Indicative of the steady-state

On the reducing side of PS II, the primary acceptor (Qa had been considered the primary acceptor until pheophytin was discovered to precede it) is reduced in less than 400 ps by Pheo . The reduction of Qa is conveniently monitored by the increase of PS II fluorescence from an initial value, Fq, to a maximal level, indicative of the steady-state level of Q /Qa- K reoxidation of Qa is prevented by the specific inhibitor DCMU (or other herbicides having the same effect), the fluorescence yield of PS II increases sharply, because Qa becomes fully reduced. The reduced form is an anion semiquinone (see the review by Cramer and Crofts [36]), and the absorption spectrum of this compound with a maximum at 326 nm serves for its identification [19] and offers an alternative method for kinetic studies of Qa redox reactions (see Ref. 37 for review). 

A concentration at some point of the water column equal to 95% of the steady-state concentration may be regarded as a value reasonably close to, and indicative of, the steady-state attained C = 0.95C88. As the concentration C given by Relationship 36 depends jointly on h, z, A, K, and ty a somewhat simpler form is obtained by considering the concentration change at the boundary z = 0. 

In the previous section it was shown that the rotation of the vector field I—H on a sphere surrounding all the steady states is -hi. This rotation is equal to the sum of the indices of the steady states, therefore the number of the steady states is odd, since the indices take only values 1. These remarks prove the following theorem... 

Proof. Since there is no eigenvalue in [0, l],j8=0 and the index of each steady state is -h 1. The sum of the indices of the steady states is also -h 1, therefore there is exactly one steady state. 

Meiron (12) and Kessler et al. (13) have shown that numerical studies for small surface energy give indications of the loss-of-existence of the steady-state solutions. In these analyses numerical approximations to boundary integral forms of the freeboundary problem that are spliced to the parabolic shape far from the tip don t satisfy the symmetry condition at the cell tip when small values of the surface energy are introduced. The computed shapes near the tip show oscillations reminiscent of the eigensolution seen in the asymptotic analyses. Karma (14) has extended this analysis to a model for directional solidification in the absence of a temperature gradient. 

Figure 5. The molar fraction Xg of Pt in the topmost atomic layer of the alloy as a function of the bulk molar fraction of Pt-Xb. Curved full line the best fit through the experimental AES data for surfaces in vacuum. The shaded area indicates the range of the steady state molar fraction of Pt, estimated by using different growth-models for the carbon(aceous) layers, calculated for the topmost layer of Pt/Cu alloys in contact with ethene, at ambient temperature. (Reproduced with permission from Ref.34. North-Holland Publ.Co.)...

The intercept should reflect the unchanging activation polarization at the two interfaces, as well as some other effects (presence of a film before anodization, time lag in attainment of the steady state, etc.). Nevertheless, the fact that it is small or negligible indicates that charge transfer processes at the interfaces are fast and that the kinetics of the growth are entirely transport controlled. 

Figure 5 shows a logarithmic plot of the steady state value of the SHG intensity versus applied voltage. The nearly quadratic response expected for a parabola is evident. A 20% variation from quadratic behavior would result in points within the limits indicated in Figure 5. 

A typical time profile of the excited PMMA-Phe fluorescence intensity decay is shown in Figure 2. The MEK permeation commences at 24 sec. The SPR increases during the plasticization period until it becomes constant, the onset of the steady state. It is characterized by a linear relationship between the amount of solvent absorbed and time. It was determined from a linear regression analysis that the PMMA-Phe fluorescence intensity starts to deviate from linearity at 197 sec. This indicates a decrease in the SPR and/or the unquenched PMMA-Phe. The decrease in SPR is unexpected at this film thickness since the SPR in thicker PMMA-Phe films show no anomaly at 1 /tm. A more plausible explanation is the reduction in available PMMA-Phe, which is expected when the front end of the SCP reaches the substrate. 

It is hardly surprising that blood phenytoin levels bear little relation to the total daily dose (B4, B5, Cl, G4, G6, L12), or that the concept of the steady-state blood levels frequently docs not hold in clinical practice (B7, M15). This indicates the necessity for regulating phenytoin therapy on the basis of blood concentrations, assuming that this bears a reasonably close correlation to the therapeutic effect. Conclusive evidence of the validity of this basic assumption is lacking (Table 1). 

An alternative mechanism has been proposed by Schneider (1988) who considers that ferritin could be also filled via a transient, mononuclear Fe " species. This species is similar to Fe in size, but is more versatile in its interaction with the protein shell. Experiments have shown that as the pH of a system containing diferric-trans-ferrin and ferritin was lowered very slowly from 7.5 to 5.0, monomeric Fe was released from the transferrin and redeposited in the ferritin (Glaus, 1989). Calculations of the iron flux across the cell membrane and estimates of the rates of interaction of the mononuclear species with ferritin and with the cell mitochondria indicated that the steady state concentration of the mononuclear Fe species would be sufficiently low for this species alone to enter the protein shell and be deposited as the iron core. Uptake of this species by the protein shell is about fiftyfold faster than the rate of hydrolytic polymerization or even of the dimerization of Fe (tiy2 1 vs. 50 ms). This hypothesis suggests an interesting direction for further research. 

