Big Chemical Encyclopedia

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

Articles Figures Tables About

Basic postulates

The basic premise of the sequential interaction (SI) model is that significant changes in enzyme conformation take place upon substrate binding, which result in altered substrate binding affinities in the remaining active sites (Fig. 8.2). For the case of positive cooperativity, each substrate molecule that binds makes it easier for the next substrate molecule to bind. The resulting v versus [S] curve therefore displays a marked slope increase as a function of increasing substrate concentration. Upon saturation of the [Pg.103]

The equilibrium dissociation constants, both macroscopic or global Kn) and microscopic or intrinsic (kn), for the various ES complexes are [Pg.104]

Upon substrate binding, dissociation constants can decrease for the case of positive cooperativity (increased affinity of enzyme for substrate) or decrease in the case of negative cooperativity (decreased affinity of enzyme for substrate). [Pg.104]

Normalization of the rate equation by total enzyme concentration (u/[Et ]), substitution of the different ES terms with the appropriate expression containing microscopic dissociation constants, and rearrangement results in the following expression for the velocity of a four-site [Pg.104]


The systems of interest in chemical technology are usually comprised of fluids not appreciably influenced by surface, gravitational, electrical, or magnetic effects. For such homogeneous fluids, molar or specific volume, V, is observed to be a function of temperature, T, pressure, P, and composition. This observation leads to the basic postulate that macroscopic properties of homogeneous PPIT systems at internal equiUbrium can be expressed as functions of temperature, pressure, and composition only. Thus the internal energy and the entropy are functions of temperature, pressure, and composition. These molar or unit mass properties, represented by the symbols U, and S, are independent of system size and are intensive. Total system properties, J and S do depend on system size and are extensive. Thus, if the system contains n moles of fluid, = nAf, where Af is a molar property. Temperature... [Pg.486]

Another aspect of qualitative application of MO theory is the analysis of interactions of the orbitals in reacting molecules. As molecules approach one another and reaction proceeds, there is a mutual perturbation of the orbitals. This process continues until the reaction is complete and the new product (or intermediate in a multistep reaction) is formed. PMO theory incorporates the concept of frontier orbital control. This concept proposes that the most important interactions will be between a particular pair of orbitals. These orbitals are the highest filled oihital of one reactant (the HOMO, highest occupied molecular oihital) and the lowest unfilled (LUMO, lowest unoccupied molecular oihital) orbital of the other reactant. The basis for concentrating attention on these two orbitals is that they will be the closest in energy of the interacting orbitals. A basic postulate of PMO... [Pg.46]

The basic postulates of radical pair theory may be summarized as follows ... [Pg.57]

Accepting all three of the basic postulates, the origin of CIDNP can now be described qualitatively. Figure 2 illustrates a variety of different radical reaction pathways known to produce polarized spectra. [Pg.58]

Kapur and Fuerstenau (K6) have presented a discrete size model for the growth of the agglomerates by the random coalescence mechanism, which invariably predominates in the nuclei and transition growth regions. The basic postulates of their model are that the granules are well mixed and the collision frequency and the probability of coalescence are independent of size. The concentration of the pellets is more or less fixed by the packing... [Pg.90]

The basic postulate of elementary molecular theories of rubber elasticity states that the elastic free energy of a network is equal to the sum of the elastic free energies of the individual chains. In this section, the elasticity of the single chain is discussed first, followed by the elementary theory of elasticity of a network. Corrections to the theory coming from intermolecular correlations, which are not accounted for in the elementary theory, are discussed separately. [Pg.341]

To demonstrate this, set F = P or Q. The two basic postulates of matrix mechanics follow directly from this, in terms of the momentum-position commutator,... [Pg.191]

Because of these properties of Hermitian functions it is accepted as a basic postulate of wave mechanics that operators which represent physical quantities or observables must be Hermitian. The normalized eigenfunctions of a Hermitian operator constitute an orthonormal set, i.e. [Pg.198]

Throughout the chapter, the importance of network formation theories in understanding and predicting structural development is stressed. Therefore, a short expose on network formation theories is given in this chapter. Although the use of theoretical modeling of network build-up and comparison with experiments play a central role in this chapter, most mathematical relations and their derivation are avoided and only basic postulates of the theories are stated. The reader can always find references to literature sources where such mathematical relations are derived. [Pg.116]

C—This is a basic postulate of kinetic molecular theory. [Pg.134]

Now that we have summarized the historical and mathematical background, the objectives, and the limitations of chemical thermodynamics, we will develop the basic postulates upon which its analytic framework is built. In discussing these fundamental postulates, which are essentially concise descriptions based on much experience, we will emphasize at all times their apphcation to chemical, geological, and biological systems. However, first we must define a few of the basic concepts of thermodynamics. [Pg.29]

The change in energy in an isothermal expansion cannot be expressed in a simple form without introducing the second law of thermodynamics. Nevertheless, we will anticipate this second basic postulate and use one of the deductions obtainable from it ... [Pg.103]

