Regression analyses oxidation

In a detailed structure-activity study Gil and Wilkinson (1977) found that of 47 substituted 1,2,3-benzothiodiazoles the 6-butyI derivative 19 is the most active inhibitor of microsomal oxidation. Regression analyses have shown that the activity of the S-, 6- and 3,6-substituted compounds can be satisfactorily described in terms of the hydrophobic bonding constant n and the Hammett constant r whereas that of the 4-substituted derivatives depend on n and the Taft s steric parameter ,. 

Equations la and lb are for a simple two-phase system such as the air-bulk solid interface. Real materials aren t so simple. They have natural oxides and surface roughness, and consist of deposited or grown multilayered structures in many cases. In these cases each layer and interface can be represented by a 2 x 2 matrix (for isotropic materials), and the overall reflection properties can be calculated by matrix multiplication. The resulting algebraic equations are too complex to invert, and a major consequence is that regression analysis must be used to determine the system s physical parameters. ... 

GP 1] [R 1] A kinetic model for the oxidation of ammonia was coupled to a hydro-dynamic description and analysis of heat evolution [98], Via regression analysis and adjustment to experimental data, reaction parameters were derived which allow a quantitative description of reaction rates and selectivity for all products trader equilibrium conditions. The predictions of the model fit experimentally derived data well. 

A dramatic departure of ozone measurements from total oxidant measurements has b Mi reported for the Houston, Texas, area. Side-by-side measurements suggested that either method was a poor predictor of the other. Consideration was given to known interferences due to oxides of nitrogen, sulfur dioxide, or hydrogen sulfide, and the deviations still could not be accounted for. In the worst case, the ozone measurements exceeded the national ambient air quality standard for 3 h, and the potassium iodide instrument read less than 15 ppb for the 24-h period. Sulfur dioxide was measured at 0.01-0.04 ppm throughout the day. Even for a 1 1 molar influence of sulfur dioxide, this could not explain the low oxidant values. Regression analysis was carried out to support the conclusion that the ozone concentration is often much higher than the nonozone oxidant concentration. 

Marxen K, Vanselow KH, Lippemeier S, Hintze R, Ruser A, Hansen U-P. Determination of DPPH Radical Oxidation Caused by Methanolic Extracts of Some Microalgal Species by Linear Regression Analysis of Spectrophotometric Measurements. Sensors. 2007 7, 2080-2095. 

Based on their chemical structure, the organic chemicals were divided into a number of categories alkanes, alkenes, amines, aromatic hydrocarbons, benzenes, carboxylic acids, halides, phenols, and sulfonic acid. Linear regression analysis has been applied using the method of least-squares fit. Each correlation required at least three datapoints, and the parameters chosen were important to ensure comparable experimental conditions. Most vital parameters in normalizing oxidation rate constants for QSAR analysis are the overall liquid volume used in the treatment system, the source of UV light, reactor type, specific data on substrate concentration, temperature, and pH of the solution during the experiment. 

We chose 60 compounds with pl50 values ranging from 7.1 to 4.9 and subjected them to regression analysis using several physicochemical parameters (Table I). The 60 compounds contained variations in six positions of the basic structure. Quantitative structure-activity correlations with as many individual uncouplers in one equation have not yet been published. As far as we know, the Hansch approach has been applied to uncouplers of oxidative phosphorylation only twice first in 1965 by Hansch and co-workers to phenols and recently by Muraoka and Terada to N-phenylanthranilic acids. From Muraoka s data we recalculated the correlation with w and o- and obtained an equation which gave the best fit (last equation, Figure 3). 

The result of the regression analysis applied, in order to calculate the heat generation data of the sawdust of Port Orford cedar, to five combinations of the value of In with that of MTs, which are each determined, based on five digital records obtained each from five adiabatic oxidatively-heating tests, which are started from each T, in the range of 164.8 to 173.3 °C with mutual intervals of 2 K, performed each, for 0.3 g each of five samples of the sawdust of Port Orford cedar charged each in the draft cell, into which air is supplied, for the time. At, required for the temperature of each sample of the sawdust of Port Orford cedar to increase by the definite value o AT of 1.25 K from the corresponding standard temperature. Data used are in common with those presented in Fig. 85 and plotted in Fig. 117. 

