Historical background

HISTORICAL BACKGROUND inhibitors, nevirapine. RECENT EXAMPLE 

Ever tried Ever failed. No matter. Try again. Fail again. Fail better. 

Even through the end of the 1980s a screening capacity of hundreds of samples per week was deaned 

Over the years, varions screening strategies have been applied to the identification of drag and lead candidates. The screening of natural product extracts for bioacTivity followed by the isolation of the active principle or principles. 

TABLE 7.1 Drugs Derived from Screening Leads  

3To place this in historical perspective, John Quincy Adams was the U.S. President at the time. The following year, Friedrich Wohler reported that the organic compound urea could be made from the inorganic reagents HOCN and NH3—the birth of organic chemistry. 

A translation of excerpts from this paper can be found in Classics in Coordination Chemistry, Part 2, G. B. Kauffman, Ed., Dover New York, 1976, pp. 21-37. 

The first compound containing carbon monoxide as a ligand was another platinum chloro complex, reported in 1867. In 1890, Mond6 reported the preparation of Ni(CO)4, a compound that became commercially useful for the purification of nickel. Other metal CO ( carbonyl ) complexes were soon obtained particularly notable was the work on iron carbonyls beginning around 80 years ago by Hieber.7 

Kealy and P. L. Pauson, Nature 1951,168, 1039. A report of the synthesis of dicyclo-pentadienyliron by Miller in 1952 showed a structure for C10H10Fe as two cyclopentadienyl groups attached to Fe by single bonds. Because Miller s laboratory work occurred in 1948, he may have been the first to synthesize ferrocene without knowing its true structure. See S. A. Miller, J. A. Tebboth, and J. F. Tremaine, J. Chem. Soc., 1952, 632. 

Ebsworth, D. W. H. Rankin, and S. Cradock, Structural Methods in Inorganic Chemistry, 2nd ed., Blackwell Scientific Publications Oxford, 1991, pp 414-417. 

Shell and Uhde Coal Gasification Technology 6.1.2.1 Historical Background 

6 Origins of Operations Research and Process Optimization 11.6.1 Historical Background 

History teaches us that until the mid-nineteenth century, the production of goods was mainly in workshops that operated in the traditional way, i.e., with low productirai volumes, starting the manufacture of a new product when the previous was finished (one to one), and without further specialization of labor, meaning a craftsman normally made the product in full. This form of craftsmanship in some cases led to high-quality products, of which those existing today are considered works of art. 

From the time indicated, the Industrial Revolution brought about the birth of the first industries, the division of labor, interest in optimizing workers time [the first operations research (OR) studies were devoted to this area], optimal placement of machines, specialization of individuals and industries, and the creation of various functional areas within companies, which sometimes had conflicting objectives. Then came the need to coordinate and define activity levels and better allocate and use resources (concept of efficiency) to achieve these levels of activity, with optimal results for the company (from a global point of view) and avoiding internal conflicts. 

The Gantt chart was invented by Henry Gantt in the early part of the last century. Gantt charts coordinate various activities (with a common ultimate goal) of various people. Such charts are the predecessor of the most powerful methods of the Critical Path Method (CPM) and Program Evaluation and Review Technique (PERT). 

OR underwent tremendous development and use during World War II it was applied to solve problems of logistics equipment and staff, as well as to plan mihtary operations themselves. Consider the following examples  

The terms a and n electrons come from quantum mechanics, but the idea that two different types of bonds between, say, carbon atoms should be distinguished occurred in organic chemistry long before the advent of quantum chemistry. A detailed historical review of the entire question is outside the scope of this article (see e.g. 2 ), and we shall remind the reader only of the milestones in the theories of unsaturated, conjugated, and aromatic compounds. 

The most basic notion of organic chemistry is probably the quadri-valency of carbon, which was very clearly formulated by K cule in 1858 3 . Olefinic compounds like ethylene suggested that the carbon atom could exhibit the valence three, but these molecules were finally formulated with a double bond, according to Erlenmeyer s proposition 4 . Kekule s benzene formula 5 completed this classic period of valence theory. About 1875, Le Bel 6 and Van t Hoff 7 introduced the theory of steric valency, where the double bonds between carbon atoms were looked at from a new point of view Van t Hoff proposed his famous model, where the tetra-hedra of doubly-bonded carbon atoms were supposed to have an edge in common and those of triply-bonded carbon atoms a face in common. This picture was quite satisfactory for isolated double bonds, but the peculiar properties of conjugated and aromatic systems could be understood only by imagining that different double bonds in a molecule can interact in a way not possible for single bonds. 

Around 1900, two new theories were developed Thiele 8 suggested that in a double bond the valencies of the atoms could not be incompletely used and that the residual valencies could interact with each other, as shown in formulas (1) (2) (3) 

Nef presented arguments against the universal quadrivalency of carbon 

These two theories can be regarded as the first realizations that a conjugated system is to be described in terms of two different kinds of bonds, those of the first kind being localized between two neighbouring atoms, those of the second kind extending over several atoms, and that the latter cannot always be represented by a single structural formula. 

The transformation of the crystalline into the glassy state by solid-state reactions is extensively reviewed in its theoretical and experimental aspects. First, we give some historical background and describe the thermodynamics of metastable phase formations, adding as well the kinetic requirements for the amorphization process. Then we discuss the different experimental routes into the amorphous state hydriding, thin diffusion couples, and other driven systems. In the discussion and the summary, we close the gap between the melting phenomena and the amorphization and provide a tentative outlook. 

Finally a new class of crystal-glass transformations are discussed by the homogeneous transition due to an instability of the crystal [2.11]. Again, the 

2 Thermodynamics of Metastable Phase Equilibria and Metastable Phase Diagrams 

It is now appropriate to ask what is meant by the free energy of a nonequilibrium phase. For example, what is meant by the liquid curve L in Fig. 2.1 when T T p Strictly speaking, thermodynamic functions can only be defined for equilibrium states, and yet it is natural to consider an undercooled liquid. Turnbull has discussed the fact that liquid metals can be extensively undercooled for extended observable times [2.12] without crystallization. The explanation for this observation lies in the resistance of the undercooled liquids to formation of crystalline nuclei of critical size. The timescale for nucleation of crystals, tn, depends strongly on undercooling as described by Turnbull. Near Tm, tn can be 

To calculate the thermodynamic functions for pure metals, one needs the thermal heat capacity C at ambient pressure. Above the Debye temperature, Cp consists of three parts a) the Dulong-Petit value of 3/cB, b) an additional linear increase proportional to temperature, which can also be seen in the thermal expansion coefficient, and c) an additional amount close to the melting temperature Tm, which results from the formation of defects (mainly vacancies). The last part can be approximated for small concentration as 

The purpose of the book is to develop internal realism, the metaphysical-epistemological doctrine initiated by Hilary Putnam (Reason, Truth and History, Introduction , Many Faces). In doing so I shall rely - sometimes quite heavily - on the notion of conceptual scheme. I shall use the notion in a somewhat idiosyncratic way, which, however, has some affinities with the ways the notion has been used during its history. So I shall start by sketching the history of the notion. This will provide some background, and it will also give opportunity to raise some of the most important problems I will have to solve in the later chapters. 

Putting it tendentiously and imprecisely, Kant held that the world as we know it is constituted, in part, by a conceptual scheme. This is tendentious, because Kant -like many other authors mentioned or hinted at in this sketch - never used the term conceptual scheme . It is also imprecise, because it lumps together two things the forms of sensibility - space and time -, which are not conceptual and play part in shaping the sensory manifold, and the a priori concepts, the categories , which create the world of appearances out of the sensory manifold. Nevertheless, the view to be developed here is a distant descendant of Kant s view, and the notion of conceptual scheme, as I shall understand it, is indeed rooted in his work. I shall maintain that there is a distinction between the world as it is and the way it appears to us, the noumena and the phenomena, in Kant s terms. The world as we know it is constituted by conceptual schemes. What conceptual schemes do is thus roughly similar to what Kant s forms of sensibility and a priori concepts do. So let me continue with the history of the notion. 

To sum it up, the logical positivists considered scientific knowledge as a two-level structure. The lower level is that observation, the upper level is that of theory, and the two are connected by correspondence rules. The sentences on the lower and the upper level are synthetic, the sentences which connect the two levels are analytic. 

