• B ASHOK

      Articles written in Indian Academy of Sciences Conference Series

    • The charged bubble oscillator: Dynamics and thresholds

      B ASHOK THOTREITHEM HONGRAY JANAKI BALAKRISHNAN

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      The nonlinear, forced oscillations of a bubble in a fluid due to an external pressure field are studied theoretically. In the presence of a constant charge on the bubble, the bubble oscillator’s behaviour changes markedly. We report results at significantly higher pressures and forcing frequencies than presented earlier. The influence of the bubble’s ambient radius on thresholds and dynamics is also reported. Charge and pressure thresholds are calculated for the system, delineating different dynamics.

      PACS Nos 05.45.-a; 05.90.+m

    • Tubes and containers at the nano and microscales: Statics and dynamics

      B ASHOK

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      We review how coaxial carbon nanotubes (CNTs) and vesicular nanotubes exhibit nonlinear oscillations and how theoretical models match with experimental observations. In particular, we discuss how coaxial CNTs may be modelled by mechanical analogues with interactions mediated by nonlinear spring forces with weakening elastic constants in addition to a weak van der Waals-like interaction. The model’s predictions are in remarkable agreement with quantum mechanical calculations for the system. Predicted oscillatory frequencies are also in agreement with those reported in the literature. We then discuss our theoretical work on nanotubes in a biological system: Nanotubes that are drawn out from micrometre-scale vesicles and which exhibit very interesting dynamics.Our theoretical model reproduces all aspects of the force–extension curves reported in the experimental literature and completely explains the dynamics of vesicular nanotubulation and force fluctuations. The serrations seen inthe force–extension curves are explained to be a consequence of stick–slip dynamics.

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