Ultrahigh torsional stiffness and strength of boron nitride nanotubes.

We report the experimental and theoretical study of boron nitride nanotube (BNNT) torsional mechanics. We show that BNNTs exhibit a much stronger mechanical interlayer coupling than carbon nanotubes (CNTs). This feature makes BNNTs up to 1 order of magnitude stiffer and stronger than CNTs.

Thermal fluctuation spectroscopy of DNA thermal denaturation.

We have developed the technique of thermal fluctuation spectroscopy to measure the thermal fluctuations in a system. This technique is particularly useful to study the denaturation dynamics of biomolecules like DNA. Here we present a study of the thermal fluctuations during the thermal denaturation (or melting) of double-stranded DNA.

Torsional stick-slip behavior in WS2 nanotubes.

We experimentally observed atomic-scale torsional stick-slip behavior in individual nanotubes of tungsten disulfide (WS2). When an external torque is applied to a WS2 nanotube, all its walls initially stick and twist together, until a critical torsion angle, at which the outer wall slips and twists around the inner walls, further undergoing a series of stick-slip torque oscillations. We present a theoretical model based on density-functional-based tight-binding calculations, which explains the torsional stick-slip behavior in terms of a competition between the effects of the in-plane shear stiffness of the WS2 walls and the interwall friction arising from the atomic corrugation of the interaction between adjacent WS2 walls.

Thermal fluctuations in histone during denaturation.

In this paper, we address the issue of thermal fluctuations during the thermal denaturation of linker histone H1 which is the basic ingredient of chromatin assembly. We measure the thermal fluctuations using a sensitive nanocalorimeter based thermal fluctuation measurement set up which can measure fluctuations of the order of 1 part per billion. We find that the denaturation of the linker histone is not a simple process.

Direct observation of large temperature fluctuations during DNA thermal denaturation.

In this Letter, we report direct measurement of large low frequency temperature fluctuations in double stranded DNA when it undergoes a denaturation transition. The fluctuation, which occurs only in the temperature range where the denaturation occurs, is several orders more than the expected equilibrium fluctuation. It is absent in single stranded DNA of the same sequence.