STUDIES ON THE PHYSIOLOGICAL AND BIOCHEMICAL ASPECTS OF OSMOREGULATION IN TWO INTERTIDAL BIVALVE MOLLUSCS

Division of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology

STUDIES ON SOME ASPECTS OF REPRODUCTION OF FEMALE ANABAS TESTUDINEUS ( BLOCH )

Department of Marine Biology, Microbiology and Biochemistry

Chelating behavior of acylhydrazones towards transition metals:Spectral and structural aspects

The current work deals with the synthesis and characterization of metal complexes derived from some substituted acylhydrazones. The hydrazones under investigation were characterized by IR, UV, NMR spectral studies and the molecular structure of one of the hydrazones was solved by single crystal XRD studies. In the present work dioxovanadium(V), manganese(II), cobalt(II/III), nickel(II), copper(II), zinc(II) and cadmium(II) complexes were synthesized and characterized by various spectroscopic techniques, molar conductance measurements, magnetic susceptibility measurements and cyclic voltammetry. Single crystals of some of the complexes were isolated and characterized by single crystal X-ray diffraction.The thesis is divided into eight chapters. Chapter 1 gives an introduction on hydrazones, diversity in their chelating behavior and their application in various fields. This chapter also describes different analytical techniques employed for the characterization of hydrazones and their metal complexes. Chapter 2 includes the synthesis and characterization of two substituted acylhydrazones. This chapter also discusses how the coordination behavior of hydrazones under investigation is interesting. Chapters 3-8 discuss the synthesis and characterization of some transition metal complexes derived from the acylhydrazones under study.The hydrazones synthesized were found to exist in the amido form. Various characterization techniques were carried out to explore the structure of the synthesized complexes. The results indicate that both the hydrazones coordinate through the pyridyl and azomethine nitrogens and amide oxygen either in enolate or neutral form. Out of synthesized complexes V(V), Zn/Cd(II) and one of the cobalt complex was found to diamagnetic. We could isolate single crystals of some of the complexes and most of the complexes crystallized were found to have a distorted octahedral geometry. Thus X-ray crystallographic study which was used as major tool in the structure determination revealed that the hydrazones undergo a rotation about the azomethine bond on complexation. We hope the work presented in the thesis would be helpful for those who are working in the field of metal complexes and can further they can be utilized for various applications.

Studies on Some Aspects of Light Beam Propagation Through Certain Nonlinear Media

This thesis deals with the study of light beam propagation through different nonlinear media. Analytical and numerical methods are used to show the formation of solitonS in these media. Basic experiments have also been performed to show the formation of a self-written waveguide in a photopolymer. The variational method is used for the analytical analysis throughout the thesis. Numerical method based on the finite-difference forms of the original partial differential equation is used for the numerical analysis.In Chapter 2, we have studied two kinds of solitons, the (2 + 1) D spatial solitons and the (3 + l)D spatio-temporal solitons in a cubic-quintic medium in the presence of multiphoton ionization.In Chapter 3, we have studied the evolution of light beam through a different kind of nonlinear media, the photorcfractive polymer. We study modulational instability and beam propagation through a photorefractive polymer in the presence of absorption losses. The one dimensional beam propagation through the nonlinear medium is studied using variational and numerical methods. Stable soliton propagation is observed both analytically and numerically.Chapter 4 deals with the study of modulational instability in a photorefractive crystal in the presence of wave mixing effects. Modulational instability in a photorefractive medium is studied in the presence of two wave mixing. We then propose and derive a model for forward four wave mixing in the photorefractive medium and investigate the modulational instability induced by four wave mixing effects. By using the standard linear stability analysis the instability gain is obtained.Chapter 5 deals with the study of self-written waveguides. Besides the usual analytical analysis, basic experiments were done showing the formation of self-written waveguide in a photopolymer system. The formation of a directional coupler in a photopolymer system is studied theoretically in Chapter 6. We propose and study, using the variational approximation as well as numerical simulation, the evolution of a probe beam through a directional coupler formed in a photopolymer system.

Dynamical aspects of coupled Rossler systems: effects of noise

Nonlinear time series analysis is employed to study the complex behaviour exhibited by a coupled pair of Rossler systems. Dimensional analysis with emphasis on the topological correlation dimension and the Kolmogorov entropy of the system is carried out in the coupling parameter space. The regime of phase synchronization is identified and the extent of synchronization between the systems constituting the coupled system is quantified by the phase synchronization index. The effect of noise on the coupling between the systems is also investigated. An exhaustive study of the topological, dynamical and synchronization properties of the nonlinear system under consideration in its characteristic parameter space is attempted.

A Study on the Transport and Distribution of Atmospheric Aerosols and its Influence on Regional Meteorological Parameters over the Indian Subcontinent

