Comparison of the Two Approaches

The functionalization of polymer approach is used much more often than the functionalization of monomer approach at present because functional polymers such as chloro-methylated polystyrene are readily available with different porosities and degrees of chloromethylation. There are relatively few situations where less work is needed to use the functionalization of monomer approach. Also, many practitioners of polymer reagents, 

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There are numerous types of instrumentation available for the measurement of XRF, but most of these are based either on wavelength dispersive methodology (typically referred to as WDX) or on the energy dispersive technique (typically known as EDX). For a detailed comparison of the two approaches for XRF measurement, the reader is referred to an excellent discussion by Jenkins [69]. 

The comparison between the ZORA and QR methods is still rather limited (70), Table II. We are currently in the process of carrying out a more thorough comparison of the two approaches. The ZORA approach is clearly superior to the QR method on theoretical grounds since it avoids - rather than circumvents - the fundamental stability problems of the Pauli operator. 

A final point concerns the comparison of the DDCI method and the CAS-SCF / CASPT2 approach. We have performed some test calculations for the step cluster using all electron basis sets ofmoderate size for all cluster atoms. These calculations not only permit a direct comparison of the two approaches for the inclusion of electron correlation but also provide a test of the ECP and basis used in the previously commented calculations Compared to the results listed in Table 2 for the surface, the DDCI excitation energies obtained with all electron basis sets change less than 0.1 eV for all states considered. Moreover. 

The reason why we prefer to present the standard scenario in a separate Section is because we feel it is premature to engage in a full comparison of the two approaches since all the details are as yet not available. 

We had earlier published an equation describing the dependence of surface tension on composition, and a comparison of the two approaches has been given here we will restrict attention to eqs. [5.5.26] and [5.5.27]. 

Both VB and MO theories utilize mathematical expressions that can rapidly become complex, even for simple organic molecules. Moreover, VB theory and MO theory are usually described with different symbols, so it can be difficult to distinguish the similarities among and differences between them. Therefore, it may be useful to consider first a very simple bonding problem, the formation of a hydrogen molecule from two hydrogen atoms. The principles will be the same as for larger molecules, but the comparison of the two approaches will be more apparent in the case of H2. 

Two approaches are used to overcome the problem of large vapor volumes for capillary columns. With the split-splitless injector (Figure 4.20), the sample is introduced via a syringe into the heated injector and evaporated. Then either only part of the evaporated sample is allowed to enter the capillary column (the so-called split mode), or alternatively most of the solvent is separated in the injector from the analytes (splitless mode). In the latter mode the analytes (usually considerably less volatile than the solvent) are re-condensed at the entrance of the column and the more volatile solvent is swept away the analytes are then flash heated to start the elution. The alternative to the split-spitless injector does not use an injector that is already heated, but rather one at around ambient temperature which, following sample injection, is heated in a controlled fashion so as to preferentially evaporate the solvent. An advantage of the heated injector is that it can be used in either mode to best suit the sample under analysis at the time. A more complete comparison of the two approaches is given below. 

Developers of internal reforming fuel cells have generally adopted one of two approaches, and these are usually referred to as direct (DIR) and indirect (HR) internal reforming. They are illustrated schematically in Figure 8.4. In some cases, a combination of both approaches has been taken. A thermodynamic analysis and comparison of the two approaches to internal reforming in the MCFC has been completed by Freni and Maggio... 

We will not discuss the eigenvectors of VV p(r), or their similarity to those of the stress tensor, any further in this work the interested reader is referred to our recent publications for mathematical details and numerical comparisons of the two approaches [28, 31, 32]. 

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