So the breakdown of the distinctions between the analytic and the synthetic on the one hand, and the observational and the theoretical on the other hand destroys the nice architecture of the logical positivist view. In the original picture one could clearly mark off the conceptual scheme both from the particular claims that can be expressed in its terms and from the content it organizes. Now these three things seem to be lumped together as an amorphous whole. 

it was exactly on the ruins of the logical positivist conception that a new notion of conceptual scheme has arisen. A new notion, which has affinities not only with the logical positivist view, but also with the Kantian and the historical- 

it cannot be said that the notion of autopoiesis is now familiar in mainstream science. The reason for this will be discussed later on, but it can be anticipated that this is partly due to the fact that autopoiesis theory is not centered on DNA, RNA, and 

The position of CFA, as well as that of its related methods, is that of a preliminary step to statistical inference. In this respect, it has been regarded as an 

Correspondence factor analysis can be described in three steps. First, one applies a transformation to the data which involves one of the three types of closure that have been described in the previous section. This step also defines two vectors of weight coefficients, one for each of the two dual spaces. The second step comprises a generalization of the usual singular value decomposition (SVD) or eigenvalue decomposition (EVD) to the case of weighted metrics. In the third and last step, one constructs a biplot for the geometrical representation of the rows and columns in a low-dimensional space of latent vectors. 

World War I and the interest in aviation gave rise to a rapid development of fluid mechanics and aerodynamics. This, in turn, gave a renewed 

Axial compressors are high speed, large volume compressors but are smaller and somewhat more efficient than comparable centrifugal com- 

The energy from the rotor is transferred to the gas by rotating blades — typically, rows of unshrouded blades. Before and after each rotor row is a stationary (stator) row. The first stator blade row is called the guide vane. 

The volume range of the axial starts at approximately 30,000 cfm. One of the largest sizes built is 1,000,000 cfm, though this size is certainly not common. The common upper range is 300,000 cfm. The axial compressor, because of a low pressure rise per stage, is exclusively manufacturetl as a multistage machine. 

By far, the largest application of the axial compressor is the aircraft jet engine. The second most common usage is the land-based gas turbine, either the aircraft derivative or generic designed type. In last place of the applications comes the process axial compressor. All principles of operation are exactly the same. About the most obvious difference is that the gas turbine compressor is a higher pressure ratio machine and therefore has more stages. 

The existence of materials now included among the conducting polymers has long been known. The first electrochemical syntheses and their characterization as insoluble systems took place well over a century ago. In 1862 Letheby reported the anodic oxidation of aniline in a solution of diluted sulphuric acid, and that the blue-black, shiny powder deposited on a platinum electrode was insoluble in HjO, alcohol, and other organic solvents. Further experiments, including analytical studies, led Goppelsroeder to postulate in 1876 that oligomers were formed by the oxidation of aniline. 

In 1968 DairOlio et al. published the first report of analogous electrosyntheses in other systems. They had observed the formation of brittle, filmlike pyrrole black on a Pt-electrode during the anodic oxidation of pyrrole in dilute sulphuric acid. Conductivity measurements carried out on the isolated solid state materials gave a value of 8 Scm . In addition, a strong ESR signal was evidence of a high number of unpaired spins. Earlier, in 1961, H. Lund had reported — in a virtually unobtainable publication — that PPy can be produced by electrochemical polymerization. 

In 1979, Diaz et al. produced the first flexible, stable polypyrrole (PPy) film with high conductivity (1(X) Scm ). The substance was polymerized on a Pt-electrode by anodic oxidation in acetonitrile. The then known chemical methods of synthesis usually produced low conductivity powders from the monomers. By contrast, electropolymerization in organic solvents formed smooth and manageable films of good conductivity. Thus, this technique soon gained general currency, stimulating further electropolymerization experiments with other monomers. In 1982, Tourillon 

From an analysis of the EPR spectra, Blumberg and Peisach (4) suggested that the coordination environment of Rieske clusters must include one or more atoms which are less electron donating than sulfur. This was significantly substantiated by studies of the Rieske 

In 1996, research groups led by Gellman and Seebach, independently reported that enantiopure short chain y9-peptides with an appropriate substitution pattern (oligomer of /9-substituted /9-amino acids 1 [10] and oligomer of trans-2-amino-cy-clohexane carboxylic acid (trans-AGHG) 2 [6], respectively) could fold in a predict- 

Before analyzing in detail the conformational behaviour of y9-peptides, it is instructive to look back into the origins and the context of this discovery. The possi-bihty that a peptide chain consisting exclusively of y9-amino acid residues may adopt a defined secondary structure was raised in a long series of studies which began some 40 years ago, on y9-amino acid homopolymers (nylon-3 type polymers), such as poly(/9-alanine) 3 [14, 15], poly(y9-aminobutanoic acid) 4 [16-18], poly(a-dialkyl-/9-aminopropanoic acid) 5 ]19], poly(y9-L-aspartic acid) 6 ]20, 21], and poly-(a-alkyl-/9-L-aspartate) 7 [22-36] (Fig. 2.1). 

From studies in solution and in the sohd state, a number of structures both sheet-like [14] and helical [19, 21, 24—36] have been proposed over the years for these polymers. Poly(/9-alanine) 3 for example crystallizes as extended chains [14] 

Interestingly, it was in a different context that both Seebach and Gellman approached the field of yS-peptides. Seebach s initial interest in yS-peptides stemmed from their resemblance to poly(yS-hydroxy alkanoates) (PHA), an ubiquitous class of biopolymers of which poly[(P)-3-hydroxybutanoic acid] (8, PHB) is the most common (for reviews see [37, 38]). 

High molecular weight PHB ( 12,000 units), which was first described more than 75 years ago is a microbial storage material (intracellular carbon source, en- 

Hold one end of the slip [of rubber]. . . between the thumb and forefinger of each hand bring the middle of the piece into slight contact with the lips . . . extend the slip suddenly and you will immediately perceive a sensation of warmth in that part of the mouth which touches it.. . . For this resin evidently grows warmer the further it is extended and the edges of the lips possess a high degree of sensibility, which enables them to dis- 

If one end of a slip of Caoutchouc be fastened to a rod of metal or wood, and a weight be fixed at the other extremity. . . the thong will be found to become shorter with heat and longer with cold. 

Finally reporting on the results of his third experiment, he concluded as follows  

The full significance of these observations could not be appreciated in advance of the formulation of the second law of thermodynamics by Lord Kelvin and Clausius in the early 1850 s. In a paper published in 1857 that was probably the first to treat the thermodynamics of elastic deformation, Kelvin showed that the quantity of heat Q absorbed during the (reversible) elastic deformation of any body is related in the following manner to the change with temperature in the work — TFei required to produce the deformation  

Lord Kelvin s close associate, the expert experimentalist J. P. Joule, set about to test the former s theoretical relationship and in 1859 published an extensive paper on the thermoelastic properties of various solids—metals, woods of different kinds, and, most prominent of all, natural rubber. In the half century between Gough and Joule not only was a suitable theoretical formula made available through establishment of the second law of thermodynamics, but as a result of the discovery of vulcanization (Goodyear, 1839) Joule had at his disposal a more perfectly elastic substance, vulcanized rubber, and most of his experiments were carried out on samples which had been vulcanized. He confirmed Gough s first two observations but contested the third. On stretching vulcanized rubber to twice its initial length. Joule ob- 

Handbook of Residue Analytical Methods for Agrochemicals. 2003 John Wiley Sons Ltd. 

The primary focus of FIFRA is to provide federal control of pesticide distribution, sale, and use. Under FIFRA, the ERA was given authority to study the consequences of pesticide usage. FIFRA requires that all pesticide uses in the United States be registered by ERA. Registration assmes that pesticides will be properly labeled and that if produced and used in accordance with specifications, pesticides will not cause unreasonable harm to the environment.  

The FQPA is another important statute for regulating pesticides. The FQPA amendments to FIFRA changed the way ERA regulates pesticides. The requirements included a new safety standard - reasonable certainty of no harm - which must be applied to all pesticides used on foods.  

The FFDCA governs the establishment of pesticide tolerance for food and feed products. A tolerance is the maximum level of pesticide residues allowed in or on human food and animal feed.  