This doctoral thesis addresses the growing concern about the significant changes in the climatic and weather patterns due to the aerosol loading that have taken place in the Indo Gangetic Plain(IGP)which includes most of the Northern Indian region. The study region comprises of major industrial cities in India (New Delhi, Kanpur, Allahabad, Jamshedpur and Kolkata). Northern and central parts of India are one of the most thickly populated areas in the world and have the most intensely farmed areas. Rapid increase in population and urbanization has resulted in an abrupt increase in aerosol concentrations in recent years. The IGP has a major source of coal; therefore most of the industries including numerous thermal power plants that run on coal are located around this region. They inject copious amount of aerosols into the atmosphere. Moreover, the transport of dust aerosols from arid locations is prevalent during the dry months which increase the aerosol loading in theatmosphere. The topography of the place is also ideal for the congregation of aerosols. It is bounded by the Himalayas in the north, Thar Desert in the west, the Vindhyan range in the south and Brahmaputra ridge in the east. During the non‐monsoon months (October to May) the weather in the location is dry with very little rainfall. Surface winds are weak during most of the time in this dry season. The aerosols that reach the location by means of long distance transport and from regional sources get accumulated under these favourable conditions. The increase in aerosol concentration due to the complex combination of aerosol transport and anthropogenic factors mixed with the contribution from the natural sources alters the optical properties and the life time of clouds in the region. The associated perturbations in radiative balance have a significant impact on the meteorological parameters and this in turn determines the precipitation forming process. Therefore, any change in weather which disturbs the normal hydrological pattern is alarming in the socio‐economic point of view. Hence, the main focus of this work is to determine the variation in transport and distribution of aerosols in the region and to understand the interaction of these aerosols with meteorological parameters and cloud properties.

Studies on Some Aspects of Landings,Utilization and Export of Commercially Important Cephalopods

In the present study two aspects of cephalopod fishery such as (i) landings and (ii) utilization including export of cephalopods from Indian are dealt with. Under the topic landings, craft, both traditional and mechanized and fishing techniques employed for capturing cephalopods are discussed. General trend in cephalopod landing in India and particularly south west coast, species composition, description and geographic distribution of important species of cuttle fishes, squids and octopus and the distribution and abundance of cephalopods along the continental shelf of the south west coast are also discussed. Some biological aspects like population parameters, maturation and spawning, food and feeding of the two representive species of cuttle fishes and squid viz, Sepia pharaonis and Loligo duvauceli are studied.Under utilization, general handling and processing of various frozen cephalopods products for exports and commercial operation in a typical plant are studied. The export of cephalopod products since its commencement is studied in detail and market strategy for enhancing the export are suggested.

Weather and climate of Penisular India modulated by Extrinsic factors- Empirical and Numerical Perspectives

The Doctoral thesis focuses on the factors that influence the weather and climate over Peninsular Indias. The first chapter provides a general introduction about the climatic features over peninsular India, various factors dealt in subsequent chapters, such as solar forcing on climate, SST variability in the northern Indian Ocean and its influence on Indian monsoon, moisture content of the atmosphere and its importance in the climate system, empirical formulation of regression forecast of climate and some aspects of regional climate modeling. Chapter 2 deals with the variability in the vertically integrated moisture (VIM) over Peninsular India on various time scales. The third Chapter discusses the influence of solar activity in the low frequency variability in the rainfall of Peninsular India. The study also investigates the influence of solar activity on the horizontal and vertical components of wind and the difference in the forcing before and after the so-called regime shift in the climate system before and after mid-1970s.In Chapter 4 on Peninsular Indian Rainfall and its association with meteorological and oceanic parameters over adjoining oceanic region, a linear regression model was developed and tested for the seasonal rainfall prediction of Peninsular India.

Seasonal and interannual variability of sea level and associated surface meteorological parameters at Cochin

This thesis entitled seasonal and interannual variability of sea level and associated surface meteorological parameters at cochin.The interesting aspect of studying sea level variability on different time scales can be attributed to the diversity of its applications.Study of tides could perhaps be the oldest branch of physical oceanography.The thesis is presented in seven chapters. The first chapter gives, apart from a general introduction, a survey of literature on sea level variability on different time scales - tidal, seasonal and interannual (geological scales excluded), with particular emphasis on the work carried out in the Indian waters. The second chapter is devoted to the study of observed tides at Cochin on seasonal and interannual time scales using hourly water level data for the period 1988-1993. The third chapter describes the long-term climatology of some important surface oceanographic and meteorological parameters (at Cochin) which are supposed to affect the sea level. The fourth chapter addresses the problem of seasonal forecasting of the meteorological and oceanographic parameters at Cochin using autoregressive, sinusoidal and exponentially weighted moving average techniques and testing their accuracy with the observed data for the period 1991-1993. The fifth chapter describes the seasonal cycles of sea level and the driving forces at 16 stations along the Indian subcontinent. It also addresses the observed interannual variability of sea level at 15 stations using available multi-annual data sets. The sixth chapter deals with the problem of coastal trapped waves between Cochin and Beypore off the Kerala coast using sea level and atmospheric pressure data sets for the year 1977. The seventh and the last chapter contains the summary and conclusions and future outlook based on this study.

Studies on the, Physical Aspects of the Mud Banks along the Kerala Coast

A detailed survey of the present knowledge on the physical aspects of the mud banks has been presented in chapter 1.The physical geographical and geological aspects of the kerala coast, the shore-line and the sea bed and the various views on the formation,movements and dissipation of the mud banks have been discussed.The scope of the present work and a description of the area of study have also been given in this chapter. The horizontal and vertical distribution and the seasonal variations of the concentration of suspended matter in the mud bank region are discussed in chapter 3.it is seen that the mud bank reses above the bottom in the form of a ridged ,irregular,solid come with a flat top. Chapter vi deals with waves and currents in the region of the mud bank. The orientation of the breakers on either side of the mud bank suggests the possibility of formation of opposing alongshore currents and convergence of energy caused by wave refraction.The distribution of currents during the formative nature and dissipating stages of the mud bank show that the converging alongshore currents give rise to offshore flows