Historical remarks

Bile has long been attributed an important role in medicine [1]. The effect of an impaired bile flow to the intestine has been known to result in steatorrhea — fat malabsorption — and defective absorption of fat-soluble vitamins, notably vitamin K [2], Thus, it is obvious that bile is important for fat assimilation from the intestine. However, it is equally apparent that when fat absorption after bile obstruction or diversion could be studied by quantitative methods, the malabsorption was found to be only partial [3]. In fact, it has seemed surprising that some 60-70% of a normal fat load is absorbed in man and the experimental animal in the absence of bile in the intestine. The absorption of nonpolar lipids, however, is much less efficient, and cholesterol absorption has been reported to have an absolute requirement for the presence of bile salts [4]. Of the bile components important for fat absorption bile salts have been ascribed the main role although experimental results are accumulating regarding the role of bile phospholipids in the specific uptake of sterols by the intestine [5]. 

All major scientific discoveries have prior arts, and STM is no exception. Imaging of individual atoms had been achieved many years before the invention of STM by field-ion microscopy (FIM) and field-emission 

The methods described above have been developed during a period of many years. They came as natural consequences of efforts to clear up as easily as possible the mechanisms of reactions which had more or less unorthodox kinetics. Some of the ideas are therefore old while others, for example the representation of a closed sequence by means of a screw line, are of quite recent date. The same is true also of the construction and application of the partition matrix. 

Other methods in which the same principles are used do actually exist. This is true of the method used by Skrabal (35), who by his criticism 

Other scientists, among them Hearon (36), have simply taken up the fundamental ideas, especially the expressions for the reciprocal velocity of linear (open or closed) sequences and used them as they stand for their special purposes or have developed them in several directions. In this connection it may be mentioned that Hammett (37) recommends the use of such expressions. As a more recent example it may also be mentioned that Sch0nheyder (38) with the same method arrived at a rather unexpected mechanism for an enzymatic reaction, the saponification of racemic i-caprylyl glycerol, by means of a certain lipase. 

Two classical papers on the mechanism of enzymatic reactions employ also the same principles, although the method is different. The first one is a paper of 1903 by Henri (39) which nowadays is not so well known as it deserves. In this paper Henri develops the theory which ten years later was used with such success by Michaelis and Menten (40), but while the latter authors restrict themselves to a rather special case, Henri s ideas comprise more general cases and his paper contains. many valuable observations which, even today, are well worth reading. 

It should be added that chemical kinetics, like any other science, can be developed only through the cooperation of the members of a team comprising all contemporary workers in that field and that any advance rests on the work of former and contemporary scientists. Such considerations form the background for the presentation of problems concerning the elucidation of the mechanisms of chemical reactions given in this paper. 

The history of intermetallics has been outlined repeatedly in some detail by Westbrook, one of the central people in the research and development of intermetallics in the second half of this century (Westbrook, 1967, 1970, 1977, 1993). Therefore only some important points are noted here. 

Intermetallics were used in this century first and primarily for applications as functional materials, as is exemplified in Table 1. Indeed the first industrial applications relied on the special magnetic behavior of certain phases, and respective materials developments led e.g. to Sendust, which shows outstanding magnetic properties and wear resistance and is widely used for magnetic heads in tape recorders (Yamamoto, 1980 Brock, 1986). In the second 

Since approx. Material or process Phase Application Reference 

2500 B. c. cementation CujAs coating of bronze tools, etc. (Egypt, Anatolia, Britain) Westbrook (1977) 

yellow brass CuZn coins, ornamental parts (Rome) Gmelin-Institut (1955) 

The phenomenon of electroluminescence in organic soUds has been known since the 1960 s at that time. Pope et al. [1] and Helfrich and Schneider [2] discovered and investigated the electroluminescence of anthracene crystals between two electrodes, an anode and a cathode. The thickness of the highly-purified anthracene crystal platelets was large in these first experiments 10-20 /wm or 1-5 mm. The two electrodes on the surfaces of the crystal platelets were silver paste or liquid, highly concentrated solutions of NaCl. The necessary external voltages varied between 50 and 2000 V. Later, Williams and Schadt [3] were the first to construct a display , likewise from anthracene crystals, but with solid, laterally-structured electrodes, and they encapsulated it to prevent its degradation in the air. 