Ever since the inception of the petroleum industry the level of fires, explosions and environmental pollution that have precipitated from it, has generally paralleled its growth. As the industry has grown so has the magnitude of its accidental events. Relatively recent events such as the Flixborough incident (1974), Occidental s Piper Alpha disaster (1988), and Exxon s Valdez oil spill (1989) have all amply demonstrated the extreme financial impact these accidents can produce. 

After the catastrophic fire that burned ancient Rome in 64 A. D., the emperor Nero rebuilt the city with fire precautions that included wide public avenues, limitations in building heights, provision of fireproof construction and improvements to the city water supplies to aid in fire fighting. Thus it is very evident that 

The Hydrocarbon Processing Industry (HPI), has traditionally been reluctant to invest capital where an immediate direct return on the investment to the company is not obvious, as would any business enterprise. Additionally financial fire losses in the petroleum and related industries were relatively small up to about the 1950 s. This was due to the small size of facilities and the relatively low value of oil and gas to the volume of production. Until 1950, a fire or explosion loss of more than 5 million U. S. Dollars had not occurred in the refining industry in the USA. Also in this period, the capital intensive offshore oil exploration and production industry were only just beginning. The use of gas was also limited early in the century. Consequentially its value was also very low. Typically production gas was immediately flared or the well was capped and considered as an uneconomical reservoir. Since gas development was limited, large vapor explosions were relatively rare and catastrophic destruction from petroleum incidents was essentially unheard of. The outlays for petroleum industry safety features were traditionally the absolute minimum required by governmental regulations. The development of loss prevention philosophies and practices were therefore not effectively developed within the industry. 

In the beginnings of the petroleum industry, usually very limited safety features for fire or explosion protection were provided, as was evident by the many early blowouts and fires. The industry became known as a risky operation, not only for economic returns, but also for safety (loss of life and property destruction) and environmental impacts, although this was not well understood at the time. 

It should also be remembered that a major incident may also force a company to literary withdrawn from that portion of the business sector where public indignation, prejudice or stigma towards the company strongly develops because of the loss of life suffered. The availability of 24 hour news transmissions through worldwide satellite networks virtually guarantees a significant incident in the hydrocarbon industry will be known worldwide very shortly after it occurs, resulting in immediate public reaction. 

Supported bimetallic catalysts have gained unquestionable importance in subjects such as refining, petrochemistry and fine chemistry since their earliest use in the 1950s [1, 2]. The catalytic behavior of such a system is influenced by the size of the metal particles and by the interactions among them and with the support and other catalyst components. The second metal may influence the first metal through electronic interactions or by modifying the architecture of the active site. Very often, the interactions between the two metals are complex and largely unknown, and consequently the preparation procedure critically influences the nature of the catalytic system obtained. 

The different strategies used to obtain bimetalhc catalysts have been well classified by Alexeev and Gates, who analyzed the structural properties of different catalysts as a function of the preparation method [3]. These authors have classified the bimetallic catalysts as described in the next four subsections. 

The Iron Oxides Structure, Properties, Reactions, Occurences and Uses. R. M. Cornell, U. Schwertmann Copyright 2003 WILEY-VCH Verlag GmbH Co. KGaA,Weinheim ISBN 3-527-30274-3 

Another early use of iron oxides was as a cosmetic. The cosmetic boxes (cockleshells) found in the Royal Cemetery in the ancient Sumerian city of Ur contained a range of different colours. XRD analysis by the Research Department of the British Museum showed that the principal components of the red and yellow colours were hematite and goethite, respectively (Bimson, 1980). One box also contained a purple powder consisting of a mixture of quartz grains and large crystals of hematite. 

Centuries after man had started to use iron oxides as colouring agents, he discovered how to smelt them. The first iron was produced between 4000 and 2000 BC. Since then, this product of iron oxides has been used in weapons, utensils, tools, implements and construction. The extensive English iron ore deposits contributed to the lead England acquired in the Industrial Revolution. 

Iron oxides have played their part in navigation. Around the first millenium AD, magnetite, in the form of lodestone, was used in the earliest, crude mariners compasses. These enabled more difficult voyages to be undertaken and thus contributed to a furthering of trade and exploration. 

The most important modern applications of iron oxides are as ores for the iron and steel industry and as pigments (Heine and Volz, 1993). Fe oxides are also used extensively as magnetic pigments in electronic recording devices and as catalysts in industrially important syntheses. Other minor, but still important applications are listed in Table 19.1 and are discussed in the following sections. 

whereas ring systems other than the six-membered borazines are the exception for boron-nitrogen systems. The reasons for this different behaviour will be discussed in later chapters. 

For better or worse, the approaches to risk assessment that have been developed for purposes of radiological protection have set a pattern which has influence approaches for assessing the risks of chemical mutagens and carcinogens. 

In addition, while hundreds of chemicals have been found to cause carcinogenic effects in laboratory animals, definite evidence of human cardnogenidty exists for only a score or more (lARC, 1982). At present, therefore, estimates of the cardnogenidty of most chemicals for man must be based largely on tests in laboratory animals, supported by andllaiy data from other types of bioassays and from knowledge of the relationship between molecular structure and biological activity. 

The reaction of octacarbonyldicobalt with various alkynes has long been known to give alkyne-bridged compounds of the type (p.rf-RC CR )Co2(CO)6 (112, 113). However, under more drastic conditions, these 

The structures of these compounds (see Fig. 1 R = H, CH3) have been established unequivocally by means of X-ray diffraction methods (47, 57, 61, 127), as well as by IR and H- and, ,C-NMR spectroscopy, and will be discussed in Sections VI and VII, respectively. 

If we try to establish the major routes that have been used for the preparation of //-methylene complexes, we find that both direct and indirect methods can be employed. The first approach involves the use of reagents that have had a long history as useful carbene precursors in 

Before discussing the various synthetic approaches to /x-methylene complexes, it should be noted that these compounds are prevalent among the Fe, Co, and Ni subgroups. They are also known to involve groups VI 

The reactivity pattern of diazoalkanes in metal carbonyl chemistry is not only governed by the nature of the starting materials (8), but also depends 

The Langmuir-Blodgett technique for deposition of ordered multilayers has origins which, in a sense, go back to classical antiquity as the present author has discussed elsewhere [3], In 1774 Benjamin Franklin [4] demonstrated that a very small quantity of oil could influence the sur- 

The technique of producing ordered layers of amphiphilic materials by evaporation in vacuo on to a suitable substrate appears to originate in the work of Agarwal [18] but has only very recently been developed. 

Other methods of film formation discussed in this book depend on allowing a melt or a solution of the material to be deposited to spread on the substrate and subsequently to solidify. An ordered structure can sometimes be imposed on such a film by the application of an electric or magnetic field if the film is in a mesophase (otherwise known as a liquid crystal) before solidification. However, any such method presupposes that the melt or solution used will spread evenly over the substrate. It is thus important to understand a little about the conditions which allow a liquid to spread on a solid surface. This topic depends on the nature of intermolecular forces, a subject which is of general relevance to the formation of organic films and which is discussed in the following section. 

Although catalytic transformations gained increasing importance after the First World War, asymmetric reactions were considered at the time to be an academic curiosity. Of note, the determination of enantioselectivity was hampered by a lack of methods to achieve not only efficient purification but also reliable analyses. Hence, the presence of a chiral impurity - which often arose from the catalyst -spoiled the determination of the correct, optical rotation-based ee-values. 

The reinvestigation of Breding s asymmetric cyanohydrin synthesis by Prelog during the mid-1950s [33] undoubtedly promoted the concept of asymmetric synthesis, and led the way to more efficient reactions. The advent of synthetically useful levels of enantioselectivity can be dated to the late 1950s, when Pracejus reported that methyl phenyl lcetene could be converted to (—)-a-phenyl methylpro-pionate in 74% ee by using O-acetylquinine as catalyst [34]. 

