Nify, Benny; Dr. Sujatha, C H(Cochin University of Science and Technology, June , 2009)
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Abstract:
The thesis deals with a benchmark study of dissolved and sedimentary sulphur
compounds which play prominent roles in the prevailing redox conditions in the
selected sites of Cochin estuarine system. Sulphur and its analogues play prominent
roles in estuarine biochemical processes. A complete knowledge on the sulphur
involvement in these processes is restricted due to the lacking of data on the organic
sulphur compounds. Sulphate and sulphide in surface and bottom water and
Sulphate, acid volatile sulphide and total sulphur in sediments were studied and
correlated to know their interrelations in determining the redox condition of the
environment. It also characterises the sediments of the sites on the basis of total
organic carbon: total sulphur ratio. The study had attempted to decrease the
concentration levels of sulphur in the sedimentary environment by the application of
a remedial measure. Knowledge of sulphur uptake by plants from prior literatures
has prompted to use phytoremediation for decreasing the sulphur concentration.
Phytoremediation is an emerging technology that uses plants to clean up or remediate
contaminated soil, sludges, sediments, and ground water through contaminant
removal, degradation or containment. The plant selected was wheat grass since
earlier studies have shown that wheat grass is effective in remediating pollutants
particularly trace metals. So reduction in the concentration of selected trace metals
was also focussed.
Description:
Department of Chemical Oceanography, Cochin University of Science and Technology
Veena Gopalan, E; Dr. Anantharaman, M R(Cochin University of Science & Technology, June , 2009)
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Abstract:
This thesis lays importance in the preparation and characterization of a
few selected representatives of the ferrite family in the nanoregime. The candidates being manganese zinc ferrite and cobalt ferrite prepared by coprecipitation
and sol-gel combustion techniques respectively. The thesis not only
stresses importance on the preparation techniques and optimization of the reaction
conditions, but emphasizes in investigating the various properties namely
structural, magnetic and electrical. Passivated nickel nanocomposites are
synthesized using polystyrene beads and adopting a novel route of ion exchange
reduction. The structural and magnetic properties of these magnetic
nanocomposites are correlated. The magnetocaloric effect (MCE) exhibited by
these materials are also investigated with a view to finding out the potential of
these materials as magnetic refrigerants. Calculations using numerical methods
are employed to evaluate the entropy change on selected samples.
Description:
Department of Physics,
Cochin University of Science & Technology
Parvathi, M R; Bindu M, Krishna; Rajesh, S; Manu P, John; Nandakumaran, V M(Elsevier, October , 2009)
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Abstract:
Dynamics of Nd:YAG laser with intracavity KTP crystal operating in two parallel polarized modes is investigated analytically and numerically. System equilibrium points were found out and the stability of each of them was checked using Routh–Hurwitz criteria and also by calculating the eigen values of the Jacobian. It is found that the system possesses three equilibrium points for (Ij, Gj), where j = 1, 2. One of these equilibrium points undergoes Hopf bifurcation in output dynamics as the control parameter is increased. The other two remain unstable throughout the entire region of the parameter space. Our numerical analysis of the Hopf bifurcation phenomena is found to be in good agreement with the analytical results. Nature of energy transfer between the two modes is also studied numerically.