In response to the need to better describe spatial variations in permeability, we designed and built a new portable field air permeameter for use on rocks in outcrop and core. In this instrument, a chamber containing a small volume of air in contact with the rock is suddenly increased in volume creating a vacuum, causing air to flow from the rock into the chamber. The instantaneous chamber volu...

The role of mast cell degranulation in increased vascular permeability in zymosan-air-pouch inflammation, an experimental model of inflammation induced by zymosan in rats, was investigated. The complement in the inflammatory pouch fluid was exhausted, and mast cells in the pouch wall subcutaneous tissues were degranulated. The histamine level in the pouch fluid was elevated immediately after ap...

Thermal resistance and air permeability of needle-punched nonwoven fabric made from jute and polypropylene blends have been studied using the Box and Behnken factorial design to observe the effect of fabric weight, needling density and blend proportion on thickness, thermal resistance, specific thermal resistance, air permeability and sectional air permeability. Correlation matrix and cluster a...

Crop rotations that include tap-rooted species of cover crops may help alleviate the deleterious effects of soil compaction on plant growth by modifying soil physical properties. We studied the effects of compaction and cover crops on the least limiting water range (LLWR) and air permeability in the surface layers of a loamy (Exp. 1) and a sandy soil (Exp. 2). There were three compaction treatm...

Effective and efficient ventilation is essential when improving energy performance and Indoor Air Quality (IAQ) of buildings. Reducing air permeability can considerably improve the energy performance of buildings; however, making the buildings more airtight may result in lower rates of natural ventilation which may in turn increase the risks of condensation and unacceptable IAQ. This study eval...

In this study, it was aimed to investigate the porosity / compactness of the knitted structures made from cotton and modal yarns and to evaluate the air permeability property for sportswear. In the experimental section, cotton and modal yarns spun in different counts ( Ne 30, Ne 40 ) with the same twist coefficient of αe = 3.53 and 3.3 respectively were knitted as single jersey fabrics in the s...

We considered small-scale measurement of permeability in pebbly sands having coarser grains supported in a finer grained matrix (fine packing). Our central question was whether air-based measurements are representative if made with a permeameter tip seal pressed in the sand matrix. We created pebbly sands and variably sorted sands, with systematic variation in aspects of their fine packing. We ...

Abstract: Several nonwovens were studied to explore the relationship between their structural characteristics, permeability and acoustic absorbing behavior. Fundamental structural parameters including thickness, gram square meter and porosity were considered. Results show that the permeability is not just linear to porosity, but also related to many other complex and difficult-to-measure parame...

A new permeation apparatus is described to measure the liquid permeability of coated and uncoated paper samples. The technique can also be applied to other consolidated porous and laminate materials and removes the artefacts of random pinholes whilst relating directly to liquid permeation rather than the more commonly used air/gas permeation. Measurements from three example papers are shown, an...