A cluster of N ligand-receptor pairs between two parallel surfaces under an applied force F=Γt with a constant loading rate Γ is considered. Our theoretical and numerical studies show that there is a characteristic force f(c) and a characteristic loading rate Γ(c). At Γ<Γ(c), the mean rupture force F(r) of the cluster is close to but lower than Nf(c). In this regime, cluster dissociation can be...

A pneumatic indentation system using a copper bellows has been developed for physiological studies where a controlled uniaxial compressive force is required to be applied to the surface of the skin. Such a system is useful for studies where the physiological response of the tissues is to be monitored following a known loading history. The indentation system is driven by a vacuum/compression pne...

Experimental and computational dynamic force spectroscopy is widely used to determine the mechanical properties of single biomolecules. Whereas so far the focus has mainly been on rupture or unfolding forces, recent force-probe molecular dynamics simulations have revealed a strong loading rate dependence of biomolecular elasticities, which cannot be explained by the established one-dimensional ...

The purpose of the study was to develop an optimized thermoreversible in situ gelling ophthalmic drug delivery system based on Pluronic F 127, containing moxifloxacin hydrochloride as a model drug. A 3(2) full factorial design was employed with two polymers: Pluronic F 68 and Gelrite as independent variables used in combination with Pluronic F 127. Gelation temperature, gel strength, bioadhesio...

In dynamic force spectroscopy, single (bio-)molecular bonds are actively broken to assess their range and strength. At low loading rates, the experimentally measured statistical distributions of rupture forces can be analysed using Kramers' theory of spontaneous unbinding. The essentially deterministic unbinding events induced by the extreme forces employed to speed up full-scale molecular simu...

When a ligand that is bound to an integral membrane receptor is pulled, the membrane and the underlying cytoskeleton can deform before either the membrane delaminates from the cytoskeleton or the ligand detaches from the receptor. If the membrane delaminates from the cytoskeleton, it may be further extruded and form a membrane tether. We develop a phenomenological model for this process by assu...

Nurses in an Armed Force Hospital (AFH) expose to stronger stress than those in a civil hospital, especially in an emergency department (ED). Ironically, stresses of these nurses received few if any attention in academic research in the past. This study collects 227 samples from the emergency departments of four armed force hospitals in central and southern Taiwan. The research indicates that t...

The effects of simulated orthodontic forces such as centrifugal force or water pressure on sodium fluoride (NaF)-induced cytotoxicity against mouse osteoblast-like cells MC3T3-E1 were investigated. Loading with centrifugal force (44.5 g/cm2) or water pressure (5 g/cm2) slightly reduced the cell proliferation and additively enhanced the cytotoxic activity of millimolar concentrations of NaF. NaF...

We revisit some aspects of the interpretation of dynamic force spectroscopy experiments. The standard theory predicts that the typical unbinding force f* is linearly proportional to the logarithm of the loading rate r when a single energy barrier controls the unbinding process. For a more complex situation of N barriers, it predicts at most N linear segments for the f* vs. log(r) curve, each se...

Tensile tests have been performed at up to five different displacement rates, from about lmm/s to over 20,000mm/s, on braided glass-fibre tubes of both square and circular cross-section and the corresponding force-displacement curves have been derived. In general both the maximum tensile force and the displacement at failure increase with increasing loading rate, implying a greater energy absor...