Human dentin is susceptible to failure under repetitive cyclic-fatigue loading. This investigation seeks to address the paucity of data that reliably quantify this phenomenon. Specifically, the effect of alternating vs. mean stresses, characterized by the stress- or load-ratio R (ratio of minimum-to-maximum stress), was investigated for three R values (-1, 0.1, and 0.5). Dentin was observed to ...

The fretting performance of self-piercing riveting joining dissimilar sheets in TA1 titanium alloy and H62 copper alloy was studied in this paper. Load-controlled cyclic fatigue tests were carried out using a sine waveform and in tension-tension mode. Scanning electron microscopy and energy-dispersive X-ray techniques were employed to analyze the fretting failure mechanisms of the joints. The e...

We study quasipolynomials enumerating proper colorings, nowherezero tensions, and nowhere-zero flows in an arbitrary CW-complex X, generalizing the chromatic, tension and flow polynomials of a graph. Our colorings, tensions and flows may be either modular (with values in Z/kZ for some k) or integral (with values in {−k + 1, . . . , k − 1}). We obtain deletion-contraction recurrences and closed ...

In this paper are reported observations on a system in which adenosine diphosphate and orthophosphate are synthesized into adenosine triphosphate by a respiring mitochondrial suspension supplied with glutamate. The ATP thus synthesized is available to a glycerinated muscle fiber which, upon developing isometric tension, hydrolyzes the ATP back to ADP and P. The hydrolysis products are then avai...

BACKGROUND Prosthetic replacement of the ascending aorta with nonelastic vascular grafts impairs the local Windkessel function. Whether this increases wall tension in the remaining aorta is still a not completely investigated hypothesis but is of clinical relevance with respect to postprocedural development of aneurysms and dissections, especially in the proximal descending aorta. METHODS Fre...

The interplay between chemical and mechanical signals plays an important role in cell biology, and integrin receptors are the primary molecules involved in sensing and transducing external mechanical cues. We used integrin-specific probes in molecular tension fluorescence microscopy to investigate the pN forces exerted by integrin receptors in living cells. The molecular tension fluorescence mi...

The present work deals with those properties of the human motor system that characterize cyclic movements of maximum (expected to be maximum) intensity. It presents the results of an experiment carried out on 11 subjects and aimed at measuring the kinematic characteristics of cyclic movements of the elbow joint executed at maximal frequency under unloaded conditions. The movements of five ampli...

The delicate structure of the lung epithelium makes it susceptible to surface tension induced injury. For example, the cyclic reopening of collapsed and/or fluid-filled airways during the ventilation of injured lungs generates hydrodynamic forces that further damage the epithelium and exacerbate lung injury. The interactions responsible for epithelial injury during airway reopening are fundamen...

A series of cyclic tension-torsion tests under symmetric shear strain and asymmetric axial stress control in various loading paths are conducted on 100 μm-diameter 316L steel wires applying a micro tensiontorsion fatigue testing apparatus. The ratcheting strain of the thin wire increases with increasing axial mean stress and decreases in a sequence of linear, rhombic and circular paths. The mac...