Apparent coefficient

Calculation of the Quotient of Purity.—From the results of analysis of the juice the percentage of sugar in the dry matter is calculated, this being known as the quotient or coefficient oj -purity. If the dry matter has been determined directly, this quotient is known as the real coefficient of purity, whereas, if the degrees Brix are taken as the dry matter, it is termed apparent. Further, if the dry matter is determined by the refractometric method, the optical quotient of purity is obtained, this being also an apparent coefficient, but usually nearer to the real value than the apparent coefficient calculated from the degrees Brix. 

Partition Coefficients. Values for log P are given in a number of monographs. Where the pH of the aqueous phase is stated, the values given are apparent coefficients at that pH (not ion-corrected). Where no pH is stated for the aqueous phase, it can be assumed that log P is for the neutral form of the substance even though it is potentially ionisable. The values given are approximate only but they serve to indicate the characteristics of the substance when it is submitted to an extraction process. 

F/=real volume of liquid at F/ =apparent volume of liquid at t°C. as measured by the graduation on the vessel, a =apparent coefficient of cubical expansion of the liquid, a=true coefficient of cubical expansion of the liquid ( l.VIII C), g=coefficient of cubical expansion of the glass of the vessel (taken as three times the coefficient of linear expansion). Then ... 

Hence the true coefficient of cubical expansion is the sum of the apparent coefficient of cubical expansion and the coefficient of cubical expansion of the vessel. 

If P is the apparent coefficient of expansion of the liquid, the apparent expansion of volume is... 

With increasing additive concentration and/or with increasing additive adsorption energy, the apparent coefficient fcj s = bj/ (1 + bsCs) decreases, and the iso-... 

In practice, because of some instrumental or environmental errors, an isosbestic point is rather a small surface than a real point, and a procedure has been proposed for its detection [8,9]. An isosbestic point is defined by the wavelength XjP (orX/p for hidden IP) as a point where the apparent coefficient of variation (CV ) is lower than a limit value (fixed to 2.5%, value obtained from a statistical study on repeatability) ... 

Table 12.4 shows that swelling is more pronounced with low-density boards compared with high-density boards, and the difference is even higher at a shortterm water absorption. Table 12.5 shows the data, but as a percentage of swelling to the initial width of the boards, and Table 12.6 shows the apparent coefficients of dimensional change, Cw... 

More data on a short-term water absorption (24 h of submerging) for composite materials show that Cj (lengthwise) and Cw (widthwise) apparent coefficients... 

Density Apparent coefficients (Cw) of widthwise dimensional change (%) ... 

Fig. 18 Apparent coefficients of intracrystalline self-diffusion of n-hexane as observed by time- and space-resolved PFG NMR in a bed of zeolite Na-X with restricted ( ) and unrestricted ( ) sorbate supply in dependence on the sorbate concentration. The real diffusivities open symbols) were calculated from these values by using the correspondence presented by Fig. 3. The full line with the indicated error bars represents the range of intracrystalline diffusivities as observed in previous PFG NMR studies with closed sample tubes. From [163] with permission...

Staxing with this frictional analogy, the inclined plane method of measuring friction would gi c an apparent coefficient of friction, since conditions are not tighll) controlled (xelocilx. for example, cannot be. specified) and there is little chance of relating the result to other conditions. 

FIGURE 18.5. In frictional interactions between a hard and a soft surface, heat, pressure, and/or plowing may cause the softer material to roll up or dislodge, reducing the real area of contact and, in some cases, producing bearings that effectively lower the apparent coefficient of friction—at the cost of damage to the softer surface. 

FIGURE 18.7. For some polymers in contact with a harder surface, small sections of the surface material may detach and slide along the surface with the harder material. The apparent coefficient of friction will then be that of polymer against polymer. 

FIGURE 18.8. A lubricant fluid in lamellar flow will offer minimum resistance to the movement of the opposing solid surfaces (a). In turbulent flow (fc), eddies and voids in the fluid will impede the smooth flow of hquid and may translate that resistance into an increase in the apparent coefficient of friction for the system. 

FIGURE 18.12. In perfect boundary lubrication (a) contact is exclusively between adsorbed layers so that the coefficient of friction corresponds to those materials. In reality, the natural irregularities in even the most polished surfaces will produce areas of direct contact between surfaces (b). The apparent coefficient of friction, therefore, will be some average value based on the relative areas of contact oA and fiA. 

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