Reduced penetration

The primary adhesive used ia hardwood plywood is urea—formaldehyde (UF) mixed with wheat flour as an extender to improve spreadabiUty, reduce penetration, and provide dry-out resistance. A catalyst may also be added to UF resias to speed the cure or to cause the UF to cure. Scavengers also may be added to reduce formaldehyde emissions from finished panels. If more water-resistance is requited using a UF bond, small amounts of melamine maybe added, producing a melamine—urea—formaldehyde (MUF) adhesive. 

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. 

Sealers. Mica is used in all types of sealers for porous surfaces, such as waHboard masonry, and concrete blocks, to reduce penetration and improve holdout (see Sealants). It permits a thicker film to be appHed and at the same time reduces sagging. Cracking is reduced by the reinforcing action of the flakes, and gaps and holes in rough masonry are bridged by the mica flakes. 

The chemical and mechanical dispersion of the drilled soHds tends to increase the percentage of smaH-sized soHds in a mud as drilling progresses. The incorporation of a limited amount of drilled soHds (several volume percent) is an economical way of increasing the density of low density muds, but it also reduces penetration rates hence, drilled soHds are usually kept to a minimum. The common clay and formation soHds encountered in normal drilling operations are as foUows ... 

Fillers are added to emulsion adhesives to build the total soflds content, to reduce penetration into a porous substrate, and to lower costs. 

Adhesives for paper tubes, paperboard, cormgated paperboard, and laminated fiber board are made from dispersions of clays suspended with fully hydrolyzed poly(vinyl alcohol). Addition of boric acid improves wet tack and reduces penetration into porous surfaces (312,313). The tackified grades have higher solution viscosity than unmodified PVA and must be maintained at pH 4.6—4.9 for optimum wet adhesion. 

The unavoidable addition of solids comes from the continual influx of drilled cuttings into the active mud system. Undesirable solids increase drilling cost because they reduce penetration rate through their effect on mud specific weight and mud viscosity. 

Decorative coatings of nickel plus chromium are cathodic to steel or zinc alloy substrates and with these protective systems deliberate use may be made of discontinuities in the chromium topcoat where corrosion of the underlying nickel will occur. If the number of these discontinuities in the chromium layer is greatly increased the current density at each individual corrosion site is reduced, penetration of corrosion through the thickness of the nickel layer is thus slowed down and the period of protection of the substrate metal is prolonged. 

Genetic transmission in nemaline myopathy is the subject of some uncertainty. A Japanese study of 50 pedigrees came to the conclusion that autosomal dominant with reduced penetrance was the most probable mode. However a Finnish study presented evidence for autosomal recessive transmission. There is no evidence that severe and mild forms are genetically distinct and several pedigrees contain members showing widely differing clinical severity. A candidate gene for autosomal dominant nemaline myopathy has been localized to chromosome Iq 21—23. 

Although suppression of FSH and LH is the primary mechanism by which combined oral contraceptives prevent ovulation, there are other mechanisms by which these hormones work to prevent pregnancy. Other mechanisms include reduced penetration of the egg by sperm, reduced implantation of fertilized eggs, thickening of cervical mucus to prevent sperm penetration into the upper genital tract, and slowed tubal motility, which may delay transport of sperm.1 Thus, in... 

Reduced penetrance and variable expressivity are factors that influence the effects of particular genetic changes. These factors usually affect disorders that have an autosomal dominant pattern of inheritance, although they are occasionally seen in disorders with an autosomal recessive inheritance pattern. 

Reduced penetrance probably results from a combination of genetic, environmental, and lifestyle factors, many of which are unknown. This phenomenon can make it challenging for genetics professionals to interpret a person s family medical history and predict the risk of passing a genetic condition to future generations. 

As with reduced penetrance, variable expressivity is probably caused by a combination of genetic, environmental, and lifestyle factors, most of which have not been identified. If a genetic condition has highly variable signs and symptoms, it may be challenging to diagnose. 

Skipped generations are not typically seen because two unaffected parents cannot transmit a disease-causing allele to their o pring (an exception occurs when there is reduced penetrance, discussed below),... 

Hydrophobe modified carboxymethyl cellulose (D) reduces penetration (compare to B). 

The model was fit to experimental planarization data with good success. Divergence from experimental results was explained by viscoelastic deformation of pad asperities. Incomplete elastic recovery reduces penetration of the trench and improves selectivity. This may be due to velocity effects (i.e., the interaction times are below the relaxation time for the material). 

Be sure to remove the extraembryonic membrane. Failure to do this may result in the lower colorimetric detection due to the reduced penetration of the probe. If technically difficult, the extraembryonic membrane should be at least partially torn. Additionally, be sure to puncture the vesicular structures such as brain, heart, and otic vesicles to prevent the false-positive staining caused by trapping of the probe. 

The reduced penetrability of cervical mucus, which contributes to the contraceptive effect, may well provide some small degree of protection against pelvic inflammatory disease. However, this effect is likely to be less than that exerted by combined oral contraceptives, since the expanded cervical ectropion found among combined oral contraceptive users is not present in users of progestogen-only contraceptives. 

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