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Extrapolation limits

Only for the (extrapolated) limit of zero bending the action spectrum reflects the absorption spectrum of the photoreceptor for phototropism (avena coleoptile). Just for this limit the UV-peak of the action spectrum disappears 162). [Pg.41]

The latter number incorporates just the chemical step(s) of formation of triazole within cucurbituril. Since the product release step apparently is at least 100-fold slower than the actual cycloaddition, the net catalytic acceleration should be adjusted downward by that amount. An instructive alternative estimation of kinetic enhancement is to compare the extrapolated limiting rate for cycloaddition within the complex (i.e. cucurbituril saturated with both reactants, k — 1.9xl0 s ) with the uncatalyzed unimolecular transformation of an appropriate bifunctional reference substrate as in Eq. (3) (k, = 2.0x 10 s ). Such a comparison of first-order rate constants shows that the latter reaction is approximately a thousandfold slower than the cucurbituril-engendered transformation. This is attributable to necessity for freezing of internal rotational degrees of freedom that exist in the model system, which are taken care of when cucurbituril aligns the reactants, and concomitantly to an additional consideration which follows. [Pg.19]

Remark 1 Assumption (i) (i.e., Y C V) eliminates the possibility of step 3b, and there are many applications in which Y C V holds (e.g., variable factor programming). If, however, Y V, then we may need to solve step 3b infinitely many successive times. In such a case, to preserve finite e-convergence, we can modify the procedure so as to finitely truncate any excessively long sequence of successive executions of step 3b and return to step 3a with y equal to the extrapolated limit point which is assumed to belong to Y fl V. If we do not make the assumption Y C V, then the key property to seek is that V has a representation in terms of a finite collection of constraints because if this is the case then step 3b can occur at most a finite number of times. Note that if in addition to Cl, we have that A represents bounds on thex-variables otX is given by linear constraints, and h,g satisfy the separability condition, then V can be represented in terms of a finite collection of constraints. [Pg.141]

M.R de Lara-Castells, et at, Complete basis set extrapolation limit for electronic structure calculations Energetic and nonenergetic properties of HeBr and HeBr2 van der Waals dimers, /. Chem. Phys. 115 (22) (2001) 10438-10449. [Pg.130]

Reduced fall-off curves of unimolecular reactions, k jk is a measure of the carrier gas concentration at log(A o/ oo) = 0 the extrapolations of limiting low and high pressure rates intersect, see text. 5-eff is given by equation (1.80). The Table gives the correction factors, by which the extrapolated limiting low-(at log (Ato/AToo) 0) or high- (at log k lk ) 0) pressure rate constants must be multiplied, to obtain the rate constants in the transition range. For details see ref. 6.)... [Pg.68]

Fig. 3.4. With a multi-frequency measurement, frequencies beyond the measurable range of the DMA can be achieved by using the superposition method. Employing the Williams-Landel-Ferry (WLF) equation, and with a treatment of the data, designated as the method of reduced variables or time-temperature superposition (TTS) it is possible to overcome the difficulty of extrapolating limited laboratory tests at shorter times to longer-term, more real world conditions. The underlying bases for TTS are that the processes involved in molecular relaxation or rearrangements in viscoelastic materials occur at accelerated rates at higher temperatures and that there is a direct equivalency between time (the frequency of the measurement) and temperature. Fig. 3.4. With a multi-frequency measurement, frequencies beyond the measurable range of the DMA can be achieved by using the superposition method. Employing the Williams-Landel-Ferry (WLF) equation, and with a treatment of the data, designated as the method of reduced variables or time-temperature superposition (TTS) it is possible to overcome the difficulty of extrapolating limited laboratory tests at shorter times to longer-term, more real world conditions. The underlying bases for TTS are that the processes involved in molecular relaxation or rearrangements in viscoelastic materials occur at accelerated rates at higher temperatures and that there is a direct equivalency between time (the frequency of the measurement) and temperature.
Basis set effects have also been examined systematically using CIS(D) and a serious of the cc-pVnZ basis sets. The results are plotted in Supporting Information. When the energy is plotted as a function of 1/n, an extrapolation limit... [Pg.274]

Here Pideai(7 ) is the resistivity without saturation, e.g., described as in Eq. (1), and Pmax is the limiting value to which the resistivity of a particular material saturates in the extrapolated limit that Pideai(T) Pmax. Rcsistivity saturation was highlighted in a seminal paper by Mooij (19) in 1973. After several decades, the phenomenon is still poorly understood see, e.g., work by Nath and Majumdar (20) on transition metal alloys and references therein. Although it may be difficult to notice a correction due to resistivity saturation in data taken for refractory compounds at low temperature, high-temperature measurements clearly reveal its existence. For example, for VN experiments (6) show the effect even below room temperature. [Pg.179]

D line of sodium), for the sugar acetates from cellulose. Upper line, a-D-acetates lower line, -D-acetates. Data from O, Hudson and Johnson 0, Dickey and Wolfrom , Wolfrom and Dacons A, Hess and Dziengel A, extrapolated limiting value for cellulose triacetate. [Pg.169]

From the limiting low- and high-pressure rate constants ko and respectively, one immediately derives the pressure at which fall-off behavior is to be expected. The center of the fall-off curve, i.e., that bath-gas concentration [M]c at which the extrapolated limiting rate coefficients intersect, is given by rearranging Eq. (2.10) to... [Pg.192]


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See also in sourсe #XX -- [ Pg.124 ]




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