Apparent kinetic constants

If the same quantity of active ingredient is concentrated in an outside shell of thickness 0.015 cm, one obtains y> = 2.27. This would yield an effectiveness factor of 0.431 in a slab geometry, and the apparent kinetic constant has risen to 99.2 sec-1. If the active ingredient is further concentrated in a shell of 0.0025 cm, one obtains y> = 0.38, an effectiveness factor of 0.957, and an apparent kinetic constant of 220 sec-1. These calculations are comparable to the data given in Fig. 15. This analysis applies just as well to the monolith, where the highly porous alumina washcoat should not be thicker than 0.001 in. 

The apparent kinetic constants were obtained from Lineweaver-Burk plots of AHH activities recorded in the presence of increasing concentrations of benzo(a)pyrene (0.001-1.0 mM). The plots were linear for both untreated and DBA-induced animals. The apparent V was 20- to 30-fold higher in hepatic microsomes from the induced skates whereas the apparent K values were of the same magnitude in control and treated fish. 

Apparent kinetic constants Vj j =0.810 mmol.mgprot. min andK = 210 mM... 

The UV/ozone process can treat pesticides without little generation of refractory products. One of the most common pesticides found in water supplies is Propoxur. The oxidation kinetics was developed in terms of the reaction orders and apparent kinetic constants (Benitez et al., 1994). The amount of chemical removed (Xp) is inversely proportional to the amount of initial Propoxur concentration (Cp), ozone partial pressure (kPa), temperature, and pH. When Propoxur is degraded by UV /ozone, the reactions can be represented by the following general reactions ... 

For calculating the external mass transfer k a value of Sh = 2 can be safely assumed. The specific mass-transfer area per unit of bed volume is p - 6(1-Eb)/dp, in which b is the bed void fraction. The combination of resistances leads to the following expression for the apparent kinetic constant ... 

The apparent kinetic constants, ka(hr 1), along the runs, showed a linear decay with vanadium concentration on catalysts. A model is developed which reproduces this finding and it could allow to shorten the screening period for demetallation catalysts. ... 

An Arrhenius plot for the apparent kinetic constant at the start of run, ka, for catalyst A, is shown in Rgure 4. From this kind of graph the apparent kinetic expressions [equation (1)] were obtained ... 

The plot of the apparent kinetic constants, ka, as a function of Wvr the vanadium deposited on catalyst, at different temperatures levels, for catalyst C, is shown in Figure 5. A linear relationship can be observed (interrupted lines in Figure 5) between both variables, for same temperature level, however the interception, at the start of run, differs from the experimental values for ka. The dot-and-segment lines in Figure 5 correspond to the interpolation between the experimental values for ka, obtained during the long deactivation test, and the ka data for the fresh catalyst. 

In order to interpret the relationship obtained between the apparent kinetic constants and the amount of vanadium accumulated on the catalysts (Figures 5 and 6), a simple model was developed. 

The Lineweaver-Burk plots of the (R)-ester, in the presence and absence of the (S)-enantiomer, exhibited a typical pattern of a competitive inhibitor with two straight lines crossing on the vertical axis. Apparent kinetic constants were evaluated from the plots and summarized in Table III. 

Table III. Apparent Kinetic Constants of Hydrolysis of Acetate of HMPC with Arthrobacter Lipase...

Figure 7-3 Inhibitor types, corresponding apparent kinetic constants, and reaction mechanisms. Here a is defined as (1 + [IJ/X i), while p is short for (1 -t- Note that the...

A non-uniform distribution of substrate and/or product between the enzyme matrix and the surrounding solution effects the measured (apparent) kinetic constants. 

In addition, the apparent kinetic constants between these families so lumped are strictly expressed according to a small number of elementary and fundamental kinetic constants. Their number remains finite, irrespective of the number of carbon atoms in the molecule furthermore, due to their intrinsic nature, it may be possible to determine them from simple model molecules. 

Based on the previous assumptions, we can rigorously and explicitly determine an analytical expression of the apparent kinetic constants, between all the lumped families (Fx -> Fy) according to intrinsic elementary kinetic constants as specified in the Single-Events theory (Cochegrue, 2001 Schweitzer, 1998 Valery, 2002). The same applies for the denominator DEN (see next Fig. 26), in which the sum of the terms expresses the competitive chemisorption of all secondary and tertiary carbocations on the acid sites. The apparent kinetics so obtained formally return Langmuir-Hinshelwood expressions, traditional... 

The apparent kinetic constants of the molecularly pure cyclic BA monomer to trimer for lipase CA were determined according to the literature using Lineweaver-Burk plots for the enzymatic ring-opening reaction of the cyclic oligomers (13,14). The apparent and Froa/Am of lipase CA for the... 

Table 5.1 reports the values of the apparent kinetic constants as obtained from fitting equations (5-16) to (5-18) to the experimental data. The standard deviations of the apparent kinetic constants and the individual 95% confidence are also included. 

Given that the photocatalytic reactions only proceed in the annulus of the photoreactor, the experimental data measured with samples taken from a well non-irradiated mixed tank, provides apparent kinetic constants (k ). These constants can be related to the intrinsic ones as follows (Wolfrum and Turchi, 1992),... 

B = 0.67. This reaction order corresponds to the shrink core reaction model. The reaction is under diffusion control, and the oxidizing agent reacts only on the surface because it has no time to diffuse internally, so the particle size becomes smaller as the conversion degree increases. In this case, the apparent kinetic constant will depend on the particle size and parameters derived fiem internal diffusion, in addition to the parameters mentioned before. 

With regards to the apparent kinetic constant, there is experimental evidence that hydrogen inhibits the reaction kinetics significantly, whereas carbon monoxide does not. From this evidence, the apparent kinetic constant is an expression of the Langmuir-Hinshelwood type [32] ... 

Apparent kinetic constants for o-dianisidine were measured at fixed concentrations of 0.4 mM hydrogen peroxide for CA[Mn] (1.2 mM for CAlI[Mn]) and 8 mM sodium bicarbonate... 

Table II. Apparent Kinetic Constants of Cellobiose Dehydrogenase from Sclerotium rolfsii for Different Electron Donors...

Equation (5.3) has a form of the Michaelis-Menten equation where the apparent kinetic constants are given by... 

Electron transfer rate constants for the proteins estimated from voltammograms of the films are difficult to interpret in a fundamental way. In particular, apparent kinetic constants may depend on various film properties... 

Function j8g(T) is empirical and could be different from that in Eq. (11) [16]. There is for the moment no published use of this theory to fit apparent kinetic constants. 

For a given thermosetting system, the chemical conversion obtained at the gel time is considered to be constant [8]. Therefore, the gel time (tg) can be related to the apparent kinetic constant of the reaction, which is related to the temperature by an Arrhenius relationship [19] ... 

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