As metals easily form Lewis acids, organic catalysts are more prone to form heteroatom-centered Lewis bases. Among these catalysts, the N- and P-based 

It should be noted that not only the Lewis base but also typical Lewis acid roles can be emulated by organocatalytic systems. The proton is arguably the most common Lewis acid found in Nature, and these exist in two forms classified by the nature of the hydrogen bond polar covalent (RX-H) and polar ionic (RX+H-Y ). In the former case, in asymmetric transformations the chiral information is dictated by the chiral anion, whilst in the latter case the anion is non-chiral and the enantioselectivity is introduced by a chiral ligand (usually an amine base), which complexates the proton. This activation is discussed more extensively in Chapter 7. 

Another particular area of organic catalysis is that of Lewis acid activation by a Lewis base. This catalysis represents a powerful means of modulating the electron density of weakly electron-withdrawing centers. Such an interaction operates under well-defined circumstances between donor and acceptor entity, and results in a decreased electron density on the central atom in question. This chemistry is described in greater detail in Chapter 10. 

Each site takes on a finite number of possible values. 

The value of each site evolves according to the same deterministic rules. 

The rules for the evolution of a site depend only on a local neighborhood 

As we shall see, the fourth characteristic can be modified to include probabilistic rules as well as deterministic rules. An important feature sometimes observed in the evolution of these computational systems was the development of unanticipated patterns of ordered dynamical behavior, or emergent properties . As Kauffman has expressed it,22 Studies of large, randomly assembled cellular automata. .. have now demonstrated that such systems can spontaneously crystallize enormously ordered dynamical behavior. This crystallization hints that hitherto unexpected principles of order may be found, [and] that the order observed may have significant explanatory import in [biology and physics]. This proposal has borne considerable fruit, not only in biology and physics, but also in chemistry. Readers are referred to reviews for applications in physics23-26 and biology 27 selected physical and chemical applications have been reviewed by Chopard and co-workers.28 

Ziegler-Natta catalysts made it possible to obtain linear polyethylene and isotactic polypropylene under mild reaction conditions however, they are not active enough to avoid the need for polymer deashing. Consequently, many efforts were undertaken in order to overcome this drawback and different directions were followed. One of these was aimed at improving the activity of TiCl3, and led to the discovery of crystalline forms of TiClg which are more active and stereospecific than those 

The development of these catalysts marked a great progress in polyethylene production, making it possible to develop high yield processes which are simpler and more economic than the traditional ones. They were not, however, suitable to produce isotactic polypropylene. 

The development of simpler, more economic processes for the production of polyethylene and polypropylene did not signify the end of MgCl2 catalyst research, but rather constituted the first phase. New, ever more sophisticated requirements, both in terms of process and product quality, have been emerging, steadily increasing the performance range required for the catalyst control of the polymer molecular structure (MWD, branching, steric purity), of its morphological properties (shape and particle size distribution), and supply of copolymers with controlled structures. 

Spurred by these requirements, industrial research on MgCl2-based catalysts has continued making it posable to achieve ever more advanced objectives. The same cannot, however, be said in regard to the scientific knowledge. Despite the numerous works published, neither the reasons why MgQ2 is such an ideal and unique support, nor the mechanisms of the stereo-regulation are completely clear. 

The purpose of this review is, therefore, to examine in depth the present state of knowledge in the hope that this may act as a starting point for further more fruitful research. 

FIGURE 10-2 Inner and Outer Orbital Complexes. In each case, ligand electrons fill the d sp bonding orbitals. The remaining orbitals contain the electrons from the metal. 

The Fisher syndrome (FS) is named after Charles Miller Fisher, a Canadian neurologist. In 1956, Miller Fisher described three patients with acute external ophthalmoplegia, absent tendon reflexes, and ataxia, who recovered spontaneously (Fisher, 1956). Some cases start as FS but subsequently develop w eakness. Finally, work over last two decades indicates that some forms of GBS lack features of demyelination and have pathophysiology that is consistent with axonal injury these cases are termed axonal GBS. 

The history of GBS is inseparably linked to the seminal paper of Georges Guillain (1876-1961), Jean-Alexandre Barre (1880-1967), and Andre Strohl (1887-1977) (Guillain et al., 1916). During the weekly meeting of the Societe medicate des hopitaux de Paris in 1916, they presented the case history of two soldiers of the VI French army, who developed flaccid sensorimotor paralysis. Both patients, without any history of preceding infection, recovered completely after a few weeks. Guillain, Barre, and Strohl were 

In the seventies. Me UPD experiments on metal single crystal faces as foreign substrates were started by Lorenz, Jiittner, Schmidt, Siegenthaler, Staikov, and Budevski et al. [3.87-3.109], Yeager et al. [3.83, 3.84], Bewick et al. [3.110-3.114], 

Schultze et al. [3.115-3.120], and Kolb et al. [3.121-3.128]. The experimental results gave evidence of the formation of well-ordered 2D Meads overlayers in the underpotential range depending on the crystallographic orientation and the crystal imperfection density of S. Electrochemical results were first hypothetically interpreted in terms of 2D Meads superlattice structures [3.87-3.89, 3.93, 3.98], which were also observed in comparative [3.121, 3.122, 3.129-3.133] and ex situ [3,123-3.128] UHV studies. 

First theoretical interpretations of Me UPD by Rogers [3.7, 3.12], Nicholson [3.209, 3.210], and Schmidt [3.45] were based on an idealized adsorption model already developed by Herzfeld [3.211]. Later, Schmidt [3.54] used Guggenheim s interphase concept [3.212, 3.213] to describe the thermodynamics of Me UPD processes. Schmidt, Lorenz, Staikov et al. [3.48, 3.57, 3.89-3.94, 3.100, 3.214, 3.215] and Schultze et al. [3.116-3.120, 3.216] used classical concepts to explain the kinetics of Me UPD and UPD-OPD transition processes including charge transfer, Meloiy bulk diffusion, and nucleation and growth phenomena. First and higher order phase transitions, which can participate in 2D Meads phase formation processes, were discussed controversially by various authors [3.36, 3.83, 3.84, 3.92-3.94, 3.98, 3.101, 3.110-3.114, 3.117-3.120, 3.217-3.225]. 

The by-products consisted of higher acids, their esters, and hydroxy ethers. The results of this experiments remained unnoticed so that work in 1949 by Wender et al. [5J - after whom this reaction was named - was a kind of rediscovery. In 1952, the essential conclusions of the work of Wietzel et al. were confirmed in a fundamental paper by Ziesecke [6]. 

In 1956 Berty [7] introduced a iodine activator to the basic catalyst cobalt carbonyl this made possible a noticeable increase in the reaction rate and represented the transition from the high-pressure syntheses (40-100 MPa) to the medium-pressure syntheses (18-40 MPa), a state-of-the-art which lasted until 1988. 

The first tumor marker reported was the Bence Jones protein. Since its discovery in 1847 by precipitation of a protein in acidified boiled urine, the measurement of Bence Jones protein has been a diagnostic test for multiple myeloma (a tumor of plasma cells). More than 100 years after its discovery, the Nobel Prize-winning studies of Porter 

As we begin the twenty-first century, new technologies are being applied to the discovery of tumor markers and their 

1980 G. Cooper, R. Weinberg, and M. Bishop Oncogene probes and transfection 

Modified from Sell S. Cancer markers. In Moossa AR, Schempff SC, Robson MC, eds. Compreliensive textbook of oncology, 2nd ed, Vol. 1, Baltimore Williams Wilkins, 1991 225-38. hCG, Human chorionic gonadotropin ACTH, adrenocorticotropic hormone AFP, alpha fetoprotein CEA, carcinoembryonic antigen. 

The potential uses of tumor markers are summarized in Table 23-3. In general, tumor markers may be used for diagnosis, prognosis, and monitoring the effects of therapy and as targets for localization and therapy. Ideally a tumor marker should be produced by the tumor cells and be 

In medicine, ancient accounts of making pills from powder mixtures can be found mostly in China where in rural areas, even today, very similar forming techniques are still applied. Honey, sugar syrup, or—later—yeast extracts were used as binders.In Europe, the same techniques are known since, at least, the Middle Ages.  

Development of this technology started with the invention of the tabletting press by the Englishman W. Brockedon in 1843. The next patents were issued several decades later in the United States to J. A. McFerran (1874), T. J. Young (1874) and J. Dunton (1876). Thereafter improvements were made in quick succession. 

