Difficulty in defining

There is difficulty in defining the absolute mobilities of the constituent ions in a molten salt, since it does not contain fixed particles that could serve as a coordinate reference. Experimental means for measuring external transport numbers or external mobilities are scarce, although the zone electromigration method (layer method) and the improved Hittorf method may be used. In addition, external mobilities in molten salts cannot be easily calculated, even from molecular dynamics simulation. 

Because the denatured state has long been thought to be essentially random and because of the inherent difficulties in defining and interpreting structural data averaged in very complex ways, protein chemists have been slow to take up the structural characterization of denatured proteins. Yet a more complete description of the relatively small amounts of persistent structure they display is not simply of academic interest. There are compelling reasons to pursue structural studies of proteins that are not folded. 

The kinetics and mechanism of formation and dissociation of macrocyc-lic complexes is an area covering a wide range of behaviour. Indeed, the mechanistic details of a particular reaction are often closely associated with both the type of metal ion present and the structural features of the cyclic ligand. As such, there are often difficulties in defining general mechanisms which have wide applicability. In this discussion, some representative reactions are considered with emphasis on those features arising from the cyclic nature of the respective systems. 

The simplest carbene is methylene (H2C ). Despite its simplicity, there has been significant difficulty in defining the properties of this compound. 

The density of He I at the boiling point at 1 atm is 125 kg m 3 and the viscosity is 3 x 10 6 Pa s. As we would anticipate, cooling increases the viscosity until He II is formed. Cooling this form reduces the viscosity so that close to 0 K a liquid with zero viscosity is produced. The vibrational motion of the helium atoms is about the same or a little larger than the mean interatomic spacing and the flow properties cannot be considered in classical terms. Only a quantum mechanical description is satisfactory. We can consider this condition to give the limit of De-+ 0 because we have difficulty in defining a relaxation when we have the positional uncertainty for the structural components. 

In most instances the test system will be self-evident (e.g., the animal to which the test article is administered or applied). Studies with micro-organisms, however, sometimes present difficulty in defining the test system. In the case of the Ames test, for example, the test system is not merely the colonies of salmonella or yeast, but includes in addition the culture medium, metabolic activation agent (if any), biotin, histidine, and buffer (if any). The last sentence of the definition makes it clear that untreated control groups also meet the definition of test system even though a test or control article is not administered or applied to such groups. 

A few special technical problems arise when attempting to mount film electrodes into conventional electrochemical cells due to difficulties in defining the electrode area and in making electrical connection to the active surface. These constraints usually result in cells that have been somewhat modified, although the same principles that were discussed in Chapter 9 still apply. In this final section we address some of these practical difficulties. 

A comparison of power requirements of different cycles can only be approximate because of the difficulty in defining equivalent operating conditions for the various cycles. Table 4 and Table 5 present values for different cycles, and for different versions of the mixed refrigerant cycle. 

Overall, an allocation based on a purely uniform benchmark creates the fewest distortions for both incumbents and new entrants. A similar approach for both facilities would increase transparency and avoid difficulties in defining what a new entrant is, relative to an existing facility (Entec and NERA, 2005). However, this does not suggest that it is desirable from an equity perspective, as power generators might receive free allowances above the level they require to cover any additional costs from the emission trading scheme. 

In spite of the remarkable difficulty in defining a detailed model, the number of computational codes introducing dielectric nonlinearity, especially in the form of dielectric saturation, is quite abundant. We quote here the main approaches more details can be found in the already quoted review [8],... 

While the concept of purity is rather straightforward for small molecules, definition of purity for a protein product can be difficult. The difficulty in defining purity arises for several reasons 1) some products, glycoproteins in particular, exist in a... 

It is interesting that the three different criteria that we have considered give us electronegativity scales that are very similar. This indicates that, despite the difficulty in defining it, the concept of electronegativity is a meaningful one. 

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