Quantitative Measures of

Non-destructive testing - Radioscopic testing - Part 1 Quantitative measurement of imaging properties, prEN 13068-1... 

Tjandra N, Szabo A and Bax A 1996 Protein backbone dynamics and N-15 chemical shift anisotropy from quantitative measurement of relaxation interference effected. Am. Chem. Soc. 118 6986-91... 

For a detailed discussion on the analytical teclmiques exploiting the amplitude contrast of melastic images in ESI and image-EELS, see chapter B1.6 of this encyclopedia. One more recent but also very important aspect is the quantitative measurement of atomic concentrations in the sample. The work of Somlyo and colleagues [56]. Leapman and coworkers and Door and Gangler [59] introduce techniques to convert measured... 

Compared witii other direct force measurement teclmiques, a unique aspect of the surface forces apparatus (SFA) is to allow quantitative measurement of surface forces and intermolecular potentials. This is made possible by essentially tliree measures (i) well defined contact geometry, (ii) high-resolution interferometric distance measurement and (iii) precise mechanics to control the separation between the surfaces. 

The PEOE method leads to only partial equalization of orbital electronegativities. Thus, each atom of a molecule retains, on the basis of Eq. (12), a residual electronegativity that measures its potential to attract further electrons. It has been shown that the values of residual electronegativities can be taken as a quantitative measure of the inductive effect [35]. 

Residual electronegativity values obtained by the PEOE method are useful quantitative measures of the inductive effect. 

The Cahn-Ingold-Prelog (CIP) rules stand as the official way to specify chirahty of molecular structures [35, 36] (see also Section 2.8), but can we measure the chirality of a chiral molecule. Can one say that one structure is more chiral than another. These questions are associated in a chemist s mind with some of the experimentally observed properties of chiral compounds. For example, the racemic mixture of one pail of specific enantiomers may be more clearly separated in a given chiral chromatographic system than the racemic mixture of another compound. Or, the difference in pharmacological properties for a particular pair of enantiomers may be greater than for another pair. Or, one chiral compound may rotate the plane of polarized light more than another. Several theoretical quantitative measures of chirality have been developed and have been reviewed elsewhere [37-40]. 

One example of a quantitative measure of molecular chirality is the continuous chirality measure (CCM) [39, 40]. It was developed in the broader context of continuous symmetry measures. A chital object can be defined as an object that lacks improper elements of symmetry (mirror plane, center of inversion, or improper rotation axes). The farther it is from a situation in which it would have an improper element of symmetry, the higher its continuous chirality measure. 

The iodine number of fats and oils provides a quantitative measurement of the degree of unsaturation. A solution containing a 100% excess of IGl is added to the sample, reacting across the double-bonded sites of unsaturation. The excess IGl is converted to I2 by adding KI. The resulting I2 is reacted with a known excess of Na2S203. To complete the analysis the excess 8203 is back titrated with coulometrically generated I2. 

The goal of chromatography is to separate a sample into a series of chromatographic peaks, each representing a single component of the sample. Resolution is a quantitative measure of the degree of separation between two chromatographic peaks, A and B, and is defined as... 

As shown in Figure 12.8, the degree of separation between two chromatographic peaks improves with an increase in R. For two peaks of equal size, a resolution of 1.5 corresponds to an overlap in area of only 0.13%. Because resolution is a quantitative measure of a separation s success, it provides a useful way to determine if a change in experimental conditions leads to a better separation. 

The values of the ratio lo/b are thus seen to be quantitative measures of the hindrance to rotation in these polymers. The following observations are pertinent to the trends in this behavior ... 

The alkyl and alkoxy substituents of phosphate or phosphonate esters also affect the phosphorylating abiUty of the compound through steric and inductive effects. A satisfactory correlation has been developed between the quantitative measure of these effects, Tafts s O, and anticholinesterase activity as well as toxicity (33). Thus long-chain and highly branched alkyl and alkoxy groups attached to phosphoms promote high stabiUty and low biological activity. 

Suppression of the tme diagonal peaks by double-quantum filtering (DQF-COSY) may resolve such problems. Finally, quantitative measurements of the magnitude of the coupling constants is possible using the Z-COSY modification, These experiments ate restricted to systems of abundant spins such as H, and which have reasonably narrow linewidths. 

The quantitative measurement of pigment or pigmented system deterioration upon exposure to heat or light used to be expressed by visual numerical standards. In modem times color differences are expressed in the CIELAB system which has become the leading method for color characterization (8). 

Interaction Parameters. Early attempts to describe PVC—plasticizer compatibiHty were based on the same principles as used to describe solvation, ie, like dissolves like (2). To obtain a quantitative measure of PVC—plasticizer compatibihty a number of different parameters have been used. More recently these methods have been assessed and extended by many workers (7—9). In all cases it is not possible to adequately predict the behavior of polymeric plasticizers. 

Analytical methods aie utilised by all branches of the chemical iadustry. Sometimes the goal is the quaUtative deterniiaation of elemental and molecular constituents of a selected specimen of matter othertimes the goal is the quantitative measurement of the fractional distribution of those constituents and sometimes it is to monitor a process stream or a static system. Information concerning the various iadividual analytical methods may be found ia separate articles dispersed alphabetically throughout the Eniyclopedia. The articles ate iatroductions to topics each of which is the subject of numerous books and other pubhcations. 

Another type of experiment involves a fluid filament being drawn upward against gravity from a reservoir of the fluid (101,213,214), a phenomenon often called the tubeless siphon. The maximum height of the siphon is a measure of the spinnabiUty and extensional viscosity of the fluid. Mote quantitative measures of stress, strain, and strain rate can be determined from the pressure difference and filament diameter. A more recent filament stretching device ia which the specimen is held between two disks that move apart allows measurements ia low viscosity Hquids (215). AH of these methods are limited to spinnable fluids under small total strains and strain rates. High strain rates tend to break the column or filament. 

Complete basic hydrolysis, followed by the quantitative measurement of hydrogen formed, can be used to determine the number of Si—H and Si—Si bonds present in a particular compound. One molecule of H2 is Hberated for each Si—H and Si—Si bond present. The total siUcon content can be obtained from analysis of the resulting siUcate solution. 

Chemical Analysis. The presence of siUcones in a sample can be ascertained quaUtatively by burning a small amount of the sample on the tip of a spatula. SiUcones bum with a characteristic sparkly flame and emit a white sooty smoke on combustion. A white ashen residue is often deposited as well. If this residue dissolves and becomes volatile when heated with hydrofluoric acid, it is most likely a siUceous residue (437). Quantitative measurement of total sihcon in a sample is often accompHshed indirectly, by converting the species to siUca or siUcate, followed by deterrnination of the heteropoly blue sihcomolybdate, which absorbs at 800 nm, using atomic spectroscopy or uv spectroscopy (438—443). Pyrolysis gc followed by mass spectroscopic detection of the pyrolysate is a particularly sensitive tool for identifying siUcones (442,443). This technique rehes on the pyrolytic conversion of siUcones to cycHcs, predominantly to [541-05-9] which is readily detected and quantified (eq. 37). 

In order to define the obese state ia a clinical setting, it is necessary to have a means of estimating the amount of adipose (fat) tissue relative to lean body mass. Whereas highly accurate determiaations of body composition require complex laboratory procedures, large clinical studies typically employ measures of skia-fold thickness (11) or more commonly, body mass iadex (BMl) as a quantitative measure of obesity. 

Eiber volume fraction is a quantitative measure of degree of reinforcement of the matrix material in a fiber-reinforced composite. If the volume of a composite material is D and the volume of the fibers is and that of the matrix is then... 

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