The technical specifications of these monitors are impressive they luminesce in the entire visible spectrum, they are bright and efficient. They are thinner and lighter than LCD monitors (liquid crystal displays) and are therefore especially suited for portable equipment. They are intrinsically emissive, and thus require no background illumination, and they have a display angle of nearly 180°. Furthermore, they are fast and thus suitable for rapid video sequences. The image points (pixels) can be switched to a completely dark state, so that higher contrast can be obtained. 

Manutiicturer Screen diagonal (inches) OLED Material Structuring Pixel number Date of publication 

We shall therefore not further discuss the technical applications of OLEDs. In future, they will presumably lead to large-area light sources in addition to large video displays. Instead, in the following we will treat the physical fundamentals of OLEDs, considering a few selected organic materials as examples. 

It is remarkable that the existence of H2O2 in air (as a gas as well as dissolved in hydrometeors) was definitely established before 1880 but the existenee of O3 was still being discussed around then. Definite proof of the existence of O3 in the atmosphere was not provided until the first spectrometric measurements at the end 

At that time, nothing was known about the atmospheric formation reactions of O3 and H2O2 and which chemical mechanisms existed between both species in the gas and aqueous phases. The formation of ozone, hydrogen peroxide and nitric acid in air had been attributed generally to variations in the electrical condition of the atmosphere (Fox 1873). The period 1850-1880 of uncounted ozone measurements using the Schonbein paper has often been criticized, and it is likely that apart from ozone, nitrous acid and hydrogen peroxide were also responsible for the blue 

Zuo and Deng (1999) are believed to be the first authors to establish that lightning can induce H2O2 production (discovered during a Florida thunderstorm). 

Before 1850, this add was wron y attributed to be NO2 or N2O4 note that sulfurous add was SO2 and no difierence with the add anhydride was made (e. g. SO2 + H2O). 

Heikes et al. (1982) first suggested the idea of atmospheric aqueous phase H2O2 formation in cloud droplets. The in-droplet chemical formation of H2O2 occurs much faster than in the gas phase. However, one must consider the liquid volume fraction (LWC) ratio as well as the occurrence of clouds to assess the share of in- 

The second case of TD, the only sibling of the first patient, was a girl in whom at the age of six enlargement and orange discoloration of the tonsils were found. Here, too, the concentration of cholesterol esters in the tonsils was extremely high. In both children plasma total cholesterol levels were below 100 mg per 100 ml. and plasma HDL were absent (Fredrickson et al. 1961 Fredrickson and Altrocchi 1962). 

The third and fourth patients with TD were detected in 1962 (Fredrickson et al.). They were sisters from Missouri, aged 8 and 12 years respectively, in whom tonsillar changes had again given the clue to the diagnosis, and in whom plasma HDL were absent. 

The last two patients, again siblings, were foimd in Kentucky. One of them was 45 years old and exhibited splenomegaly and signs of hypersplenism. His plasma total cholesterol level was below 50 mg per 100 ml. His brother, 3 years older, died suddenly, presumably from myocardial infarction. Plasma HDL could not be found in either subject. 

With the benefit of the hindsight acquired in this period of rapid progress we can see that some of the hypotheses which were hesitantly advanced by early workers do in fact have a wide range of validity. The neglect of many-body effects, which was no more than a pious hope, has turned out to be remarkably successful. Second, the nearly-free-electron description of solids has been justified, systematized, and 

We must not lose sight of the fact that nature, as presently understood, often poses the same question with an unknown, or only partially specified structure. For example, an impurity in a semiconductor may involve a large local distortion rather than an ideal substitution of the foreign atom. In the absence of an exact specification of this distortion, it must be determined as part of the solution to the problem. A similar situation is confronted in the study of amorphous semiconductors, and indeed the whole field of alloys, so we are not speaking of some abstruse or unusual systems but rather a wide range of solids. 

