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Absence integral

The Landolt reaction (iodate + reductant) is prototypical of an autocatalytic clock reaction. During the induction period, the absence of the feedback species (Irere iodide ion, assumed to have virtually zero initial concentration and fomred from the reactant iodate only via very slow initiation steps) causes the reaction mixture to become kinetically frozen . There is reaction, but the intemiediate species evolve on concentration scales many orders of magnitude less than those of the reactant. The induction period depends on the initial concentrations of the major reactants in a maimer predicted by integrating the overall rate cubic autocatalytic rate law, given in section A3.14.1.1. [Pg.1097]

Accuracy, however, in biomolecular trajectories, must be defined somewhat subjectively. In the absence of exact reference data (from experiment or from an analytical solution), the convention has been to measure accuracy with respect to reference trajectories by a Verlet-like integrator [18, 19] at a timestep of 1 or 0.5 fs (about one tenth or one twentieth the period, respectively, of the fastest period an 0-H or N-H stretch). As pointed out by Deufihard et al. [20], these values are still larger than those needed to... [Pg.230]

One of the advantages of the Verlet integrator is that it is time reversible and symplectic[30, 31, 32]. Reversibility means that in the absence of numerical round off error, if the trajectory is run for many time steps, say nAt, and the velocities are then reversed, the trajectory will retrace its path and after nAt more time steps it will land back where it started. An integrator can be viewed as a mapping from one point in phase apace to another. If this mapping is applied to a measurable point set of states at on(> time, it will... [Pg.300]

Two states /a and /b that are eigenfunctions of a Hamiltonian Hq in the absence of some external perturbation (e.g., electromagnetic field or static electric field or potential due to surrounding ligands) can be "coupled" by the perturbation V only if the symmetries of V and of the two wavefunctions obey a so-called selection rule. In particular, only if the coupling integral (see Appendix D which deals with time independent perturbation theory)... [Pg.596]

Molecular dynamics calculations use equations 25-27. HyperChem integrates equations 26 and 27 to describe the motions of atoms. In the absence of temperature regulation, there are no external sources or depositories of energy. That is, no other energy terms exist in the Hamiltonian, and the total energy of the system is constant. [Pg.71]

The subscripts D,j denote the integration over the domain D and the boundary 7, respectively. Note that the boundary dfl of is a combination of the sets r,F, r. The formulae (3.15), (3.16) hold true for the domain despite the absence of regularity of dfl. To verify this we can extend the graph F, so that the domain is divided into two parts. For each part the formulae (3.15), (3.16) are valid, hence the statement follows. We should note at this point that the external normals on F, F have opposite directions. [Pg.178]

As PWB technology is refined to provide greater integration using finer conductor lines, there is renewed interest in hquid resists. The absence of a cover sheet and the abihty to apply thinner films both contribute to improved resolution and to an intrinsically lower consumables cost (16,17). [Pg.117]

In the absence of beat generation, one-dimensional steady-state condrrction may be expressed by integrating Eq. (5-1) ... [Pg.555]

In the first case, that is with dipoles integral with the main chain, in the absence of an electric field the dipoles will be randomly disposed but will be fixed by the disposition of the main chain atoms. On application of an electric field complete dipole orientation is not possible because of spatial requirements imposed by the chain structure. Furthermore in the polymeric system the different molecules are coiled in different ways and the time for orientation will be dependent on the particular disposition. Thus whereas simple polar molecules have a sharply defined power loss maxima the power loss-frequency curve of polar polymers is broad, due to the dispersion of orientation times. [Pg.114]

Figure 10-4A(3). Longitudinal fins resistance welded to tubes. The welding of the fins integral to the parent tube ensures continuous high heat transfer efficiency and the absence of any stress concentrations within the tube wall. (Used by permission Brown Fintube Co., A Koch Engineering Co., Bui. 80-1.)... Figure 10-4A(3). Longitudinal fins resistance welded to tubes. The welding of the fins integral to the parent tube ensures continuous high heat transfer efficiency and the absence of any stress concentrations within the tube wall. (Used by permission Brown Fintube Co., A Koch Engineering Co., Bui. 80-1.)...
The integral terms representing AH and AH can be computed if molal heat capacity data Cp(T) are available for each of the reactants (i) and products (j). When phase transitions occur between T and Tj for any of the species, proper accounting must be made by including the appropriate latent heats of phase transformations for those species in the evaluation of AHj, and AH terms. In the absence of phase changes, let Cp(T) = a + bT + cT describe the variation of (cal/g-mole °K) with absolute temperature T (°K). Assuming that constants a, b, and c are known for each species involved in the reaction, we can write... [Pg.356]

Furthermore, the restrictions on operating voltage that apply to titanium in a marine enviroment are not always relevant to titanium in soils free of chloride contamination. Coke breeze is, however, an integral part of the groundbed construction and ensures a lower platinum consumption rate. However, for some borehole groundbeds, platinised niobium is preferred, particularly in the absence of carbonaceous backfill or in situations where the water chemistry within a borehole can be complex and may, in certain circumstances, contain contaminants which favour breakdown of the anodic Ti02 film on titanium. In particular, the pH of a chloride solution in a confined space will tend to decrease owing to the formation of HOCl and HCl, and this will result in an increase in the corrosion rate of the platinum. [Pg.169]

As we saw in Section 3.2, in the absence of disorder (A(x)=Ao), the electron spectrum has a gap between the energies =-Aq and e=+Ao- Disorder gives rise to the appearance of electron states inside the gap, although for weak disorder a pseudogap still exists. Using the phase formalism [471, Ovchinnikov and Erikhman derived a losed expression for the integrated average density of states (J of the... [Pg.49]

Many pitfalls await the unwary. Here is a short list, compiled from more detailed considerations by Bunnett.8 One should properly identify the reactants. In particular, does each retain its integrity in the reaction medium A spectroscopic measurement may answer this. The identities of the products cannot be assumed, and both a qualitative identification and a quantitative assay are in order. Pure materials are a must—reagents, salts, buffers, and solvent must be of top quality. Careful purification is always worth one s time, since much more is lost if all the work needs repeating. The avoidance of trace impurities is not always easy. If data are irreproducible, this possibility must be considered. Reactions run in the absence of oxygen (air) may be in order, even if the reactants and products are air-stable. Doing a duplicate experiment, using a spent reaction solution from the first run as the reaction medium, may tell whether the products have an effect or if some trace impurity that altered the rate has been expended. [Pg.11]

To verify the integrity of the extraction system in the presence of bisulfate, an experiment was run in which the TTA stoichiometry was determined at constant acidity and two different concentrations of HSOIJ. At 0.015 M HSOiJ, the Pu(IV)-TTA stoichiometry was 3.79 (+ 0.25) while at 0.07 M HSOiJ, the stoichiometry was 3.84 (+ 0.33). Both values are in agreement with observed stoichiometries in the absence of HSOi . [Pg.259]

Arrangements 1 and 2 make it difficult to account for the absence of odd orders from (0001), and the absence of all first orders from planes having h + 2i) integral and l odd. Any of the remaining arrangements accounts for the above observations. [Pg.556]

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. [Pg.300]


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See also in sourсe #XX -- [ Pg.143 ]




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Absences

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