Barrier systems are designed to control contaminant migration. Geomembranes are commonly used as part of a composite liner in landfill cover, base liner systems and sometimes vapour barriers. In landfill applications, the primary function of the geomembrane liner is to control contaminant transport from the leachate (dissolved phase) and landfill gas (vapour phase) out of the landfill thus mini...

Cilia and flagella are membrane-sheathed, microtubule-based protrusions that decorate the surface of many eukaryotic cells. At their base, they form a selective barrier that concentrates certain proteins within the cilia but excludes others. Kee et al. (2012) now propose that nuclear pore complex proteins form a fundamental part of this diffusion barrier.

Impermeable barriers were inserted into the stage-20 to -21 leg bud to test whether or not such an interruption of diffusion of the proposed morphogen from the polarizing zone would result in failure of leg elements to develop anterior to the barrier. Tantalum foil was placed at somite levels 30/31 or mid-31 through the dorsoventral extent of the leg bud separating anterior from posterior mesod...

The metal-insulator-semiconductor (MIS) diode is the most useful device in the study of semiconductor surfaces. The current-voltage data of the metal-insulatorsemiconductor Schottky diode are simulated using thermionic emission diffusion equation taking into account the interfacial layer parameters. The calculated current–voltage data are fitted into ideal thermionic emission diffusion equation...

In this study, the physical and electrical characteristics of Al2O3/La2O3/Al2O3/Si stack structures affected by the thickness of an Al2O3 barrier layer between Si substrate and La2O3 layer are investigated after a rapid thermal annealing (RTA) treatment. Time of flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) tests indicate that an Al2O3 barrier laye...

Non-local reaction-diffusion equations arise naturally to account for diffusions involving jumps rather than local diffusions related to Brownian motion. In ecology, long distance dispersal require such frameworks. In this work we study a one-dimensional non-local reaction-diffusion equation with bistable and monostable type reactions. The heterogeneity here from due to the presence of a barrie...

The claudins have recently been identified as a large family of transmembrane proteins located at tight junctions between epithelial cells; they create the paracellular diffusion barrier and, surprisingly, may also confer channel-like selectivity for passage of solutes through the tissue barrier.

QUANTIFYING the lung’s capacity for O2 uptake by diffusion across the alveolo-capillary tissue-plasma barrier followed by binding to hemoglobin is not straightforward, owing to the nonlinearity of the oxyhemoglobin dissociation curve. Direct assessment of lung diffusing capacity for O2 (DLO2) is possible only by employing invasive methods under hypoxic conditions, i.e., when alveolar capillary ...

Ultrafast optical spectroscopy was utilized to investigate charge transfer dynamics across organic semiconductor tetracene/C60 interfaces in the presence of a LiF barrier layer. Photoinduced absorption spectra in the 1.6−2.3 eV range reveal a strong effect of the intermediate LiF barrier layer on dynamics of the charge transfer excitons (CTE) creation and recombination. Increasing thickness of ...

The helium and oxygen gas barrier properties of poly(lactide) were investigated as a function of stereochemistry and crystallinity degree. Poly(L-lactide) and poly(D,L-lactide) films were obtained by extrusion and thermally cold crystallized in either a0or a-crystalline form with increasing crystallinity degree. Annealing of the films at low temperatures yielded to a0-crystals as well as the cr...