Empirical nature

Customarily, it is assumed that e is unity and that ]l = p,cos 9, where 0 is the angle of inclination of the dipoles to the normal. Harkins and Fischer [86] point out the empirical nature of this interpretation and prefer to consider only that AV is proportional to the surface concentration F and that the proportionality constant is some quantity characteristic of the film. This was properly cautious as there are many indications that the surface of water is structured and that the structure is altered by the film (see Ref. 37). Accompanying any such structural rearrangement of the substrate at the surface should be a change in its contribution to the surface potential so that AV should not be assigned too literally to the film molecules. 

The correlations used are based partly on theoretical consideration and partly on empirical observations. The basic filtration data are correlated by application of the classic cake-filtration equation, aided by various simplifying assumptions which are sufficiently valid for many (but not all) situations. Washing and drying correlations are of a more empirical nature but with strong experimental justification. If steam or thermal diying is being examined, additional correlations are required beyond those summarized below for such applications, it is advisable to consult an eqmpment manufacturer or refer to pubhshed technical papers for guidance. 

Bamford, Jenkins and coworkers131157 concluded that many of the limitations of the Q-e scheme stemmed from its empirical nature and proposed a new scheme containing a radical reactivity term, based on experimentally measured values of the rate constant for abstraction of benzylic hydrogen from toluene (Ay i), a polar term (the Hammett o value) and two constants a and J which are specific for a given monomer or substrate (eq. 57) 146... 

Alex Rosenberg I didn t address your point about linear versus non-linear causality. I guess for the last three generations, opponents of quantitative and other kinds of empirical natural and social sciences have been making heavy... 

Concepts like electronegativity, inductive, resonance effects, etc. have been developed by the chemist to bring order into a wealth of experimental observations. They are of an empirical nature defying an unequivocal theoretical derivation. Any attempt to put these concepts onto a quantitative basis has to face up to this situation. Values calculated for these electronic effects must be compared with experimental data in... 

In an extension of their work, Goodhart and coworkers developed a system [45] whereby the final desired color of a compressed table formulation was first chosen from a standard color chart (such as the Munsell compilation [40]). This color was then analyzed as to its CIE parameters, and these parameters were in turn used to develop a colorant combination that would produce a match of the desired color. The ultimate end of this work was to produce a database of sufficient depth that the empirical nature of color matching could be eliminated. 

In spite of its empirical nature, weathering behaviour can in some circumstances be predicted with a level of accuracy acceptable for design. Examples are given in Section 12.4. 

The general approach is illustrated in detail for the case of aqueous ferrous and ferric ions, and the calculated rate constant and activation parameters are found to be in good agreement with the available experimental data. The formalisms we have employed in studying such complicated condensed phase processes necessarily rely on numerous approximations. Furthermore, some empirical data have been used in characterizing the solvated ions. We emphasize, nevertheless, that (1) none of the parameters were obtained from kinetic data, and (2) this is, as far as we are aware, the first such theoretical determination to be based on fully Ab initio electronic matrix elements, obtained from large scale molecular orbital (MO) calculations. A molecular orbital study of the analogous hexaaquo chromium system has been carried out by Hush, but the calculations were of an approximate, semi-empirical nature, based in part on experi-... 

The above examples illustrate the versatility and overlapping substrate specificities of peptidases, but they also serve to explain the difficulties faced by medicinal chemists who try to design bioactive peptides that have improved pharmacokinetic properties. Clearly, general predictive rules and a global understanding of the in vivo fate of peptides are not in sight, but the sections below will show that medicinal chemists have developed various successful strategies of a rather empirical nature [7][181-188],... 

Here, V is the sliding velocity in cm/s, P is the pressure in MPa, and T is the interface temperature in degrees Celsius. The constants in the equation have units and these units have been omitted for clarity. At temperatures less than about 110 °C, the stress at the interface is due to a frictional force mechanism. At temperatures higher than 110 °C, the forces are from a viscous mechanism. The friction coefficients provided by Eq. 5.31 have the proper trends. Coefficients derived from the equation, however, need to be used with care because of its empirical nature and the difficulties in measuring frictional data. 

The highly empirical nature of chemometric tools can lead to customer suspicion regarding the efficacy of chemometric models and... 

In fact, the chemical industry often favors heterogeneous catalysis, which is also more than a century old (Sabatier was probably one of its real fathers), despite its so-far empirical nature. The development of better catalysts in heterogeneous catalysis has always relied on empirical improvement since it has been difficult to characterize active sites on the surfaces, as the so-called active sites are usually small in number(s). Presently, the number of accepted elementary steps (as defined above) is stiU Hmited to a few examples, mostly demonstrated by means of surface science [1-3] and the predictive approach, based on molecular concepts. 

