water content

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water content 

Water in a contact lens expressed as a percentage of the total mass of the lens in its hydrated state under equilibrium conditions with physiological saline solution containing 9 g/l sodium chloride at a temperature of 20 ± 0.5ºC and with a stated pH value.
where M is the mass of hydrated lens, m is the mass of dry lens.The US Food and Drug Administration (FDA) has categorized hydrogel contact lenses into four groups according to their water content and their surface reactivity (referred to as ionic if it contains more than 0.2% ionic material, and nonionic otherwise). Group 1: water content less than 50% and non-ionic. Group 2: water content greater than 50% and non-ionic. Group 3: water content less than 50% and ionic. Group 4: water content greater than 50% and ionic.
References in periodicals archive ?
When thermodynamic equilibrium prevails, residual water contents do not exist and the water content becomes zero at around pFo6.
Groenevelt PH, Grant CD (2004) A new model for the soil-water retention curve that solves the problem of residual water contents.
1/[lambda]], to obtain the values of residual water content and the pore size distribution index in the micropores.
The residual water content and pore size distribution index in micropores were obtained from the fitting procedure.
Groenevelt PH, Grant CD (2004) A new model for the soil water retention curve that solves the problem of residual water contents.
r]))-1/[lambda], to obtain the values of residual water content and the pore size distribution index in the micropores.
Estimation methods are very sensitive to the choices of residual water content and match point (Stephens and Rehfeldt 1985), but agree very well with direct measurements when the residual water contents and match points are similar (Wright et al.
especially considering that data could be obtained only from the very wet end of the relationship for most of the techniques, and that the Mualem curve was forced to fit a residual water content that was probably too low for a fine-textured soil.