We report on frictional strengthening (healing) in granular quartz gouge as a function of time of true stationary contact. To distinguish between the slip-dependent [Ruina, 1983] and time-dependent [Dieterich, 1979] friction constitutive laws, we designed tests similar to conventional slide-hold-slide (SHS) tests except that shear load was completely removed prior to holds. We find large healin...

The effect of shear stress at the endothelium in the attenuation of the noradrenaline-induced constriction of the femoral vascular bed perfused at a constant blood flow was investigated in 16 anesthetized cats. It is known that the adrenergic vasoconstriction of the femoral vascular bed is considerably greater at a constant pressure perfusion than at a constant blood flow. This difference may d...

the propose of this paper is to introduce a new model for crude oil fouling in preheat trains of crude distillation unit. the experimental results of australian light crude oil with the tube side surface temperatures between 200-260 oc and fluid velocity ranged 0.25 to 0.4m/s were used. the activation energy of chemical reaction depends on the surface temperature has been calculated.  the model...

A qualitative analysis of changes in hydrodynamic parameters during keyhole formation by thermocapillary melt removal under the point action CW laser radiation is presented. It established that rapid surface deformation leads to adhesion viscous sublayer melting boundary and creation shear structure flow which stimulates acceleration growth. Keywords: formation, radiation, effect, flow, sublaye...

The P2X 1 receptor is a fast ATP-gated cation channel expressed in blood platelets, where its role has been difficult to assess due to its rapid desensitization and the lack of pharmacological tools. In this paper, we have used P2X 1 / and wild-type mouse platelets, treated with apyrase to prevent desensitization, to demonstrate the function of P2X 1 in the response to thrombogenic stimuli. In ...

OBJECTIVE To evaluate, in vitro, the shear bond strength presented by three brands of polycrystalline ceramic brackets and one brand of metallic bracket; verify the adhesive remnant index (ARI) after the tests, and analyze, through scanning electron microscopy (SEM) the enamel surface topography after debonding, detecting the release of mineral particles. METHODS Sixty bovine lower incisors w...

Different techniques have been introduced for the removal of ceramic brackets. Since the early 1990s, lasers have been used experimentally for debonding ceramic brackets. The goal of this study is to give a comprehensive literature review on laser-aided ceramic bracket debonding. PubMed and Google Scholar databases were used to identify dental articles with the following combination of key word...

We present the theoretical and analytical bases of optimal techniques to measure weak gravitational shear from images of galaxies. We first characterize the geometric space of shears and ellipticity, then use this geometric interpretation to analyse images. The steps of this analysis include: measurement of object shapes on images, combining measurements of a given galaxy on different images, e...

We present a CFD model that predicts the sedimentation of activated sludge in a full-scale circular secondary clarifier that is equipped with a suction-lift sludge removal system. The axisymmetric single-phase model is developed using the general-purpose CFD solver FLUENT 6, which uses the finite-volume method. A convection-diffusion equation, which is extended to incorporate the sedimentation ...