Abstract An analysis based on the law of linear momentum conservation demonstrates unequivocally that mass fraction is scalar whose gradient determines gas diffusion, both molecular and turbulent. It illustrates sizeable errors in previous micrometeorological definitions turbulent flux fluctuations other scalars such as mixing ratio or density. In deference to law, we put forth a new definition...

We used carbon monoxide (CO) as a probe to quantitatively measure intestinal unstirred water layers in vivo. CO has several features that make it uniquely well suited to measure the unstirred layer in that its tight binding to hemoglobin makes uptake diffusion limited, and its relatively high lipid solubility renders membrane resistance negligible relative to the water barriers of the unstirred...

For an optimal functionality and a high durability of the planned SIS18 beam loss collimators a low ion-induced desorption yield of the collimator material is required. Gold coated copper was found to be the material of choice: copper has a high thermal conductivity, a high specific heat and can be produced with high purity for reasonable prizes. The gold layer prevents the copper from oxidatio...

double layer zno/sno2 thin film resistive gas sensors were fabricated by successive pvd of those oxides onto porcelain substrates. the metallic contacts were provided by electron beam evaporation of platinum onto substrates prior to deposition of the gas sensitive layers. deposits were thermally annealed at different temperatures. it was shown that the activation energy of electrical conduction...

Polymer electrolyte membrane(PEM) fuel cells have higher efficiency and energy density and are capable of rapidly adjusting to power demands. Effective water management is one of the key issues for increasing the efficiency of PEMFC. In the current study, a three-dimensional(3D) lattice Boltzmann model is developed to simulate the water transport and oxygen diffusion in the gas diffusion layer(...

Water transport through gas diffusion layer of proton exchange membrane fuels cells is investigated experimentally. A filtration cell is designed and the permeation threshold and the apparent water permeability of several carbon papers are investigated. Similar carbon paper with different thicknesses and vailable online 26 February 2011

Recently, 2-dimensional electron gas (2-DEG) was discovered at the interface of Al₂O₃/SrTiO₃ (STO) heterostructures, in which the amorphous Al₂O₃ layers were grown by atomic layer deposition (ALD). The saturated electron density at the Al₂O₃/STO heterostructures above the critical thickness of Al₂O₃ is explained by an oxygen diffusion mechanism.