Curve peeling

From the curve peeling operation we thus obtained the following intercepts, hybrid transfer constants and half-life times of the a-and (3-phases ... 

FIGURE 3.8 "Curve-peeling" technique used to estimate the coefficients and exponents of Equation 3.5. Data points ( ) are plotted on semilogarithmic coordinates and the points for the cc-curve (o) are obtained by subtracting back-extrapolated -curve values from the experimental data. 

Values for the data equation parameters can be obtained by the technique of curve peeling" that was illustrated in Figure 3.8. After plotting the data, the first step is to identify the terminal exponential phase of the curve, in this case termed the j3--phase, and then back-extrapolate this line to obtain the ordinate intercept (BO- It is easiest to calculate the value of by first calculating the half-life of this phase. The value for j3 then can be estimated from the relationship j3 = ln2/b/2 - The next step is to subtract the corresponding value on the back-extrapolated jS-phase line from each of the data point values obtained during the previous exponential phase. This generates the Q -line from which the a-slope and A intercept can be estimated. 

Even though computer programs now are used routinely for pharmacokinetic analysis, most require initial estimates of the model parameters. As a result of the least-squares fitting procedures employed, these computer programs generally yield the most satisfactory results when the technique of curve peeling is used to make reasonably accurate initial estimates of parameter values. 

The development of a successful pharmacokinetic model allows one to summarize large amounts of data into a few values that describe the whole data set. The general procedure used to develop a pharmacokinetic model is outlined in Table 10.1. Certain aspects of this procedure have been described previously in Chapters 3 and 8. For example, the technique of curve peeling" frequently is used to indicate the number of compartments that are included in a compartmental model. In any event, the eventual outcome should be a model that can be used to interpolate or extrapolate to other conditions. 

Although a number of software packages of this types are available to facilitate analysis of these types of data, most of the software requires the kineticist to provide initial estimates of parameter values. The technique of "curve peeling" is widely used for this purpose, and also provides an initial evaluation of data quality. 

Two batches of 2 mm zucchini hypocotyl segments (3 g fw/90 ml 1.5%(w/v) sucrose at 25 C) were loaded for 50 min to equivalent levels of [ C] using 0.3 /xM [ 1 - CjlAA in the absence of quercetin and 0.18 /xM [1- C]IAA in the presence of 10 /xM quercetin. The segments were collected, rinsed briefly with 50 ml ice-cold sucrose (1.5%), and then resuspended in 150 ml 1.5% sucrose (25 C conical flask) and placed in an orbital shaker (120 rpm) at 25 C. Samples of medium (1 ml) were withdrawn over a 60 min time course and transferred to a scintillation fluid designed to count aqueous samples [5]. Conventional compartmental analysis by curve peeling [3, 29, 37] allowed estimation of first-order rate constants for efflux from the tissue considered to be comprised of a series of three compartments. 

Tackifying resins enhance the adhesion of non-polar elastomers by improving wettability, increasing polarity and altering the viscoelastic properties. Dahlquist [31 ] established the first evidence of the modification of the viscoelastic properties of an elastomer by adding resins, and demonstrated that the performance of pressure-sensitive adhesives was related to the creep compliance. Later, Aubrey and Sherriff [32] demonstrated that a relationship between peel strength and viscoelasticity in natural rubber-low molecular resins blends existed. Class and Chu [33] used the dynamic mechanical measurements to demonstrate that compatible resins with an elastomer produced a decrease in the elastic modulus at room temperature and an increase in the tan <5 peak (which indicated the glass transition temperature of the resin-elastomer blend). Resins which are incompatible with an elastomer caused an increase in the elastic modulus at room temperature and showed two distinct maxima in the tan <5 curve. 

Figure 2. Transmission-Wave-Length Curves for Dyed Benzene Extractives from Peel of Parathion-Treated Navel Oranges...

Fig. 34 Peel force versus distance curves for polysulfide/nanoclay adhesive systems...

In the literature, there are several reports that examine the role of conventional fillers like carbon black on the autohesive tack (uncured adhesion between a similar pair of elastomers) [225]. It has been shown that the incorporation of carbon black at very high concentration (>30 phr) can increase the autohesive tack of natural and butyl rubber [225]. Very recently, for the first time, Kumar et al. [164] reported the effect of NA nanoclay (at relatively very low concentration) on the autohesive tack of BIMS rubber by a 180° peel test. XRD and AFM show intercalated morphology of nanoclay in the BIMS rubber matrix. However, the autohesive tack strength dramatically increases with nanoclay concentration up to 8 phr, beyond which it apparently reaches a plateau at 16 phr of nanoclay concentration (see Fig. 36). For example, the tack strength of 16 phr of nanoclay-loaded sample is nearly 158% higher than the tack strength of neat BIMS rubber. The force versus, distance curves from the peel tests for selected samples are shown in Fig. 37. 

Fig. 37 Peel force versus distance curves of and BCLNA16...

Fig. 11. Dependence of the peel strength of tin plate/epoxy systems on coating thickness for coatings cast from DTPM and methyl cello-solve. These theoretical curves were constructed using experimental values for modulus, critical coating thickness, solvent evaporation rate, solution concentration and interfacial work of adhesion96 (Reprinted from Ref. 96, p. 123 by cautesy of Plenum Press)...

It should be noted that approximately 1% of the APS used in the last experiment appears to be APS monomers before dilution. Could this low monomer concentration be responsible for adhesion It should be noted that the residual monomers present in this highly-oligomerized solution correspond to a 0.001 vol % solution if one were to remove the oligomerized APS. As a result of this observation, the dependence of the adhesion of thin films to native-oxide silicon wafers as a function of the concentration of the APS under conditions of T H stress was investigated. Adhesion studies were performed using APS solutions with concentrations that varied from the industry standard of 0.1 vol % down to 0.00001 vol %. The test wafers were prepared and exposed to T(200) and T(500) conditions as discussed above. Adhesion was measured by 90° peel test, as discussed above. The results of this study are presented in Fig. 13. The Lx-axis is APS concentration which decreases from left to right. The y-axis is the adhesion in the units of g mm"The three curves are the results at T(0), T(200) andT(500). 

These formatted outputs are stored on a flexible disk exactly the same as printed. Later the data on the disk are stored by sample number and project. All raw and reduced data for a project are stored on a single flexible disk. After the data have been stored on a flexible disk, it is a simple matter for the computer to make summaries or do trend analyses. An example of one of these summaries is shown in Figure 5. In this example, the percent of 1 C remaining in the peel and fruit at various time periods after spraying apples with a 1 C labeled compound, was analyzed by a curve fit program. 

To conclude with the primary electrode characteristics, we describe briefly the DLC electrodes. The data are scarce and partly contradictory, probably due to the differences in film preparation methods. According to Howe [60], even films as thin as 50 nm are quite stable against corrosion. However, in later works [61, 62] such thin films turned permeable for electrolytes. The penetration of the electrolyte to a substrate metal resulted in its corrosion and, ultimately, in film peeling. Thicker films (0.1 to 1 pm) were less subjected to damage. The current-potential curves in supporting electrolytes resemble those for crystalline diamond electrodes (see Figs. 7, 8) the potential window is narrower, however [63], Fluorination of a-C H enhances corrosion resistance of the films significantly [64],... 

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