Mesoporous separation layers are commonly in the transient - regime among Knudsen diffusion and molecular diffusion
, with large effects on the selectivity (separation factor).
Existing theories, however, predict a huge inner gas pressure (typically around 30 atm) and, consequently, molecular diffusion
theory would predict that they would dissolve extremely quickly - on a timescale of about 1 microsecond.
Where [??] is air density, [u.sub.j] is air velocity, [C.sub.i] is the mass fraction of chemical species, [R.sub.i] is the reaction source term, [D.sub.i] is the molecular diffusion
coefficient, and [S.sub.i] is source term.
Diffusion tensor imaging (DTI) can quantitatively analyze the water molecular diffusion
in skeletal muscle fibers, which is combined with high-resolution anatomical images to show the arrangement and connection of muscle fibers.
Searching for the chemical and physical mechanisms that determine the final properties of the latex has involved the application of organic and physical chemistry, surface chemistry, reaction kinetics, thermodynamics, molecular diffusion
. Molecular diffusion
is the result of molecular thermal motion and collision, the mass flux density J (kg x [m.sup.-2] x [s.sup.-1]) caused by which can be described by Fick's law:
IVIM DWI, which was initially described by Le Bihan and Turner  in brain imaging, has the potential to measure both true molecular diffusion
and the incoherent motion of water molecules in the capillary network.
Figure 4 presents the types of diffusion in porous materials, and these include molecular diffusion
, Knudsen diffusion, and a mixture of both diffusion types .
Based on some microstudy on aging of the asphalt binder, it is seen that there are two reasons for the decrease of molecular diffusion
of aged asphalt: on the one hand, the molecular size of asphaltene, resin, and aromatic decreases; on the other hand, free volume space for saturate reduces.
Scarpa et al., "Cellulose nanofibrils films: molecular diffusion
through elongated nanocavities," Journal of Physical Chemistry C, vol.
To test the feasibility of this diffusion microchip system, Coomassie Brilliant Blue G-250 (Bionovas, Toronto, Canada) and potassium ferricyanide (Merck, Darmstadt, Germany) were selected, respectively, as model color compounds for observing molecular diffusion
through the donor cell into the receptor and sequential flow in the microchannel.
In this stage, transformation of Ft to F6 in [S.sub.IN] was likely to be affected by the molecular diffusion
in micropores of the soil minerals [9, 10].