Newer final forms of agglomerated products, such as spheronized and and instantized materials, were developed during the twentieth century but have already found many diversified applications and gained wide acceptance. Therefore, the most diverse, mainly small scale use of agglomeration methods can be found in the pharmaceutical industry. 

While the emphasis of this chapter cannot be directed toward providing a complete and exhaustive coverage of agglomeration in the pharmaceutical industry, each of the major methods will be reviewed and pharmaceutical applications will be briefly discussed. This treatment will provide an indication of what is being done, where one can turn to for additional information, and what type of new technologies are emerging. 

Titanium dioxide (TiOa) quickly became the semiconductor of choice for the photoelectrode on account of its many advantages for sensitised photochemistry and photoelectron chemistry it is a low-cost, widely available, non-toxic and bio- 

Biedler and coworkers [123] reported that Chinese hamster cells selected for resistance to actinomycin D also showed cross-resistance to mithramycin, vinblastine, vincristine, puromycin, dauromycin, democolcine, and mitomycin C. Thus, upon selection with a single cytotoxic drug, mammalian cells became simultaneously cross-resistant to a range of drugs with different chemical structures and molecular 

When he set up an independent research group at The Fry the, Chatt recognised 

They imparted organic solubility on the complexes which were formed from them. The solubility in a particular solvent could also be modified by changing the length of the alkyl substituent and introducing phenyl substituents. 

I think that the discovery that he could make complexes which were soluble in non-polar and relatively unreactive solvents such as benzene (more widely used in those days than now) and diethyl ether (tetrahydrofuran did not become readily available until the late 1950s) proved to be a particularly important observation, because it opened up the possibility of doing meta- 

Chatt appreciated early on that phosphine ligands are particularly effective in forming stable complexes with the platinum metals. Indeed his determination to put this characteristic on a more quantitative basis led to the important Class (a) and Class (b) classification scheme of metal-ligand interactions proposed jointly with Ahrland and Davies.This work was subsequently subsumed into Pearson s general Hard and Soft acid and base classification scheme.  

Therefore, it was Tolman rather than Chatt who was able to show how steric effects associated with phosphine ligands could be put on a more quantitative basis using the cone angle concept.A mathematically defined cone was projected from the metal atom to the surface of the ligand as defined by the van der Waals radii of the atoms on the surface of the ligand. I suspect that Chatt, Wilkinson and Malatesta all probably had an appreciation of the importance of steric effects, but in my opinion they lacked the mathematical background to articulate it in a way which could be readily appreciated by other coordination chemists. 

and rubber are probably the earliest known materials of construction for the chemical processing industry. Interestingly, it took a little more than a century for rubber to be established as a lining material after Charles Goodyear accidentally discovered vulcanized rubber in 1839. Wood is the first composite material to be used in the chemical processing industry. Until the onset of World War II, these naturally occurring materials continued to play a major role in chemical handling applications. 

Although stainless steels were discovered at the turn of the century and copper silicon alloys started to emerge at about the same time, the real explosion of materials research and development began at around the beginning of World War II. Polymer science and technology were no exception. Nylon was already developed at the DuPont Company. Alloy 20 was developed by DuPont in the late thirties. At about the same time, polytetrafluoroethylene (PTFE) (Teflon ) was discovered which led to further development of fluoropol5miers and ushered in an era of high-performance polymer materials for corrosion control. 

The 1950s were known for the explosive development and growth in elastomers. DuPont Company developed a whole range of synthetic elastomers such as neoprene (polychloroprene), Hypalon (chloro- 

Elastomers are a special class of nonrigid materials distinguished by high elongation and high recovery. 

A complete description of a polymer system must necessarily include references to all three categories. Some examples below illustrate the point. 

Copyright 1996 by Academic Press, Inc. All rights of reproduction in any form reserved. 

Pharmacomechanical mechanisms for relaxation include (1) G kinase-dependent increases in the activity of sarcoplasmic reticulum Ca pumps (SERCA). Ca pumps on the plasma membrane may also be stimulated (not shown). This increase in Ca sequestration and extrusion decreases [Ca +Jj and induces relaxation as shown in the foregoing. (2) Some agents appear to decrease 1,4,5-1P3 formation and may relax smooth muscle by decrease Ca + release (not shown) (3) Finally, increases in [cAMP] activate cAMP-dependent protein kinase (A kinase), which could phosphorylate myosin light chain kinase and decrease its Ca sensitivity (this mechanism has not been demonstrated in intact smooth muscle). 

Pharmacomechanical coupling was primarily studied by measuring [Ca +J and myosin regulatory light chain phosphorylation in intact and skinned smooth muscle. Several groups found that stimuli increased 

As will be detailed in the following, both disciplines were correct. Pharmacomechanical coupling represents increases in both [Ca +Jj and the [Ca +Jj sensitivity of phosphorylation beyond that expected given the level of depolarization. 

When it was observed that the DNQ/novolac resists in use at the time became more transparent on exposure (i.e., they bleached). Dill used this change in optical absorbance as a way of monitoring the kinetics of exposure. He developed a first-order model of exposure consisting of three parameters A, B, and C, now called the Dill model, which accurately fit the experimental measurement results of the transmittance of a resist coating on an optically matched glass wafer as a function of exposure dose. The Dill parameters A, B, and C, describe bleachable absorbance, nonbleachable absorbance, and exposure rate constant, respectively.  

452 456 (1975) F.H. Dill, A.R. Neureuther, J.A. Tuttle, and E.J. Walker, Modeling projection printing of positive photoresists, IEEE Trans. Electron Dev. ED-22(7), 456 464 (1975). 

It should be pointed out that the first commercial simulator was DEPICT, which was based on SAMPLE, and was developed by Bob Pack of Technology Modeling Associates. DEPICT was released to the marketplace in 1986, but eventually faded away into oblivion after a few acquisitions of the parent company by other companies.  

Other commercial lithography simulators of note include Solid, which was developed by Wolfgang Hencke of the Fraunhofer Institute in 1991. Solid was the first 3D lithography simulator. It was first commercialized in 1992 by Silvaco, but subsequently was released in 1994 as SOLID-C by SIGMA-C.  

there are several companies that sell lithography simulators (see Table 12.1), and simulation can even be performed over the Internet using programs at a web site at the University of California at Berkeley. 

When ethylenediamihe molecules in [Co(en)3p are replaced by an optically active diamine such as R(—)-propylenediamine (R-pn), the resulting two optical isomers or diastereoisomers are no longer in equal amounts. This preference for one optical isomer or one diastereoiK mer over the other has been called ligand stereospecificity In the same se, the term stereoselectivity has been used by Dunlop and Gillard, who defined it as the behavior of molecular diastereoisomers In this chapter, the word stereoselectivity is used to mean inclination in abundance of the diastereoisomers of one geometrical isomer. This word differs from either stereoselective reaction or stereospecific reactions .  

Tris(propylenediamine)cobalt(III) salts were first synthesized from racemic pro-pylenediamine Later, the synthesis with the optically active base showed that the action of S(+)-pn on [CoCl2(R-pn ] ve a mixture of —)[Co(R-pn)j] and (-t-)[Co(S-pn)3] rather than [Co(R-pn 2(S-pn)p. After all the salts prov to be (+)[Co(S-pn)3]Br3 from the S-base and (—)[Co(R-pn)3]Br3 from 

In 1959 Corey and Bailar d t with stereo specific effects in complex ions. The results of the conformational analysis for the [Co(en)3] ion showed that one conformational form of a chelated en, /e/ , is more stable than the other, ob , by ca. 0.6 kcal/mol. For the tris(propylenediamine)cobalt(III) ion, the three most stable pn chelate rings are suggested to have equatorial conformation with 

The reactions by which steraoisomas are formed or used up at different rates are called er selective reactions, while the ructions by which specific stereochonical compounds are 

Thus these works stimulated great interest in the stereoselective formation of diastereoisomers. 

An abnormal change of the dehydration rate, J, of crystalline hydrates with an increase of water vapour pressure, P, was discovered by Topley and Smith (T-S) in 1931 [1] in their studies of the dehydration rate of MnC204 2H2O. In contrast to the expected monotonous decrease of the rate with increasing Pw, the dehydration rate, on reaching a certain critical pressure (about 0.1 Torr), begins to increase, passes through a maximum (about 1 Torr), and then decreases (Fig. 7.1). 

