A one dimensional isothermal mathematical modeling of cathode side of a Proton Exchange Membrane (PEM) fuel cell is developed for the water management problem. Water transport is investigated in both cathode Gas Diffusion Layer (GDL) and membrane through solving appropriate equations for fluid flow and mass transport in GDL and water transport within the membrane. The gaseous mixture flowing in...

Introduction: The compositional variations [1 and references therein] in the zoned metal grains from the CH and CB chondrites are generally interpreted as unequivocal evidence for their condensation from a parcel of H 2-rich gas with solar or somewhat increased dust/gas (D/G) ratios [2,3]. Although different origins of such gas are discussed [e.g., 4-7], its high enrichment in H 2 [8] and low a...

Introduction Articular cartilage lacks the ability to sufficiently repair itself. Tissue engineering approaches may initiate functional repair and, therefore, are considered for the treatment of articular cartilage defects. Our method adopts a porous PEGT/PBT scaffold (PolyActive, IsoTis N.V.) with similar mechanical properties to native cartilage, which acts as a 3 dimensional carrier for seed...

Abstract The diffusion coefficients in gases and liquids calculated by the molecular dynamics method with use of hard absolutely rough elastic spheres model are compared those using Lennard-Jones potential. It is shown that dependences reduced on density similar, but differ numerically for different intermolecular interaction models. simulation results have been experimental data gaseous liquid...

Cavitation of water in xylem vessels followed by embolism formation has been authenticated for more than 40 years. Embolism formation involves the gradual buildup of bubble pressure (air) to atmospheric pressure as demanded by Henry's law of equilibrium between gaseous and liquid phases. However, the tempo of pressure increase has not been quantified. In this report, we show that the rate of pr...

The homogeneous (gas-phase) and heterogeneous (catalytic) ignition of fuel-lean premixtures is investigated analytically and numerically in two-dimensional laminar channel-flow configurations with uniform incoming properties and isothermal catalytic walls. First-order matched activation energy asymptotics are employed, along with a one-step catalytic reaction and a one-step large activation ene...

A gas diffusion sequential injection system for spectrophotometric determination of free chlorine is described. The detection is based in the colorimetric reaction between free chlorine and a low toxicity reagent o-dianisidine. A gas diffusion unit is used to isolate free chlorine from the sample in order to avoid possible interferences. This feature results from the conversion of free chlorine...