Some General Remarks

It is in principle very simple to change the emission wavelength of the efficient blue cathode-ray phosphor ZnS Ag, vix. by replacing part of the zinc by cadmium. 

However, the (Zn,Cd)S system has several disadvantages. In the first place, the use of cadmium has become inacceptable for environmental reasons. The red phosphor on this basis has still another large disadvantage, viz. in order to obtain red emission the larger part of the broad band emission of this phosphor is situated in the near infrared. The maximum of the emission band is close to 680 nm. This implies that the lumen equivalent of this phosphor is low (2S%). For Y2O2S Eu with line emission this is 55% [ I ]. 

Long ago it was predicted that color television with a satisfying brightness would only be possible with a phosphor which emits in the red by line emission around 610 nm [2]. Now we know that only the Eu ion is able to satisfy this requirement. In fact the introduction of Eu +-activatcd phosphors in the color-television tube was a breakthrough not just the red, but the total brightness increased strongly. It was also the introduction of rare-earth phosphors leading to many other improvements (e.g. in luminescent lamps) and the end of the domination of the sulfides. 

The philosophical divide we saw in, for example, the exchange between Dewar and Halgren, Kleir and Lipscomb (6.2.5.1), persists. One gets the impression that certain journals are reluctant to publish purely theoretical semiempirical papers  

Since probability-generating functions are not often used in polymer science, we first give a brief outline of the properties before applying them to the problems of branched polymers. 

Let wx be a probability distribution (e.g. the weight fraction of a polymer) of finding an event (the degree of polymerization), where x is an integer. Then the corresponding generating function W (s) is defined as the sum over all the events wx multiplied by a variable s raised to the x-th power 

Strength theories provide the means for describing complex stressed states. However, the strength characteristics themselves, that is, a, Ty, and others, depend on the conditions under which the tests are being carried out, that is, they depend on the rate of loading, the temperature, the media, etc., and need therefore to be determined under a broad range of conditions. Initially, let us focus on the role of temperature, as this is the factor of primary importance. 

Physical-Chemical Mechanics of Disperse Systems and Materials 

FIGURE 5.12 The effect of temperature on material strength (on breaking stress, 0b, and the yield stress, Xy). 

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SOME GENERAL REMARKS UPON COLORIMETRIC DETERMINATIONS... 

Some general remarks upon colorimetric determinations 672... 

Before proving this theorem, we will make some general remarks about the nature of the one-electron functions ipk(x) or spin orbitals. For the two values of the spin coordinate f — 1, such a function y)k(r, f) has two space components... 

The purpose of the collection of papers in this volume is to review what can be said about the susceptibility to liquefaction of coals from different parts of the world. We and later authors will present data relative to coals of the areas with which we are familiar. However, with the Editor s approval, we are going to devote the first part of this paper to making some general remarks about coal geology and geochemistry, in the hope that this will provide a useful background to what comes later. 

This section starts with some general remarks concerning scale-up of chemical reactors. Then the influence of chemical kinetics, heat transfer, and mass transfer on scale-up of reactive systems is discussed. Finally, scale-up from the results of calorimetric equipment, such as the ARC and VSP, is reviewed. 

The FACTS database does not show detailed accident analysis information, nor does it show in great detail which factors caused the accident. It mainly describes what happened and what were the consequences together with some general remarks about the causes. 

As demonstrated in most of the other chapters of this book, there is a countless - and growing - number of applications of allenes in preparative organic chemistry. A need for an extra section on the use of allenic hydrocarbons in synthesis may therefore not be apparent. However, since this chapter concentrates on the construction and then preparation of novel jr-systems - neglecting all non-hydrocarbon substituents - some general remarks on the preparative usefulness of the parent systems seem to be in order. 

Second, the mapping approach to nonadiabatic quantum dynamics is reviewed in Sections VI-VII. Based on an exact quantum-mechanical formulation, this approach allows us in several aspects to go beyond the scope of standard mixed quantum-classical methods. In particular, we study the classical phase space of a nonadiabatic system (including the discussion of vibronic periodic orbits) and the semiclassical description of nonadiabatic quantum mechanics via initial-value representations of the semiclassical propagator. The semiclassical spin-coherent state method and its close relation to the mapping approach is discussed in Section IX. Section X summarizes our results and concludes with some general remarks. 

Some general remarks on the reactivity of organic compounds... 

Ill Coupling Reactions at Metal Centres A. Some General Remarks... 

Diffusion problems in systems involving forced and free convection are good illustrations of the importance of presenting all three of the equations of change as a prelude to a general discussion of diffusion. Only a handful of idealized problems of this type have been solved analytically. Since they are, however, of considerable importance in chemical engineering it is worth while to make some general remarks about them. 

Many problems appear to be ripe for a more quantitative discussion. What is the error involved in the introduction of unstable states as asymptotic states in the frame of the 5-matrix theory 16 What is the role of dissipation in mass symmetry breaking What is the consequence of the new definition of physical states for conservation theorems and invariance properties We hope to report soon about these problems. We would like, however, to conclude this report with some general remarks about the relation between field description and particles. The full dynamical description, as given by the density matrix, involves both p0 and the correlations pv. However, the particle description is expressed in terms of p (see Eq. (50)). Now p has only as many elements as p0. Therefore the... 

For some general remarks on microwave spectra see Section 2.4.3.2. 

As the scope of the present chapter is to stress limits and background for the Gaussian theory, a discussion of the said viscosity-molecular weight relationships is omitted. Some general remarks will be made in the discussion of the next section. 

Some General Remarks on the Structure of Smectic Polymers 199... 

In the first part of our chapter the occurrence of H3 heteroreceptors in the CNS and in the retina will be described. Then the location of the H3 heteroreceptors will be discussed. (The term "heteroreceptor" will be used in a relatively broad sense in this article, i.e. regardless of whether the presynaptic location on the nerve endings themselves has been proven or not.) Next, interactions between H3 heteroreceptors and other types of presynaptic receptors will be considered. Finally, some general remarks with respect to H3 heteroreceptors as targets for new drugs will be given. 

After some general remarks on the relations between semiconductor properties and their use as photocatalysts, this text will first deal with oxidations of organic compounds.The interactions of illuminated semiconductors with gaseous C>2 (and, for comparison, with gaseous NO) will be then presented, whereas the last part will consider metal/semiconductor photocatalysts and the organic reactions they allow. In this presentation, the results of this laboratory will be highlighted. 

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