The model suggested by Bertrand et al. [11-13] assumed the existence of a spatial gradient of temperature in the reaction zone. In this model the abnormal rise of the dehydration rate with was attributed to the increase of heat transfer from the furnace to the self-cooled reactant. Model calculations and experiments on the evaporation and condensation of ethanol and water vapours provided a convincing proof of this mechanism. In the experiments [13], the temperature of the evaporating liquids turned out to be much lower than that of the heater. For instance, for ethanol the difference from the thermostat temperature (300 K) was as much as 45 K or 15%. However, this model remained unclaimed during the following 20 years of studies on the T-S effect. Such a considerable difference in temperatures between the crystalline hydrate and the furnace seemed improbable to the majority of researchers. 

For modelling of the T-S effect, L vov et al. [3] used the software described in Sect. 6.1 and parameters listed in Table 7.2. 

The calculation results are shown below in a graphic form. As may be deduced from the shape of the curves J = f Pw) in Figs. 7.2 and 7.3, the Pw rise from 10 to 10 bar leads to the rate increase and the appearance of maxima on the curves, which is in complete agreement with experimental observations. This is due to the increase in the thermal conductivity of water vapour which results in a decrease of self-cooling. The T-S effect becomes more marked with a rise of Tf and n, which is also in good correspondence with the experimental data [12, 13] and, in particular, with an intensification of the effect with the decrease of powder grain size [13]. 

Nevertheless, the comparison of calculation curves J = f Pw) presented in Figs. 7.2 and 7.3 with the experimental curve in Fig. 7.1 reveals also some inherent differences in their shapes. Firstly, over the initial part of the experimental curve the decomposition rate decreases with P rise, and a minimum is formed. Secondly, the decrease of dehydration rate after the maximum occurs much faster than in the calculations, so that the maximum on the experimental curves J = /(Pw) is sharper. 

Chemists in the 19 century were aware of the connectivity and the basic geometries of their molecules, and therefore of structural formulae, but they were unable to quantify the structures of molecules on a metric basis. In addition to chemical bonds, they were aware of van der Waals interactions, electrostatic interactions, steric hindrance, Kekule conjugation, and donor-acceptor interactions. However, detailed information on electronic and molecular structure was lacking. 

The 20 century brought two important advances. With the development of diffraction techniques, the arrangement of atoms could be determined on a metric basis. Depending on the size of the molecule, the quality of the crystal and the accuracy of the experiment, well-defined bond lengths, valence and torsional angles, as well as non-bonded contacts, could be determined. 

The application of molecular mechanics to metal complexes developed in parallel with its application to organic molecules. Indeed, the earliest report that considered the importance of non-bonded interactions in determining the relative stabilities of isomeric molecules was a 1944 study of the six isomers of the coordination compound [Co((S)-pn)2(N02)2] (pn = propane-1,2-diamine) [1]. A number of similar, though more detailed, studies performed during the 1950s and 1960s [2-4] led to the 

There followed research into pyridinium and imidazolium chloroaluminate ionic liquids by Hussey, Seddon and Welton (investigation of transition metal complexes 

The concept of a polymer-hydraulic cement system is not new, and in 1923 the first patent of the system had already been issued to Cresson.t l 

In the 1960s, styrene-butadiene rubber-, polyacrylic ester-,l and poly(vinylidene chloride-vinyl chloride)- modified mortars and concretes became increasingly used in practical applications. Since the 1960s, the practical research and development of polymer-modified mortar and concrete have been considerably advanced in various countries, particularly U.S.A., U.S.S.R., West Germany, Japan, and U.K. Consequently, a considerable number of publications including patents, books, papers, and reports have appeared. Of these, the main and important studies are as follows  

Books written by Cherkinskii, Namiki and Ohama, Solomatov,P l Satalkin et al.,P l Paturoey, Wilson and 

Papers written by Wagner,I2 l-P2] petri, ] Mori, Kawano, Obama et al.,I land Ohama.P l I 

Papers presented at main congresses and conferences on polymers in concrete listed in Table 1.1. 

The first organometallic compound to be reported was synthesized in 1827 by Zeise, who obtained yellow needle-like crystals after refluxing a mixture of PtCl4 and PtCl2 in ethanol, followed by addition of KCl solution. Zeise correctly asserted that this yellow product, subsequently dubbed Zeise s salt, contained an ethylene group. This assertion was questioned by other chemists, most notably Liebig, and it was not verified conclusively 

The product was surprisingly stable it could be sublimed in air without decomposing and was resistant to catalytic hydrogenation and Diels-Alder reactions. In 1956, X-ray 

Bisphenol A (BPA)-based polycarbonate (PC) is one of the most versatile and widely used engineering thermoplastics on the market. This amorphous material offers 

Copyright 2006 by The McGraw-Hill Companies, Inc. Click here for terms of use. 

As such, polycarbonate is used in at least 27 major industry segments, ranging from telecommunications components, to eyewear, to health care devices, to optical storage discs. A more extensive description of markets and apphcations is provided later in this chapter. 

Initially, just two major resin manufacturers— in North America and Europe— produced polycarbonate. The industry has since expanded to include a half-dozen other supphers in Europe, Asia/Padfic, and North America. Currently, polycarbonate is produced on four continents. Demand for this versatile polymer has increased steadily since its commercial introduction in the early 1960s. Compounded annual growth rates typically average 10%. 

The random motions of a flexible chain floating in a solvent are fascinatingly complex. Some years ago, thanks to a series of careful mechanical experiments together with some elegant theoretical work these motions appeared to be well understood. However, there are some serious flaws in the classical picture. Thus, we do not review it in detail (it is lucidly described in Ref. 6) but fuesent only basic ideas, show their limitations, and proceed directly to more general scaling concepts. 

The classical picture is based on the notion of relaxation modes for one chain. It first appeared in a 1953 paper by P. E. Rous and was based on the following model  

We then assume that the velocity of bead n is a linear function of the forces applied to n (and its neighbors) 

On the whole, the three assumptions lead us to a very simple Rouse equation (VI.S) describing the relaxation of an elongated state of the chain. Because it is a linear equation, the solutions can be analyzed in terms of eigenmodes 

This is a quadratic dispersion relationship (l/xp p ). Note that the longest relaxation time p = ) scales like hP in the Rouse model. 

The commercial use of hydrated fillers was given a great boost in the mid-1970s, by legislation in the USA requiring carpet backing to be flame retarded, an application for which aluminium hydroxide was ideally suited. 

Today ATH is a well established flame-retardant additive, especially for unsaturated polyesters, elastomers and some thermoplastics. 

Growing concerns over the problems (real or imagined) associated with organo-halogen flame retardants is now creating further opportunities, especially in other polymers, notably polyolefins and polyamides, where ATH is not ideally suited because of its relatively low decomposition temperature. This has led to a surge of interest in other 

The development of fomal safety management systems for offshore oil and gas facilities can be said to have started with the Piper Alpha catastrophe that occurred in 1988. Offshore platforms had had safety programs before that time, of course, usually built around Safety Cases (described in Chapter 8). But Piper Alpha ushered in a new and much more thorough approach to system safety. 

Following the accident, an investigation was conducted by a committee headed by the Scottish High Court judge. Lord Cullen. The committee s report was highly critical of the safety programs that had been in place in the North Sea facilities prior to the accident. 

In the United States (principally the Gulf of Mexico) the response to the Piper Alpha incident was equally vigorous, but followed a different path. The American 

Petroleum Institute (API) developed their Recommended Practice 75 (RP 75), which recommended that offshore facilities develop a Safety and Environmental Management Program (SEMP). Like a safety case, RP 75 is mostly nonprescrip-tive. However, it makes extensive reference to industry standards (mostly from the American Petroleum Institute), and so it is perceived as being considerably more prescriptive then the safety case approach. Nor does RP 75 require that a formal assessment of acceptable risk (ALARP) be determined. 

Reasons for not using safety cases in the United States include the following  

Mining of lead ores is recorded at Mount Laurion in Greece in the fifth century BC. It was mined by the Phoenicians in Spain and later by the Romans in the Rio Tinto region, as well as in Derbyshire in Great Britain and widely throughout Europe, but particularly in Silesia, Bohemia and the Hartz Mountain area of Germany. 

