery of lodestone. Since then, man has been applying this principle of magnetism to build devices for various applications. Magnetism can be classified broadly into five categories. They are diamagnetic, paramagnetic, ferromagnetic antiferromagnetic and ferrimagnetic. Of these, ferro and ferri magnetic materials assume great commercial importance due to their unique properties like appropriate magnetic characteristics, high resistivity and low eddy current losses. The emergence of nanoscience and nanotechnology during the last decade had its impact in the field of magnetism and magnetic materials too. Now, it is common knowledge that materials synthesized in the nanoregime exhibit novel and superlative properties with respect to their coarser sized counterparts in the micron regime. These studies reveal that dielectric properties can be varied appreciably by high-energy ball milling in nanosized zinc ferrites produced by coprecipitation method. A semi conducting behaviour was observed in these materials with the Oxygen vacancies acting as the main charge carrier for conduction, which was produced at the time of coprecipitation and milling. Thus through this study, it was possible to successfully investigate the finite size effects on the structural, electrical and magnetic properties of normal spinels in the ultra fine regime
Santhakumari, N C; Dr.Girijavallabhan,C P(Cochin University Of Science And Technology, February 15, 1992)
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Abstract:
Solid electrolytes for applications like
chemical sensing, energy storage, and conversion have been
actively investigated and developed since the early
sixties. Although of immense potential, solid state
protonic conductors have been ignored in comparison with
the great interest that has been shown to other ionic
conductors like lithium and silver ion conductors. The
non-availability of good, stable protonic conductors could
be partly the reason for this situation. Although organic
solids are better known for their electrical insulating
character, ionic conductors of organic origin constitute a
recent addition to the class of ionic conductors.
However, detailed studies (N1 such conductors are scarce.
Also the last decade has witnessed an unprecedented boom
in research on organic "conducting polymers". These newly
devised materials show conductivity spanning from
insulator to metallic regimes, which can be manipulated by
appropriate chemical treatment. They find applications in
devices ranging from rechargeable batteries to "smart
windows".
This thesis mainly deals with the synthesis and
investigations on the electrical properties of (i) certain organbc protonic conductors derived from ethylenediamine
and (ii) substituted polyanilines
Description:
Department
of Physics, Cochin University of Science and Technology
Priyesh, K. V.; Dr.Ramesh, Babu T.(Cochin University of Science and Technology, May , 2014)
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Abstract:
The present study described about the interaction of a two level atom and squeezed field with time varying frequency. By applying a sinusoidal variation
in the frequency of the field, the randomness in population inversion is reduced and the collapses and periodic revivals are regained. Quantum optics is an emerging field in physics which mainly deals with the interaction of atoms with quantised electromagnetic fields. Jaynes-Cummings Model (JCM) is a key model among them, which describes the interaction between a two level atom and a single mode radiation field. Here the study begins with a brief history of light, atom and their interactions. Also discussed the interaction between atoms and electromagnetic fields. The study suggest a method to manipulate the population inversion due to interaction and control the randomness in it, by applying a time dependence on the frequency of the interacting squeezed field.The change in behaviour of the population inversion due to the presence of a phase factor in the applied frequency variation is explained here.This study also describes the interaction between two level atom and electromagnetic field in nonlinear Kerr medium. It deals with atomic and field state evolution in a coupled cavity system.
Our results suggest a new method to control and manipulate the population of states in two level atom radiation interaction,which is very essential for quantum information processing.We have also studied the variation of atomic population inversion with time, when a two level atom interacts with light field, where
the light field has a sinusoidal frequency variation with a constant phase. In both coherent field and squeezed field cases, the population inversion variation is completely different from the phase zero frequency modulation case. It is observed that in the presence of a non zero phase φ, the population inversion oscillates sinusoidally.Also the collapses and revivals gradually disappears when φ increases
from 0 to π/2. When φ = π/2 the evolution of population inversion is identical to the case when a two level atom interacts with a Fock state. Thus, by applying a phase shifted frequency modulation one can induce sinusoidal oscillations of atomic inversion in linear medium, those normally observed in Kerr medium.
