Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Possible types

The possible types of symmetry for the Hamiltonian of an isolated molecnle in field-free space (all of them are discussed in more detail later on in the article) can be listed as follows ... [Pg.141]

The electron density distributions are approximated by a series of poin t charges. There are four possible types of coninbniion s, i.e. [Pg.286]

Solvents exert their influence on organic reactions through a complicated mixture of all possible types of noncovalent interactions. Chemists have tried to unravel this entanglement and, ideally, want to assess the relative importance of all interactions separately. In a typical approach, a property of a reaction (e.g. its rate or selectivity) is measured in a laige number of different solvents. All these solvents have unique characteristics, quantified by their physical properties (i.e. refractive index, dielectric constant) or empirical parameters (e.g. ET(30)-value, AN). Linear correlations between a reaction property and one or more of these solvent properties (Linear Free Energy Relationships - LFER) reveal which noncovalent interactions are of major importance. The major drawback of this approach lies in the fact that the solvent parameters are often not independent. Alternatively, theoretical models and computer simulations can provide valuable information. Both methods have been applied successfully in studies of the solvent effects on Diels-Alder reactions. [Pg.8]

FIG. 28-10 Six possible types of behavior for an active/passive alloy in a corrosive environment. [Pg.2431]

Let us now turn to the influence of vibrations on exchange chemical reactions, like transfer of hydrogen between two O atoms in fig. 2. The potential is symmetric and, depending on the coupling symmetry, there are two possible types of contour plot, schematically drawn in fig. 17a, b. The O atoms participate in different intra- and intermolecular vibrations. Those normal skeleton... [Pg.34]

The alkyl-bridged structures can also be described as comer-protonated cyclopropanes, since if the bridging C—C bonds are considered to be fully formed, there is an extra proton on the bridging carbon. In another possible type of structure, called edge-protonated cyclopropanes, the carbon-carbon bonds are depicted as fully formed, with the extra proton associated with one of the bent bonds. MO calculations, structural studies under stable-ion conditions, and product and mechanistic studies of reactions in solution have all been applied to understanding the nature of the intermediates involved in carbocation rearrangements. [Pg.317]

Air jets are used for many purposes. Some of these are described in other parts of this chapter, but it is not possible to describe all the possible types and uses. The fundamentals regarding velocity, flow rate, and spreading of round, radial, and plane jets are described in Sections 7.4 and 7.7. When jets are used inside rooms, they do not need to have any corresponding exhaust air. Exhausted air is needed for supply jets in general ventilation, but if the jet s air is taken from the room and blown into the room again, no exhaust is needed. If the air is taken from outside the room, it is necessary to have the same flow rate exhausted from the room. [Pg.919]

Velluz and co-workers named these compounds 19-nor-flfce )-steroids recognizing two possible types, i.e., 0 5A)abeo (127) and 5 0- )abeo (128). " ... [Pg.395]

The eight possible types of simply supported (prefix S) and clamped (prefix C) edge boundary conditions [combinations of the conditions in Equation (5.9)] are commonly classified as (see Almroth [5-6]) ... [Pg.284]

Many compounds, of which [NiBr2(PEtPh2)2] mentioned above is one, exist in solution as mixtures of isomers giving rise to intermediate values of (0-3.2 BM). Such behaviour, previously regarded as anomalous is due to one of three possible types of equilibria ... [Pg.1160]

The simplest possible attraetor is a fixed point, for which all trajectories starting from the appropriate basin-of-attraction eventually converge onto a single point. For linear dissipative dynamical systems, fixed-point attractors are in fact the only possible type of attractor. Non-linear systems, on the other hand, harbor a much richer spectrum of attractor-types. For example, in addition to fixed-points, there may exist periodic attractors such as limit cycles for two-dimensional flows or doubly periodic orbits for three-dimensional flows. There is also an intriguing class of attractors that have a very complicated geometric structure called strange attractors [ruelleSO],... [Pg.171]

