Instability, qualitative approach

Even though many compounds discussed in the above presentation are thought to be important in meat flavor, a delicate blend of these compounds and other ingredients at the appropriate concentration is needed to synthesize acceptable flavor. In view of the possible instability of the flavor compounds themselves, precursors that supply the precise mixture of volatiles upon heating will be needed. Attempts have already been made to use this approach as judged by the numerous patented mixtures of precursors listed in the literature. More effort should be given to the quantitative aspects of meat flavor production and work must be continued on the qualitative aspects of the volatiles and the appropriate Maillard reaction precursors chosen. 

It is believed that the electrochemical reductive of aliphatic halides [58], benzyl halides and aryldialkylsulfonium salts [89] are concerted, i.e., electron acceptance is concomitant with bond cleavage, due in part to the a nature of the LUMO as well as the instability of the anion-radical species and stability of the products. If the anion-radical is not a discrete chemical entity back ET cannot take place. Therefore, the efficiency of PET bond cleavage reactions would be expected to be greater for the reasons mentioned above. However, due to the localized nature of the a molecular orbitals the probability for intermolecular and intramolecular ET, for example, to a a MO may be quite low. However, the overall efficiency of PET concerted bond cleavage reactions may approach unity provided that ET to the This topic clearly requires further consideration and research using fast kinetic laser spectrophotometric techniques to go beyond the qualitative discussion provided here. 

It is readily evident that this time te, reduces rapidly as the Reynolds number increases beyond Recr2- Also as one approaches Rccri from above, te increases in almost an unbounded manner. We emphasize that the periodic variation of lift was obtained without any artificial excitation, as has been done in many previous investigations. This figure qualitatively displays the fact that the instability and its supercritical saturation changes when the Reynolds number transits through Recr2-... 

The key feature distinguishing the OOA from the cooperative JT effect is the way the chemical bonding effects are included. This will be an important part of the present study. In Sect. 2, we present a simple qualitative description of the cooperative JT effect. First, in Sect. 2.1, we demonstrate the chemical nature of the JT instability. In Sect. 2.2, the cooperative JT effect is presented as interplay of short-range chemical bonding effects with the long-range intercell elastic coupling. To reveal the most important differences of the two approaches from one another, in Sect. 3 we present a simplified version of the OOA. In Sect. 4, we discuss some additional effects that are closely related to JT instability in crystals. 

Reversed-phase HPLC is the method of choice for the quantitative analysis of procyanidins. In view of the known instability of procyanidins and the problem of developing suitable sample clean up procedures direct analysis of crude extracts is probably the best approach for quantitation. However, the separation capacity of HPLC in combination with the most commonly used UV detection at 280 nm is generally insufficient to generate useful quantitative results. Direct chromatographic determination of procyanidins in qualitative analysis has been frequently performed for example in the analysis of wine [168,252], beer [32], grape seeds [28], rhizomes of tormentil (Potentilla tormentilla) [253], Sesbania sesban... 

The disadvantages of CE compared to IC include lower sensitivity, higher concentration detection limits, and somewhat poorer reproducibility of qualitative and quantitative data owing to instability of the electroosmotic flow (EOF). IC has so far been developed more extensively. Validated procedures and computer optimization approaches are available... 

Finally, other issues like the qualitative behaviour of solutions (stability, instability and asymptotic stability), can be analysed using this approach. Moreover, in all the examples studied, solutions exhibited weak stability, which in terms of the electrochemical problem means that experimental errors in the initial surface concentrations tend to remain limited as the reaction proceeds to completion. Nevertheless, these experimental errors never tend to vanish, and this fact is a consequence of having a null eigenvalue. As observed earlier, all these facts can be proved combining mathematical theorems with chemical laws, so they can be easily generalised to other unimolecular reactions mechanisms. 

The macroscopic desaiption has been impressively successful in a number of areas, such as fluid mechanics, for studying complex flows and fluid instabilities, including the Rayleigh-Taylor, Kelvin-Helmholz, and Richtmyer-Meshkov instabilities. But it becomes inaccurate for problems in which the detailed atomistic processes affect the macroscopic behavior of the medium, or when the scale of the medium is small enough that the continuum approximation becomes questionable. Such situations are often found in studies of properties and defects of micro- or nanosystems where the continuum methods can describe only qualitative tendencies, the quality of quantitative results may be difficult to ascertain. Also, the approach has limited applicability since it does not incorporate molecular-scale enthalpic interactions between different species present in the system and requires input (viscosities. 

These results were interpreted by means of numerical simulations of the inhomogeneous deformation field, a disadvantage of this approach. However, it allows, in principle, for high deformation rates, and, because the flow is confined, it is thought that flow instabilities are prevented. Only qualitative agreement was obtained. 

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