Frequently Used Indices

Other quite frequently used indices are the Randic index and the information-topological indices such as the Bonchev index (see Chapter VIll, Section 1 in the Handbook), Up to now several hundred indices have been devised. 

A frequently used indicator of how much two gases (say, gas m and gas n) in a multicomponent gaseous mixture are separated with respect to each other through a membrane is called separation factor. It is defined as... 

A bioconcentration factor (BCF) is the ratio of the concentration of a chemical in an aquatic organism to that in the surrounding water, and is the most frequently used indicator of a compound s propensity to bioconcentrate in aquatic organisms [15]. Bioconcentration factors are determined primarily using steady-state concentrations, or by using kinetically derived uptake and elimination rates [3]. A summary of bioconcentration factors reported for explosives and related compounds in invertebrate and fish species is provided in Table 6.1. 

The oxygen consumption and yields of oxidation products are frequently used indices of radiation-induced degradation by oxidation. The oxidation process depends on the irradiation conditions, i.e. the atmosphere, pressure, dose rate, temperature and sample dimensions. The oxygen uptake may be determined by measurements of the oxygen content before and after irradiation, where the oxygen products include carbon dioxide, carbon monoxide, water, hydroperoxide, alcohols, ketones and carboxylic acids [3]. 

The two most frequently used indices for describing the distribution of the... 

Several drug indexes are available that can supplement this text by serving as a detailed source of information about individual drugs. One of the most readily available and frequently used indexes is the Physicians Desk Reference, or PDR. The PDR is published annually by Thomson PDR, Montvale, NJ 07645-1742. 

The Subject Index is the most frequently used index published by CA. Statistics show that this is true by a wide margin. 

Which of these or some other location indexes one uses is a matter of personal choice and convenience, depending on the type of problem studied. The mean is by far the most frequently used index, and for this reason, only the mean will be discussed further. 

The luminometer index (ASTM D 1740) is a characteristic that is becoming less frequently used. It is determined using the standard lamp mentioned above, except that the lamp is equipped with thermocouples allowing measurement of temperatures corresponding to different flame heights, and a photo-electric cell to evaluate the luminosity. The jet fuel under test is compared to two pure hydrocarbons tetraline and iso-octane to which are attributed the indices 0 and 100, respectively. The values often observed in commercial products usually vary between 40 and 70 the official specification is around 45 for TRO. 

Hence, they take account of only the structure constitution (topology). One of the first and most frequently used topological indices is the Wiener index. It has the form of Eq. (3), where D,y are all the routes from atom i to atom j. 

Direct or indirect methods may be used to determine moisture in dehydrated foods. Indirect methods must be calibrated in terms of direct methods—the most common of which are the oven, distillation, and Fischer methods. Accuracy of the direct methods is difficult to evaluate except by comparison with a chosen reference method. Several reference methods are reviewed, but none can be given an unqualified recommendation as most practical and suitable for all foods. An indirect measure of moisture is the equilibrium vapor pressure of water, which can be measured easily and accurately. Arguments are presented to show that vapor pressure may be a better index of the stability of dehydrated foods than the moisture content, which has been frequently used for this purpose. 

AAoisture determination is probably one of the most important and most widely used analytical measurements in the processing and testing of food products. It is of economic importance both to the consumer and to the food technologist. To the technologist, the moisture content is frequently an index of stability and quality of food, while to the consumer, it may serve as a measure of quantity as well as a measure of quality. 

The normalization method is the easiest and most straightforward to use but, unfortunately, it is also the least likely to be appropriate for most LC analyses. To be applicable, the detector must have the same response to all the components of the sample. An exceptional example, where the normalization procedure is frequently used, is in the analysis of polymers by exclusion chromatography using the refractive index detector. The refractive index of a specific polymer is a constant for all polymers of that type having more than 6 monomer units. Under these conditions normalization is the obvious quantitative method to use. 

Preceding the indexes there is a list of those abbreviations that are frequently used in the text of the volume at hand or in companion volumes. This list varies somewhat in length from volume to volume that is, it becomes more comprehensive as new volumes are published. 

