http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/487 2013-05-18T17:16:27Z 2013-05-18T17:16:27Z Reena Mary, A P Narayanan, T N Vijutha, Sunny Sakthikumar, D Yasuhiko, Yoshida Joy, P A Anantharaman, M R http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2964 2012-07-17T20:30:07Z 2010-01-01T00:00:00Z

Synthesis of Bio-Compatible SPION–based Aqueous Ferrofluids and Evaluation of RadioFrequency Power Loss for Magnetic Hyperthermia Reena Mary, A P; Narayanan, T N; Vijutha, Sunny; Sakthikumar, D; Yasuhiko, Yoshida; Joy, P A; Anantharaman, M R Bio-compatible magnetic fluids having high saturation magnetization find immense applications in various biomedical fields. Aqueous ferrofluids of superparamagnetic iron oxide nanoparticles with narrow size distribution, high shelf life and good stability is realized by controlled chemical co-precipitation process. The crystal structure is verified by X-ray diffraction technique. Particle sizes are evaluated by employing Transmission electron microscopy. Room temperature and low-temperature magnetic measurements were carried out with Superconducting Quantum Interference Device. The fluid exhibits good magnetic response even at very high dilution (6.28 mg/cc). This is an advantage for biomedical applications, since only a small amount of iron is to be metabolised by body organs. Magnetic field induced transmission measurements carried out at photon energy of diode laser (670 nm) exhibited excellent linear dichroism. Based on the structural and magnetic measurements, the power loss for the magnetic nanoparticles under study is evaluated over a range of radiofrequencies.

2010-01-01T00:00:00Z Chitra, R N Kuriakose, V C http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2909 2012-05-21T20:30:12Z 2008-01-01T00:00:00Z

Phase synchronization in an array of driven Josephson junctions Chitra, R N; Kuriakose, V C We consider an array of N Josephson junctions connected in parallel and explore the condition for chaotic synchronization. It is found that the outer junctions can be synchronized while they remain uncorrelated to the inner ones when an external biasing is applied. The stability of the solution is found out for the outer junctions in the synchronization manifold. Symmetry considerations lead to a situation wherein the inner junctions can synchronize for certain values of the parameter. In the presence of a phase difference between the applied fields, all the junctions exhibit phase synchronization. It is also found that chaotic motion changes to periodic in the presence of phase differences.

2008-01-01T00:00:00Z Chitra, R N Kuriakose, V C http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2908 2012-05-21T20:30:12Z 2008-01-01T00:00:00Z

Creation and Annihilation of Fluxons in ac‐driven Semi-annular Josephson Junction Chitra, R N; Kuriakose, V C A new geometry (semiannular) for Josephson junction has been proposed and theoretical studies have shown that the new geometry is useful for electronic applications [1, 2]. In this work we study the voltage‐current response of the junction with a periodic modulation. The fluxon experiences an oscillating potential in the presence of the ac‐bias which increases the depinning current value. We show that in a system with periodic boundary conditions, average progressive motion of fluxon commences after the amplitude of the ac drive exceeds a certain threshold value. The analytic studies are justified by simulating the equation using finite‐difference method. We observe creation and annihilation of fluxons in semiannular Josephson junction with an ac‐bias in the presence of an external magnetic field.

2008-01-01T00:00:00Z Chitra, R N Kuriakose, V C http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2907 2012-05-21T20:30:11Z 2008-01-01T00:00:00Z

Phase effects on synchronization by dynamical relaying in delay-coupled systems Chitra, R N; Kuriakose, V C Synchronization in an array of mutually coupled systems with a finite time delay in coupling is studied using the Josephson junction as a model system. The sum of the transverse Lyapunov exponents is evaluated as a function of the parameters by linearizing the equation about the synchronization manifold. The dependence of synchronization on damping parameter, coupling constant, and time delay is studied numerically. The change in the dynamics of the system due to time delay and phase difference between the applied fields is studied. The case where a small frequency detuning between the applied fields is also discussed.

2008-01-01T00:00:00Z