Beyond these well established characteristic features however the total width of the electron distributions is much narrower for the argon target than for neon or helium. These patterns are due to the signatures of the initial state wave function. In figure 3, a systematic discrepancy between experiment and theory appears at higher electron energies. This discrepancy occurs due to one of the basic postulates of the CDW-EIS model, namely that it is based on the independent electron model which considers there... [Pg.323]

The molecular theory of elasticity of polymeric networks which leads to the equation of state, Eq. (28), rests on the following basic postulates Undeformed polymeric chains of elastic networks adopt random configurations or spatial arrangements in the bulk amorphous state. The stress resulting from the deformation of such networks originates within the elastically active chains and not from interactions between them. It means that the stress exhibited by a strained network is assumed to be entirely intramolecular in origin and intermolecular interactions play no role in deformations (at constant volume and composition). [Pg.41]

The basic postulate of irreversible thermodynamics is that, near equilibrium, the local entropy production is nonnegative ... [Pg.28]

The next reasonable step in studying our chemical games is to consider ensembles of A s and B s (e.g., topers and policemen), when they are randomly and homogeneously distributed in the reaction volume and are characterized by macroscopic densities of a number of particles. The peculiarity of the A + B -y B reaction is that the solution of a problem with a single A could be extrapolated for an ensemble of A s (in other words, a problem is linear in particles A). As it was said above, it is analytically solvable for Da = 0 but turns out to be essentially many-particle for Db = 0. It is useful to analyze a form of the solution obtained for the particle concentration tia (t) in terms of the basic postulates of standard chemical kinetics (i.e., the mean-field theory). [Pg.21]

Extended relativity (ER) simply follows from the two basic postulates of SR ... [Pg.684]

We have seen that mononuclear complexes with or without the first-order angular momentum can be theoretically treated in a different degree of complexity. Thus we can speak of some magnetotheoretical hierarchy (Table 2). Depending on the basic postulate about the extent of the active space (a space of kets included in the zero-order Hamiltonian) various levels of the theory can be distinguished. [Pg.9]

Further basic postulates deal with structures, those relatively permanent structures/functions/subsystems of the mind/brain that act on information to transform it in various ways. Arithmetical skills, for example, constitute a (set of related) structure(s). The structures of particular interest to us are those that require some amount of attention/awareness to activate them. Attention/awareness acts as psychological energy in this sense. Most techniques for controlling the mind are ways of deploying attention/awareness energy and other kinds of energies so as to activate desired structures (traits, skills, attitudes) and deactivate undesired structures. [Pg.11]

Let us now look at the basic elements of this systems approach, the basic postulates about what lies behind the phenomenal manifestations of experience, in the following chapters we will put these basic elements of awareness, energy, and structure together into the systems we call states of consciousness. [Pg.18]

It should be noted that even if antihydrogen were to be formed by this technique, the prospects for precision studies of the kind outlined in subsection 8.3.1, which might offer a challenge to some of the basic postulates of physics, are not likely to be easy. [Pg.386]

American Mandrake is an entirely different plant from White Bryony or English Mandrake, dealt with elsewhere. Preparations of the rhizome of the American Mandrake are found in practice to be much more effective than those of the resin. This is one of the many confirmations of one of the basic postulates of herbal medicine—the nearer we can get to natural conditions the better the results. Therapeutic principles are never the same when taken from their proper environment. [Pg.61]

In the following we present the axioms or basic postulates of quantum mechanics and accompany them by their classical counterparts in the Hamiltonian formalism. We begin the presentation with a brief summary of some of the mathematical background essential for the developments in the following. It is by no means a comprehensive presentation, and the reader is supposed to have some basic knowledge about quantum mechanics that may be obtained from any of the many introductory textbooks in quantum mechanics. The focus here is on results of particular relevance to the subjects of this book. We consider, for example, a derivation of a formal expression for the flux density operator in quantum mechanics and its coordinate representation. A systematic way of generating any representation of any combination of operators is set up, and is of immediate usage for the time autocorrelation function of the flux operator used to determine the rate constants of a chemical process. [Pg.343]

The key word for the calculation in the basic postulate is number. What we are claiming is that there is no difference in probability between any distinguishable microscopic configuration of the system. All we have to do is count the possible microscopic configurations corresponding to a state. Therefore, what the microscopic description of thermodynamics comes down to in the end is just counting ... [Pg.133]


See other pages where Basic postulates is mentioned: [Pg.239]    [Pg.436]    [Pg.513]    [Pg.8]    [Pg.375]    [Pg.338]    [Pg.413]    [Pg.60]    [Pg.27]    [Pg.21]    [Pg.293]    [Pg.52]    [Pg.263]    [Pg.58]    [Pg.28]    [Pg.435]    [Pg.62]    [Pg.291]    [Pg.295]    [Pg.4]    [Pg.15]    [Pg.54]    [Pg.133]   
See also in sourсe #XX -- [ Pg.22 ]




SEARCH



Basic Mechanistic Concepts Kinetic versus Thermodynamic Control, Hammonds Postulate, the Curtin-Hammett Principle

Irreversible thermodynamics basic postulate

Postulates of Quantum Mechanics Basic Applications

© 2024 chempedia.info