CODATA recommended values, adapted from [1,2] and http //physics.nist. gov/cuu/Constants/index.html Frequently used fundamental physical constants... 

The SEC mechanism demands only an isocratic (constant composition) solvent system with normally a single solvent. The most frequently used organic solvents are THF, chloroform, toluene, esters, ketones, DMF, etc. The key solvent parameters of interest in SEC are (i) solubility parameter (ii) refractive index (iii) UV/IR absorbance (iv) viscosity and (v) boiling point. Sample solutions are typically prepared at concentrations in the region of 0.5-5 mg mL-1. In general an injection volume of 25-100p,L per 300 x 7.5 mm column should be employed. For SEC operation with polyolefins chlorinated solvents (for detector sensitivity and increased boiling point) and elevated temperatures (110 to 150 °C) are required to dissolve olefin polymer. HFIP is the preferred solvent for SEC analysis of polyesters and polyamides. 

The Euclidean distance is the dissimilarity index most frequently used. It is characterized by invariance to translation and rotation,... 

The first step in the procedure is to conceptually divide the process into separate process units. A process unit is a single pump, a reactor, or a storage tank. A large process results in hundreds of individual units. It is not practical to apply the fire and explosion index to all these units. The usual approach is to select only the units that experience shows to have the highest likelihood of a hazard. A process safety checklist or hazards survey is frequently used to select the most hazardous units for further analysis. 

The frequently used Dow Fire Explosion Hazard Index (1987) gives penalties for fired equipment and certain specified rotating equipment. These are a part of the Special Process Hazards term of the Dow Index. 

In any chromatographic analysis the method of detection is determined by the nature of the analyte and the mobile phase used must not interfere with this system. The use of ultraviolet absorption detection systems is very common but the solvents used must not absorb significantly at the wavelength used. For instance, absorption at 280 nm is frequently used to detect protein but some solvents, e.g. acetone, absorb at this wavelength. Similarly the use of concentration gradients in the mobile phase may present problems with refractive index and electrochemical detection systems. 

Since the concentration is proportional in many individual cases to an easily delermined physical constant, such as specific gravity (e.g.. of solutions), the index of refraction, specific rotatory power (e.g., sugar solutions, tcrpcncsi. such constants are frequently used to ascertain and express concentration data. 

The detectors most frequently used in HPLC are of the refractive index (RI), conductivity, and UV-Vis types. While RI detectors are probably the most flexible, they are somewhat sensitive to changes in pressure, temperature, and the composition of the mobile phase, which demand... 

First, a high index of suspicion for first episodes of depression should accompany the assessment of adolescent girls (Fig. 14—29), since this illness is frequently missed, and despite the lack of formal approval of antidepressants for use in anyone under the age of 18, the newer antidepressants are frequently used for this purpose, and their safety has been well established in children and adolescents for related conditions such as obsessive-compulsive disorder (see Chapter 5). Also, the use of oral... 

Most of the physical properties of the polymer (heat capacity, expansion coefficient, storage modulus, gas permeability, refractive index, etc.) undergo a discontinuous variation at the glass transition. The most frequently used methods to determine Tg are differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical thermal analysis (DMTA). But several other techniques may be also employed, such as the measurement of the complex dielectric permittivity as a function of temperature. The shape of variation of corresponding properties is shown in Fig. 4.1. 

A chromatographic technique frequently used in polymer and dendrimer analysis is size exclusion chromatography (SEC) [13], which is often also called gel permeation chromatography (GPC). It is a straightforward method of determining the relative molar mass, the molar mass distribution, and the polydispersity index (PDI) with compatively modest consumption of material and time. 

There are plenty of other examples (e.g., polypropylene and HDPE) where the Herfindahl Index, a measure of industry concentration frequently used by antitrust authorities, is rather high in North America and Western Europe. This necessarily limits the opportunities for Western players to grow by means of mergers and acquisitions in their own domestic markets. 

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