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 ?
The residual water content, C, is the amount of non-connected water that remains at the hydraulic cut-off suction, [h.
Nimmo JR (1991) Comment on the treatment of residual water content in "A consistent set of parametric models for the two-phase flow of immiscible fluids in the subsurface" by L Luckner et al.
Abbreviations: Se = the effective degree of saturation, th = the volumetric water content, thr = residual water content, ths = saturated volumetric water content, thm, thim= mobile and immobile water content, respectively, thFC = volumetric water content of soil at field capacity (cm3 cm-3); thWP = volumetric water content of soil at wilting point (cm3 cm-3).
Data show that (Table II) the residual water contents (thr) were in range of 0.
Commercially available lubricating oils are delivered by most manufacturers with low residual water content.
The fitted residual water content was affected by adding the wet end h([theta]) points, giving a significantly higher [[theta].
The parameters that were directly calibrated by fitting the model's prediction to observed data were: boundary pressure potential, boundary water content, residual water content, pore size distribution index in micropores, boundary hydraulic conductivity, tortuosity factors in macropores and micropores, dispersivity, and mixing-depth.
Equation 9 resembles that proposed by van Genuchten (1980), except that we replace van Genuchten's residual water content, [[theta].
The parameters directly calibrated by fitting model prediction to observed data were: boundary pressure potential, boundary water content, residual water content, pore size distribution index in micropores, boundary hydraulic conductivity, tortuosity factors in macropores and micropores, dispersivity, and mixing-depth.
r] is the residual water content, a is a curve-fitting parameter (equivalent to the reciprocal of the air-entry value), [Psi] is the matric potential or pressure head, n is another curve-fitting parameter, and m = (1 - 1/n).