We report the observation of remarkable water molecule-induced stiffening in ZnO nanobelts using atomic force microscopy three-point bending test. It was found that the elastic modulus of ZnO nanobelts could increase significantly from 40 GPa under ambient condition up to 88 GPa at the relative humidity level of 80%. The physical mechanism for this phenomenon was explained in terms of increasing surface stress induced by water molecule adsorption on ZnO nanobelt surface. Our first-principles density functional theory calculations revealed that the water molecules adsorbed on the ZnO surface would attract surface Zn atoms to move outward and hence increase the value of surface stress of ZnO surface. For more details, please see 

Dear iMechanicas,

I just started doing nanoindentation tests on dry biological samples (wood) with a flat punch tip and I have problems analyzing the results! I would be happy if anybody could give me some suggestions.

While running a test I receive quiet good force-displacement curves (no adhesion, good surface find, no time-depend behavior) but the values for the recieved elastic modulus are not stable! The value scatters over the whole range of displacement.

And sometimes the curve for the Phase angle is not like usual. Sometimes it just shows a wild zick-zack pattern.

Unfortunaltely I have no one to ask at my institute :(

Dear friends,

I want to share our recent research work on NiAl nanowire, which is published in Nanotechnology, IOP publishing. The abstract of the paper is given below. Further details can be found at "Vijay Kumar Sutrakar et al 2009 Nanotechnology 20 295705 (9pp)   doi: 10.1088/0957-4484/20/29/295705"

Can we map the eastic modulus of a and c domians? Can we mechanically switch the domains and let them function as nanoactuators and sensors?