1 When the last tube is filling, remove the tourniquet. 2  Remove the needle from the patient's arm using a swift backward motion. 3  Place gauze immediately on the puncture site. 4  Apply and hold adequate pressure to avoid formation of a hematoma.
Thermal Diffusivity. a physical parameter of a substance that characterizes the rate of change of its temperature in transient thermal processes. Thermal diffusivity is a measure of the thermal-inertia properties of a substance. It is numerically equal to the ratio of the substanceâs thermal conductivity and the product of its specific heat (at constant pressure) and density. Thermal diffusivity is expressed in m 2 /sec.
For other uses, see Diffusivity (disambiguation) . Diffusivity or diffusion coefficient is a proportionality constant between the molar flux due to molecular diffusion and the gradient in the concentration of the species (or the driving force for diffusion).Diffusivity is encountered in Fick's law and numerous other equations of physical chemistry.ypically, a compound's diffusion coefficient is ~10,000Ã as great in air as in water. Carbon dioxide in air has a diffusion coefficient of 16 mm 2 /s, and in water its diffusion coefficient is 0.0016 mm 2 /s.