We noticed that the entanglement between the atom and field can be controlled by
varying the period of the field frequency fluctuations. The system has been solved numerically and the behaviour of it for different initial conditions and different susceptibility values are analysed. It is observed that, for weak cavity coupling the effect of susceptibility is minimal. In cases of strong cavity coupling, susceptibility factor modifies the nature in which the probability oscillates with time. Effect
of susceptibility on probability of states is closely related to the initial state of the system.
Leela, N K; Madhavan Pillai, P; Dr. Vijay Nair, G(Regional Research Laboratory (CSIR), July , 2002)
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Abstract:
In the present scenario, there is an increasing demand for natural products in
food industry, pharmaceuticals, cosmetics and agricultural sectors. In this context
phytochemical study to identify newer chemicals has got great relevance.
Phytochemical studies have become more reliable and encouraging with the
development of modern analytical techniques.In the present work the leaves of Piper colubrinum (Piperaceae), aerial parts
of Mussaenda fiondosa (Rubiaceae) and Humboldtia vahliana (Leguminosae) and
the pericarp of fruits of Artocarpus heterophyllus (Moraceae) were investigated for
their secondary metabolites. The major compounds isolated belong to the groups of
flavonoids and triterpenoids.Naturally occurring flavonoids have been used widely in chemotaxonomic
studies of plants. Flavones and flavonols constitute a group of biosynthetically
related natural products. No universal function has been established for flavones
and flavonols in plants. However, many functions in individual plants have been
demonstrated. These include protection of plants from ultraviolet light, insects and
pests; pollinator attractants; antioxidants; plant hormone controllers; enzyme
inhibitors and allelopathic agents. Flavonoids are attracting the attention of medical
scientists in recent years because of their anticarcinogenic, antiallergic and antiinflammatory
properties. The recent discovery that flavonoids are involved in the
process of nitrogen fixation in plants also opens the way for agricultural application
of these constituents.Triterpenoids are another class of compounds that are ubiquitous in plants.
Some triterpenoids present in the latex and resins of plants are believed to be
involved in chemical defence against pathogens and herbivores. Triterpenoids
possess various biological properties including anti-inflammatory, antifeedant,
pesticidal, fungitoxic and antimicrobial activities. Triterpenoids with cytotoxic
activity and inhibitory effect on seed germination are also known.
Christudhas, Williams B; Dr.Chandrasekaran,M(Cochin University of Science and Technology, August 9, 1999)
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Abstract:
There is no baseline data available at present on the nature of various
diseases that occur in a orchid population, under cultivation, in any commercial
orchid farm maintained by small scale entrepreneurs who invest considerable amount of money, effort and time. The available data on type of disease symptoms, causative agent, , nature of pathogens, as to bacteria or ftmgi or any other biological agents, and their source, appropriate and effective control measures could not be devised, for large scale implementation and effective management, although arbitrary methods are being practiced by very few farms. Further influence of seasonal variations and environmental factors on disease outbreak is also not scientifically documented and statistically verified as to their authenticity.
In this context, the primary objective of the present study was to create a data
bank on the following aspects
1. Occurrence of different disease symptoms in Dendrobium hybrid over a period of one year covering all seasons
2. Variations in the environmental parameters at the orchid farms
3. Variations in the characteristics of water used for irrigation in the selected orchid farm
4. Microbial population associated with the various disease symptoms
5. Isolation and identification of bacteria isolated from diseased plants
6. Statistical treatment of the quantitative data and evolving statistical model
Description:
Department of Biotechnology, Cochin
University of Science and Technology
Maya,K; Seralathan,P(Dept. of Marine Geology and Geophysics,Faculty of Science, March , 2005)
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Abstract:
The present study is an attempt to address issues related to sediment properties like texture, mineralogy and geochemistry as well as water quality of two important rivers of central Kerala-the Periyar and the Chalakudy rivers. The main objectives of the study are to investigate the textural and mineralogical characteristics as well as transportation and depositional mechanisms of the sediments of Periyar and Chalakudy rivers, to find out the geochemical variability of organic carbon, phosphorus and certain major (Na,K,Ca and Mg) and minor/trace(Mn,Pb,Ni,Cr, and Zn) elements in the bulk sediments and mud fraction of these rivers, to evaluate the status of heavy metal pollution registered in the sediments of these rivers, to assess the physico-chemical characteristics and water quality of Periyar and Chalakudy rivers and to estimate the dissolved nutrient flux through the Periyar and Chalakudy rivers into the receiving coastal waters.