The individual values of the two coefficients, a and h, of Eq. (44) holding for the individual oxidatively-heating processes, in the early stages, of 0.3 g each of the sawdusts of fourteen wood species, other than Port Orford cedar, charged each in the draft cell and subjected each to the adiabatic oxidatively-heating test were also calculated by applying the regression analysis to the individual combinations of the value of In with that of 1/T, and are presented in Table 21. 

A regression analysis has been performed (45) on the chemical shifts of some azine-N-oxides in terms of 10 parameters which include interactions between the N-0 moiety and the nitrogen atoms at positions 2, 3, and 4 in the six-membered ring. Effects due to additional fused rings in the system and corrections for interactions between pyridine-type nitrogen atoms are also included. The additivity rules for the shifts are then used to predict those for a number of azine N-oxides which have been hitherto unknown or not examined by nitrogen NMR spectroscopy. (45)... 

Figure 12.20 The rate of oxidation of pyrite (r = rf(FeS2l/t/< in mo /m s) near 25"C and 1 bar pressure. Whole model and leverage plots for multiple linear regression analysis of published and measured rate data for the aqueous oxidation of pyrite (a) Oxidation of pyrite by dissolved oxygen (b) Oxidation of pyrite by ferric iron under an N2 atmosphere and (c) Oxidation of pyrite by ferric iron in the presence of dissolved oxygen. Reprinted from Geochim. et Cosmochim. Acta, 58, M. A. Williamson and J. D. Rimstidt, The kinetics and electrochemical rate-determining step of aqueous pyrite oxidation, 5443-54, 1994, with permission from Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington 0X5 1GB, U.K.

The beta coefficients (standard regression coefficients, Snedecor and Cochran, 1980) of the different species obtained from the multiple regression analysis of the data were in the order Fe, Mn oxide-bound = organic-bound > carbonate-bound (following the scheme of Tessier et al., 1979), indicating the importance of both Fe, Mn oxide-bound and organic-bound Cd species in estimating the CAI of the soils (Eq. (1), Table 17). In the scheme of Krishnamurti... 

Linear regression analysis showed that the production rates of DMS were closely correlated to DMSPd concentrations in the microlayer (i =0.5563, n=8, P=0.03) as well as in the subsm-face water (i =0.6220, n=8, P=0.02). The DMS production through enzymatic DMSP cleavage generally exceeded its microbial consumption rates, leading to net DMS production. The imbalance in these two processes might be caused by other sink pathways for DMS such as photochemical oxidation and sea-to-air emission. 

Our study relied on regression analysis to examine the relative effects of two related dietary factors (TG and oxidized TG). Obviously, it would be better if we could have compared the effects of fresh and aged walnut oil on factor Vila. Furthermore, we need to identify the active component. However, it is of interest that plasma linoleic acid had been identified as the factor that activated factor VII in Swedish men (52). In that study, oxidation products of linoleic acid were not measured. Could it be that linoleic acid reflected the absorption of linoleic acid oxidation products in the Swedish study Perhaps the oxidized linoleic acid and not the cfr.cw-linoleic acid itself was the activator of factor VII. 

In this example, the fit between the experimental data and a linear regression model was shown to be very good with a coefficient of determination equal to 0.93. Considering that the production of carbon oxides is expected to be equal to zero when the production of acrolein is zero, the regression analysis may be completed by assuming that the curve begins at the origin. In this case, the slope of the curve equals 0.18 and the coefficient of determination becomes 0.91. 

Figure 3. Individual bond lengths observed for more 40 oxide crystalline materials, R(MO), (a) plotted against the individual Brown-Sharmon (1973) bond strengths, s and (b) plotted against s/r calculated for the bonds. The MO bonds comprising first-row M-cations (r = 1) are plotted as open symbols while those comprising second-row M-cations (r = 2) are plotted as solid symbols. A regression analysis of the data used to construct Figure 3b yielded the expression R = I39(s/ry (Gibbs et al., unpublished data).

---