Systematics, explanations

Much of the published work on extrusion has attempted to correlate process conditions and formulation with final product properties. Correlations are almost always found, and may be systematic within the particular set of variables examined, but do not survive when further parameters are examined in other studies. This makes them of limited use in even qualitative explanation of product properties. Re-examination of published data, bearing in mind the effect of material states on the expansion process after the die, shows that there is a systematic explanation that can be related to the material properties of the extruded mass, during the dynamic formation of bubbles and cellular structures. However, because of the transformation of materials within the barrel, both at the microscopic and molecular level, it is unrealistic to expect test methods on raw materials alone to relate directly to product structures and... 

A systematic explanation of the spreading phenomena observed requires consideration of mechanisms which will account for the invariable advance of a primary film, and relate the presence of volatile impurities to the spreading of secondary films and the frequent development of a ridge at their leading edge, account for the distinct recession of some liquids from a boundary at which they exhibit a zero contact angle, and explain the upward transport of significant amounts of liquid in films a micron or more thick. 

As we mentioned earlier, Massa has recently investigated the question of compatibility of low-molecular-weight PS in PMMA and P(MMA-S) (31). In terms of the present report, type [1] phase behavior represents a compatible polymer/polymer system, and there is good qualitative agreement between the data reported here and that obtained by massa. However, we do note that the limits of compatibility observed here for the PS/PMMA system (Figure 19) seem somewhat less restrictive, while at the other extreme appear somewhat more restricted for the PS/P(25MMA-75S) system (Figure 22) at present we have no systematic explanation to offer for these rather minor differences. 

What way is then really truel In the spirit of the philosophical ideas of Poincare, such question is not correct. The second approach is more us l allowing for systematic explanation and prediction of much wider range of phenomena. In other words, the system approach is much more efficient, because it gives the uniform theoretical basis for wider range of phenomena which remain mysterious in the framework of non-system approach. ... 

Lack of systematic explanation of the environmental aspect of cracking. Specific environments are more consistent with the adsorption theory. 

As pointed out by Henri Wahl, author of the chapter on the dyestuffs industry in le Grignard . All of this work was primarily aimed at finding a systematic explanation for the structure of dyestuffs. Thanks to modern physics, however, we now know that the absorption of visible and ultra-violet light is due to the presence in the molecule of mobile electrons or delocalised electrons. These electrons are responsible for the special properties of the double bonds, and they exist only if there are double bonds. See V. Grignard, G. Dupont and R. Locquin eds.. Trade de chimie organique (Paris, 1953), vol. 22, pp. 304-305. 

Hitherto, literature does not supply a systematic explanation of lead markets, never mind a theoretical model. Instead, most authors offer lead market definitions that already include explanations for the leading role of a market. Takeuchi and Porter (1986, p. 129) define lead markets as country markets with the most demanding buyers or those buyers most likely to adopt innovations". Johansson and Roehl (1994, p. 142) define lead(ing) markets as countries of demanding and sophisticated customers which compete fiercely and demand a continuous flow... 

A systematic difference is found, supported by indirect evidence that from experience precludes any explanation other than effect observed. This case does not necessarily call for a statistical evaluation, but an example will nonetheless be provided in the elemental analysis of organic chemicals (CHN analysis) reproducibilities of 0.2 to 0.3% are routine (for a mean of 38.4 wt-% C, for example, this gives a true value within the bounds 38.0. .. 38.8 wt-% for 95% probability). It is not out of the ordinary that traces of the solvent used in the... 

The molecular modelling approach, taking into account the pyruvate—cinchona alkaloid interaction and the steric constraints imposed by the adsorption on the platinum surface, leads to a reasonable explanation for the enantio-differentiation of this system. Although the prediction of the complex formed between the methyl pyruvate and the cinchona modifiers have been made for an ideal case (solvent effects and a quantum description of the interaction with the platinum surface atoms were not considered), this approach proved to be very helpful in the search of new modifiers. The search strategy, which included a systematic reduction of the cinchona alkaloid structure to the essential functional parts and validation of the steric constraints imposed to the interaction complex between modifier and methyl pyruvate by means of molecular modelling, indicated that simple chiral aminoalcohols should be promising substitutes for cinchona alkaloid modifiers. Using the Sharpless symmetric dihydroxylation as a key step, a series of enantiomerically pure 2-hydroxy-2-aryl-ethylamines... 

In electroanalysis, the techniques are pre-eminently based on processes that take place when two separate poles, the so-called electrodes, are in contact with a liquid electrolyte, which usually is a solution of the substance to be analysed, the analyte. By means of electrometry, i.e., by measuring the electrochemical phenomena occurring or intentionally generated, one obtains signals from which chemical-analytical data can be derived through calibration. Often electrometry (e.g., potentiometry) is applied in order to follow a reaction that goes to completion (e.g., a titration), which essentially represents a stoichiometric method, so that the electrometry merely acts as an end-point indicator of the reaction (which means a potentiometric titration). The electrochemical phenomena in electroanalysis, whether they take place in the solution or at the electrodes, are often complicated and their explanation requires a systematic treatment of electroanalysis. 

Structural chemistry or stereochemistry is the science of the structures of chemical compounds, the latter term being used mainly when the structures of molecules are concerned. Structural chemistry deals with the elucidation and description of the spatial order of atoms in a compound, with the explanation of the reasons that lead to this order, and with the properties resulting therefrom. It also includes the systematic ordering of the recognized structure types and the disclosure of relationships among them. 

Although an explanation for the substituent effects on the thermal stability of the thiepin ring awaits further systematic studies, an attractive way of explaining these effects would be a concept of "effective descontinuity of cyclic conjugation proposed recently by Inagaki ... 

The resulting coumarin derivatives were isolated with >99% purity using the automated LC/MS purification system. Although there were neither rational explanation nor deduced structure-photophysical property relationships, this study successfully demonstrated the application of a combinatorial approach for the development of novel fluorescent compounds. The systematic transformation of... 

---