Saturation (chemistry)

About: Saturation (chemistry) is a research topic. Over the lifetime, 15075 publications have been published within this topic receiving 258689 citations.

Properties of Porous Media Affecting Fluid Flow

Abstract: Following the Burdine approach, based on a model developed by Wyllie and Spangler, a theory is presented that develops the functional relationships among saturation, pressure difference, and permeabilities of air and liquid in terms of hydraulic properties of partially saturated porous media. The theory is based only on the capillary pressure-desaturation relationships for porous media. Procedures for determining these hydraulic properties from capillary pressure-desaturation curves are described. Permeabilities to the wetting and nonwetting phases as a function of capillary pressure and saturation are predicted from the experimentally determined hydraulic properties. The results for all media studied are in close agreement with the theory.

Stomatal Control of Transpiration: Scaling Up from Leaf to Region

Abstract: Publisher Summary The study of leaf anatomy and of the mechanisms of the opening and closing of stomatal guard cells leads one to suppose that the stomata constitute the main or even the sole regulating system in leaf transpiration. Meteorologists have developed a wide variety of formulae for estimating evaporation from vegetation that are based entirely on weather variables and take no account at all of the species composition or stomatal properties of the transpiring vegetation. These “potential evaporation” formulae are widely and, to a large degree, successfully used for estimating evaporation from vegetation that is not water-stressed. Transpiration depends on stomatal conductance, net radiation receipt and upon air saturation deficit, temperature, and wind speed. Saturation deficit and wind speed vary through leaf boundary layers, through canopies, and through the atmosphere above the canopies. The sensitivity of saturation deficit to changes in stomatal conductance depends on where the saturation deficit is measured. If all of the stomata on a single leaf change aperture in unison, there may be a substantial change in saturation deficit measured at the leaf surface but a negligible change in saturation deficit measured a centimetre or two away, outside the leaf boundary layer.

Code Saturation Versus Meaning Saturation: How Many Interviews Are Enough?

Abstract: Saturation is a core guiding principle to determine sample sizes in qualitative research, yet little methodological research exists on parameters that influence saturation. Our study compared two approaches to assessing saturation: code saturation and meaning saturation. We examined sample sizes needed to reach saturation in each approach, what saturation meant, and how to assess saturation. Examining 25 in-depth interviews, we found that code saturation was reached at nine interviews, whereby the range of thematic issues was identified. However, 16 to 24 interviews were needed to reach meaning saturation where we developed a richly textured understanding of issues. Thus, code saturation may indicate when researchers have "heard it all," but meaning saturation is needed to "understand it all." We used our results to develop parameters that influence saturation, which may be used to estimate sample sizes for qualitative research proposals or to document in publications the grounds on which saturation was achieved.