The history of lead is also inextricably linked with the mining and recovery of silver, which was produced for its value as a currency of trade, as well as a precious metal for the manufacture of jewellery and artefacts. Because of lead s association with silver and its potential use for degrading silver coinage, lead mining and smelting operations were often closely controlled by the application of strict laws. 

But the real star in the story, a man unjustly forgotten today, is Francis Hauksbee (1713), who was the first to study the phenomenon in a 

FIGURE 2.17. Capillary rise. The narrower the tube, the higher the liquid rises. (From a A Drop of Water A Book of Science and Wonder by Walter Wick. Published by Scholeustic Press, a division of Scholastic Inc. Photograph 0 1997 by Walter Wick. Reproduced by permission.) 

The rise of the liquid occurs in air just as well as in vacuum (refuting Rohault s theory that the lack of air is responsible), 

The effect is not specific to a cylindrical geometry. The liquid rises just as well between two parallel plates close to each other, but the height reached is then half that attained in a tube of diameter equal to the separation between the plates. 

The effect also occurs with other solids (marble, brass) and other liquids (alcohol, essence of turpentine, common oil). 

Scientists as early as the mid-1950s recognized the importance of using metallocene compoxmds in conjunction with aluminum alkyls for olefin polymerization. 

The interaction of bis(cyclopentadienyl)titanium dichloride [(Cp) TiCy and diethylaluminum chloride in toluene was reported in 1957 by Breslow [ 16-18] as a weakly active ethylene polymerization catalyst if the DE AC was allowed to react with the titanium compoxmd for more than one hour. Much more active catalysts were found if oxygen was introduced with the ethylene 

One interesting feature of Breslow s research with these homogeneous catalyst systems was the type of polyethylene which was isolated. Polyethylene prepared with these catalysts was more linear, as indicated by a lower methyl content (melting point of 137 C), and had a narrower molecular weight distribution than the polymer provided by the Mulheim catalyst. It is possible that some of these homogeneous systems may have been single-site catalysts, in which case this type of polyethylene would have had a MWD as indicated by the Mw/Mn value of 2 or one Flory component in the polymer. 

However, almost twenty years later, Breslow [19] reported in 1975 a similar polymerization system with very high ethylene polymerization activity if Cp TiCl was added to toluene in the presence of dimethylalu-minum chloride (DMAC) previously treated with water. The combination of Cp TiCl and only dimethylaluminum chloride (DMAC) in the absence of water had low activity as an ethylene polymerization catalyst. The water/ Al molar ratio of 0.2-0.5 provided a highly active catalyst, while a higher water/Al ratio 0.5 provided a very low activity catalyst. Some of Breslows data is shown in Table 4.2. 

A similar catalyst water-activation affect was reported by Reichert and Meyer in 1973, which was two years earlier than the Breslow results, in which the catalyst system Cp Ti EtCl/EtAlCl and water was investigated [20]. 

Not withstanding the recent developments of synthetic stmctural polymers, naturally occurring polymers have been used for thousands of years and early civilizations understood how to mix fibers (such as wheat flax) with resins to obtain added strength. For example, pottery cemented with natural resins have been found in burial sites that date back to 4000 BC. A cedar chest with extensive glue constmction was found in King Tutankhamen s tomb and dates back to 1365 BC. Clegg and Collyer, (1993) report that bitumen, a complex mix of heavier petroleum fractions, is men- 

One of the first man-made polymers was Parkesine, so named after its inventor Alexander Parkes. It was introduced in about 1862 but was not a commercial success (Fried, (1995)). However, this early effort led to the development of celluloid (cellulose nitrate) by John Hyatt in 1870 which was a commercial success. The first truly synthetic polymer was a phenol-formaldehyde resin called Bakelite developed in 1907 by Leo Baekeland but it would be two more decades before the nature of the polymerization process would be understood sufficiently to develop polymers based upon a rational process. 

Until Kekule in 1877, all geometrical formulas referred to the structure and behavior of small molecules. However, Kekule in 1877 during a lecture upon becoming the Rector of the U. of Bonn advanced the hypothesis that the natural organic substances associated with life (proteins, starch, cellulose, etc.) may consist of very long chains and derive their special properties from this peculiar structure (Tolbolsky and Mark, (1971)). 

Herman Staudinger who was awarded a Nobel Prize in 1953 for his work (see below for other Nobel Prize winners in polymer science) proposed the macromolecular hypothesis in the 1920s explaining the common molecular makeup of macromolecular materials. He contradicted the prevalent view of his time that polymeric substances were held together by partial valances and instead proposed the idea of long molecular chains. He accurately gave the proper formulas for polystyrene, polyoxymethylene (paraformaldehyde) and for rubber (Flory, (1953)). 

In 1929 W. H. Carothers was the first to clearly define what we know today as the basic parameters of polymers science. Clearly stating his ob- 

The unit of electrical potential, the volt, is named after Alessandro Volta (1745-1827), an Italian physicist whom history credits with the inventions of the battery and the capacitor (a device that stores electrical charge). 

The unit of electrical current, the ampere, is named after Andr6 Marie Ampere (1775-1836), a French mathematician and physicist whom history credits with the invention of the galvanometer (a device that measures electrical currents). 

The unit of electrical resistance, the ohm, is named after Georg Simon Ohm (1787-1854), a German physicist who discovered the law that bears his name. Ohms Taw states that the potential difference (in volts) measured in an electrical circuit equals the product of the current (in amperes) times the resistance (in ohms). 

Static electricity was known in early times, but also was not understood. The first electrical machine was developed by von Guericke in 1672. This was followed by improved machines in the early 1700s that increased interest in the phenomenon. An outcome of this was the recognition by DuFay (1692-1739) that two t) es of electricity exist (+ and -). 

Franklin, a very practical person, is a good example of a case where curiosity led to invention. He shared the view of Bacon who is reported to have said that all good science must have practical results. 

Volta s experiments were repeated and verified by a munber of people including the chemist Davy. The development of electrical theory and technology was well on its way. For the next forty years, many significant experiments were performed and many discoveries made in the laboratories of Europe. Very important contributions were made by the following  

Faraday was an extremely talented experimentalist who made many important contributions not only to electrical technology, but also to chemistry and material science. A few of these contributions include  

The first of these diseoveries led to the electric motor and the second and third to two t5 es of electrical d5mamos (electrical generators). 

unstable piezoelectric effects in commercially available synthetic polymers such as polystyrene, polypropylene and poly(methyl methacrylate) were reported in 1968. However, the major breakthrough came in 1969 with the discovery by Kawai [6] that stretched and poled poly-(vinylidene fluoride) (PVDF) exhibited the largest known piezoelectric 

Investigations in the 1970s were extended to include copolymers of vinylidene fluoride (VDF) with related fluorinated vinyl monomers vinyl fluoride (VF), trifluoroethylene (TrFE) and tetrafluoroethylene (TeFE) [7, 8]. The latter two copolymers were found to crystallize into polar form without the stretching stage required by PVDF. This facilitates processing, and thus offers a wider range of potential device structures. Research in the 1980s has therefore focused on the ferroelectric behaviour and piezoelectric activity of vinylidene fluoride-trifluoroethylene copolymers. 

Investigations into alternative piezoelectric polymers, both semicrystalline and amorphous, continued into the 1980s, and two of the most significant discoveries are worth a brief mention. Of semicrystalline materials, the odd-membered polyamides (or nylons), particularly nylon-11, were found to exhibit reasonable piezoelectric activity, especially when mechanically oriented [9]. The highest piezoelectricity in an amorphous polymer was discovered in 1980 [10] in a copolymer of vinylidene cyanide and vinyl acetate. 

However, this chapter is concerned with ferroelectric polymers. As PVDF and the VDF/TrFE copolymers are the main polymers known to exhibit ferroelectricity, their properties and applications will be discussed at length in the following sections. 

Metal-containing polymers form some of the basis of life as we know it. They are at the heart of respiration and photosynthesis and thus are integral to plant and animal life. It has also been established that metal-containing coordination polymers were formed in the ancient art of leather tanning, although it is unknown when 

Macromolecules Containing Metal and Metal-like Elements, 

Volume I A Half-Century of Metal and Metalloid-Containing Polymers, By Alaa S. Abd-El-Aziz, Charles E. Carraher, Jr., Charles U. Pittman, Jr., John E. Sheats, and Martel Zeldin ISBN 0-471-45832-5 Copyright 2003 John Wiley Sons, Inc. 

