Effectiveness, volume based

Volume and Lattice Enthalpy. In the example of GeFg" intercalation just described, we departed from the case of MFg- guest species. GeFj- has one fewer F ligand therefore, it must have an effective volume, based on Zachariasen s criterion (34), approximately 17 A less than MFg". For closely packed guest species, this effective volume would be important. First let us examine the consequences of volume on lattice enthalpy. 

A uniform stress field must exist over the entire gage-section volume to eliminate volume-based statistical failure effects (e.g., a realistic distribution of ordinary defects must exist for the test to be representative of the actual material). 

As mentioned in the introduction, the first empirical correlation between the absolute configuration of dopants and the handedness of induced cholesterics was proposed in 1975.20 The first attempt to find a general correlation was a few years later Krabbe et al.58 related the sense of the cholesteric to a stereochemical descriptor of the dopant based on the effective volume of the substituents and listed many compounds following this rule. However, exceptions were described at that time,59 and, furthermore, this approach neglects the role of the structure of the nematic solvent in determining the sense of the cholesteric. It is well known that chiral compounds may induce cholesterics of opposite handedness in different nematics.60,61... 

The concept of a theoretical plate is based on the number of equilibria that may have taken place during the separation process and this number is related to the number of times the effective volume of a column is greater than the peak volume. The variance (a2) for the peak is a measure of the broadening of the injection volume while the square of the retention time (fR2) is a measure of the effective column volume for that compound. Hence the number of theoretical plates (AO may be calculated from the following equation ... 

Jenner [275] has presented a thorough description of several possible contributions to both the intrinsic and the environmental parts of the activation volumes, based on accurate experimental observation of pressure effect on reactions in solutions. The intrinsic contribution to the activation volume essentially derives from the differences in structure between the transition state and the reacting species, so it is directly related to the partial cleavage and formation of chemical bonds in the transition state. In cases where the environmental contribution is negligible, the activation volume variation gives a direct insight in the molecular mechanism [275, 280]. In this case in fact, considering... 

Depending on the particular method of polymer HPLC, is defined in different ways. It is the total volume of pores, Vp, in a porous packing but it can be also related to the total surface of packing (mostly to the surface situated within the pores) or to the effective volume of bonded phase. The volume of pores is relatively well defined in the case of many packings applied in polymer HPLC and plays an especially important role in the exclusion-based separations (Sections 16.3.3, 16.3.4, and 16.4.1). The exclusion processes, however, play an important role in the coupled techniques of polymer HPLC (Section 16.5). In the latter cases, the surface of packings and the effective volume of bonded phase are to be taken into account. In some theoretical approaches also, surface exclusion is considered. 

The separation of chemical species by size exclusion chromatography is more reproducible than any other type of chromatography. Once the SEC columns, the mobile phase (most often a pure solvent like THF or toluene), and the flow rate are selected, the retention volume (or retention time assuming the flow rate does not change) is primarily a function of linear molecular size, which can be obtained from the valence bond structure if the compound is known. Some of the chemical species can interact with the solvent forming complexes with an effective linear size greater than that of the molecule. This causes the expected retention volume, based on "free" molecular structure, to shift to a lower but very reproducible retention volume. Phenols in coal liquids form 1 1 complex with THF (9,10) and carry the effective linear molecular size to increase. As a result phenolic species elute sooner than expected from their... 

The formation and transport properties of a large polaron in DNA are discussed in detail by Conwell in a separate chapter of this volume. Further information about the competition of quantum charge delocalization and their localization due to solvation forces can be found in Sect. 10.1. In Sect. 10.1 we also compare a theoretical description of localization/delocalization processes with an approach used to study large polaron formation. Here we focus on the theoretical framework appropriate for analysis of the influence of solvent polarization on charge transport. A convenient method to treat this effect is based on the combination of a tight-binding model for electronic motion and linear response theory for polarization of the water surroundings. To be more specific, let us consider a sequence... 

Schematic drawings of some typical modem furnace black reactors are shown in Figure 50. They all have a gas-tight metal jacket. The reaction zone is coated with a ceramic inner liner, generally on an alumina base, which is stable to temperatures of ca. 1800 °C. Several quenching positions allow the changing of the effective volume of the reactor. This allows variation of the mean residence time of the carbon black at the high reaction temperature. Typical residence times for reinforcing blacks are 10-100 ms.

To reduce the inflow of toxic substances into basin waters efficiently, the Corporation required information on which effluents posed the greatest hazard to the river. While chemical data on many of the effluents were available, their diverse composition was difficult to interpret in terms of hazard potential. Moreover, hazard is not only linked to chemical composition of an effluent, but also on the toxic effects it can have on a variety of freshwater organisms. Adverse effects on biota are also influenced by the volume of wastewater discharged at different times of the year. Hence, the Corporation searched for a cost-effective approach, based on ecotoxicological principles, to rank the various effluents (there are several hundred sources), in terms of their toxic loading, so that subsequent efforts (such as clean up actions) could be prioritized. 

Fig. 37. The ratio of the equivalent hard sphere volume fraction based on the measured intrinsic viscosity as a function of for polyfmethyl methacrylate) spheres with grafted poly( 12-hydroxy stearic add) layers such that a/L = 4.7 (Mewis et ai, 1989). Open and closed circles correspond to the low and high shear limits of suspension viscosity.

FIGURE 18.16 Theophylline pharmacodynamics in patients with asthma. Effect, which was measured as improvement in forced expiratory volume in 1 second (FEVI), is related to the serum drug level in six patients, who were studied after placebo and tliree incremental doses of theophylline. An Emax model is fit to the concentration-effect data. Based on this analysis, a therapeutic range of 10-20 pg/mL was proposed (shaded area). (Adapted from data published by Mitenko PA, Ogilvie RI. N Engl J Med 1973 289 600-3.)... 

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