Background: A special hydroxypropylmethylcellulose powder (Nasaleze®) has been used for the alleviation of nasal symptoms of allergic rhinitis since 1994. The efficacy of the product has been recently proven but the mechanism of action was still largely unknown. The aim of the study was to investigate the hypothesis that the gel formed after moisture absorption in the nose might act as mechanic...

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 ...

The intestinal epithelium demonstrates differential properties, providing both barrier and transport functions with respect to luminal molecules. Intestinal permeability relates to barrier function and, although it is the ‘permeation’ of molecular markers that is used to measure ‘permeability’, the terms are often confused. Permeability is that property of the intestinal epithelium or of a memb...

Computational techniques predict the barrier performance of poly(lactide) composites, studying relationship between free volume, polymer morphology and gas diffusion.

The diffusion of water in amorphous SiC a-SiC was investigated by molecular modeling methods based on density functional theory. It was assumed that the structure of a-SiC at the molecular level can be described by a model that takes into account a distribution of cage structures which consist of SiC units forming n-member rings from a suitable precursor in a chemical vapor deposition process. ...

Using density-functional theory we investigate several properties of Al (111), Al (100), Al (110), and stepped Al (111) surfaces. We report results of formation energies of surfaces, steps, adatoms, and vacancies. For the adsorption and diffusion of Al on flat regions of Al (111) surfaces we find the hcp site energetically slightly preferred over the fcc site. The energy barrier for self-diffus...

We present a model for diffusion in a molecularly crowded environment. The model consists of random barriers in a percolation network. Random walks in the presence of slowly moving barriers show normal diffusion for long times but anomalous diffusion at intermediate times. The effective exponents for square distance vs time usually are below one at these intermediate times, but they can also be...

The structural features that affect continuity of ultrathin diffusion barriers on porous low-dielectric-constant ~k! thin films has been investigated. The dimensions of interconnected nanopores in a series of Dow Corning XLK films are found to increase as the dielectric constant becomes smaller. The minimum thickness required for tantalum ~Ta! to form a continuous barrier layer is affected by t...

Polarization of the plasma membrane (PM) into domains is an important mechanism to compartmentalize cellular activities and to establish cell polarity. Polarization requires formation of diffusion barriers that prevent mixing of proteins between domains. Recent studies have uncovered that the endoplasmic reticulum (ER) of budding yeast and neurons is polarized by diffusion barriers, which in ne...

Nuclear pore complexes (NPCs) form aqueous conduits in the nuclear envelope and gate the diffusion of large proteins between the cytoplasm and nucleoplasm. NPC proteins (nucleoporins) that contain phenylalanine-glycine motifs in filamentous, natively unfolded domains (FG domains) line the diffusion conduit of the NPC, but their role in the size-selective barrier is unclear. We show that deletio...