The theory which is today called Brillouin-Wigner perturbation theory was introduced in three seminal papers published in the 1930s. The first of these, which appears to be not so well known as the other two, was published in 1930 by 

Lennard-Jones [37]. (Indeed, some authors [38,39] refer to the method as Lennard-Jones-Brillouin-Wigner perturbation theory .) Subsequently, L. Brillouin published his famous paper in 1932 [40] whilst E.P. Wigner s paper appeared some 2 years later [41]. In this section, we provide a brief synopsis of each of these important papers. 

During the period 1963-1971, P.-O. Lowdin published a series of papers [42-53] with the general title Studies in Perturbation Theory , which afforded deep insight into perturbation theory expansions, the relation between different expansions and their application to quantum mechanical problems. We conclude this section with a brief overview of Ldwdin s work on perturbation theory. 

The seminal paper on what is nowadays called Brillouin-Wigner perturbation theory by Lennard-Jones was published in the Proceedings of the Royal Society of London in 1931. It was communicated by R.H. Fowler and received on 1st September, 1930. Here we reproduce Lennard-Jones introduction  

There are, however, certain disadvantages in the perturbation theory in its present form, which limit the extent of its applications to complex problems of atomic and molecular structure. If the interaction of atoms, for instance, is to be calculated, as is most desirable, improved methods will have to be found. 

From 1880 onwards, the specific properties of bases were studied. Realizing that reactions in solutions involve ionized species, Arrhenius defined an acid as an hydrogen-containing substance that dissociates into a proton H+ and an anion when dissolved in water  

which are the products of acid-base reactions, are thus not necessarily electrically neutral but rather exhibit well-defined acid-base properties in water. Acidity appears as a relative concept and the existence of amphoteric substances, i.e. substances which can behave either as acids or bases depending on the circumstances, is stressed. The proton concentration, [H+], quantifies the acidity of a solution and the pH scale is established  

A small pH indicates an acidic solution and a large pH indicates a basic solution. Yet, Arrhenius definition presents several shortcomings. It does not recognize as acids molecules such as SO2 or CO2 which do not contain hydrogen atoms, nor as bases molecules like NH3 without OH groups. It restricts the acid-base reactions to the aqueous medium and postulates the existence of the free proton H+. 

The next historical stage is the Bronsted-Lowry theory (Bronsted, 1923 Lowry, 1923a 1923b) which generalizes the definition of a base to proton-acceptor substances  

Each acid is now associated with a base. An amphoteric molecule may belong to several conjugate acid-base pairs, and may serve as the acid in one conjugate pair and as the base in another pair. Bronsted denies that acid-base reactions necessarily produce salt and water. He proposes the more general protolysis equation, independent of the solvant  

The development of PTR-MS owes much to its precursors, the FA and SIFT techniques. However, PTR-MS is intended as an analytical technique rather than a means of measuring kinetics and it achieves this by essentially inverting the original aims of the FA and SIFT techniques. Instead of measuring the rate coefficient for a specific reaction, it is now presumed known from earlier kinetic studies or it can be deduced from calculations, as described in Section 2.23.2, or it may be omitted completely if gas calibration is employed (as described in Chapter 4). This information can then be used to determine the concentration of a compound, as shown later in Section 1.4.3. 

A second innovation introduced by Lindinger and co-workers yielded a simpler and even more compact instmment. This was achieved by replacing the mass-selected H3O + source with a hollow cathode discharge, which with a suitable design (see Chapter 3) was found to deliver an almost perfectly pure ( 99.5%) source of H3O+ without any need for a mass 

The years following the seminal work by Lindinger and his team have seen a variety of new developments. For example, time-of-tlight and ion-trap mass spectrometers have been employed in PTR-MS instead of quadrupole mass spectrometers. Furthermore, other types of ion sources have been introduced, including radioactive sources. Developments such as these will be covered in detail in Chapter 3. 

Other management systems, in particular safety cases, frequently require that a detailed report is prepared, showing how safety was analyzed and how it is to be managed. This report is frequently submitted to the regulators. 

All management systems must include an audit process. In the words of one plant manager, There is always news about safety, and some of that news is bad. Audits, reviews, and gap analyses are needed to ferret out the bad news. The audit results are used as the basis for the next SMS iteration. 

For facilities that are still in the design stage, the actions taken, particularly during the Risk Assessment step, will change for each iteration. For example, early evaluations of risk will use a Hazard Identification (HAZID) technique later on, as detailed engineering information becomes available, the more comprehensive Hazard and Operability Study (HAZOP) method wiU be used. 

Safety programs are developed in response to incidents—particularly catastrophic events. Some of the events that led to the development of SMSs offshore are described in Chapter 2. An overview of some of the more important regulatory and standards-setting developments (offshore and onshore) is provided here. 

Grove conducted his first fuel cell experiment in Swansea, Wales, and a description of this experiment was put in an article on research into electrode materials for batteries. In his experiment, platinum electrodes were placed in test tubes of oxygen and hydrogen and half submerged in a bath of dilute sulfuric acid (Fig. 1.1). 

Milewski et al.. Advanced Methods of Solid Oxide Fuel Cell Modeling, 1 

After the presentation of the fuel cell made by Mond and Langer in London, two researchers called Langer and Thompson presented the results of their earlier work (allegedly 1887) on a similar device, as they wanted to claim that they first performed this type of experiment. 

The amount of coal consumed in the cell at nominal load, kg/kW/h The amount of coal consumed to maintain the eell temperature, kg/kW/h The summary consumption of coal, kg/kW/h 

Jacques device was reviewed by Haber and Bruner in 1904, and they claimed that the chain reaction was as follows carbon reacts with the electrolyte and the electrolyte with the electrodes, instead of direct oxidation of coal. This meant that the fuel in the fuel cell was its electrolyte and electrodes and therefore it could hardly be considered electricity produced directly from coal. To build a coal-fueled fuel cell, in 1912, Baur and Ehrenberg tested a number of different electrolytes, including hydroxides, carbonates, silicates and borates. A mixture of carbonates of alkali metals was used by Baur and Brunner in 1935, and it was found that the application to the flow of carbon dioxide improves cell performance (see Figs. 1.5 and 1.6) 

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But there is a price to be paid. Good Workmanship acceptance criteria for conventional techniques must, to a certain extent, be conservative, in order to compensate for the inherent "limitations" of conventional NDT. And, what is worse, the degree of conservatism is more or less unknown. Therefore the question can be asked "if the historic background of present NDT practice would not exist, what would we like to know today about a weld to be able to accept or reject it "... 

A major difficulty in an inorganic text is to strike a balance between a short readable book and a longer, more detailed text which can be used for reference purposes. In reaching what we hope is a reasonable compromise between these two extremes, we acknowledge that both the historical background and industrial processes have been treated very concisely. We must also say that we have not hesitated to simplify complicated reactions or other phenomena—thus, for example, the treatment of amphoterism as a pH-dependent sequence between a simple aquo-cation and a simple hydroxo-anion neglects the presence of more complicated species but enables the phenomena to be adequately understood at this level. 

Time Averages, Ensemble Averages and Some Historical Background... 

The number of C H2n+2 iso mers has been calculated for values of n from 1 to 400 and the comment made that the number of isomers of C167H336 exceeds the number of particles in the known universe (10 °) These obser vations and the historical background of isomer calcu lation are described in a pa per in the April 1989 issue of the Journal of Chemical Edu cat/on (pp 278-281)... 

Historical Background.—Relativistic quantum mechanics had its beginning in 1900 with Planck s formulation of the law of black body radiation. Perhaps its inception should be attributed more accurately to Einstein (1905) who ascribed to electromagnetic radiation a corpuscular character the photons. He endowed the photons with an energy and momentum hv and hv/c, respectively, if the frequency of the radiation is v. These assignments of energy and momentum for these zero rest mass particles were consistent with the postulates of relativity. It is to be noted that zero rest mass particles can only be understood within the framework of relativistic dynamics. 

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