Heterogeneous Multiscale Methods for modelling surface topography in Elastohydrodynamic Lubrication line contacts

A multiscale method for the Elastohydrodynamic Lubrication (EHL) of line contacts is derived based on the Heterogeneous Multiscale Methods. Periodicity applies to the topographical features and lubricant flow, data is homogenised over a range of variables at a micro-scale and coupled into a macro-scale model. This is achieved using flow factors as calculated from metamodels, which themselves evolve with the solution procedure. Results are given for an idealised topography and illustrate significant deviations from smooth surface assumptions as quantified by the flow factors. Improvements in the accuracy and efficiency with previous work and large fluctuations due to micro-EHL are also presented. Validation of the multiscale method with a deterministic topography is provided demonstrating good accuracy and efficiency

Two-scale EHL: three-dimensional topography in tilted-pad bearings

Derived from the Heterogeneous Multiscale Methods (HMM), a two-scale method is developed for the analysis of Elastohydrodynamic Lubrication (EHL) and micro-EHL in tilted-pad bearings with three-dimensional topography. A relationship linking the pressure gradient to mass flow rate is derived and represented in the bearing domain through homogenisation of near-periodic simulations describing the Fluid Structure Interaction (FSI) of topographical features. For the parameters investigated the influence of compressibility and piezoviscosity was found to be more significant than that of non-Newtonian (shear-thinning) behaviour on textured bearing performance. As the size of topography increased two-scale solutions demonstrated that at constant load the coefficient of friction increased and the minimum film thickness decreased over a range of pad lengths and tilt angles

Noradrenaline modulation of calcium channels in single smooth muscle cells from rabbit ear artery

‘The definitive version is available at www.blackwell-synergy.com '. / PubMed Central Copyright The Physiological Society/ Blackwell Publishing [Full text of this article is not available in the UHRA]Peer reviewe

A novel receptor-operated Ca2+-permeable channel activated by ATP in smooth muscle

Original article can be found at: http://www.nature.com/nature/index.html Copyright Nature Publishing Group. DOI: 10.1038/328275a0 [Full text of this article is not available in the UHRA]Peer reviewe

Two types of calcium channels in single smooth muscle cells from rabbit ear artery - studied with whole cell and single channel recordings

Original article can be found at: http://ovidsp.tx.ovid.com/spa/ovidweb.cgi Copyright American Heart Association, Inc. [Full text of this article is not available in the UHRA]AB Freshly dispersed rabbit ear artery cells were studied using patch-clamp techniques to measure membrane currents in whole cells and single-channel currents in membrane patches. Whole-cell calcium currents recorded at physiologic extracellular calcium concentrations were small (~10 pA). Recordings with 110 mM external barium gave much larger currents and revealed two current components with properties similar to those in other vascular smooth muscle preparations and to the calcium currents designated as T and L in heart cells and neurons. T current was activated with weak depolarizations and inactivated rapidly, while L current was activated with relatively strong depolarizations and inactivated more slowly. L current was Increased by dihydropyridine agonists and decreased by dihydropyridine antagonists, while T current was unaffected. Recordings from cell-attached and outside-out membrane patches with 110 mM external barium showed unitary calcium channel currents with conductances of 8 and 25 pS. The small conductance channels had kinetic properties that accounted for T current in the whole-cell recordings, while the 25-pS channels showed the voltage dependence, the time dependence, and the dihydropyridine sensitivity expected for L-type channels. We conclude that vascular smooth muscle cells contain two types of calcium channels with properties very similar to those described for T- and L-type calcium channels in other cell types; the L current appears to be the predominant current component in whole-cell recordings.Peer reviewe