Apparent and true

Table 3. Apparent and True pH of Aqueous Hydrogen Peroxide...

Depending on seasonal demands, the gasoline end point can range from 38()°F to 450°F (193°C to 232°C). Undercutting of gasoline increases the LCO product and can appear as low conversion. Therefore, it is necessary to distinguish between the apparent and true conversion. The apparent conversion is calculated before the gasoline end point adjustment is made, and the true conversion is calculated after the adjustment. 

The kinetics of Zn(II) electroreduction in water-methanol mixtures containing 1 M NaCl04 and TU was also investigated as a function of temperature [62]. The values of activation energy of Zn(II) electroreduction in these mixtures reached a maximum in the solution with 20 vol % of methanol. The apparent and true rate constants of the first and second electron charge transfer of Zn(II) electroreduction on Hg electrode in aqueous solution, and in the mixtures of water with methanol 91 vol %, DMSO 70 vol %, and DMF 90 vol % containing TU were estimated [63]. 

ASTM D-167. Standard Test Method for Apparent and True Specific Gravity and Porosity of Lump Coke. 

The behaviour of the glass electrode has also been examined.42-43 The glass-calomel electrode system yields stable and reproducible potentials which vary in the normal way with changes in hydrogen ion concentration. However, the EMF of the couple shifts several hundred millivolts as the solution composition changes from water to hydrogen peroxide. Table 1.2 summarizes the apparent and true pH of aqueous solutions of hydrogen peroxide. 

Table 1.2 Apparent and true pH of aqueous hydrogen peroxide...

In the case of a smaller LB sample (case I), both LD and LB signals are negligibly small compared with the CD signal. The apparent and true CD spectra are virtually the same (Fig. 31c), and the LB spectrum (Fig. 31a) is also almost... 

Mercury Porosimetry Method Mercury is a nonwetting liquid that must be forced to enter a pore by application of external pressure. Consequently it is an extremely useful and convenient liquid for measuring the density of powders and/or particles. This method can measure the apparent and true density of one sample by... 

FIGURE 24 Apparent and true surface contact area. 

Gotmar, G., Fornstedt,T., Guiochon, G. Apparent and true enantioselectivity in enantioseparations. Chirality, 2000,12, 558-564. 

FIGURE 17.3 Apparent and true deformation parameters of a test piece (of semihard cheese) under compression (as in Figure 17.Id), a is stress, e is strain. Apparent stress is force over initial cross-sectional area apparent strain is change in height over initial height (i.e., Cauchy strain). 

Just to give an idea how different are the apparent and true shear rates, we will notice that the higher the shear thinning effect, the larger the difference. For example, at the power-law index n = 0.8, the difference in shear rates and, hence, apparent and true viscosities is 6.25%. For n = 0.2, the difference is 100%. 

Smiricky, M.R. C.M. Grieshop D.M. Albin J.E. Wubben V.M. Gabert G.C. Fahey, Jr. The influence of soy oligosaccharides on apparent and true ileal amino acid digestibilities and fecal consistency in growing pigs./. Anim. Sci. 2002, 80, 2433-2441. 

Angkanaporn, K. V. Ravindran W.L. Bryden. Additivity of apparent and true ileal AA digestibilities in soybean meal, sunflower meal, and meat and bone meal for broilers. Poult. Sci. 1996, 75, 1098-1103. 

The apparent density is also badly defined. It actually uses volumes of a polymer sample measured either by microscopy or by mercury pycnometry under 1 atm pressure. With pores large enough, these methods can provide different results. From this consideration it follows that the most reliable method of measuring the pore volume W, of a porous material, by comparing its apparent and true densities, bears serious uncertainty. 

Furuya S., Kaji Y., 1991. Additivity of the apparent and true digestible amino acid supply in barley, maize, wheat or soya bean based diets for growing pigs.An/m. Feed ScLTechnoL, 32,321-331. 

The choice of method depends primarily on the information required, and secondarily on the field of study, the amount of substance available, the time required, and, when necessary, on the effort required to purify the samples. Determinations are generally made at various concentrations. Then the apparent molar mass is calculated with the aid of an ideal theoretical relationship—that is, a relationship that only applies strictly at infinite dilution. This apparent molar mass must then be extrapolated to zero concentration to obtain the true molar mass. Apparent and true molar masses may differ considerably. Coil-shaped macromolecules of number-average molar mass of 10 g/ mol can, for example, have an apparent number-average molar mass in good solvents of 555 000 g/mol at a concentration of 0.01 g/ ml and 110 000 g/mol only, on the other hand, when the concentration is 0.1 g/ml. 

Several sources report the specific gravity of some vegetable fibers. They are listed in Table 8.6. The range of values given suggests that attainment of precision in this measurement is difficult. Part of the problem may be in the porous nature of the fibers. Sinha [159,160] gives the explicit value for porosity, as well as apparent and true density of some vegetable fibers these are summarized in Table 8.7. 

Porosity, Apparent, and True Density of Some Vegetable Fibers... 

Comparison between Eqs. (56) and (57) gives the correlation between the apparent and true activation volumes ... 

Now consider Dorn s method (see Sect. 5.1) of calculating both the apparent and true activation parameters. 

Coke is a porous carbon material consisting of a network of pores of various dimensions and shapes, some of which are closed, but the majority of which are interconnected. Generally, porosity of industrial cokes is determined indirectly from the ratio of apparent and true relative densities, according to the equation... 

A full description of the determination of apparent and true specific densities of lump coke is given in the ISO 1014 and ASTM D167 procedures. 

The apparent and true rate constants for the imidazole-catalysed oxidation of zinc 5,15-di(( rf/t(9-methyloxyphenyl)-2,3,7,8,12, 13,17,18-octamethylporphyrin (ZnP) with organic peroxides in o-xylene was studied. The metalloporphyrin chromophore decomposed completely during the reaction of ZnP with peroxides. The geometric characteristics of the optimized ZnP structure and intermediates of the oxidation were obtained by the PM3 quantum-chemical method. The deformational strains in the ZnP macrocycle increased during the reaction. 

Table 13.2 Apparent and true ileal protein digestibility values as determined by the N-isotope dilution techniques...

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