We report a comparative study of the structure and frictional properties of self-assembled monolayers (SAMs) generated by the adsorption of three homologous 17-carbon alkanethiolssheptadecanethiol, 2,2dipentadecyl-1,3-propanedithiol, and 2-pentadecyl-1,3-propanedithiolsonto the surface of Au(111). The structural properties of these SAMs were characterized by atomic force microscopy, surface inf...

We investigated the coordination of fingertip forces in subjects who used the tips of two fingers to restrain an instrumented manipulandum with horizontally oriented grip surfaces. The grip surfaces were subjected to tangential pulling forces in the distal direction in relation to the fingers. The subjects used either the right index and middle fingers (unimanual grasp) or both index fingers (b...

Frictional costs are defined as the disutility related to the conduct of an online transaction. Thus, frictional costs can accrue through the consumer‘s decision-making process prior to an online transaction, e.g., bidding in interactive pricing mechanisms like auctions. We present two models for the measurement of frictional costs in Name-Your-Own-Price auctions where these costs can either be...

Carbon nanotubes (CNTs) are well known for their exceptional thermal, mechanical and electrical properties. For many CNT applications it is of the foremost importance to know their frictional properties. However, very little is known about the frictional forces between an individual nanotube and a substrate or tip. Here, we present a combined theoretical and experimental study of the frictional...

Friction limits the operation of macroscopic engines and is critical to the performance of micromechanical devices. We report measurements of friction in a biological nanomachine. Using optical tweezers, we characterized the frictional drag force of individual kinesin-8 motor proteins interacting with their microtubule tracks. At low speeds and with no energy source, the frictional drag was rel...

Wepresent results from laboratory experiments and anumericalmodel for frictional weakening and shear localization. Experiments document strain localization in sheared layers at normal stresses of 0.5 to 5MPa, layer thicknesses of 3 to 10mm, and imposed slip velocities of 10 to 100 μm/s. Passive strain markers and the response to load perturbations indicate that the degree of shear localization ...

Using frictional force microscopy (FFM), the friction surface characteristics were compared between twisted nematic (TN) mode and vertical alignment (VA) mode alignment films (AFs). The friction asymmetry was detected depending on temperature conditions on TN mode AF, but not on VA mode AF. The difference between two modes was explained by leaning intermolecular repulsion caused by the pre-tilt...

A new approach for estimating the interfacial frictional shear stress in fiber-reinforced ceramics is presented. The approach is based upon measurement of the temperature rise which occurs during the cyclic loading of ceramic composites. This temperature rise, which is caused by the frictional slip of fibers within the composite, is related to the level of frictional shear stress which exists a...

We consider dynamic problems which describe frictional contact between a body and a foundation. The constitutive law is viscoelastic or elastic and the frictional contact is modelled by a general subdifferential condition on the velocity, including the normal damped responses. We derive weak formulations for the models and prove existence and uniqueness results. The proofs are based on the theo...

a r t i c l e i n f o Recent high-resolution GPS and seismological data reveal that tectonic faults exhibit complex, multi-mode slip behavior including earthquakes, creep events, slow and silent earthquakes, low-frequency events and earthquake afterslip. The physical processes responsible for this range of behavior and the mechanisms that dictate fault slip rate or rupture propagation velocity ...