The rate of vivo accumulation of both inhibitor proteins steadily Increases, reaching a steady state after nine hours. However, a second wound at nine hours results in a tripling of the steady state rate of inhibitor accumulation over the next several hours. The data Indicates that the second wound causes no change in the apparent translational efficiencies of the mRNA for Inhibitors I and II but causes Increased rates of inhibitor accumulation by providing more translatable inhibitor messages when the plant s translation system is operating at high efficiency. 

The greater melt viscosities observed for some branched polymers, as compared with linear ones of the same MW, are not accounted for by current theories, as indicated in Section 5. The greater values of the steady state compliance mentioned above is also unexpected theory (128) would suggest a difference in the opposite sense. 

Determination of the steady-state peroxide concentration during acetaldehyde oxdiation experiments indicates that for manganese and cobalt acetates this concentration is below 0.01M while for copper (II) acetate values as high as 0.046M have been obtained. 

This equation indicates that the steady state velocity of the fluid is a linear function of the pressure. 

In the steady state, a plot of pressure change against time should be linear. Any departure from linearity in the direction of increasing slope with time indicates that the steady state has not been reached. Leakage around the edges of the test piece will only result in an unexpectedly high rate of... 

The kinetic model developed from the detailed experimental data obtained with Pd(l 11) holds similarly for other single crystal planes as well as for the results from polycrystalline material. Without reviewing all the available measurements in detail, only two sets of data from the first study of this type with Pdf 110) will be mentioned (2). Figure 38 shows the variation of the steady-state rate of C02 formation with pco at constant oxygen pressure (Po2 = 1 x 10-7 Torr) and temperature (T= 520 K). For pco p0l, r increases linearly with the CO pressure while the simultaneously monitored LEED pattern indicates the presence of appreciable amounts of oxygen on the surface. Under these conditions case 2 is valid, whereby (15) correctly describes the observed kinetics. For pco > p0l the reaction rate becomes... 

For nonmonotonic kinetics the stability details of the steady states A, B, and C are indicated by arrows in Figure 3.29. The stability behavior of the different steady states is explained below using chemico-physical reasoning. This applies to the earlier-mentioned adiabatic and nonadiabatic nonisothermal CSTRs as well. 

Analysis of the steady-state voltage characteristics of the thick film oxygen sensor and conventional crucible-type oxygen sensor indicates agreement between the theoretical curves and the experimental curves. 

The potassium channels present in neuronal membranes could also be affected by phenothiazine derivatives. In the study performed by Ogata et al. [255] it was shown that CPZ (9) interfered with several types of potassium channels present in membranes of neurons of the newborn rat cultured dorsal root ganglia. Reversible reduction of the amplitude was found for transient and delayed rectified K+ currents, while inward rectified K+ current remained unaffected by CPZ (9). The block of delayed rectified K+ current by CPZ (9) was, however, less potent than block of the transient one. The hyper-polarizing shift of the steady-state inactivation curve for transient K+ current indicated that CPZ (9) binds preferably to the channels in the inactivated state. 

The presence of a trapping center is very important since Eq. (19) indicates that the steady-state strength of the photoinduced space-charge field depends on the number density of the deep traps. Nevertheless, the nature of the traps in organic PR materials is the least studied of all the elements for the PR effect. The main reason is the lack of structural information of the trapping centers. The amorphous nature of these materials warrants the existence of a variety of trapping centers, such as energy levels localized at impurities or structural defects. However, one can differentiate between deep traps, which are localized... 

Model calculations indicated that the addition of 5 percent humus to a SB slurry wall would delay breakthrough (defined as 5 percent of the steady-state flux) from approximately 5 years to more than 100 years (Figure 3). 

The most important observation in the pre-steady-state kinetics of the CN system is that after a short lag (100 msec) there is a phase (lasting about 3 sec) where the evolution of H2 is linear and only after these 3 sec does CN reduction occur. This long lag prior to CN reduction would correspond to 18 to 20 electron transfer steps from the Fe protein. More realistically this delay probably involves a CN -induced modification of the enzyme, such as a ligand substitution reaction (this modified state of the enzyme is designated as. E in Figure 21). However, this modification step is too slow to be part of the steady-state cycle for CN reduction. Also, it cannot be a slow activation of the enzyme prior to turnover, since the onset of H2 evolution is the same in both the presence and the absence of CN . Steady-state observations indicate that cyanide binds to a more oxidized form of the MoFe protein than binds N2, but that state cannot be defined because of the long lag phase. 

To interpret differences in the relaxation times, it is necessary to start from the analysis of eigenvalues of the matrix for (2)—(3) linearized in the neighbourhood of the steady state (indicated by ). This matrix corresponds to the characteristic equation... 

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