Compensation effect INDEX

It is not easy to compare the activity of the V-W-Ti catalysts here tested with the lot of chromia, Pt and Pd based catalysts previously used because they have different shapes (monoliths and spheres) and because very different particle sizes arc involved (having thus very different effectiveness factors). For conqiarison purposes, all X-T curves were adjusted to a simple fust order kinetic model (with rate based on overall volume of catalyst, both for monoliths and for fixed beds). From the kinetic constants so obtained (see details of the method in ref 7), the preexponential factors (ko) of the Arrhenius law and the apparent energies of activation (E, p) were calculated for all catalysts. One example is shown in Figure 17. By the well Imown compensation effect between ko and E,pp, the kg values so obtained were recalculated for a given E.pp value of 44 kJ/mol. Such new ko value was used [7] as an activity index of the catalyst. 

Interpretation of NMR well logs is usually made with the assumption that the formation is water-wet such that water occupies the smaller pores and oil relaxes as the bulk fluid. Examination of crude oil, brine, rock systems show that a mixed-wet condition is more common than a water-wet condition, but the NMR interpretation may not be adversely affected [47]. Surfactants used in oil-based drilling fluids have a significant effect on wettability and the NMR response can be correlated with the Amott-Harvey wettability index [46]. These surfactants can have an effect on the estimation of the irreducible water saturation unless compensated by adjusting the T2 cut-off [48]. 

Here functions Qnt X), Qj(X), and QP(X) can be determined experimentally using calibration samples. If these functions are linear independent then the parameters Ank, A, and Ap can be uniquely determined from the variation of P /1, , n2,. .. /( . /. / considered as a function of X. In particular, the side effects, i.e., the temperature and pressure dependences, can be eliminated from the transmission spectrum. The sensing method based on this simple idea was applied in Ref. 69 for determination of microfluidic refractive index changes in two microcapillaries coupled to a single MNF illustrated in Fig. 13.26c. The developed approach allowed to compensate the side temperature and pressure variation effects. 

Just like refractive index, the °Brix scale is quite dependent on the temperature. Manual Abbe refractometers do not compensate for this temperature effect. Special correlation tables are used to adjust the readings to a standard temperature, 20°C. Digital refractometers, on the other hand, can operate over a fairly wide range of sample temperatures (+15 to +40°C) and automatically apply these temperature corrections. See Workplace Scene 15.2. 

When a differential refractometer is used as a detector, instrumental broadening of the GPC chromatogram is compensated to some extent by another effect due to the tendency for specific refractive indexes of polymer solutions to decrease with decreasing molecular weight in the low-molecular-weight range. 

Figure 17.9 shows the principle of the antireflection/antistatic thin hlms formed on the panel surface. There is a layer of hhn having a high refractive index (Sn02) and a layer of him having a low refractive index (Si02). Light rehection is reduced since they are mutually compensated by the interference effect on all areas of the interface between these layers of him. 

This correction seems not to be able to resolve the problem of temperature dependence of AH° and AS°. However, AC°p is typically small and its effect on AH° and AS° tend to compensate each other. For this reason, in much estimation for thermochemical values at elevated temperatures, the values for 298.15° K are used. The index for AH° and AS° indicating the temperature is not necessary when T = 298.15° K. 

FIGURE 4.13 Schlieren signals recorded for different solutions with the same refractive index. Carrier stream = water coiled reactor length = 100 cm a. b, c, d = 2.0 mol L-1 HC1,11.2% (m/v) sucrose, 14% (m/v) glycerol, and 24.13% (m/v) ethanol respectively. Other conditions are as in Fig. 4.13. Reprinted from Anal. Chim. Acta 234 (1990) 153, E.A.G. Zagatto, M.A.Z. Arruda, A.O. Jacintho, I.L. Mattos, Compensation of the Schlieren effect in flow-injection analysis by using dual-wavelength spectrophotometry, with permission from Elsevier (Ref [28]). 

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