Field-widening approach

The discussion above has been more or less empirical and descriptive. However, considerable effort has been made to interpret 3-SCS on a more physical basis. Electric-field effects (71-75) were invoked to explain signal shifts of 3-carbon atoms induced by protonation of amines (157,158) (cf. Section II-B-3). This approach was later extended to other functionalities by Schneider and coworkers, who assumed that the SEF component (E2) rather than inductive properties of the substituents should be responsible for 3-SCS (113). They found fairly linear correlations of 3-SCS(X ) and 3-SCS(X ) in cyclohexyl derivatives (76) and attributed the difference between these for a given X to a widening of the C -Cp-Cv bond angle by 2.2° in the axial conformer (114,159). The decrease of 3-SCS in the order primary Cp —> secondary Cp — tertiary Cp — quaternary Cp was explained by electron-charge polarization in the Cp-C" bond(s) induced by the LEF component of the C -X dipole, which is already of significance at this distance, though ( 2) still dominates (160). Such an electron flow toward the 3 carbon is expected to be much more pronounced in C-C than in C-H bonds because of the polarizability difference (aCH = 0.79 acc = 1.12) (150,151,160). 

Phosphorus-31 MRS is continuing to advance and see wider application. The capability to perform P MRS on both clinical and high-held animal scanners is steadily becoming more widespread. Advances such as high magnetic fields and improved RF hardware, data-acquisition approaches, spectrum analysis automation, and pulse sequences promise a technique of increased speed and spectral and spatial resolution, with a widening range of potential applicahons. 

As the spacing between the 103 CS planes in the array widens, the influence of the strain fields will become less important. Ultimately, the (presumably) chemical factors which govern the CS-plane type will prevail. As 102 CS planes form in isolation, this C5-plane type should nucleate between wider 103 CS planes. This is indeed found to be so, and examples are shown in Figure 45. The CS plane on 102 seems to grow until it approaches the existing 103 neighbours to a distance of about 1.5 nm or so. When the CS planes become closer than this, the 102 plane either... 

The modern practice of symbolizing substitution by placing the respective designations before the otherwise unaltered name of the parent compound grew from this approach. The field for substitution names widened beyond limits when, with the inauguration of structural chemistry and the aromatic theory, a detailed picture of the chemical formula became available and hydrocarbon radicals now competed with inorganic substituents in producing an unforeseen multiplicity of names. 

The dramatic increase in the number of publications devoted to LC/MS over the last decade is a strong indication that further progress in this field is assured. This scientific competition and exploration between the current approaches will eventually result in the development of a more universal interface. Until that time, the three major interface types will continue to be used for a ever widening variety of compound classes pushing the limits via modifications to the principal designs. 

This book is the fifth in the series Lecture Notes on Impedance Spectroscopy which has the aim to widen knowledge of scientists in this field by presenting selected and extended contributions from the International Workshop on Impedance Spectroscopy (IWIS 13). The book reports about new advances and different approaches in deahng with impedance spectroscopy including theory, methods and apphcations. The book is interesting for researchers and developers in the field of impedance spectroscopy. I thank all contributors for the interesting contributions and the reviewers who supported the decision about publication with their valuable comments. 

Field-flow fractionation was developed about the same time as SEC the first FFF paper was published in 1966 [1]. However, major instrumentation problems were not solved as quickly for FFF as they were for SEC as instrumentation became available for SEC, there was then less incentive for the development and application of FFF instrumentation. For almost twenty years, the only active group involved in the development of FFF for polymer analysis was the University of Utah group from which the FFF concept originated. However, as the demands placed on polymer characterization tools become more stringent and the applications more exotic, the FFF approach is gaining increased attention from a widening circle of users. 

The success of widening the operating temperature for water-based proton conduction system has so far not been matched in the field of intrinsically dry proton conductors. Although interesting developments were reported in the field of polymers having tethered imidazole groups [31-34], these and other approaches based on phosphonated polymers, either in their pure form or as acid-base copolymers or blends, show conductivity values, which are at least an order of magnitude too low [34—36]. 

The attractive property of the compounds under discussion is the relative simplicity of their crystal structures. Therefore, with the development of algorithms, programs and methods of the computational solid-state physics, they were constantly the objects of theoretical calculations they were the test models which were used to verify newly proposed approaches. As a consequence, taking the evolution of ideas on the electronic structure of these compounds as an example, it is possible to follow the development of the theory of crystals, which broadens its field of application, and widens the range of problems solved. 

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