Although any arbitrary labeling scheme for the global states may be used to define these matrices, the most convenient one for our purposes here is one that exploits our knowledge of the possible types of global states. In particular, we label according to the following scheme ... [Pg.226]

An exhaustive list of all possible types of data suitable for chemometric treatment together with all possible types of predictions made from the data would fill a large chapter in this book. Table 1 contains a brief list of some of... [Pg.5]

Water-Soluble Exotoxins. In this area, we enter into the slightly muddy waters of the lower molecular weight compounds which elicit toxic responses in susceptible host insects. Without reference to molecular identity, it is possible to sift through the various reports on the effects of bacillus-produced soluble exotoxins and recognize three possible types of material which are produced under appropriate conditions by specific strains of bacilli ... [Pg.77]

Alpha-quartz has many useful properties which lead to its wide use in industry as a glass, ceramic and molecular sieve. However, undoubtedly its most technically important use occurs by virtue of its piezo-electric properties, which allow it to be used as a frequency regulating device in satellites, computers, and the ubiquitous quartz-watch . Unfortunately, it has been found that quartz crystals are susceptible to damage by radiation, and that this is associated with the presence of defects in the crystal lattice. These defects, particularly aluminum and hydrogen, are grown into the crystal and so far have proved impossible to remove. This problem has been the cause of intensive research, which has led to some information on the possible types of defects involved, but has failed to produce details of their geometries, and the way in which they interact. [Pg.70]

This approach can be generalized to all possible types of experimental data that may be generated. All chemical structures available in public databases or internal to a company typically feature at least the in vitro binding assay data and additionally, the three-dimensional structure of the protein and/or bound ligand. A chemical compound C will therefore be ... [Pg.335]

It is hardly possible to predict that a general theory will ever be evolved which will cover all possible types of industrial emulsions and foams. However, it seems that if the information described were gathered in a systematic fashion, the data could be classified in a logical order for different types of emulsions. Hence, cosmetic-type emulsions, salad dressing, and mayonnaise-type emulsions would each fall into its own individual category. The suggestion therefore is made that a repository of such information be made available to all who are interested. [Pg.71]

This is the simplest possible type of neuron, used here for didactic purposes and not because it is the configuration to be recommended. Let us suppose that for this isolated neuron w, = 1, Wj = 2 and 7=1. The line in Fig. 33.20 then gives the values of x, and Xj for which E = 7. All combinations of x, and Xj on and above the line will yield E > 7 and therefore lead to an output y, = 1 (i.e. the object is class K), all combinations below it toy, = 0. The procedure described here is equivalent to a method called the linear learning machine, which was one of the first supervised pattern recognition methods to be applied in chemometrics. It is further explained, including the training phase, in Chapter 44. [Pg.234]

Fig. 2. Energy level diagram for the three possible types of soliton. Fig. 2. Energy level diagram for the three possible types of soliton.
Table 3. Possible types of leakage of C02 in a geological storage [13,14,15]. Table 3. Possible types of leakage of C02 in a geological storage [13,14,15].
Using the other equations for U, H, A, or S gives the other possibilities. Type III (15 possibilities plus reciprocals)... [Pg.22]

In most kinetic responses studies to date, the linear velocity of the organism is the activity parameter that is affected by the stimulus. Since this is not the only possible type of kinesis, the following (incomplete) subdivision may be used ... [Pg.52]


See other pages where Possible types is mentioned: [Pg.359]    [Pg.70]    [Pg.2181]    [Pg.51]    [Pg.117]    [Pg.865]    [Pg.693]    [Pg.242]    [Pg.254]    [Pg.272]    [Pg.543]    [Pg.114]    [Pg.229]    [Pg.220]    [Pg.369]    [Pg.335]    [Pg.7]    [Pg.20]    [Pg.22]    [Pg.110]    [Pg.109]    [Pg.313]    [Pg.147]    [Pg.168]    [Pg.435]    [Pg.448]    [Pg.128]   
See also in sourсe #XX -- [ Pg.317 ]




SEARCH



© 2024 chempedia.info