Penetrant permeability

Durchgabet/. filtration transmission. Durchgang, m. passage duct transit. durchgiLiigig, a. penetrable, permeable thoro general, usual. 

CA 61, 8124(1964) (Satd soln of AN in liquid NH3 is pumped into drill holes and penetrates permeable earth layers. Shaped charge fuse is used for initiation. This method permits one to explode the total chge, because of the continuous distribution of expl in the earth formation)... 

Accurate description of barrier films and complex barrier structures, of course, requires information about the composition and partial pressure dependence of penetrant permeabilities in each of the constituent materials in the barrier structure. As illustrated in Fig. 2 (a-d), depending upon the penetrant and polymer considered, the permeability may be a function of the partial pressure of the penetrant in contact with the barrier layer (15). For gases at low and intermediate pressures, behaviors shown in Fig. 2a-c are most common. The constant permeability in Fig.2a is seen for many fixed gases in rubbery polymers, while the response in Fig. 2b is typical of a simple plasticizing response for a more soluble penetrant in a rubbery polymer. Polyethylene and polypropylene containers are expected to show upwardly inflecting permeability responses like that in Fig. 2b as the penetrant activity in a vapor or liquid phase increases for strongly interacting flavor or aroma components such as d-limonene which are present in fruit juices. 

This simple model is applied to chemical weathering of silicates caused by the interaction of rainwater penetrating permeable rocks downward to interpret Goldich s weathering series. 

Chain length of sodium alkyl carboxylate Human skin penetration Permeability constants (//cmmin ), 6mM solution for 6h in vitro Rat skin penetration Amount penetrating 7.5 cm of skin, applied for 15 min 0.1ml of 6mM solution Inhibition of DNA synthesis in vitro Cone. (mM) required to inhibit uptake of HTdR into fibroblasts in vitro Mast cell lysis in vitro Cone. (mM) to release histamine from mast cells in vitro Fibroblast lysis in vitro Cone. (mM) to release Cr-labelled cytoplasm from fibroblasts in vitro... 

Figure 24.13 Ratio of penetrant permeability in the nanocomposite to that in the pure polymer as a function of filler volume fraction (Merkel et al., 2002).

The main factors affecting small penetrants permeability in polymeric material include free volume and its distribution, " density, tanperature and pressure, crystallinity," polymer chain length, mobility and packing, solute size, and affinity for the material. In addition, computational parameters used in the simulations such as the type of force field employed and the size of the model also affect the permeability value computed. An increase in tanperature generally leads to a decrease in the solubility and conversely for the diffusion. For all three physical quantities P, S, and D, the tanperature dependence can be described by a Van t Hoff-Arrhenius equation. In particular, for the solubility... 

Where d = total metal thiekness penetrated f = frequency (X = permeability cr = conduetivity... 

An additional benefit of prethickening is reduction in cake resistance. If the feed concentration is low, there is a general tendency of particles to pack together more tightly, thus leading to higher specific resistances. If, however, many particles approach the filter medium at the same time, they may bridge over the pores this reduces penetration into the cloth or the cake underneath and more permeable cakes are thus formed. 

Specific barriers may serve to limit dmg distribution. The placental barrier is of obvious importance to dmg action in the fetus. Dmg transfers across the placenta primarily by Hpid solubiHty. Hence, this barrier is not particularly restrictive. Similarly, the Hpid solubiHty of a dmg is a primary deterrninant in access to the brain and cerebrospinal fluid. Generally, hydrophilic or charged dmgs can also penetrate to these latter areas, but the result is slow and incomplete. The blood brain barrier is composed of cells having tight junctions which are much less permeable to solutes than are the endotheHal cells of other tissues. 

A more polar comonomer, eg, an AN comonomer, increases the water-vapor transmission more than VC when other factors are constant. For the same reason, AN copolymers are more resistant to penetrants of low cohesive energy density. AH VDC copolymers, however, are very impermeable to ahphatic hydrocarbons. Comonomers that lower T and increase the free volume in the amorphous phase increase permeability more than the polar comonomers higher acrylates are an example. Plasticizers increase permeabiUty for similar reasons. 

The grounding or penetration depth of the electrical resistance in conductors is, according to Eq. (3-42), dependent on the specific resistance and the frequency. The penetration depth, t, is the distance at which the field strength has fallen by 1/e,- is the relative permeability [35] ... 

Overall board density will strongly affect core layer plasticization and density profile (Fig. 12), as at the highest overall board density a steep density gradient appears between the surface and core layers of the board. This is due to the greater difficulty encountered by the steam to penetrate and plasticize it. At lower density, the greater mat permeability enables a faster steam throughflow of the board, comparable to a steam injection process. The final result is similar as the overall board density is closer in value to both core and surface densities. 

Exercise also increases skin circulation and perspiration, which both enhance dermal penetration of compounds into the body. Furthermore, skin lesions, such as wounds and dermatitis, can increase the permeability of the skin to chemicals. Also, exposure of the skin to solvents and removal of skin fat increase dermal penetration of a number of compounds. Compounds penetrate the skin more readily in places where the skin is thin, like the face, hands and scrotum. Increased dermal blood flow due to exercise facilitates the penetration of the skin by chemicals. 

Dissolved Gas. Gas which enters the borehole when penetrating a high pressure zone may not dissolve immediately in the mud. The free gas considered here is the gas entering the borehole minus the dissolved gas. Table 4-128 indicates the maximum volume of dissolved gas at bottomhole conditions expressed in percent of annulus mud volume. Thus, when entering a high pressure permeable formation this much gas will dissolve first before free gas appears in the mud. 

Basically all formations penetrated during drilling are porous and permeable to some degree. Fluids contained in pore spaces are under pressure that is overbalanced by the drilling fluid pressure in the well bore. The bore-hole pressure is equal to the hydrostatic pressure plus the friction pressure loss in the annulus. If for some reason the borehole pressure falls below the formation fluid pressure, the formation fluids can enter the well. Such an event is known as a kick. This name is associated with a rather sudden flowrate increase observed at the surface. 

Timber species also vary in the treatability of the heartwood - with preservatives in an impregnation plant, and are classified into four categories according to the depth of penetration which can be achieved permeable (complete penetration) moderately resistant (6-18 mm lateral penetration) resistant (3-6 mm lateral penetration) and extremely resistant (no appreciable lateral and very little end-grain penetration). 

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