The folding and stability of transmembrane proteins is a fundamental and unsolved biological problem. Here, single bacteriorhodopsin molecules were mechanically unfolded from native purple membranes using atomic force microscopy and force spectroscopy. The energy landscape of individual transmembrane alpha helices and polypeptide loops was mapped by monitoring the pulling speed dependence of th...

The mechanical unfolding of the muscle protein titin by atomic force microscopy was a landmark in our understanding of single-biomolecule mechanics. Molecular dynamics simulations offered atomic-level descriptions of the forced unfolding. However, experiment and simulation could not be directly compared because they differed in pulling velocity by orders of magnitude. We have developed high-spe...

Biomolecular motors can pull and viscously drag membranes. The resulting elongations include cell protrusions, tether networks, and sensorial tentacles. Here we focus on the extraction of a single tube from a vesicle. Via a force balance coupled to binding kinetics, we analytically determine the phase diagram of tube formation as function of the motor processivity, the surface viscosity of the ...

Softness is one of the most important properties for an apparel fabric. This paper investigated the feasibility of objective evaluation of fabric softness by measuring the forces of pulling a fabric specimen through a series of parallel pins. The specific pulling forces of fabric specimens were compared with those indexes obtained both from FAST (Fabric Assurance By Simple Testing) tests and su...

The effect on intraocular pressure (IOP) from dogs pulling against a collar or a harness was evaluated in 51 eyes of 26 dogs. The force each dog generated while pulling against a collar or a harness was measured. Intraocular pressure measurements were obtained during application of corresponding pressures via collars or harnesses. Intraocular pressure increased significantly from baseline when ...

The paper presents an experiment of a collective pulling of one object by three Lego R ©robots. The robots use two parameters to orient their pulling force: 1. the direction to the nest 2. the local perception of the movement of the prey. Three behavior-based programs have been experimented to study the impact of each parameter. Although a solution can be found by using random trials in the dir...

We consider the stretching of a thin viscous thread, whose viscosity depends on temperature, that is heated by a radiative heat source. The thread is fed into an apparatus with a fixed speed and stretched by imposing a higher pulling speed at a fixed downstream location. We show that thermal effects lead to the surprising result that steady states exist for which the force required to stretch t...

Notch signaling is repeatedly used during animal development to specify cell fates. Using atomic force microscopy on live cells, chemical inhibitors, and conventional analyses, we show that the rate of Notch signaling is linked to the adhesion force between cells expressing Notch receptors and Delta ligand. Both the Notch extracellular and intracellular domains are required for the high adhesio...

Molecular dynamics simulations supplement single-molecule pulling experiments by providing the possibility of examining the full free energy landscape using many coordinates. Here, we use an all-atom structure-based model to study the force and temperature dependence of the unfolding of the protein filamin by applying force at both termini. The unfolding time-force relation τ(F) indicates that ...

Titin, a 1 micron long protein found in striated muscle myofibrils, possesses unique elastic and extensibility properties, and is largely composed of a PEVK region and beta-sandwich immunoglobulin (Ig) and fibronectin type III (FnIII) domains. The extensibility behavior of titin has been shown in atomic force microscope and optical tweezer experiments to partially depend on the reversible unfol...