History of concepts

G.-M. Schwab History of Concepts in Catalysis The concept of catalysis can be attributed to J. Berzelius (1838), whose formulation was based on the manifold observations made in the 17th and 18th centuries. This article traces the development of this and related theories along with the scientific research and empirical material from which they are drawn. 

G. -M. Schwab History of Concepts in Catalysis. -J. Haber Crystallography of Catalyst Types. -G.Froment, L. Hasten Catalytic Kinetics Modelling. -A J. Lecloux Texture of Catalysts. - K Tanabe Solid Acid and Base Catalysts. 

Viewing the history of concepts in terms of grand themes allowed Mayr to give his story the hero it had lacked. As a promoter of systematics, the situation he found himself in was a competitive one, as he explained in the opening sentences of Systematics and the Origin of Species. 

A man who has followed the history of concepts during several decades has seen that an older concept has seldom been totally replaced or refuted by a newer one, but that usually an older concept has been... 

The idea that unsymmetrical molecules will orient at an interface is now so well accepted that it hardly needs to be argued, but it is of interest to outline some of the history of the concept. Hardy [74] and Harkins [75] devoted a good deal of attention to the idea of force fields around molecules, more or less intense depending on the polarity and specific details of the structure. Orientation was treated in terms of a principle of least abrupt change in force fields, that is, that molecules should be oriented at an interface so as to provide the most gradual transition from one phase to the other. If we read interaction energy instead of force field, the principle could be reworded on the very reasonable basis that molecules will be oriented so that their mutual interaction energy will be a maximum. 

The history of EM (for an overview see table Bl.17,1) can be interpreted as the development of two concepts the electron beam either illuminates a large area of tire sample ( flood-beam illumination , as in the typical transmission electron microscope (TEM) imaging using a spread-out beam) or just one point, i.e. focused to the smallest spot possible, which is then scaimed across the sample (scaiming transmission electron microscopy (STEM) or scaiming electron microscopy (SEM)). In both situations the electron beam is considered as a matter wave interacting with the sample and microscopy simply studies the interaction of the scattered electrons. 

Our purpose in this introduction is not to trace the history of polymer chemistry beyond the sketchy version above, instead, the objective is to introduce the concept of polymer chains which is the cornerstone of all polymer chemistry. In the next few sections we shall introduce some of the categories of chains, some of the reactions that produce them, and some aspects of isomerism which multiply their possibilities. A common feature of all of the synthetic polymerization reactions is the random nature of the polymerization steps. Likewise, the twists and turns the molecule can undergo along the backbone of the chain produce shapes which are only describable as averages. As a consequence of these considerations, another important part of this chapter is an introduction to some of the statistical concepts which also play a central role in polymer chemistry. 

To provide a rational framework in terms of which the student can become familiar with these concepts, we shall organize our discussion of the crystal-liquid transition in terms of thermodynamic, kinetic, and structural perspectives. Likewise, we shall discuss the glass-liquid transition in terms of thermodynamic and mechanistic principles. Every now and then, however, to impart a little flavor of the real world, we shall make reference to such complications as the prior history of the sample, which can also play a role in the solid behavior of a polymer. 

Lipson (1943, 1944), who had examined a copper-nickeMron ternary alloy. A few years ago, on an occasion in honour of Mats Hillert, Cahn (1991) mapped out in masterly fashion the history of the spinodal concept and its establishment as a widespread alternative mechanism to classical nucleation in phase transformations, specially of the solid-solid variety. An excellent, up-to-date account of the present status of the theory of spinodal decomposition and its relation to experiment and to other branches of physics is by Binder (1991). The Hillert/Cahn/Hilliard theory has also proved particularly useful to modern polymer physicists concerned with structure control in polymer blends, since that theory was first applied to these materials in 1979 (see outline by Kyu 1993). 

Perhaps the last general overview of crystallography in all its many aspects, including crystal chemistry and crystal physics and the history of crystallographic concepts, as well as the basics of crystal structure determination, was a famous book... 

The literature in this area is extensive and some of the concepts and symbolism may be transitory. This chapter reviews the field at a level and with a coverage adequate for the experimentalist to use the standard relationships and to follow their use in the mechanistic literature. Research on the meaning of the extrathermody-namic relationships themselves is beyond our needs the interested reader can explore these ideas further in the references cited. Grunwald has reviewed the early history of LFERs. 

From the time of Dalton the history of the atom has been a march of triumph. Wherever the concept of the atom was employed for the interpretation of observational measurements, it supplied lucid explanation conversely, such success became overwhelming evidence for the existence of the atom. 

In this chapter, by using the examples of -lactams we have briefly examined how microbial cultures may be used to produce sufficient antibiotics to meet market demands. We have also explained how enzymes (or cells) may be used to biotransform, and thereby diversify, antibiotics. By outlining the history of penicillin production, we explained how analysis and manipulation of culture regimes may be used to enhance the yields of antibiotics (and other secondary products). These studies led to die concept of directed biosynthesis by precursor feeding. 

Based on the practical history of scale-up, most fermentation processes for alcohol and organic acid production have followed the concepts of geometric similarity and constant power per unit volume. From the above concept, and as a strong basis for translation of process criteria, only physical properties of the process were considered in the scale-up calculation. For power consumption in an agitated vessel, there is a fixed relation between impeller speed, N, and impeller diameter, l)t. The constant power per unit volume, for a mechanical agitated vessel is given by ... 

The present article will consist of a brief History of SP (Section II) Representative SP and their Uses (Section III) Production Methods of Representative Propellants (Section. IV) Physical Characteristics of Representative Propellants (Section V) Chemical Characteristics Performance (including modern concepts of ignition and combustion) (Section VI) Explosion Hazards (Section VII) and Brief Summaries of Recent Literature on SP (Section VIII)... 

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