Discussion of concept

In this chapter, our goal is to provide a working knowledge of HTS with enough detail to enable and enrich the communication between chemists or biologists and their HTS colleagues. The discussions of concepts, processes, and technical details are interspersed with some of our approaches at Wyeth used only as examples. 

Some chapters overlap in general content (e.g., basic principles of stable isotopes in precipitation are covered to different degrees in all stable isotope chapters), but no attempt was made to limit authors discussion of principles, or somehow attempt to arrive at a consensus view on any specific topic. Because science advances by critical discussion of concepts, such restrictions were viewed as counterproductive. This does mean that different chapters may present different views on reliability of paleoelevation estimates, and readers are advised to read other chapters in the book on related topics - they may be more closely linked than they might at first appear ... 

Kooijman SALM. 2001. Quantitative aspects of metabolic organization a discussion of concepts. Phil Trans R Soc London B 356 331-349. 

Topics not included here or appearing in more length elsewhere include book-length discussions of concepts and summaries,toxic metal ions in the environment and nervous system, " and cisplatin as an anticancer agent (see Platinum-based Anticancer Drugs). An element by element discussion of toxicity appears in a convenient handbook. ... 

A highly regarded professor in industrial engineering observed, after participating with safety practitioners in what he considered a baffling discussion of concepts, that what we who call ourselves safety professionals actually do will never be accepted as a profession by those outside our field until we agree on a clear definition of our practice. 1 agree with that premise, and I will explore in this chapter the scope and function of the professional safety position and will define the practice of safety in terms of a societal responsibility. 

Klaassen, Curtis D. Casarett DouU s Toxicology The Basic Science of Poisons. 7th ed. New York McGraw-Hill, 2008. The gold standard of toxicology, includes detailed discussions of concepts, principles, and mechanisms of toxicology. 

Activities increase knowledge and understanding Discussion of concepts is intensive so we gain more knowledge It improves the thinking levels beyond the textbooks... 

Carr, D. and N. Herz. 1989. Concise Encyclopedia of Mineral Resources. Oxford, U.K./ New York Pergamon Press Cambridge, MA MIT Press. Based on material from the Encyclopedia of Materials Science and Engineering, first published in 1986, with revisions and updated material. This woik is both a dictionary of terminology and encyclopedic discussion of concepts in mining and mineral resources, nonmetallic minerals, and advances in materials science and engineering. 

A case can be made for the usefulness of surface tension as a concept even in the case of a normal liquid-vapor interface. A discussion of this appears in papers by Brown [33] and Gurney [34]. The informal practice of using surface tension and surface free energy interchangeably will be followed in this text. 

A variety of experimental data has been found to fit the Langmuir equation reasonably well. Data are generally plotted according to the linear form, Eq. XVn-9, to obtain the constants b and n from the best fitting straight line. The specific surface area, E, can then be obtained from Eq. XVII-10. A widely used practice is to take to be the molecular area of the adsorbate, estimated from liquid or solid adsorbate densities. On the other hand, the Langmuir model is cast around the concept of adsorption sites, whose spacing one would suppose to be characteristic of the adsorbent. See Section XVII-5B for an additional discussion of the problem. 

The matter of surface mobility has come up at several points in the preceding material. The subject has been a source of confusion—see Ref. 112. Actually, two kinds of concepts seem to have been invoked. The first is that invoked in the discussion of physical adsorption, which has to do with whether the adsorbate can move on the surface so freely that its state is essentially that of a two-dimensional nonideal gas. For an adsorbate to be mobile in this sense, surface barriers must be small compared to kT. This type of mobile adsorbed layer seems unlikely to be involved in chemisorption. 

To extract infomiation from the wavefimction about properties other than the probability density, additional postulates are needed. All of these rely upon the mathematical concepts of operators, eigenvalues and eigenfiinctions. An extensive discussion of these important elements of the fomialism of quantum mechanics is precluded by space limitations. For fiirther details, the reader is referred to the reading list supplied at the end of this chapter. In quantum mechanics, the classical notions of position, momentum, energy etc are replaced by mathematical operators that act upon the wavefunction to provide infomiation about the system. The third postulate relates to certain properties of these operators ... 

One may note, in concluding this discussion of the second law, that in a sense the zeroth law (thennal equilibrium) presupposes the second. Were there no irreversible processes, no tendency to move toward equilibrium rather than away from it, the concepts of thennal equilibrium and of temperature would be meaningless. 

Almost everyone has a concept of pressure from weather reports of tlie pressure of the atmosphere around us. In this context, high pressure is a sign of good weather while very low pressures occur at the eyes of cyclones and hurricanes. In elementary discussions of mechanics, hydrostatics of fluids and the gas laws, most scientists leam to compute pressures in static systems as force per unit area, often treated as a scalar quantity. They also leam that unbalanced pressures cause fluids to flow. Winds are the flow of the atmosphere from regions of high to low... 

This review has covered many of the essential features of the physical chemistry of nanocrystals. Rather than provide a detailed description of the latest and most detailed results concerning this broad class of materials, we have instead outlined the fundamental concepts which serve as departure points for the most recent research. This necessarily limited us to a discussion of topics that have a long history in the community, leaving out some of the new and emerging areas, most notably nonlinear optical studies [152] and magnetic nanocrystals [227]. Also, the... 

Some of the concepts that chemists have introduced for the discussion of chemical reactivity are summarized below. Much of this will be common knowledge to readers that have studied chemistry they can easily skip this section. However, for readers from other scientific disciplines or whose chemical knowledge has become rusty, some fundamental concepts are presented here. 

In this chapter we shall discuss some of the general principles involved in the two most common simulation techniques used in molecular modelling the molecular dynamics and the Monte Carlo methods. We shall also discuss several concepts that are common to both of these methods. A more detailed discussion of the two simulation methods can be found in Chapters 7 and 8. 

This chapter covers a number of concepts or properties that did not relate to material discussed in earlier chapters. Some of these techniques are seldom needed. Others just do not merit a chapter of their own because they are easy to apply. 

There are a number of important concepts which emerge in our discussion of viscosity. Most of these will come up again in subsequent chapters as we discuss other mechanical states of polymers. The important concepts include free volume, relaxation time, spectrum of relaxation times, entanglement, the friction factor, and reptation. Special attention should be paid to these terms as they are introduced. 

It is not particularly difficult to introduce thermodynamic concepts into a discussion of elasticity. We shall not explore all of the implications of this development, but shall proceed only to the point of establishing the connection between elasticity and entropy. Then we shall go from phenomenological thermodynamics to statistical thermodynamics in pursuit of a molecular model to describe the elastic response of cross-linked networks. 

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

Discussion of the concepts and procedures involved in designing packed gas absorption systems shall first be confined to simple gas absorption processes without compHcations isothermal absorption of a solute from a mixture containing an inert gas into a nonvolatile solvent without chemical reaction. Gas and Hquid are assumed to move through the packing in a plug-flow fashion. Deviations such as nonisotherma1 operation, multicomponent mass transfer effects, and departure from plug flow are treated in later sections. 

Because of the interrelationship of the system measures, rehabihty should not be considered by itself since, if taken alone, it does not express the totahty of attributes that contribute to system effectiveness. However, in practice, rehabihty has gained the most acceptance and uniformity of definition. The other concepts described are not always defined uniformly from group to group and are sometimes used interchangeably. Further discussion of these concepts is found in References 1 and 2. 

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