The granulometric characteristics as well as statistical parameters of the sediments of Periyar and Chalakudy rivers depend on the flow pattern controlled by the gradient of the terrain. Compared to Periyar, fluctuations in the dispersal of particles are more in Chalakudy river. In Periyar river, the P and Fe in bulk sediments show a positive correlation with C-org, while in Chalakudy river, both the elements are related to THM concentration. In general, C-org, Fe and P Shows an increasing trend downstream. In Periyar river, the P and Fe in bulk sediments show a positive correlation with C-org, while in Chalakudy river, both the elements are related to THM concentration. Among these two rivers, the pollution of water is several fold higher in Periyar river due to influx due to influx of considerable quantity of liquid and solid wastes of industrial/domestic/urban origin. Nutrient analysis reveals 2-3 times increase in N and P during monsoon season whereas SiO2-Si shows a decreasing trend.
Kala, K; Dr. N. Manoj(Cochin University of Science and Technology, July 3, 2016)
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Abstract:
Organic molecules with π-conjugated scaffolds end-capped with electron donor and acceptor groups are widely investigated due to their immense application potentials and hence belong to a promising area of organic chemistry. Donor-acceptor materials have found wide variety of applications such as dyes in dye-sensitised solar cells (DSSCs), organic photovoltaics, organic light emitting diodes, nonlinear optical devices, chemosensors, diagnostic probes and as therapeutic agents. Despite their use in such a wide range of applications, many fundamental properties of donor acceptor materials are still poorly understood. Even simple structural modifications can bring unexpected electronic and photophysical properties and wider understanding of the interaction between donor and acceptor is thus required. Furthermore, many such systems show diversity in properties in solution state or in their condensed state such as crystalline or amorphous forms. For example, some of these molecules show aggregation induced quenching or enhancement in emission in the solid state. Thus, structural motifs that facilitate intermolecular interaction via hydrophobic association, hydrogen bonding or electrostatic effects can lead to excellent control over their supramolecular functions. Some of the important structural types which used as donors are triarylamines, carbazoles, phenothiazine, fluorenes, thiophenes, and oligothiophenes. Strongly electron withdrawing groups or electron deficient heterocyclic systems such as oxadiazoles, diarylborons, quinolines, quinoxalines, thienopyrazines, and benzothiadiazoles, cyanoacetic acid, rhodanine-3-acetic acid, barbituric acid, and thiobarbituric acid etc., have been used as the acceptors in the
design of donor-acceptor systems.
Rekha R mallia; Dr.Prathapan, S(Cochin University of Science and Technology, December , 2007)
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Abstract:
The thesis entitled ‘Studies on the Solvent Dependence in the
Reaction of a Few (Anthracen-9-yl)methylamines and Sulfanes with
Reactive Acetylenes’ is divided into six chapters. ln Chapter l a general
survey of electron transfer reactions, Diels-Alder reactions and Michael-type
additions is presented. A detailed discussion on the synthesis of several
(anthracen-9-yl)methylamines is presented in Chapter 2. In Chapter 3,
results of preliminary photophysical studies on a few (anthracen-9yl)
methylamines are compiled. A detailed discussion on extensive
examination of dependence in the reaction of (anthracen-9-yl)methylamines
with reactive acetylenes is presented Chapter 4. Details on the synthesis and
reaction of a few (anthracen-9-yl)methylsulfanes with DMAD are described in
Chapter 5.