UNLABELLED Mechanical strain applied to bone leads to bone remodeling. In the oral cavity, it is unclear how such mechanical force applied to move teeth orthodontically induces alveolar bone remodeling. It is known that osteoclasts are the only cells that are responsible for bone resorption, while the formation and activity of osteoclasts are regulated by osteoblasts. So it is believed that ost...

Physical forces play important roles in regulating cell proliferation, differentiation, and death by activating intracellular signal transduction pathways. How cells sense mechanical stimulation, however, is largely unknown. Most studies focus on cellular membrane proteins such as ion channels, integrins, and receptors for growth factors as mechanosensory units. Here we show that mechanical str...

GTP-hydrolyzing G proteins are molecular switches that play a critical role in cell signaling processes. Here we use molecular dynamics simulations to show that Ras, a monomeric G protein, can generate mechanical force upon hydrolysis. The generated force levels are comparable to those produced by ATP-hydrolyzing motor proteins, consistent with the structural similarities of the catalytic regio...

In recent years the atomic force microscope (AFM) has evolved from a high resolution imaging tool to an enabling platform for physical studies at the nanoscale including quantitative mapping of mechanical characteristics of surfaces providing simultaneous topography and mechanical property maps across the length scales. In the work presented here peak force tapping AFM was utilized to elaborate...

By ab initio quantum mechanical calculations on P 2 S^ its equilibrium energy, geometry and vibrational frequencies along with their PED values have been obtained. The basis sets STO-5G, 6-31G, STO-5G* and 6-31G* were employed, and force field calculations were carried out at the STO-5G and the STO-5G* levels. The calculations show that the assignment for some bands between 180 and 260 cm " 1 s...

Microsystems are providing key advances in studying single-cell mechanical behaviours. The mechanical interaction of cells with their extracellular matrix is fundamentally important for cell migration, division, phagocytes and apoptosis. As the displacement and scales of cellular phenomena is comparable to optical wavelength, optical metrology offers superior resolution and real-time imaging ca...

Weaning covers the entire process of liberating the patient from mechanical support and from the endotracheal tube. Many controversial questions remain concerning the best methods for conducting this process. An International Consensus Conference was held in April 2005 to provide recommendations regarding the management of this process. An 11-member international jury answered five pre-defined ...

We characterize the force-dependent unfolding pathways and intermediate configurations of the green fluorescence protein (GFP) using novel atomistic simulations based on potential energy surface exploration. By using this approach, we are able to unfold GFP to significantly longer end-to-end distances, i.e. 40 nm, as compared to that seen in previous atomistic simulation studies. We find that t...

Mechanical damage of polymers is often a destructive and irreversible process. However, desirable outcomes may be achieved by controlling the location of chain cleavage events through careful design and incorporation of mechanically active chemical moieties known as mechanophores. It is possible that mechanophores can be used to generate reactive intermediates that can autopolymerize or cross-l...

Force control implemented by a passive mechanical device (perhaps a wrist) has inherent advantages over active implementations. A passive mechanical device can regain some of the versatility of its active counterpart if it incorporates mechanical elements with programmable parameters, e.g. damping coefficients or spring stiffnesses. We wish to characterize the range of accommodation matrices th...