Results 1 - 5 of 5
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[en] Most current non-contact-atomic force microscopy (nc-AFM) techniques rely on vibrating the measuring lever at resonance using amplitudes that are large compared to typical interaction length scales. Here we present results of simulations that show that off-resonance, small amplitude AFM provides an alternative non-contact technique in which force gradients can be measured directly without the need of mathematical de-convolution. We show that under a wide range of reasonable conditions the measurements are linear and quantitative
[en] Nanofluids exhibit some intriguing thermal properties, and have great potential to increase efficiency in various heat technological applications in micro- and nano-technology. Recent studies on mass transport in nanofluids yielded some interesting but controversial results. In this communication, we report the tracer diffusion of fluorescent dye in different nanofluids. Measurements were performed using fluorescence correlation spectroscopy (FCS). Nanoparticle concentration in the nanofluid varied up to 1.7 vol%, and the diffusion coefficient of fluorescent dye was measured. Our results showed no significant changes in diffusion of dyes in the concentration range used, and the results indicate that more research is needed to completely understand the diffusion in nanofluids. This communication brings upon the powerful FCS technique for the first time to study the dynamics of nanofluids.
[en] Molecular motors are the workhorses of living cells. Seemingly by ‘magic’, these molecules are able to complete purposeful tasks while being immersed in a sea of thermal chaos. Here, we review the current understanding of how these machines work, present simple models based on thermal ratchets, discuss implications for statistical physics, and provide an overview of ongoing research in this important and fascinating field of study. (key issues review)
[en] The viscous behavior of liquids under nanoconfinement is not well understood. Using a small-amplitude atomic force microscope, we found bulk-like viscosity in a nanoconfined, weakly interacting liquid. A further decrease in viscosity was observed at confinement sizes of a just few molecular layers. Overlaid over the continuum viscous behavior, we measured non-continuum stiffness and damping oscillations. The average stiffness of the confined liquid was found to scale linearly with the size of the confining tip, while the damping scales with the radius of curvature of the tip end
[en] Electrochemical deposition of metals onto foreign substrates usually occurs through Volmer-Weber island growth. The mechanism of island nucleation and growth dictates the shape, orientation and number density of islands, and ultimately, the structure and properties of thin films. With increasing emphasis on deposition of ultrathin films and nanostructures, it is critically important to understand the kinetics of nucleation and growth. Here we provide a comprehensive review of island growth in electrodeposition and summarize methods for mechanistic analysis in both the kinetic and diffusion limited regimes. (topical review)