Intrinsic properties, definition

Thickness. The traditional definition of thermal conductivity as an intrinsic property of a material where conduction is the only mode of heat transmission is not appHcable to low density materials. Although radiation between parallel surfaces is independent of distance, the measurement of X where radiation is significant requires the introduction of an additional variable, thickness. The thickness effect is observed in materials of low density at ambient temperatures and in materials of higher density at elevated temperatures. It depends on the radiation permeance of the materials, which in turn is influenced by the absorption coefficient and the density. For a cellular plastic material having a density on the order of 10 kg/m, the difference between a 25 and 100 mm thick specimen ranges from 12—15%. This reduces to less than 4% for a density of 48 kg/m. References 23—27 discuss the issue of thickness in more detail. 

There are no universally accepted definitions of bulk, fine, and specialty chemicals, nor are these classifications based on any intrinsic properties. For example, a substance that is currently viewed as a bulk chemical may well have been classified as a fine chemical at an earlier stage in its development. 

In the above relationship p is an intrinsic property called the specific resistance (or resistivity) of the conductor. The definition of the specific resistance of any given conductor follows from this relationship. It is the resistance in ohms of a specimen of the material, 1 cm long and 1 cm2 in cross-sectional area (units ohm cm-1), the length being in the direction of the current and the cross-section normal to it. In other words, the specific resistance p of a conductor is the resistance of a cube of 1 centimeter edge. If the conductance is denoted by C = 1 /R, then the specific conductance (or conductivity) K, is given by JC= 1/a (units ohm-1 cm-1, mho cm-1, reciprocal ohm cm-1). Therefore, the relationship R = aL/A may be written as R = L/KA (units ohms) and the conductance can be expressed as C = 1/R = KA/l (units reciprocal ohms). 

It was not until recently that Chen and Goodman probed the influence of the oxide support material on the intrinsic properties at the metal surface. By covering a titania support with one or two flat atomic layers of gold they eliminated, direct adsorbate-support interactions as well as particle size and shape effects. Their results definitively showed that the electronic properties at the metal surface changed due to charge transfer between the support and the metal. Furthermore, their comparison of one- and two-layer films highlighted the dependence of these effects on the thickness of the metal slab. 

A definite theoretical explanation of this behavior is not available. It is important to realize that the preference of a metal for 3C as opposed to 2C complexes or for 5C as opposed to 3C complexes may be either intrinsic or induced by adsorption of less reactive carbonaceous fragments and carbon (for simplicity, we shall refer to both of these as carbon ) on the metal (alloy) surface. Also, the choice of the reaction conditions (apparent contact time, poisoning or self-poisoning of the catalyst, etc.) influences the temperature range in which the catalysts can be tested, and since the selectivity in various complex formations is also temperature dependent, one must always analyze which aspects of the product distributions are intrinsic properties of a metal and which are induced by often unavoidable side reactions. 

In all considerations above we have assumed the most natural theoretical definition of nuclear form factors, namely, the form factor was assumed to be an intrinsic property of the nucleus. Therefore, the form factor is defined via the effective nuclear-photon vertex in the absence of electromagnetic interaction. Such a form factor can in principle be calculated with the help of QCD. The electromagnetic corrections to the form factor defined in this way may be calculated in the framework of QED perturbation theory. Strictly speaking all formula above are valid with this definition of the form factor. 

Following the definition (Equation 1), / -values can be obtained by measurement of the fesp-values for the enzymatic reaction of the enantiomers. Considering practical limitations, i.e. the availability of chirally pure enantiomers, E-values are more commonly determined by evaluating the ee-values as a function of the extent of conversion in batch reactions (see [28, 29] and [30] for overviews). It must be emphasized that the relationship between E, the intrinsic property, and , the realization of this property, shows a (complex) dependence on the concentrations (more precisely, the mass-action equivalents or thermodynamic activities) of the... 

One of the most important parameters in static LLS is the specific refractive index increment (dn/dC), defined as Zzmc o(dn/9C)T,p,A- Since this parameter is not an intrinsic property of the polymer, the conditions of fixing temperature T, pressure P and wavelength of light in vacuum X are needed in its definition. Note that, according to Eq. (2.1), an error of E% in dn/dC will lead to an error of 2E% in the derived Mw. 

Often safety data or material safety data sheets mention the thermal stability as an intrinsic property of a substance or mixture. In fact, this is an oversimplification of a concept that must be defined in a more comprehensive way. Basically, a substance or a mixture is thermally stable in a situation where the heat released can be removed in such a way that no temperature increase occurs. This definition... 

Hie selection of a solid catalyst for a given reaction is to a large extent still empirical and based on prior experience or analogy. However, there are now many aspects of this complex situation that are quite well understood. For example we know how the true chemical kinetics, which are an intrinsic property of the catalyst, and all the many aspects of transport of material and heat around the catalytic particles, interact. In other words, the physical characteristics around the catalyst system and their effects on catalyst performance are well known today. The chemist searching for new and better catalysts should always consider these physical factors, for they can be brought under control, and often in this way definite gains can usually be made both in activity and in selectivity. Further, this knowledge enables us to avoid... 

There are no universally accepted definitions of bulk, fine, and specialty chemicals, nor are these classifications based on any intrinsic properties. A substance that is currently viewed as a bulk chemical might well have been classified as a fine chemical at an earlier stage in its development. A useful working definition of a fine chemical is one with a price of more than 10 US dollars kg and a volume of less than 10000 tons per annum on a worldwide basis. We make no distinction between fine chemicals, that are often intermediates, and specialty chemicals such as pharmaceuticals, pesticides, and flavors and fragrances. The type of technology used to manufacture these products is dictated more by volume than by product application. 

The intrinsic properties are the amount of radioactivity and factors which give a measure of the risk for the worker (e.g. the radiotoxic properties of the particular nuclide as given by the ALI or DAC values). It is not possible to draw any definite conclusions about the hazard ft om a certain amount of a radiotoxic substance. The hazard risk may only be evaluated from its radiotoxicity value. For that purpose, it is also necessary to consider its chemical form and pathways to man, which are considered to be extensive properties. ALI values do take into account if the chemical form is "soluble" or "insoluble", but this is, of course, a rather crude subdivision. The DAC values consider the particle size and time of exposure to that particular air condition (e.g. in a factory). However, it does not consider the particular ways by which the substance is released to the environment (cf. 21.11.1). 

In the subsequent subsections substituent effects on definite molecular properties are interpreted in terms of current concepts of electronic theories that is, the overall observable substituent effects are related to intrinsic properties of the substituents. For this purpose two levels of semiquantitative approaches are used ... 

The quantum mechanical viable definition being an intrinsic property of an atom, that is a quantum object, the electronegativity has to include the quantum nature of the electronic systems to whom is associated. The present scales are accommodated within conceptual DFTby employing the softness realization (4.226), which contains three quantum constraints such the translational invariance condition, the Hellmann-Feynman theorem, and the normalization of the linear response function are. 

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