This correction plays a key role in any cosmological application. Without it, SNIa events could not be used as distance indicators. However, its purely empirical nature remains unsatisfactory to demanding theoretical minds. We would like to be able to explain physically why some explosions are weaker than others, and what effect this has on the appearance of the object. This involves building detailed models of these explosions and the way radiation is hansferred through the expanding envelope, similar to those made to describe atomic bombs or spheres struck by laser beams, which implode before exploding. 

The forthcoming years will offer a great deal of excitement if the CALPHAD method is extended and infused with new ideas and directions. For our part, we would like to see efforts continue which place CALPHAD on the soundest possible physical basis so that the semi-empirical nature of the subject area can be reduced. This, alongside the exciting new areas of application which are continually appearing, promises to provide the necessary scientific stimulus to keep alive the long pioneering tradition of the early workers in this field. 

The curves represent a plot of Log.(/V),(Reduced Plate height)against Log.(v), (Reduced Velocity). The lower the Log.(/7) curve versus the Log.(v) curve the better the column is packed. At low velocities the (B) term dominates and at high velocities the (C) term dominates as in the Van Deemter equation. The best column efficiency is achieved when the minimum is about 2 particle diameters and thus, Log (.ft) Is about 0.35. The minimum value for (H) as predicted by the Van Deemter equation has also been shown to be about two particle diameters. The optimum reduced velocity is in the range of 3 to 5 that is Log.(v ) takes values between 0.3 and 0.5. The Knox equation is a simple and effective method of examining the quality of a given column but, as stated before, is not nearly so useful In column design due to the empirical nature of the constants. 

In spite of their empirical nature, the correlations shown in Fig. 3 indicate a good overall chemical consistency of the three types of complexes considered. 

Haloform reaction, 237, 296 Halogenation alkanes, 300, 323 alkenes, 179,186, 313 benzene, 138,316 ketones, 295 Hammett equation, 362 additional parameters, 374, 388, 395 derivation of, 362 deviations from, 375 empirical nature of, 395 implications of, 394 reaction pathway, and, 375 solvent effects and, 388 spectroscopic correlations, 392 standard reaction for, 362, 395 steric effects and, 361, 383 thermodynamic implications of, 394 Hammett plots, 359 change in rate-limiting step and, 383 change in reaction pathway and, 378... 

These two papers by Boulduc and Lemery demonstrate a level of empirical knowledge about the neutral salts that is confident and mature. It is the empirical nature of that knowledge that should be stressed here, for the composition of neutral salts is always expressed in terms of other material bodies, the acids and the bases of which they are composed, the... 

In general, most of the extrusion work has necessarily been of an empirical nature. Nevertheless, important practical conclusions have been drawn by each of the authors. The nature of the problem is such, however, that a more detailed review could still not encompass all the necessary trends hence the interested reader is referred directly to the original sources for additional details. 

The formation of relatively stable fluorescent products by the reaction of adrenaline with ethylenediamine (and certain other primary amines) in air, first reported in 1948 by Natelson et was adapted by Weil-Malherbe and Bone in 1952 for the assay of catecholamines.197 198 Since 1952 much work, largely of an empirical nature, has been carried out to improve the analytical procedure since often apparently minor variations of the reaction conditions have a significant effect on the fluorescence observed (see Section V, E, 4). Paper chromatographic examination of the reaction mixtures obtained from adrenaline and noradrenaline suggested that more than one product could be formed in each case.199-205 The main fluorescent product of the interaction of adrenochrome (1) (obtained by oxidation of adrenaline) and ethylenediamine in air has been obtained as a crystalline solid by Harley-Mason and Laird and shown to be 2,3-dihydro-3-hydroxy-l-methylpyrrolo[4,5-g]quinoxaline (94) (7% yield).206,207 This compound has two hydrogen atoms less than... 

Equation presented picviousiy pi ox ide tool for aiming at this trade-ofT however, because of the empirical nature of some of the underlying assumptions, engineering judgment must also be utilized. This is best illustrated in the following wo example ... 

The thermodynamic models used in these industrial process optimizations are mostly of a semi-empirical nature because ... 

Very little data is available on the measurement of heat transfer coefficient. Hands15 mentions the empirical nature of the coefficient and the numerous factors which will affect its value, particularly between rubber and a fluid. Griffiths and Norman66 calculated the heat transfer coefficients for rubbers in air and water. Hall et al67 investigated the effect of contact resistance on steady state measurements of conductivity. 

Table IV shows the calculated and observed energies of transition in the three ions considered here, and it is seen that the first absorption by ClO

In vitro protein digestibility requires preparation of a treated sodium caseinate standard. Because of the empirical nature of these determinations, it is critical that results for the so-... 

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