Generalization of Explanations

Many transition metal-catalyzed reactions have already been studied in ionic liquids. In several cases, significant differences in activity and selectivity from their counterparts in conventional organic media have been observed (see Section 5.2.4). However, almost all attempts so far to explain the special reactivity of catalysts in ionic liquids have been based on product analysis. Even if it is correct to argue that a catalyst is more active because it produces more product, this is not the type of explanation that can help in the development of a more general understanding of what happens to a transition metal complex under catalytic conditions in a certain ionic liquid. Clearly, much more spectroscopic and analytical work is needed to provide better understanding of the nature of an active catalytic species in ionic liquids and to explain some of the observed ionic liquid effects on a rational, molecular level. 

Turndown can be applied to all types/styles of tray columns however, it is more relevant to sieve and valve trays. The generally accepted explanation of turndown is as follows [199] (also see Figure 8-101) ... 

We have seen how chemists measure the heat of is a very useful and reliable generalization. It a reaction. Using a compilation of measured makes us wonder Why should it be so The values, we can predict the energy changes of explanation, as usual, is found by connecting the many reactions that have not been measured, behavior of a chemical system to the behavior Thus, the rule of Additivity of Reaction Heats of other systems that are better understood. 

We will divide the process of generalization into two parts. In the first, we will consider only the generalization of the explanation while leaving its structure unchanged. In the second, we will consider the generalization of the structure itself. 

Shavlik, J.W., Extending Explanation-Based Learning by Generalizing the Structure of Explanations. Morgan Kaufmann, San Mateo, CA, 1990. 

Having a closer look at the pyramid algorithm in Fig. 40.43, we observe that it sequentially analyses the approximation coefficients. When we do analyze the detail coefficients in the same way as the approximations, a second branch of decompositions is opened. This generalization of the discrete wavelet transform is called the wavelet packet transform (WPT). Further explanation of the wavelet packet transform and its comparison with the DWT can be found in [19] and [21]. The final results of the DWT applied on the 16 data points are presented in Fig. 40.44. The difference with the FT is very well demonstrated in Fig. 40.45 where we see that wavelet describes the locally fast fluctuations in the signal and wavelet a the slow fluctuations. An obvious application of WT is to denoise spectra. By replacing specific WT coefficients by zero, we can selectively remove... 

The research also revealed new complexities and some questions are still to be answered. The molybdate(VI) system in particular needs further clarification regarding the existence of some polyions. More kinetic and thermodynamic data would also help to improve our understanding of these systems and perhaps lead to a general inclusive explanation of the mechanism of polyoxoanion formation. In this respect the new information about some structural preferences of the different metals in mixed polyoxoanions is of interest and a useful addition to known facts regarding polyoxometalate structures (181). 

Chemical philosophy. .. has for its aim to reveal the general principles of the science. .. [to give its history], to give an explanation of the most general of chemical phenomena, to establish the link between facts and the cause of the facts. Chemical philosophy makes abstract the special properties of bodies it is composed of the general study of the material particles chemists call atoms and the forces to which these particles are submitted. 22... 

Lapworth continued to caution Robinson that it was desirable to use reaction signs as generalizations of facts rather than as explanations based on hypotheses. 95... 

Polymer brushes were found to minimize adsorption of proteins by the soft or steric repulsion of the flexible yet immobihzed macromolecules [179], although a generally valid explanation of the protein resistant properties of some hydrophihc brushes is not available. A similar explanation can be formulated for the improvement of the colloidal stability of particle suspensions, when polymer brush-type layers are bound to small particles. This and other intriguing features of polymer brushes prompted a remarkable experimental and theoretical research activity in order to understand and exploit the unique properties of polymer brushes. 

The general observation in the published work has been that for species such as hexamminechromium, thiocyanatopentammine, or the hexa-aquo ion where O18 exchange was looked at, irradiation produced a substitution reaction and nothing else. Moreover the reaction mode was independent of wave length, and the quantum yields did not change much. From a morphological point of view, there are essentially three types of explanations. First all excited states independently lead to the same chemical sequence, and we suppose that the primary act is simply a heterolytic bond fission. 

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