Pores substrate

Electrostatic Agglomerated Ultra-Wide-pore Substrates... 

Structure EANPS = electrostatic agglomerated nonporous substrate, EAWPS = electrostatic agglomerated wide-pore substrate, PGPS = polymer grafted porous substrate, SMPSS = silane modified porous silica substrate, CMS = chemically modified substrate, APCS = adsorbed polymer coated substrate. 

Here we suggest that ions or molecules temporarily bound to the membrane surface may have their transmembrane movement enhanced by pore formation and that this possible mechanism also has catalytic features. This additional hypothesis envisions that local membrane conformational changes can result from both the local transmembrane voltage and the surface binding of a transported molecule (S). That is, a pore-substrate complex is formed. One possible outcome is transmembrane transport in which S is temporarily bound to the inner surface of a pore, with subsequent electrical lateral motion (relative to the pore inner surface) by diffusion or lateral drift to the other side. Alternatively, as a pore shrinks and closes, S is presented to the other side of the membrane. In either case, upon dissociation, transport of S will have been accomplished. 

Fig. 4. The simple pore. (A) formal representation (B) cartoon diagram. Rate constants /, and /2 describe the formation, and 62 the breakdown of the pore-substrate complex at sides I and 2 of the membrane, respectively. The solid circle represents the substrate molecule. E is the unoccupied pore, ES is the pore occupied by the substrate S.

Pore-substrate Pore-product Pore-intermediate 2... 

Absorption. Some inks (eg, oil-based newspaper inks) dry by penetration or absorption into the pores of the printed stock, which has a blotter or sponge effect. This is accompHshed by the gross penetration of the ink vehicle into the pores of the substrate, the partial separation of the vehicle from the pigment, and the diffusion of the vehicle throughout the paper. The abiHty of an ink to penetrate into paper depends on the number and size of the air spaces present in the paper, the affinity or receptivity of the stock for the ink, and the mobiHty of the ink. 

Under severe conditions and at high temperatures, noble metal films may fail by oxidation of the substrate base metal through pores in the film. Improved life may be achieved by first imposing a harder noble metal film, eg, rhodium or platinum—iridium, on the substrate metal. For maximum adhesion, the metal of the intermediate film should ahoy both with the substrate metal and the soft noble-metal lubricating film. This sometimes requires more than one intermediate layer. For example, silver does not ahoy to steel and tends to lack adhesion. A flash of hard nickel bonds weh to the steel but the nickel tends to oxidize and should be coated with rhodium before applying shver of 1—5 p.m thickness. This triplex film then provides better adhesion and gready increased corrosion protection. 

Formulas for representative floor poHshes are Hsted in References 3, 12, 13, and 25. An aqueous formula may contain 0—12 wt % polymer, 0—12 wt % resin, 0—6 wt % wax, 0.3—1.5 wt % tris(butoxyethyl)phosphate, 1—6 wt % glycol ether, and 0—1 wt % zinc, with water filling the rest. Water-clear floor finishes contain Htfle or no wax, whereas buffable products contain relatively large amounts of wax. Sealers contain Htfle wax and relatively large amounts of emulsion polymers (28). For industrial use, sealers are appHed to porous substrates to fiH the pores and prevent poHshes that are used as topcoats from soaking into the floor. 

Membranes. Membranes comprised of activated alumina films less than 20 )J.m thick have been reported (46). These films are initially deposited via sol—gel technology (qv) from pseudoboehmite sols and are subsequently calcined to produce controlled pore sizes in the 2 to 10-nm range. Inorganic membrane systems based on this type of film and supported on soHd porous substrates have been introduced commercially. They are said to have better mechanical and thermal stabiUty than organic membranes (47). The activated alumina film comprises only a miniscule part of the total system (see Mel rane technology). 

Dj IE, ratio of a crack is held constant but the dimensions approach molecular dimensions, the crack becomes more retentive. At room temperature, gaseous molecules can enter such a crack direcdy and by two-dimensional diffusion processes. The amount of work necessary to remove completely the water from the pores of an artificial 2eohte can be as high as 400 kj/mol (95.6 kcal/mol). The reason is that the water molecule can make up to six H-bond attachments to the walls of a pore when the pore size is only slightly larger. In comparison, the heat of vaporization of bulk water is 42 kJ /mol (10 kcal/mol), and the heat of desorption of submonolayer water molecules on a plane, soHd substrate is up to 59 kJ/mol (14.1 kcal/mol). The heat of desorption appears as a exponential in the equation correlating desorption rate and temperature (see Molecularsieves). 

Another class of water-based materials that has recently (ca 1997) begun to see use ia masoary water repeUeacy treatmeats is sUicoae elastomer latex (89), which can deHver a water-permeable sUicone mbber film. These latex elastomers are ideal as water repeUents for substrates that contain very large pores, such as concrete block. In addition, the elastomer can bridge minor cracks, and wUl expand and contract with the substrate. 

The other type of nickel electrode involves constmctions in which the active material is deposited in situ. This includes the sintered-type electrode in which nickel hydroxide is chemically or electrochemically deposited in the pores of a 80—90% porous sintered nickel substrate that may also contain a reinforcing grid. 

Sulfur dyes are used for dyeing ceUulosic fibers. They are insoluble in water and are reduced to the water-soluble leuco form for appHcation to the substrate by using sodium sulfide solution. The sulfur dye proper is then formed within the fiber pores by atmospheric oxidation (5). Sulfur dyes constitute an important class of dye for producing cost-effective tertiary shades, especially black, on ceUulosic fibers. One of the most important dyes is Cl Sulfur Black 1 [1326-82-5] (Cl 53185), prepared by heating 2,4-dinitrophenol with sodium polysulfide. 

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