Permeability, evaluation

Water vapour polyethylene has a low permeability, evaluated from 0.9 up to 2.5 compared to the full range of 0.05 up to 400 for all tested plastics. 

Gases polyethylene has a rather high permeability, evaluated at ... 

Gases polypropylene has a rather high permeability, evaluated at o air 700 versus a full range of 3 up to 2750 for all tested plastics... 

Sugano, K. and Sakai, K. (2004) Mucopolysaccharide-layered lipid membrane, membrane permeabilitymeasuring filter/apparatus /kit, membrane permeability evaluation method, and test substance-screening method. Patents 31362, 2005221442, 20040206. 

The van der Waals interaction were calculated using the equation given in [166] which is a result of numerical computation of the complete expressions for the van der Waals interactions in a free liquid film rivw [148] with dielectric permeabilities evaluated by the method of Persegian and Ninham [210] (see also Section 3.4.1.2). 

A short-term test that measures transepidermal water loss (TEWL) is also used to measme barrier integrity and has been mentioned specifically as an acceptable method by the Emopean Union s Scientific Committee for Cosmetics and Non-Food Products (Scientific Committee, 2003). Measinement of TEWL from skin samples in diffusion cells appears to be a potentially convenient method that does not use radiolabeled material. However, some effort appears to be necessary to obtain consistent measmements, including the possible need for rooms with controlled environments for humidity and temperature (Benech-Kieffer et al., 1998). Some reports have found differences between skin permeability evaluations by tritiated water and TEWL methods (Chilcott et al., 2002). 

Sharma, V. Marwaha, R.K. Dureja, H. Permeability evaluation through chitosan membranes using Taguchi design. Sci. Pharm. 2010, 78 (42), 977-983. 

Gas/Oil Relative Permeabilities at Connate Water Saturation. The same core that was used for water/oil relative permeability evaluations, core MCF3, was re-saturated with oil after the waterflood. Next, nitrogen was injected at a flow rate of 6 ml/hr. The oil recovery was determined at consistent time intervals. Problems were experienced with the backpressure regulator, such that the pressure readings were too erratic to be useful in the relative permeability curve evaluation. Only the residual oil saturation to gas and the gas endpoint relative permeability were determined in the presence of connate water ... 

The carboxyl groups of the albumin blended chitosan membranes were activated with carbodiimide. The membranes were dipped in a solution containing 1% carbodiimide, in 0.05H phosphate buffer (pH = 8.3) for 30 min. at 4 C, and the excess diimide was washed from the membrane with buffer solution. The complex was dissolved in phosphate buffer (pH = 8.3) and added to the previously equilibrated, activated albumin blended chitosan membranes, and kept 5 hrs. at 4 C for coupling. At the end of this process, the unbound complex was washed off with buffer. These membranes were used for platelet adhesion studies and permeability evaluation. A few albumin chitosan membranes were also exposed to carbodiimide for various time intervals to evaluate the effect of crosslinking on their permeability properties. 

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