Of course, there is no problem at all in principle. Structure is itself an electronic property, in that it must be determined by the Coulomb forces of the electrons (and nuclei) of the system and should be derivable from the Hamiltonian. The troublesome needle-inhaystack aspect of structure determination is often a nuisance here, but even if we are lucky enough to be faced with a choice between a few reasonable structures (as in the impurity problem), the fact is that the description of the cohesive forces of solids is a difficult and delicate business. Perhaps the stumbling-block of structure determination has been overemphasized here, but there does not seem to be a wide realization of the problem and its importance to future progress. 

The above remarks have been more of a setting of the scene than a historical survey. In the subsequent sections, topicality and experimental evidence are further emphasized, at the risk of an inadequate coverage of the classic calculations and eternal verities of the subject. It is partly out of respect for the available basic literature that such a policy was adopted. We should mention Slater (for an authoritative and exhaustive survey), Callaway (for a general account of the theory), and Ziman (for a recent summary of various mathematical techniques and their interrelationships) as three such sources to which the reader may turn for guidance, as did the author on occasion. In particular, considerations of space and the spirit of this treatise have precluded the inclusion of much mathematical detail, and rather than setting forth an incomplete description of this, inviting misunderstanding, it has been avoided almost entirely. 

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Abstract After some historical remarks we discuss different criteria of dynamical stability of stars and the properties of the critical states where the loss of dynamical stability leads to a collapse with formation of a neutron star or a black hole. At the end some observational and theoretical problems related to quark stars are discussed. 

Nano-structures comments on an example of extreme microstructure In a chapter entitled Materials in Extreme States , Cahn (2001) dedicated several comments to the extreme microstructures and summed up principles and technology of nano-structured materials. Historical remarks were cited starting from the early recognition that working at the nano-scale is truly different from traditional material science. The chemical behaviour and electronic structure change when dimensions are comparable to the length scale of electronic wave functions. Quantum effects do become important at this scale, as predicted by Lifshitz and Kosevich (1953). As for their nomenclature, notice that a piece of semiconductor which is very small in one, two- or three-dimensions, that is a confined structure, is called a quantum well, a quantum wire or a quantum dot, respectively. 

In this chapter, we provide a general overview of the field of chemometrics. Some historical remarks and relevant literature to this subject make the strong connection to statistics visible. First practical examples (Section 1.5) show typical problems related to chemometrics, and the methods applied will be discussed in detail in subsequent chapters. Basic information on univariate statistics (Section 1.6) might be helpful to understand the concept of randomness that is fundamental in statistics. This section is also useful for making first steps in R. 

The organization of the book is as follows The first chapter. Overview, describes the basic facts, concepts, and a brief account of its history. This chapter is written at a general physics level and can be read as an independent unit. The last section, Historical Remarks, is an integrated part of the presentation of basic concepts in STM. As an introductory chapter of a textbook, it is not intended to be an authoritative and comprehensive treatment of the history of STM. However, serious efforts have been made to ensure the authenticity and accuracy of the historical facts. In addition to conducting an extensive literature search, I have consulted several key scientists in STM and related fields. 

The pi theorem is often associated with the name of E. Buckingham, because he introduced this term in 1914. However, the proof of this theorem was already accomplished in the course of a mathematical analysis of partial differential equations by A. Federmann in 1911. (See [6], section 4.6 Historical remarks concerning the pi theorem.)... 

The first experimentalist who became interested in synchrotron radiation was Blewett in 1946, who measured the enei y loss due to this radiation. However, he was not able to detect the radiation itself In 1947, according to the illustrative historical remarks made by Baldwin F. Haber was able to see the synchrotron radiation with help of a mirror. The first investigations of the properties of this radiation were performed by Elder et al. 

HISTORICAL REMARKS. THE LAWS OF CONSTANT PROPORTIONS, SIMPLE MULTIPLE PROPORTIONS, AND COMBINING WEIGHTS... 

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