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Acceptor species concentrations

Acceptor species concentrations, equations, 400-401 Acentric materials biomimetic design, 454-455 synthesis approaches, 446 Ar-(2-Acetamido-4-nitrophenyl)pyrrolidene control of crystal polymorphism with assistance of auxiliary, 480-482 packing arrangements, 480,481-482/ Acetylenes, second- and third-order optical nonlinearities, 605-606 N-Acetyltyrosine, phase-matching loci for doubling, 355,356/, t Acid dimers, orientations, 454 Active polymer waveguides, applications, 111... [Pg.720]

Figure 6 Distribution of reported organic matter turnover under the various TEAPs in pristine surface water sediments and groundwater aquifers (a) and landfill-leachate contaminated groundwater (b). The respiration rates in pristine groundwater ((a) middle and right panels) were modeled using total electron acceptor species concentration (geochemical) and carbon isotope fractionation (isotopic constraints) (after Murphy and Schramke, 1998 and... Figure 6 Distribution of reported organic matter turnover under the various TEAPs in pristine surface water sediments and groundwater aquifers (a) and landfill-leachate contaminated groundwater (b). The respiration rates in pristine groundwater ((a) middle and right panels) were modeled using total electron acceptor species concentration (geochemical) and carbon isotope fractionation (isotopic constraints) (after Murphy and Schramke, 1998 and...
Donor and acceptors can be covalently linked using a chemical spacer. Assume that we have the same D-A pair Eosin-Phenol Red. In this case we will have a mixture of two linked donor-acceptor species (Eosin-Phenol Red protonated and Eosin-Phenol Red unprotonated) characterized by the same distance distribution and different critical distances (ftoi = 28.3 A and Rm = 52.5 A) for FRET. A distribution of D- to -A distances will be present because the linker is typically flexible. The fractional intensity of the first species at time t = 0 is gi and that of the second species is (1 - 1). The fractional intensity at time t = 0 is equal to fractional concentration of each form, which can be in case of pH indicator (Phenol Red) calculated using Eq. (10.31). The donor fluorescence intensity decay of the mixture is described by the equation... [Pg.324]

Root exudation of benzoxazinones has been described for wheat, rye, corn, and quackgrass,24,63 which may increase the concentration within the rhizosphere. The major part of the compounds present in the soil of rye or corn fields, however, originate from rotting plant material.3 Another important prerequisite is the genotype. Visible effects of phytotoxicity imply sensitive acceptor species. Weed control by benzoxazolinones is only possible when the seedlings of a given species respond to the compounds with reduced viability that finally results in severe damage and death. [Pg.98]

The experimental quantum yield for a phenomenon induced by energy transfer is defined in exactly the same way as that for direct excitation (see Section III.B.l). However, the quantum yield will usually be a function of the concentration of the acceptor species. The mechanistic quantum yield given in eq. (20) for the sequence 05-53-47-11 can be put in the form... [Pg.187]

The theories proposed to explain the formation of passivation film are salt-film mechanism and acceptor mechanism [21]. In the salt-film mechanism, the assumption is that during the active dissolution regime, the concentration of metal ions (in this case, copper) in solution exceeds the solubility limit and this results in the precipitation of a salt film on the surface of copper. The formation of the salt film drives the reaction forward, where copper ions diffuse through the salt film into electrolyte solution and the removal rate is determined by the transport rate of ions away from the surface. As the salt-film thickness increases, the removal rate decreases. In the acceptor mechanism, it is assumed that the metal-ion products remain adsorbed onto the electrode surface until they are complexed by an acceptor species like water or anions. The rate-limiting step is therefore the mass transfer of the acceptor to the surface. Recent studies confirmed that water may act as an acceptor species for dissolving copper ions [22]. [Pg.325]

The corresponding kinetic scheme is as illustrated in Scheme 8.21. This kinetic scheme bears some similarity to the simplest kinetic scheme and hence the simplest Briggs-Haldane steady state kinetics treatment can usefully apply on the assumption that the donor species D is in excess (i.e., [D] 2> [A]) and so is constant during the progress of the reaction. In this case, we can make the assumption that acceptor species A behaves in an equivalent manner to a biocatalyst substrate and donor species D to the biocatalyst itself at a fixed total concentration of [D]q. Hence, Equation (8.6) neatly transforms into... [Pg.471]

The interfacial concentration of Fe " is in good agreement with solubility data. The increase of pH by H+ migration is reflected in the profile of SO . It is concluded that no barrier layer is involved in the mass transport control of iron dissolution. The heterogeneous reaction rate is reported as not dependent on the HSO4 concentration therefore, the only acceptor species likely to limit the dissolution rate is water [74]. This is compatible with the modified form (29) of the initial step of dissolution in which one water molecule is dissociated and the depletion of free water at the electrode surface by Fe(II) hydration and electromigration of hydrated Fe(II) away from the surface. [Pg.141]

For ionizable sample molecules, it is possible to create an effective sink condition in PAMPA by selecting buffers of different pH in the donor and acceptor compartments. For example, consider salicylic acid (v>Ka 2.88 see Table 3.1). According to the pH partition hypothesis, only the free acid is expected to permeate lipophilic membranes. If the donor pH < 2 and the acceptor pH is 7.4, then as soon as the free acid reaches the acceptor compartment, the molecule ionizes, and the concentration of the free acid becomes effectively zero, even though the total concentration of the species in the acceptor compartment may be relatively high. This situation may be called an ionization-maintained sink. [Pg.138]

Exciplexes are complexes of the excited fluorophore molecule (which can be electron donor or acceptor) with the solvent molecule. Like many bimolecular processes, the formation of excimers and exciplexes are diffusion controlled processes. The fluorescence of these complexes is detected at relatively high concentrations of excited species, so a sufficient number of contacts should occur during the excited state lifetime and, hence, the characteristics of the dual emission depend strongly on the temperature and viscosity of solvents. A well-known example of exciplex is an excited state complex of anthracene and /V,/V-diethylaniline resulting from the transfer of an electron from an amine molecule to an excited anthracene. Molecules of anthracene in toluene fluoresce at 400 nm with contour having vibronic structure. An addition to the same solution of diethylaniline reveals quenching of anthracene accompanied by appearance of a broad, structureless fluorescence band of the exciplex near 500 nm (Fig. 2 )... [Pg.195]


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