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Pressure swing adsorption (PSA) is a technique used to separate some gas species from a mixture of gases (typically air) under pressure according to the species' molecular characteristics and affinity for an adsorbent material.
The most appropriate method to use is normally the one where the method is aligned to the end use of the data. For example, to choose whether a chemical compound should be measured by dynamic light scattering or laser diffraction , one generally considers the expected size range, the sample type (liquid or solid), the amount of sample available ...
Vacuum swing adsorption (VSA) uses the same principle as PSA but swings between vacuum pressures and atmospheric pressure. [2] PSA and VSA techniques may be combined and are called "vacuum pressure swing adsorption" (VPSA) in this case.
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One point of possible objection interests the uncertainties associated with a PSA. The PSA (Probabilistic Safety Assessment) has often no associated uncertainty, though in metrology any measure shall be related to a secondary measurement uncertainty, and in the same way any mean frequency number for a random variable shall be examined with the dispersion inside the set of data.
PSA is a commonly used medicinal chemistry metric for the optimization of a drug's ability to permeate cells. Molecules with a polar surface area of greater than 140 angstroms squared (Å 2 ) tend to be poor at permeating cell membranes. [ 1 ]
Pressure-sensitive adhesive (PSA, self-adhesive, self-stick adhesive) is a type of nonreactive adhesive which forms a bond when pressure is applied to bond the adhesive with a surface. No solvent, water, or heat is needed to activate the adhesive.
The number of points accessible is multiplied by the portion of surface area each point represents to calculate the ASA. The choice of the 'probe radius' does have an effect on the observed surface area, as using a smaller probe radius detects more surface details and therefore reports a larger surface.